Report Order WT 97-12
Amendment of the Amateur Service Rules to Provide For Greater Use of Spread Spectrum Communication TechnologiesAdopted: August 31, 1999
Released: September 3, 1999
- fcc99234.doc (MS Word, 284k)
- fcc99234.pdf (pdf v4.0, 62k)
Petition for Partial Reconsideration
Clearwire Technologies, files Petition for Partial Reconsideration (October 25, 1997). (pdf, 867K)
Comments on Reconsideration
Clearwire Technologies withdraws Petition (pdf, 89k)
WT Docket No. 97-12
WT Docket No. 97-12, released March 3, 1997. (WP, 67K)
WT Docket No. 97-12, released March 3, 1997. (txt, 19K)
WT Docket No. 97-12, released March 3, 1997. (pdf, 1482K)
Comments to WT Docket No. 97-1
- Tucson Amateur Packet Radio Corp 5/5/97
- Tucson Amateur Packet Radio Corp 5/5/97
- Lyle V. Johnson, WA7GXD 5/5/97
- Philip R. Karn, Jr, KA9Q 5/5/97
- Robert A. Buaas, K6KGS 5/5/97
- Central States VHF Society 5/5/97
- William A. Tynan, W3XO 5/5/97
- Part 15 Coalition 5/5/97
- AMSAT 5/5/97
- 220 MHz. Spectrum Management Association of Southern California (220sma) 5/5/97
- Manager of the National Communications System 5/5/97
- Comments of Robert Brown, N7STU
- Comments of Metricom, Inc.
- Comments of Raphael Soifer, W2RS
- Reply Comments of John R. Ackermann, AG9V
- Reply Comments of AMSAT
- Reply Comments of AMERICAN RADIO RELAY LEAGUE, INCORPORATED
- Reply Comments of CENTRAL STATES VHF SOCIETY
- Reply Comments of Steven S. Dimse, K4HG
- Reply Comments of Robert A. Buaas, K6KGS
- Reply Comments of James Barron, Jr, KA5WSS
- Reply Comments of Guy Story, KC5GOI
- Reply Comments of Anthony McConnell, N3JLI and Jacob Brodsky, AB3A
- Reply Comments of Thomas C. McDermott, N5EG
- Reply of Glenn E Elmore, N6GN
- Reply Comments of Steven K. Stroh, N8GNJ
- Reply Comments of TUCSON AMATEUR PACKET RADIO CORPORATION
- Reply Comments of Raphael Soifer, W2RS
- Reply Comments of ROBERT J. CARPENTER
- Reply Comments of WILLIAM A. TYNAN W3XO
- Reply Comments of THE W5YI GROUP
- Reply Comments of John R Bingham, W7WKR
- Reply Comments of John C. Koster, W9DDD
- Reply Comments of Lyle Johnson, WA7GXD
The Initial Filing, assigned as RM-8737
ARRL Petition for Rulemaking, filed December 12th, 1995.
Comments to RM-8737
- Nels Harvey, WA9JOB 2/20/96
- San Bernardino Microwave Society 2/20/96
- Robert A. Buaas, K6KGS 2/23/96
- Southern California Repeater and Remote Base Association (SCRRBA), 2/23/96
- SouthEastern Repeater Association, Inc 2/23/96
- TAPR Comments 2/26/96
- National Communications System, 2/26/96
- George Isely, WD9GIG, President, Mid-America Coordination Council, Inc., 2/26/96
- Whit Brown, WB0CJX, Frequency Coordination Chairman, Mid-America Coordination Council, Inc., 2/26/96
- John Mock KD6PAG 2/27/96
- The Indiana Repeater Council, 2/28/96
- Henry Ruh, KB9FO, Publisher, Amateur Television Quarterly, 2/28/96
- Charles M. Albert, Jr. KC6UFM, 3/4/96
- Mike Cheponis, K3MC 3/4/96
Reply Comments to RM-8737
- Mike Cheponis, K3MC 3/6/96
- Bill Tynan, W3XO 3/11/96
- AMSAT 3/11/96
- TAPR 3/11/96
- Phil Karn 3/11/96
- Robert A. Buaas, K6KGS 3/11/96
- Steven Bible, N7HPR 3/11/96
- Naval Postgraduate School 3/11/96
- National Communications System, 3/11/96
- Charles M. (Marty) Albert, Jr. KC6UFM 3/13/96
Additional Notes and Comments
Page note: Correction of spelling or other errors in the above documents were not made so that they may reflect the exact wording submitted to the FCC. If the author of any the above comments finds a mistake with data entry, please let us know so that we might correct the error. These documents are made available for the general amateur community and are being made available as accurate as possible.
Tucson Amateur Packet Radio Corp, comments to Docket rm8737 May 5th, 1997
Before the
Federal Communications Commission
Washington, D.C. 20554
In the Matter of ) WT Docket No.rm8737
)
Amendment of Amateur Service ) RM-8737
Rules to Provide For )
Greater Use of Spread )
Spectrum Communication )
Technologies )
To: The Commission
COMMENTS OF
TUCSON AMATEUR PACKET RADIO CORPORATION
The Tucson Amateur Packet Radio Corporation ("TAPR")
submits these comments in response to the above-referenced
notice of proposed rule making (the "NPRM") released by the
Commission on March 3, 1997.
BACKGROUND AND STATEMENT OF INTEREST
TAPR is a non-profit (501(c)(3)) scientific and educational
organization with more than 2,500 members worldwide. It is
chartered to engage in three principal activities: scientific testing
and research into the development and improvement of
technological systems for use in the amateur radio service
including, but not limited to, digital packet radio
communications; research and testing of systems, hardware, and
software for packet radio local area networks and computer
network systems; and disseminating to the public the
information obtained as a result of such research and testing.
TAPR was founded in 1982 as a national organization
with interests in the areas of packet and digital communications.
It grew out of a 1981 effort to design a packet radio Terminal
Node Controller, or "TNC," that would be available to amateurs
at a modest cost. From these initial designs emerged what is
now the de facto standard in amateur and many commercial
packet radio operations.
Today, TAPR continues as an international, membership-
supported research and development organization for the
amateur radio community. TAPR continues to develop new
communications technology, provide kits for the amateur
community, and promote the advancement of the amateur art
through publications, meetings, and communications standards.
TAPR also maintains a web site (http://www.tapr.org), which
includes a page specifically addressing current amateur spread
spectrum issues (http://www.tapr.org/ss).
DISCUSSION
TAPR generally supports the proposed rule changes the
Commission makes in its NPRM. Spread Spectrum ("SS")
technology has not made great advances in the amateur radio
service since it was first permitted in 1985, in part due to the fact
that, by today's standards, the Part 97 regulations on amateur SS
are extremely restrictive. In particular, the small number of
fixed spreading codes permitted under Section 97.311(d)(1)
inhibits the use and development of SS by amateur radio
stations. TAPR believes that it is in the public interest, and in
the interest of the amateur radio service , to change the rules for
SS in order to accelerate the adoption of SS by the general
amateur community.
TAPR in general supports many of specific rule change
recommendations made by the Commission.
First, TAPR supports the Commission's proposal to
modify Part 97.311(b) as it pertains to the unintentional
triggering of repeater inputs. This provision is redundant when
considered in relation to the existing sections in Part 97 which
deal with how interference should be treated and handled. This
single provision alone has been a subject of concern for some
time to members of the repeater operator/owners community
and rightly so.
However, for this same reason TAPR feels that the
proposed wording of this section puts an unnecessary burden on
those who choose to utilize SS emissions. After being
authorized as a legal emission mode in the service for over
fifteen years now, it now seems inappropriate to continue to
single out SS to be considered secondary to all other allowable
emission modes authorized in the service. We therefore ask the
Commission to strike the proposed section 97.311(b) in its
entirety. The Commission's rules in this area should go no
further than to set a maximum transmitter power output level
and to set limits on spurious emissions outside the amateur
radio bands.
Second, TAPR supports the Commission's decision to
delete sections 97.311(c) and (d), in order to permit SS emissions
and spreading codes that are not currently authorized.
Elimination of the rule that dictates specific spreading codes in
necessary to facilitate further experimentation and deployment
of SS technology in the amateur radio service. In particular the
removal of the provision that restricted the use of hybrid SS
emissions will open up potentially new areas of interesting
experimentation that have not been allowed for over fifteen
years now.
While, as noted above, TAPR agrees with many of the
Commission's proposed rule changes, it disagrees with a few of
the proposed changes contained in the rulemaking.
First, TAPR does not agree with the proposed automatic
power control provision of section 97.311(g). Although TAPR
supported the ARRL proposal for this provision in the
comments and reply comments that it filed in RM-8737, it no
longer feels that this provision should become a part of the rules
governing SS emissions. Further discussion and
experimentation that has taken place since the petition phase of
this proceeding has convinced TAPR that the implementation of
this provision would impose a serious handicap on the future
development of this emission mode. While TAPR agrees that
technically it is simple to control the output power of a
transmitter, it is quite another matter to make this control
automatic and foolproof over the wide range of applications and
uses that are common today in the service. For instance, the
implementation of this provision would make it impossible to
use SS emissions in the point-to-multipoint packet radio
networks that are common in the service today because it would
be difficult to transmit a single packet which would not exceed
the Eb/N0 level at the nearest station. TAPR therefore asks the
Commission to strike the proposed automatic power control
language of this section. TAPR feels that the provisions of
section 97.313(a), which limits the power level to the minimum
required to maintain communications is all that is necessary to
cover the concerns which prompted this proposed rule change.
Further, TAPR would like to see the limit on transmit
power to 100 watts of this section also deleted. While TAPR does
feel that 100 watts of power is more than enough for most
terrestrial SS operations, this limit may present problems for
some of the more interesting applications in the service today
such as EME (Earth-Moon-Earth) operations. It would appear
that the 100 watt limit was imposed back in 1985 out of a concern
for limiting the range of possible SS interference, this concern
appears groundless in the operating environment that we now
face today. TAPR therefore asks the Commission to strike this
provision and allow SS emissions that same transmitter power
levels allowed for the other emission modes authorized for the
service.
Second, TAPR does not agree with the Commission's
decision to allow sections 97.311(e) and (f) to stand as written.
Both sections place a significant record-keeping burden on any
operator who wishes to make use of the SS emission mode.
While these sections may have made sense back in 1985, twelve
years later all they serve to do is to present a serious impediment
to any amateur operator who wishes to experiment and deploy
this mode. TAPR therefore asks the Commission to now
establish parity between SS and all of the other emission modes
(including pulse) and delete the burdensome provisions and
requirements of these sections.
In addition to the rule changes proposed in the NPRM,
TAPR would also like the Commission to consider the making
additional changes in the rules affecting SS emissions.
First, TAPR would ask that the Commission allow SS
emissions on all amateur radio bands above 50 MHz. As we
have stated earlier, TAPR feels that the Commission's rules for
SS should go no further than to set a maximum transmitter
output power level and to set reasonable limits on spurious
emissions outside the amateur radio bands. Conventions for all
other parameters of operation such as operating frequencies,
modulation method, bandwidths, protocols, etc. are best left to
the development of the amateur radio community itself. Such
an approach would be in line with the stated policy of the
Commission itself in the NPRM to develop rule changes which
are "...consistent with our policy of encouraging greater
spectrum flexibility by enabling licensees to introduce
innovative technologies and to respond quickly to demands for
new and different services and applications, without
administrative delays". TAPR feels that SS technology will
provide for such innovation in the service and has great
applicability to amateur bands below 70 cm (SS now only being
allowed on bands 70 cm and above).
Second, TAPR feels that the station identification
requirements of section 97.119(b)(5) should be deleted. The
interference and harm to the band in which an SS station is
operating that would be caused by a requirement to use a CW
identification far outweighs the benefits that would accrue for
monitoring purposes from the use of such an ID. Further, it is
vital to avoid an ID requirement that would in itself cause
interference even when the associated SS emission does not.
TAPR feels that it would be better for the amateur radio
community to develop approaches for handling the necessary
functions of monitoring and identification of SS emissions.
CONCLUSION
SS technology can provide many useful benefits to the
amateur radio community if its use becomes more widespread
and mainstream. In order to accomplish this however, certain
changes must be made to the Commission's rules governing the
use of SS in the amateur radio service. By making these changes,
the Commission will create a regulatory environment that will
give members of the amateur radio service enough flexibility to
develop innovative equipment and hardware employing
SS technology.
For these reasons, TAPR urges the Commission to
promptly issue a report and order in this rulemaking as soon as
possible to facilitate the development and deployment of SS
communications in the amateur radio service, as proposed in
the NPRM and as modified herein.
Respectfully submitted,
THE TUCSON AMATEUR PACKET RADIO CORPORATION
By: Dewayne Hendricks
Tucson Amateur Packet Radio Corporation
8987-309 E Tanque Verde Rd #337
Tucson, Arizona 85749-9399
(940) 383-0000
AMERICAN RADIO RELAY LEAGUE INCORPORATED, comments to Docket rm8737 May 5th, 1997
Before the
FEDERAL COMMUNICATION COMMISSION
Washington, D.C. 20554
In the Matter of )
)
Amendment of the Amateur Service ) WT Docket No. rm8737
Rules to Provide For Greater Use )
of Spread Spectrum Communications )
Technologies )
)
To: The Commission
COMMENTS OF THE
AMERICAN RADIO RELAY LEAGUE INCORPORATED
The American Radio Relay League, Incorporated (the League), the national association of amateur radio operators in the United States, by counsel and pursuant to Section 1.415 of the Commission's Rules (47 C.F.R. paragraph 1.415) hereby respectfully submits its Comments in response to the Notice of Proposed Rule Making (the Notice), FCC 97-10, released March 3, 1997. The Notice proposes to amend the Amateur Service Rules, Part 97, to facilitate Spread Spectrum (SS) communications by means of additional spreading codes, and to cause the incorporation of automatic power limiting circuitry to limit power to that actually necessary to carry out the communications. The Notice is based on the League's petition RM-8737, filed in December of 1995. For its comments on the proposals contained in the Notice, the League states as follows:
1. The Notice proposal is essentially a deregulatory plan to encourage and facilitate experimentation with SS communications in the Amateur Service. The League wholeheartedly supports each of the proposals. The rule changes offer the opportunity to experiment with SS modes, thus to develop practical applications in addition to those already known.
2. In amateur applications, the bands above 420 MHz are presently used principally for narrowband modes. The proposed new rules for SS systems in those same bands will allow experimentation and maximized compatibility between wideband and narrowband communications. The Notice would at once permit experimentation with SS spreading codes that will minimize potential [1] interaction with narrow band communications modes, and also limit power automatically to the absolute minimum necessary to establish and continue the communications. This combination of benefits from the proposed rule changes should be sufficient to minimize any interaction between amateur emission modes. The effect of the automatic power limitation on interference potential is obvious. The relief of restrictions on spreading codes will permit experimentation with a wide variety of spreading codes, thus to determine which are least likely to cause interaction with narrowband amateur emission modes. In any case, amateurs are called upon to cooperate in the use of shared frequency bands regardless of emission type. As has always been the case, advance planning and coordination will facilitate harmonious use of both SS and narrowband communications modes. Any fear of interference to voice repeaters or weak-signal communications can and should be avoided by intraservice cooperation in the selection of frequencies, rather than by restricting emissions types for SS communications The latter has served to restrict the ability to experiment with SS communications. The Commission has established the correct presumption in favor of encouraging experimentation while at the same time proposing mechanisms to limit interference potential.
3. That there is interest in experimentation with SS communications is indisputable. However, the bulk of SS experimentation over the past few years has been conducted pursuant to extended Special Temporary Authorizations granted by the Commission. That fact evidences both the overly restrictive nature of the current SS rules, and the effect thereof on SS experimentation and utilization in the Amateur Service. The Notice suggests a modest deregulatory effort, and is properly aimed at increasing the flexibility of spread spectrum users in order to allow the development of compatible system which maximize spectrum efficiency. The amendment of the rules to permit experimentation is a proper course of action for the Amateur Service, which is a fundamentally self-regulating service that makes its own efficient accommodations for the varied uses of its frequency allocations.
4. The Commission properly had proposed no restrictions on amateur SS operation in order to protect Part 15 devices, which operate at sufferance to licensed services in certain bands. No such restrictions exist relative to other emission modes, and there is no justification for any restrictions on any licensed service's use of its own allocations in order to protect SS Part 15 devices.
5. Comments on the League's Petition, RM -8737, variously supported even greater flexibility for amateur spread spectrum operations, or reduced flexibility in order to protect other narrowband amateur operations or certain kinds of unlicensed, Part 15 intentional radiators. In its proposal, the Commission has recognized that these competing objectives have been carefully balanced in the rules proposed therein. The League commends the Commission for its balanced approach and urges that the rules be adopted as proposed at the earliest opportunity.
Therefore, the forgoing considered, the American Radio Relay League, Incorporated supports the Notice proposal, and respectfully requests that the Commission move quickly to implement the rules in the Appendix B thereto.
Respectfully submitted,
THE AMERICAN RADIO RELAY
LEAGUE, INCORPORATED
225 Main Street
Newington, CT 06111
By Christopher D. Imlay
Its General Counsel
BOOTH FRERET, IMLAY & TEPPER, P.C.
1233 20th Street, N.W., Suite 204
Washington, D.C. 20036
(202) 296-9100
May 5, 1997
[1] The League, as stated in its petition, PM-3787, is unaware of any instances of interference to amateur narrowband communications from amateur SS communications using the saem or adjacent frequencies.
LYLE V. JOHNSON WA7GXD, comments to Docket 97-12 May 5th, 1997
Before the
Federal Communications Commission
Washington, D.C. 20554
In the Matter of ) WT Docket No.97-12
)
Amendment of Amateur Service ) RM-8737
Rules to Provide For )
Greater Use of Spread )
Spectrum Communication )
Technologies )
COMMENTS OF LYLE V. JOHNSON WA7GXD
Introduction
I have been a licensed radio Amateur since 1964 (WN6JLR) at age 13 and have held my present station callsign since 1967. My operator license is Extra Class.
I am cofounder of Tucson Amateur Packet Radio, and served on its Board and as its President for many years, including the time of the TNC and TNC-2 projects. I was also a leading member of the project teams that created those devices. Since 1983, I have been a volunteer engineer for AMSAT. I was a principal designer of the Digital Communications Experiment aboard the UO-11 amateur spacecraft, and I was responsible for much of the design of the computer systems aboard the MicroSats (AO-16, DO-17, WO-18, LO-19, AO-27). I currently am heavily involved in the technical design of many of the systems aboard the upcoming Phase 3 D satellite (control computer, digital communications system, etc.).
It is from the perspective of one who has been a direct participant at the forefront of some of the more sweeping technical developments within the amateur radio community over the past several years, and without commercial interest, that I offer the following comments.
Overview
The proposed new rules will in general be conducive to increased experimentation and development of SS techniques within the Amateur community. However, I perceive three impediments in the proposed rules that may serve to defeat much of the stated purpose of the rulemaking.
Specifically, I request that part 97.119(b)(5) be changed to allow identification of an SS station by means of SS techniques, that part 97.311(e) be simplified or eliminated, and that part 97.311(g) be retained in its present form.
Discussion
Station Identification
The original ARRL petition for rulemaking specifically avoided requesting a change to SS station ID requirements, but did question the practicality of narrowband identification for SS operation (footnote 7 of the petition of 12 December 1995).
There are three purposes that come to mind when considering ID requirements. The first is to facilitate communications between stations; the second is to allow monitoring by other stations; the third is to more easily identify a station causing harmful interference.
Part 97.119(b)(5) presently requires that a narrowband ID be sent, or that the SS emission be altered so that a narrowband CW or phone receiver can determine the station callsign.
I suggest that this requirement is at odds with a stated purpose of this rulemaking, "to develop more effective and efficient uses of the radio spectrum."
Many commenters to the original proposal expressed concerns about potential interference to narrowband users. Others pointed out that many SS stations could coexist with many narrowband stations over the same overall spectrum without mutual interference. To allay the fears of the former, and allow demonstration of the benefits of the latter, SS emissions must necessarily be "invisible" to a narrowband station's receiver.
But, we have in place a rule that requires the SS station to operate in a way that guarantees the emission will be heard by narrowband receivers!
Consider that, if the ID is not to cause harmful interference, the SS station operator must listen on the chosen narrowband frequency before sending the ID since the normal operation of the SS station would have correctly led a narrowband user to conclude the spectrum was available for him to occupy. The normal method employed by amateur operators to determine if a channel is available for use is to listen for a brief period of time, perhaps several seconds. If no activity is detected, the operator usually sends a brief transmission inquiring if the frequency is occupied. If this does not elicit a response, he or she concludes the channel is available and commences operation.
If, several minutes into operation the receiver at the narrowband station is trampled by an SS station's sudden narrowband-compatible ID, the narrowband operator will be subjected to annoying, and perhaps harmful, interference. Such operation can only strengthen fears that SS operation will lead to interference with narrowband operation. This type of problem can easily be avoided if SS stations are allowed to send their ID in the same manner as they are sending other information by narrowband-invisible SS!
It seems reasonable, then, that in order to comply with the present rule, the SS station operator has two choices, neither of which are good:
1) The SS operator must have in operation simultaneously a narrowband radio and an SS radio to reasonably meet the station identification requirement and not cause potentially harmful interference to the narrowband user. The narrowband transmitter must operate any time the SS one does, to preclude a narrowband station from occupying the ID frequency the SS operator has chosen.
2) The SS station must operate in a manner such that its signal is always detectable by a narrowband receiver in order to preclude the narrowband user from occupying the identification frequency the SS operator has chosen.
Both of these scenarios are clearly in direct opposition to an important stated reason for SS operation and experimentation in the Amateur Radio Service: that of more efficient spectrum utilization. It also forces the SS station to add to narrowband channel congestion, which precisely feeds the fears expressed in the arguments of many of the commenters to this proceeding.
For SS to be practical, casual listening must be possible or the SS station operator will never be able to communicate with anyone else. Thus, it seems reasonable that SS station operators will publicly disseminate information about their transmission format and frequencies so that others can communicate with them. If this is not done, SS is unlikely to ever achieve widespread use, in which case this mode will not be responsible for causing much interference to anyone.
This dissemination could be on a narrowband channel giving callsign and other details of operation. This is analogous to early packet operation, where stations would coordinate on a local VHF FM repeater, then change frequency to operate on packet. Later, as packet gear became more widespread, it was no longer necessary to coordinate using other modes, packet-only operations commenced and have become ubiquitous.
It seems reasonable that SS operation, if it in fact becomes popular, will follow a similar path. Early on, station information will be easily available by non-SS means, including station ID, because it is the only way the SS station operator can attract other station operators with which to communicate.
Later, if SS operation evolves into a practical mode, equipment will be widely available to anyone who cares to purchase it in a competitive marketplace. Such equipment will necessarily be able to operate on the then-popular SS modes and monitor such transmissions at will. It seems unreasonable to assume that SS will be widespread enough to cause harmful interference to narrowband users, yet remain unidentifiable by easily available means.
Thus, practical concerns will make it easy for a narrowband user to be able to reasonably identify an SS station early on. As the SS modes become popular, the narrowband user can obtain an SS radio, or ask an SS-equipped station to monitor for a particular transmission if he wishes to identify it. Regulatory monitoring facilities will have access to the same information and equipment on the same widely-available basis.
This has been the historic pattern when new modes are developed and then adopted. It seems reasonable that SS will follow the same pattern.
Since virtually every other authorized mode in the Amateur Service is allowed by 97.119 to ID by the communications method being employed for the primary communications, it is reasonable that SS stations have this same freedom. If the SS station is sending voice, then the ID is in SS-voice in the English language - this is already covered by 97.119(b)(2). If the SS station is sending data, then the ID should use a standard data format (e.g., ASCII callsign information) - this is already covered by 97.119(b)(3). If images, then 97.119(b)(4) already covers the ID requirement.
If the ideal of efficient spectrum utilization is indeed a goal of these proceedings, the requirement of a narrowband ID is contrary and should be eliminated.
If a malicious individual wants to use an SS transmitter to cause harmful interference, he or she will likely have to be discovered via direction-finding (DF) techniques, just as the few malicious interferers are tracked today. In spite of requirements that they identify themselves, such operators are unlikely to comply with the rule that they provide a narrowband-compatible station ID.
My point is that it is in the SS station operator's self-interest to promulgate information about his station in a manner that is easily discovered or he cannot communicate with other stations. If the only means employed to do this is SS, then the implication is that SS is sufficiently entrenched that monitoring receivers are readily available at inexpensive prices.
For these reasons and others, I respectfully submit that it is logical and compelling for the Commission to rescind Part 97.119(5) as a part of this rulemaking.
Station Record Keeping
Part 97.311(e) places a significant record-keeping burden on any station operator who wishes to use an SS radio. This level of record-keeping presents a serious impediment to an amateur who wishes to experiment with this mode. There is no similar record-keeping requirement for any other mode of operation within amateur radio, so it only seems rational to ask the question:
How does this detailed level of record keeping assist in the Commission's stated purpose of this proceeding to, among others, "encourage the amateur service community to expand its experimental activities with SS" and to allow "licensees flexibility to develop more effective and efficient uses of the radio spectrum"?
A person performing technical investigation and experimentation will, as a normal part of that process, keep such records as he or she deems appropriate to document the phenomenon or feature being investigated. The fact that the information being sent may represent a voice, a picture, or text may be irrelevant. If the methods employed are generally known to practitioners of the art and well-understood, a requirement to keep a detailed technical description of a circuit's operation seems superfluous.
Further, if the experimenter is using a subset of available packaged integrated circuits to perform a function, detailed information regarding the internal operation of the chip may not be easily available for him or her to provide the documentation required by this rule. This may preclude the use of readily available, proven technology for portions of an experimental SS radio design.
In order for SS to become generally useful in the Amateur Radio Service, it must necessarily be used by communicators as well as technical developers.
A person whose pursuit of SS within amateur radio is simply to utilize a more interference-resistant mode in, say, a local emergency (flood, fire, etc.) may not have the technical expertise or know-how to comply with this rule. This doesn't limit their ability to effectively use the SS radio as a practical matter.
I suggest that technical investigators will create records pertinent to the investigation as a natural course of their investigation, and that potential communicators will often not be in a position to comply with the present rule due to a lack of information and understanding.
Thus, I request the Commission:
1) drop the present requirement and mark 97.311(e) as "reserved" or
2) rewrite 97.311(e) to read in its entirety "Logs and notebooks pertaining to technical investigations in SS on amateur radio frequencies be retained by the licensee for a period of one year following the date of the last entry."
Power Control
Part 97.311(g) currently allows SS emissions with a maximum power output of 100 watts. This seems a reasonable limit, and it is very simple to construct a transmitter which falls within this rule.
The proposed rule modifies this considerably, requiring a measurement of received energy per bit, spectral power density of noise and interference. Then a computation must be performed and a limit of the received signal strength be enforced by the local station commanding the distant transmitter to adjust its power output level.
Implementation of this rule might be feasible (technically and economically) in point-to-point communications between two Amateur stations. It is being done in commercial CDMA cellular telephones because it is technically necessary in a system of numerous mobiles "connected" to a central cell site using DSSS modulation techniques.
Unfortunately, to allow cooperative operation of SS radios from multiple sources, control protocols must be designed, agreed upon and implemented. It is one thing for an innovative cellular manufacturer to promulgate such protocols under the umbrella of its various patents; it is quite another for multiple, parallel and independent developers, such as amateurs, to define, agree upon and implement such a scheme as a practical matter. This requirement effectively places a significant barrier to be overcome and a barrier which in itself constrains traditional amateur communications practice.
Amateur operation is frequently quite different than commercial cell phone operation, and often uses multipoint-to-multipoint and point-to- multipoint topologies.
For example, it is common practice to engage in "roundtable" discussions among several amateur stations in varying geographic relationships. This is a case of multipoint-to-multipoint operation. If station A is 1 mile from station B but 20 miles from station C, how does station A set its transmitter to comply with the proposed regulation? If the signal is in compliance at intended receiver B, it may be weak or unusable at intended receiver C. If set to be useable at intended receiver C, station A's transmissions will very likely be non- compliant with the new proposed rule at simultaneously intended receiver B.
If a station is transmitting through a linear translator (e.g., a spacecraft) this becomes even more of an issue as the capability of amateur stations receiving such transmissions vary dramatically with antenna size, location (urban versus rural) and other factors for a transmission with many intended recipients. How would one set a telemetry downlink from a spacecraft using SS techniques to ensure no ground station ever had a signal which exceeded the threshold in the new rule? This is an example of point-to-multipoint communications.
While many more examples could easily be cited, my point is that automatic power control as specified in the proposed regulations will render unfeasible one of the traditional, and popular, styles of Amateur radio communications, and preclude the use of SS in technically advanced projects such as amateur spacecraft.
Finally, Part 97.313(a) already requires that Amateur stations use the minimum power necessary for the intended communication, regardless of mode. Thus, SS operation is already reasonably constrained. Singling out SS operators as being inherently more likely to flaunt this rule, and thus requiring some sort of "silicon cop" to achieve compliance, seems unreasonable.
The new rule is more restrictive than the old, and in the absence of
evidence in the record that the existing SS power rule has led to
difficulties, I request the Commission retain Part 97.311(g) in its
present form.
Conclusion
Amateur spread spectrum communications will be greatly facilitated by the present proposed rules changes if Parts 97.119(b)(5) , 97.311(e), and 97.311(g) are amended as suggested in this comment. The retention of 97.119(b)(5) will necessarily cause SS stations to interfere with narrowband users, severely curtailing the development and use of SS as a viable means of amateur communications and diluting the mode's potential for spectrum efficiency. The retention of 97.311(e) unnecessarily burdens the potential SS communicator and technical investigator, reducing their incentive to contribute to the development and deployment of SS modes within the Amateur Radio Service. The proposed 97.311(g) rule, if adopted, will prevent traditional amateur multipoint-to-multipoint operation and inhibit the use of SS in point- to-multpoint applications, such as spacecraft telemetry.
Thank you for your consideration of these comments in this proceeding.
Respectfully Submitted,
Lyle V. Johnson 02 May 1997
Page 5 of 6
RM-8737 Comments of Lyle V. Johnson
Philip R. Karn, Jr, KA9Q, comments to Docket 97-12 May 5th, 1997
Washington, DC
In The Matter of ) Amendment of the Amateur Service ) Rules to Provide For ) WT Docket No. rm8737 Greater Use of Spread ) Spectrum Communication ) RM-8737 Technologies )
Introduction
I respectfully offer these comments to the Commission in support of
the proposed liberalization of the existing rules to permit expanded
use of spread spectrum (SS) communications in the Amateur Radio
Service. While I am a member of the ARRL Future Services Committee
and an employee of Qualcomm Incorporated, a major developer and
manufacturer of commercial digital spread spectrum cellular telephone
equipment, the opinions expressed here are strictly my own.
Spread spectrum has become an important communication technology. The many advantages of this technique include:
- improved resistance to multipath propagation, especially in urban environments;
- increased resistance to interference, both intentional and unintentional;
- reduced average transmitter power requirements, when combined with error control coding and automatic transmitter power control;
- increased spectrum capacity, especially when carrying intermittent traffic;
- special features, such as accurate ranging
But spread spectrum is, so far, almost entirely a non-amateur phenomenon. While many license-free devices incorporating spread spectrum have been used under Part 15.247 rules, and while the large scale deployment of CDMA (spread spectrum) digital cellular telephones is now underway, use of spread spectrum under the existing amateur rules remains almost nonexistent.
Why Amateur SS Has Failed
The reasons for this include restrictive rules, the lack of suitable equipment and resistance from certain elements of the amateur community. Also, the ready availability of Part 15.247 equipment to amateurs has significantly diluted potential interest in spread spectrum operations under Part 97 rules. Not only are the Part 15 rules far more liberal in the allowed modulation methods and spreading codes, but Part 15 operation also permits encryption and commercial use -- two practices prohibited under amateur rules -- yet, ironically, the Part 15.247 bands are shared with the amateur service. In any event, it is safe to say that far more amateurs are presently conducting spread spectrum operations under Part 15.247 than under Part 97 rules.
But Part 15.247 devices are invariably proprietary "black boxes" designed for ease of use by a nontechnical consumer. While they are quite useful to amateurs (and others) in a "utility" mode (e.g., as Internet access links) Part 15 was not intended to further the basis and purposes of the Amateur Service.
The Amateur Service Needs Maximum Rule Flexibility
The amateur service needs its own spread spectrum rules specifically
designed to promote the basis and purposes of the service,
particularly technical experimentation, development and
self-training. This is best accomplished with an absolute minimum of
restrictive regulation, deferring as much as possible to the amateur
community to produce its own operating standards and practices to
minimize harmful intra-service interference.
The FCC's rules should therefore go no further than to set a maximum transmitter power level and to set limits on spurious emissions outside the amateur bands. In the context of the present proceeding, therefore, the Commission should permit spread spectrum operations on all amateur bands, including HF, not just those above 50 MHz or 219 MHz.
Conventions regarding all other parameters, including operating frequencies, modulation type, bandwidths, protocols, etc, are best left to the amateur community, as it can react to changing needs and local conditions far more rapidly than the Commission.
HF spread spectrum is particularly interesting, given its inherent ability to deal with interference and ionospheric multipath. Even without full-blown spreading, relaxing the existing bandwidth limits on HF digital modes would permit the use of more power-efficient modulation and coding schemes that could easily permit transmitter power reductions of 10-15 dB or more for a given data rate. Such gains have already been demonstrated by lab and field tests published in QEX that compared military standard HF digital modems operating in 3 KHz channels with those designed within the amateur community for the arbitrarily narrow 500 Hz data channel. A general reduction in average amateur HF transmitter power levels is clearly a desirable goal.
Intra-Amateur Interference Issues
The complete deregulation of amateur spread spectrum may seem like a
radical suggestion that would lead to anarchy on the ham bands. Yet
the existing FCC rules technically permit many things that, if widely
practiced, would also lead to anarchy on the ham bands. For example,
there are no specific prohibitions in the rules against
- Operating local FM simplex on the input of a repeater;
- Conducting high power terrestrial DX operations on the downlink of an amateur satellite;
- Conducting local operations on the various EME and DX calling frequencies;
- Operating 100 KHz bandwidth digital links on the 432.1 MHz weak signal calling frequency;
Even if the rules were amended to permit spread spectrum on all amateur bands, other rules would continue to apply with full force, such as 97.313 (no more power than required to maintain communications), 97.101(c) (priority given to emergency operations) and 97.101(d) (no malicious interference). And the present rules would make spread spectrum operations secondary to other operations.
It is impossible to say that under absolutely no circumstances could spread spectrum operations interfere with traditional narrow band operations. But it is wholly inappropriate to demand such guarantees in the first place. Yes, amateur frequencies are still occasionally involved in emergency communications despite being almost completely eclipsed in recent years by cellular phones, portable satellite links and the like. But the amateur service has always been primarily an experimental, technically-oriented service. It is not a critical operational safety-of-life service like public safety or aviation, nor is it a common carrier utility like cellular telephones. Some level of unintentional interference is therefore to be expected and tolerated.
Discussion of the Proposed Rules
I generally support the rules proposed by the Commission with the following
exceptions and additions:
Increase the maximum power allowed for SS emissions directed to space
100W is probably enough for any conceivable terrestrial spread
spectrum operation, particularly if strong error-control-coding
techniques are incorporated to improve the power efficiency of the
communication over traditional narrow band signal formats.
But the 100W limit may present a problem for certain promising deep-space applications of spread spectrum, particularly EME (Earth-Moon-Earth) operation with the moon as a passive reflector. The EME link is characterized by severe multipath, making spread spectrum a highly promising technique. The high antenna gains and skyward-pointing antennas generally used with EME clearly make the 100W limit unnecessary to protect terrestrial operations.
Another promising use for high power SS transmissions is communications with interplanetary spacecraft. Discussions are already underway within AMSAT for an amateur-built spacecraft to be flown to Mars, and it would be beneficial to use high power SS transmissions for accurate ranging measurements over interplanetary distances.
I therefore suggest a waiver on the 100W SS power limit for space communications. If the Commission feels it necessary, it could use language similar to that of existing section 97.313(f) to allow use of the waiver only above a certain antenna elevation. (That section specifies that the -3dB point of antenna main lobe be above 10 degree elevation.)
Eliminate the automatic power control requirement
I originally conceived and devised the proposed requirement for
automatic transmitter power control with a received Eb/N0 limit. My
proposal was adopted by the ARRL Future Systems Committee, of which I
am a member, and then by the League in its RM-8737 filing.
I no longer believe this provision should be codified in the FCC rules. It is possible to conceive of situations where it would be difficult or impossible to meet this requirement. The best example is in a multicast situation (one transmitter sending to several receivers simultaneously), where one cannot reach all stations with an acceptable signal without exceeding the Eb/N0 at the nearest station. In any event, the provisions of 97.313, particularly paragraph (a) limiting power to the minimum required to maintain communications would still apply, as it does to all amateur communications.
Ways The Amateur Service Can Mitigate SS Interference
The present proceeding addresses the rules the Commission should
establish regarding spread spectrum operation, and in my opinion these
rules should be kept to an absolute minimum to promote flexibility and
self-regulation within the amateur community. Nevertheless, I believe
it would be useful to put into the record some of the approaches that
could (and should) be used on a voluntary basis to minimize
interference.
This is only a partial list, based on my own ideas and experience. Nonetheless, I believe it shows the potential of the amateur service to devise its own effective and novel solutions to mutual interference problems. I'm sure that other amateurs can add substantially to this list.
Automatic power control
Although I no longer feel it should be a mandatory rule, I still firmly believe in the value of automatic transmitter power control and the minimization of receiver Eb/N0 ratios with the strongest available error control coding. Analysis and field tests of SS-CDMA channel capacity performed at Qualcomm and elsewhere conclusively show the close inverse relationship between receiver Eb/N0 and overall system capacity: every 3dB reduction in Eb/N0 ratio translates directly into a 3dB increase (a doubling) of the number of users that can simultaneously share the channel.
I will certainly endeavor to incorporate power control and strong coding into any system I design, and I will strongly encourage other designers to do likewise.
Directional antennas
It almost goes without saying that when a point-to-point link is desired,
directional antennas are always helpful in minimizing the amount of
energy radiated in directions other than the intended receiver.
Min-power relaying
It is now well established in studies and experiments with
self-organizing distributed packet radio networks (e.g., DARPA SURAN)
that it is far more efficient, spectrally speaking, to cover
significant distances by relaying data across a series of relatively
short links at low power than to send it at high power over long
links. This approach is straightforward to implement in existing
packet network routing algorithms if the "link cost metric" used in
the calculations is simply the estimated transmitter energy required
to reach the next station. The routing algorithm will then work to
minimize the total transmitted energy, summed over all of the nodes in
the path, needed to reach a specified destination.
Alternatively, the link metric can be an automatic estimate of the number of neighboring stations that will have to be "jammed" by the present transmitter using whatever power is needed to reach the next hop. I presented a talk on this specific topic at the 1991 ARRL Digital Communications Conference.
Modifications of these techniques can be used to implement multicasting by relaying relatively low power transmissions to each intended receiver across a spanning tree instead of "blasting" the transmission at high power to all the receivers simultaneously.
These techniques clearly work toward minimizing the total interference potential of a spread spectrum packet radio network.
Geographical Bandplans
Amateur bandplans have already established band segments on the basis
of geographical region of use rather than modulation mode. This is
especially true in the VHF and UHF bands, where segments are set aside
for satellite, local utility and terrestrial weak signal DX
operations. The local utility segments are further subdivided into
repeater input, repeater output and simplex segments. In mountainous
areas such as California, the repeater channels are further divided
into "high altitude" (wide area) and "low altitude" (local area)
coverage. Even on the HF bands, subbands are frequently set aside by
convention for "DX windows" to keep them clear of strong local
interference.
Geographical bandplans are a highly effective way to mitigate the "near-far problem". Although usually associated with spread spectrum signals, the near-far problem also exists with conventional narrowband methods, because no receiver is perfect at rejecting strong unwanted signals. This is precisely why these plans evolved in the first place.
Much of the interference potential of, say, a local utility SS link to weak signal DX operations can be completely avoided by such plans. Moreover, the DX operators would be free to use wideband SS-like techniques (such as strong error control coding) within the DX segments for their own purposes.
Narrowband Identification of Spread Spectrum Signals
There has been much discussion within the amateur community of the
need to identify interfering signals, especially experimental spread
spectrum signals for which the necessary demodulation equipment may
not be widely available.
It is my opinion that no special ID rules are really needed here. If a spread spectrum signal does interfere with a traditional narrowband user, then by definition it can be heard by that user. Conventional "fox hunting" (direction finding) techniques can then be used to locate the source of the SS interference, just as they have long been used to identify other interference sources, both narrowband and broadband (e.g., power line interference).
It would be possible in some (but not all) SS systems to incorporate a CW ID that could be demodulated by a conventional receiver. There are many ways to do this, including:
- Gating the entire spread emission on and off with Morse Code;
- Injecting a weak discrete spectral component somewhere in the SS emission and gating it with a Morse identifier;
- "Notching" part of the spread emission with a filter that is gated in and out with the Morse ID
While such an ID scheme would clearly be desirable, I argue against making it mandatory. I can easily conceive of situations where it would be difficult or impossible to implement, and the chances of causing harmful interference are nonetheless low. The best example would be a very high speed packet radio modem using spread spectrum, where the transmissions are very much shorter than a Morse ID at a reasonable speed.
Furthermore it is vital to avoid an ID requirement that would itself cause interference even when the associated SS emission does not. To this end, if other commenters persuade the Commission to adopt a narrowband CW ID requirement, then the power spectral density of the ID (as measured in a typical narrowband receiver bandwidth, e.g., 3 KHz) should not be any greater than the power spectral density of the spread emission that it identifies.
Local Coordination
A highly effective interference mitigation technique is to simply
announce one's intentions to the local amateur community. There are
now many ways that local amateurs can communicate on a regular basis,
ranging from traditional meetings and newsletters to packet bulletin
boards and Internet newsgroups and web pages.
If it were customary to give notice of spread spectrum operations, including transmitter location, modulation type, bandwidth, power levels, antenna patterns, etc, to the local amateur community, then anyone experiencing interference from an unidentified source would know who to ask.
I have conceived of a more automatic and general technique for dynamic local spectrum management based on packet radio. It is a generalization of the "Busy Tone Multiple Access" scheme that has been in the literature for years. Imagine a local community of radio amateurs who, by convention, all monitor a fixed packet radio channel in addition to an operational radio frequency (e.g., a DX channel on HF). The stations could announce their receive frequencies on the local packet channel, asking others to stay clear. Such a feature could easily be automated, perhaps integrated with the existing APRS (Amateur Packet Reporting System) that displays GPS station location information. Such a system could work to prevent inadvertent local interference between all types of amateur operations, not just those involving spread spectrum.
Conclusion
I again state my very strong support for the Commissions' proposal to
liberalize the spread spectrum rules. Spread spectrum operations
should be permitted on as many amateur bands as possible, on a
secondary basis, subject only to a total power limit (100W, waived for
space operations) and to all the other rules governing the use of
minimum necessary power, avoidance of intentional interference, and
the like.
Concerns about interference to narrowband operations, while not entirely unfounded, are greatly overblown. The amateur service is fundamentally experimental in nature, and interference has long been a fact of life in the amateur service. These issues are best resolved by the good will and cooperation of the amateurs themselves, not inflexible and detailed rules established by the Commission.
Indeed, given the overall industry trend toward more flexible, dynamic and efficient usage of radio spectrum, the creation of effective cooperative procedures for interference mitigation is itself an opportunity for the amateur service to contribute significantly to the state of the radio art.
Respectfully submitted
Philip R. Karn, Jr., KA9Q
ROBERT A. BUAAS, K6KGS, comments to Docket rm8737 May 5th, 1997
Before the
Federal Communications Commission
Washington, D.C. 20554
In the Matter of ) WT Docket No.rm8737
)
Amendment of Amateur Service ) RM-8737
Rules to Provide For )
Greater Use of Spread )
Spectrum Communication )
Technologies )
To: The Commission
COMMENTS OF ROBERT A. BUAAS, K6KGS
Background
I have been licensed in the Amateur Radio Service since 1953. I earned my Amateur Extra Class license in 1961, when I was age 17. For most of my lifetime, I have enjoyed the privilege of experimenting with radio communications, a pasttime I truly love. In addition, I hold a Special Temporary Authorization (STA) dated December 27, 1994, that permits experimentation with any Spread Spectrum (SS) technology in all Amateur spectrum above 50 Megahertz. My involvement with Amateur SS dates back to its original contemplation by AMRAD, in whose STA I participated. I have contributed to the development of successful commercial Part-15 SS systems, and I am a charter member in IEEE P802.11 (the Wireless LAN Ethernet Standard development project).
Introduction
I view the adoption of the Rules Change contained in the proceeding with considerable dismay. While its claimed goal is to simplify and encourage SS, it in fact would contribute to the reduction or elimination of its use.
Precious few of the commenters in this proceeding have any personal practical experience with SS. I find it curious that the spokespeople for the weak-signal interests, particulary Tynan of AMSAT, continue to present their conjectures of doom as fact, without bothering to conduct any realistic tests to validate their claims. Recently, I was invited to speak at the NASA Jet Propulsion Laboratory to Amateurs interested in the current state of affairs in Amateur SS. That opportunity was particularly rewarding, in that some of those same members are responsible for the SS technology used in NASA's deep space weak-signal communications. The concerns of the FM/repeater community are also unfounded, and I address their situation in the Discussion below.
That Commercial interests, particulary Part-15 promoters, seek parity with Amateur operators in the context of this proceeding seems to me to be entirely inappropriate. Metrocom and Symbol Technologies wish to advance their business interests at the expense of Amateur Radio operators opportunity and earned privilege at advancing the State of the Art in Radio Communication. Such is one of the Purposes of the Amateur Radio Service. Part-15 proponents knew and continue to know the Rules and relative priorities of the two Services when they chose to enter the business. Such are the risks of business, and they deserve to abide by their decisions.
Summary
I urge that Commission turn aside this proposal in favor on one which implements the spirit of the environment provided for participants of the STA(s), to wit, (a) operation in any Amateur bands at 50 MHz and above without restriction, (b) use of any coding and/or modulation technology imaginable, (c) permit "in-mode" identification, and (d) eliminate restrictions, thus providing encouragement for designs that reduce interference. I made the same recommendation in my filings on RM-8737. To date, no one has come forward with any evidence that Amateur SS emissions have interfered with anyone.
While I admire the elegance of Phil Karn's proposal for Automatic Power Control (I enjoyed the several discussions we had during its gestation), and I encourage its use, I cannot agree that the specifics of this proposal belong in the Rules. We already have a provision that says: "Use Minimum Power." Rules should apply to ALL systems, not just new ones. There are so many violations of this Rule now, I find it entirely inappropriate that only SS should be saddled with a proposal this specific. After all, it is the very nature of the specificity of the current Part 97 Rules for SS that have all but prevented its use.
Spectral Partitioning, of the variety practiced currently, also is without merit. What will happen when the day comes that a novel weak- signal application wishes to use the very SS technology now proven for deep space, yet the Rules prevent it use in spectrum reserved for weak- signals? Such Rules have proven to be short sighted. The results of this proceeding will affect Amateur Radio for at least a decade. Few of us have sufficient vision to see that distance into the future. Let history be our guide.
Discussion
In this section, I wish to turn some illumination on the subject of conjectured INTERFERENCE to existing operations. This a popular topic, to say the least. I have been the subject of some criticism from those who dispute my claims that properly designed SS system have minimum liklihood of causing interference. Most vocal has been the Repeater Coordination community, yet they have to conduct any independent studies or come forward with documented cases of interference. They certainly have the means and expertise to do their own tests, yet they refuse, and complain all the while.
Having once been a Frequency Coordinator, I understand their position, and their frustrations. They have only one degree of freedom, the Frequency Domain, in which to operate. Perhaps they have two, if one considers the Spatial Domain (stations that would otherwise interfere unacceptably, were it not for the distance or terrain that separates them). The degree of freedom they don't command is the Time Domain. Dealing in the Time Domain requires systems complexity that is currently beyond current Amateur practice. The consequence that Amateur repeaters cannot handle frequency agility has lead to the operational mentality that a Coordinated Repeater "owns" the frequency on which it operates, whether it is IN USE or NOT. Alternative use of its input frequency could mean denial-of-service to authorized repeater users, and thus is defined as INTERFERENCE. Notwithstanding, the Rules are very specific, saying that no Amateur station has any title to any particular frequency. Repeater Owners believe the contrary, and they act like it. Repeater Wars have been fought over single frequencies.
What is fundamentally interesting is the NOT part of the notion above. The prevailing attitudes have lead to particularly low levels of spectral utilization in the Amateur VHF and UHF bands. This is obvious to anyone who looks casually but critically at consecutive scans on the face of a spectrum analyzer. On any one scan, there are very few spectral lines representing current usage. The situation is very dynamic, as repeater transmitters activate and deactive at essentially random times in response to the needs of their respective users. Several years ago, when I began designing STA experiments for assessing the coexistance potential in "densely populated" repeater spectrum, I began collecting real-time utilization data, principally for use in simulations, testing the merits of a variety of frequency and time hopping patterns. This data validated my operational experiences that the interference to existing system was negligable.
Consider for a moment the age-old question: "Is there sound when a tree falls in the forest, if no one is around to hear it?" The following charts show that very little of the popular repeater spectrum is actually in use at any one instant. Conversely, much is available to time-agile systems on a minimum/non-interference basis. The vertical axis is percentage of total spectrum in use; the horizontal axis are the hours in a day. Predictably, certain times see more activity than others. What is not obvious is the low level of simultaneous demand. These charts show, even for the allegedly densely-populated Los Angeles area (for the most part, each of the 133 146-MHz and the 200 445-MHz repeater channels have multiple coordinations per channel), in the TIME domain, the spectrum utilization is well below ten percent (10%).
146010-147990 445000-449975
10 + 10 +
| | *
08 + ** 08 +
% | % | * *
06 + * * * 06 + ** * *
U | * ** * U | * * **
S 04 + * S 04 + * ** **
E | ** * * * * E | *
02 + * * ** 02 + *
|* |* *
00 +----+----+----+----+----+ 00 +----+----+----+----+----+
0 5 10 15 20 25 0 5 10 15 20 25
HOUR OF DAY HOUR OF DAY
The charts contained in Appendix-A further elaborate on these findings. The first set of 24 charts show the contiguous part of the 2-Meter repeater band hour by hour. The presentation is useful in seeing the probability of collision FHSS systems would experience. The vertical axis shows the frequency of occurance; the horizontal axis shows the number of possible collisions. The second set of 24 charts show data taken simultaneously with the 2-meter data, but for the 445-MHz band. These data conclusively show why our experimental systems achieved no measurable impact. THERE WASN'T ANY IMPACT TO BE HAD.
Further, this situation is little different elsewhere.
It is easy to see why various Commercial interests have launched efforts to reallocate Amateur spectrum to their Service(s).
There is some good news here: given that Amateurs would embrace this technology, and rise to the technical challenges it poses (which are not minor), there need never again be denial of service for Amateurs needing to communicate. FH is one of the simplest and easiest SS systems in operation today. Most Amateur VHF/UHF transceivers contain all the elements needed to do FHSS. By design, they are not configured properly, and the software needed to acquire and maintain synchronization is missing. Most also require slight modifications to the Frequency Synthesizer.
Of course, if this mode catches on, there will be little need for Frequency Coordinators -- their power and prestige will be gone. Simple public databases on the Internet will serve to negotiate and declare code sequences and timebase references.
The examples given here are but few of the many possibilites for coding technology, SS representing a small piece along that continuum. My view is that the Amateur Rules should permit the widest possible interpretation and latitude.
Writing Rules requires VISION; we seem to lack the very thing we most need now.
Conclusion
Spread Spectrum is a complicated art. Even the simplest SS system designs have been, to date, beyond the technical reach of all but the most advanced Amateurs. Yet, it offers considerable promise, not the least of which is much better spectral utilization than is the current practice. Perhaps more importantly, Amateur Radio is one of few vehicles for encouraging young people into taking up a professional careers in Radio Engineering. Without the freedom to try new ideas, those individuals will turn elsewhere. The Internet is currently a powerful draw. Fewer and fewer radio engineers are entering the field from college. I believe that it is the Commission's responsibility to nurture this Service, not limit it or contribute to its demise. I urge you to see the detractors in their true light, and adopt the proposal I make in the Summary above.
RESPECTFULLY SUBMITTED,
By_______________________ Robert A. Buaas, K6KGS
May 2, 1997
Mailing Address: 10044 Adams Ave. #108 Huntington Beach, CA 92646
E-Mail: buaas@wireless.net
-----------------------------------------------------------------------------APPENDIX-A
146010-147990 hour-24 146010-147990 hour-01 30 + 30 + | | | * | * | * | % | % | 20 + * 20 +* S | S | A | A | M | M | P | * P | L 10 +* L 10 + * E | E | S | S | | * | | * | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-02 146010-147990 hour-03 30 + * 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | M | P | P | * L 10 + L 10 + E | E | S | S | | * | | | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-04 146010-147990 hour-05 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | * A | ** M | M | * P | * P | * * L 10 + L 10 + E | E |** S | * S | * | | | * | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-06 146010-147990 hour-07 30 + 30 + | | | | | | % | % | 20 + * 20 + S | * S | * A | * A | * M | M | P | P | ** L 10 + * * L 10 + E | * E | * S |* S | *** | * * | * * | * ** | * ** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-08 146010-147990 hour-09 30 + 30 + | | | | | | * % | % | 20 + 20 + * S | S | A | A | * M | * * M |* P | P | L 10 + * *** L 10 + E | * * E | * S | * S | | * | ** | ** ** | ** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-10 146010-147990 hour-11 30 + 30 + | | | | | | % | % | 20 + * 20 + S | S | * A | A | * M | * M | * P | * P | L 10 + ** L 10 + ** * E | * E | * S |* * * S | * | | * | ** | * * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-12 146010-147990 hour-13 30 + 30 + | | | | | | % | % | 20 + 20 + * S | * S | * * A | * A | M | ** M | * P | P | L 10 + * * L 10 + * E | E | * S | * S | | * | * | * ** |** *** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-14 146010-147990 hour-15 30 + 30 + | | | | | | % | * % | 20 + * 20 + S | S | A | * A | * M | M | * P | * P | * * * L 10 + * L 10 + E | E | * S | * * S | ** | | * *** | *** | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-16 146010-147990 hour-17 30 + 30 + | | | | | | % | % | 20 + 20 + S | * S | A | * A | * M | M | * P | * P | * * * L 10 + * * L 10 + * E | * E | * S | * ** S | * | * |* * | * * | ** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-18 146010-147990 hour-19 30 + 30 + | | | | | * | % | * % | 20 + 20 + S | * S | A | A | * M | M | * * P | * P | * L 10 + L 10 + * * E |* * E | S | S | * | * | ** * | * | * * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-20 146010-147990 hour-21 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | * A | M | * M | ** P | ** * P | * L 10 + * L 10 + * * E | E | * * * S | * S | * | ** * | * | * * | ** * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
146010-147990 hour-22 146010-147990 hour-23 30 + 30 + | | * | | * | | % | % | 20 + ** 20 + S | * S | * A | * A | M | M |* P | P | * L 10 + * * L 10 + E | E | S | S | | * | |* * | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-24 445000-449975 hour-01 30 + 30 + | * | | |* | | % | % | 20 + 20 + * S | S | A | * A | M | M | P | P | ** L 10 + L 10 + * * E | E | S | * S | | | * | ** | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-02 445000-449975 hour-03 30 + 30 + |* | | | | | % | % | 20 + 20 +* S | S | A | A | M | M | P | P | L 10 + L 10 + E | E | S | S | * | * | * | * * | *** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-04 445000-449975 hour-05 30 + 30 + | | | | | | % | % | 20 + 20 + S | S |* A | A | * M | M | * P | P | L 10 + L 10 + E | * E | ** * S | S | * | * * | *** | * | * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-06 445000-449975 hour-07 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | M | P | P | * L 10 + ** L 10 + * * * E | * * E | * * S | * S | * * * | ** * ***** ** * | * ** |* ** * *** | ** *** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-08 445000-449975 hour-09 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | M | * P | * * * P | ** L 10 + * * * L 10 + * E | * E | * ** S | * S | | ** * * | * *** | * *** | ** **** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-10 445000-449975 hour-11 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | M | ** P | P | L 10 + * * L 10 + * E | * * ** * E | * ** S | * S | ** * ** | ** * ** | |* **** * | * *** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-12 445000-449975 hour-13 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | M | P | * P | * L 10 + * ** *** L 10 + * * E | * E | * * S | S | *** | ***** | * ** * *** | **** | * * 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
445000-449975 hour-14 445000-449975 hour-15 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | M | * M | P | P | L 10 + *** L 10 + * * ** E | * * E | * * * * S | * *** S | * * | ** | * * | * ** | * ** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
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445000-449975 hour-18 445000-449975 hour-19 30 + 30 + | | | | | | % | % | 20 + 20 + S | S | A | A | * M | M | P | P | ** L 10 + * * L 10 + * * E | * * * * E | ** * S | * * * S | | **** * | * ** | *** **** * | ** ** 00 +----+----+----+----+----+----+ 00 +----+----+----+----+----+----+ 0 5 10 15 20 25 30 0 5 10 15 20 25 30 CARRIERS PRESENT CARRIERS PRESENT
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Central States VHF Society, comments to Docket rm8737 May 5th, 1997
Before the
Federal Communications Commission
Washington, D.C. 20554
In the Matter of ) WT Docket No.rm8737
)
Amendment of Amateur Service ) RM-8737
Rules to Provide For )
Greater Use of Spread )
Spectrum Communication )
Technologies )
To: The Commission
COMMENTS Of The Central States VHF Society
Background
The Central Sates VHF Society (CSVHFS) was founded in 1967 to promote the use of the VHF, UHF and microwave amateur bands. One of our principal activities is to hold an annual conference in which those interested in the higher amateur frequencies can meet and exchange ideas and information as well as test antennas and other equipment. We invite leaders in the field of higher frequency operation to present papers, which for a number of years have been published in Proceedings form by the American Radio Relay League. Although our membership is not large, compared with some amateur organization, several hundred, they are some of the leaders in the field of amateur VHF, UHF and microwave techniques. Despite the fact the CSVHFS primarily targets those in the Central portion of the U.S., amateurs from all over this country and many overseas countries have attended and participated in our annual Conferences. It should be noted that the facet of Amateur Radio, to which CSVHFS members devote much of their time, is what has been termed "weak signal" work. Those following this endeavor constantly strive for greater and greater distances on all of the amateur bands from 50 MHz through the higher microwave frequencies. This effort has, over the years, led to many contributions to the radio art, including improved performance receiving, and transmitting equipment and more efficient and better antenna systems. Weak signal operators have also learned how to take advantage of various types of anomalous propagation, often missed or ignored by the professionals. These include long haul tropospheric ducting, tropospheric scatter, reflections from ionized meteor trails, the aurora, ionospheric scatter, Sporadic E Layer propagation and various F Layer phenomena. Many have also been very active in developing techniques and equipment needed to reflect their signals off the moon. This is called Earth-Moon-Earth or EME, and requires very exacting station construction and superior operating skills. These activities have led to many advances in the radio art that have found their way into a number of non-amateur applications. It is anticipated that additional advancements will be made by weak signal operators if they are able to continue their activities.
It should be apparent that many weak signal activities require a very low noise level in the receiver, and most amateurs who seriously work the bands above 50 MHz employ receivers with noise figures of 1 dB or less.. This, coupled with the high gain antennas commonly used, make their stations particularly vulnerable to any increase in the noise level. Thus, any significant increase in noise level will render their work impossible, and their continuing contributions to radio communications will, therefore, cease..
Introduction
On behalf of its members and others involved in weak signal work on all of the bands above 50 MHz, CSVHFS wishes to file comments in the Subject Docket, which proposes to liberalize the Amateur Service Rules relative to spread spectrum operation. After reviewing the NPRM and many of the comments filed under RM-8737, we have become concerned that widespread use of spread spectrum may pose a serious threat to weak signal work, when it is operated on the frequencies customarily used for that work.
Summary
CSVHFS understands, and is sympathetic to, the intent of the Commission's Proposed Rule Making to liberalize, and thereby encourage, the development of spread spectrum in the Amateur Service. We feel that various types of spread spectrum may have an application in the kind of work our members, and other weak signal operators, engage in. As noted, our organization has, since its inception, wholeheartedly supported the development of new technologies in and for the Amateur Service, in particular better exploitation of the amateur VHF, UHF and microwave assignments. Although, spread spectrum may represent a significant vehicle for facilitating improved communication between licensed amateurs, we are concerned that it may also present a significant threat to current weak signal activities under the proposed rules. We understand the Commission's desire to provide rules aimed at providing the maximum degree of flexibility for accomplishing the increased use and development of spread spectrum, however, we contend that such rules must be consistent with preserving the viability of current communications capabilities, especially including those associated with various kinds of weak signal work. We will suggest certain provisions which we believe must be included in any new rules the Commission my adopt to promote the development of spread spectrum techniques which will allow its development without materially impacting existing weak signal amateur activities. These provisions will be outlined in these comments.
CSVHFS believes that, to maximize the flexibility for developing spread spectrum techniques for uses other than its apparent advantages in local communication applications, two classes of spread spectrum should be defined by the Commission and implemented in any new Rules. These will be defined and certain frequency bands suggested for each.
Discussion
While some feel that spread spectrum promises improvement in amateur communication, CSVHFS contends that its unbridled authorization and widespread use, on frequencies customarily used for weak signal work has the potential of rendering useless many of the current communications techniques practiced on the VHF, UHF and microwave amateur bands particularly the weak signal long-haul applications employed by our members..
Some may contend that the fact that spread spectrum has been authorized on 420 MHz and above for over ten years, demonstrates that it poses minimal interference threat to other modes. CSVHFS believes that this argument is fallacious. Even those supporting more flexible rules for spread spectrum have agreed that the number of amateurs using it during this period has been extremely small. Furthermore, CSVHFS is not aware of any tests that have been conducted between the spread spectrum operators, who were active, and weak signal VHF/UHF operators. No such tests have ever been reported in the amateur press or in papers presented at our annual Conferences. What tests that reportedly did take place, were poorly advertised in advance; and involved only SS operation in the presence of FM voice repeaters, not weak signal stations. As part of their argument that spread spectrum offers little or no interference to other modes, its proponents cite only occasional short lived signals on a specific channel as characteristic of the type of interference that spread spectrum might present to other modes. Of note is the fact that these illustrations deal only with FM repeaters, not weak signal work such as long haul tropospheric propagation or EME). While this interference scenario may be valid for FM repeaters and a single SS station, or even a few such stations; it is unrealistic if spread spectrum should become a popular mode. It is also invalid for almost all weak signal modes. If spread spectrum does become a popular mode, these short bursts of interference will be repeated by each spread spectrum station on the air at the time. Thus, spread spectrum interference, instead of being an occasional "pip", will take the form of continuous "hash". We have seen calculations that indicate that spread spectrum operation has the potential for raising the noise floor by as much as 50 dB, or even more, over existing levels. With an activity that cannot tolerate a noise floor increase of even a few dB, this will have the effect of eliminating all possibility of weak signal - long-haul work. .
CSVHFS further believes that, if significant interference does result from spread spectrum operation, it will only serve to divide the amateur community and result in impeding the growth and development of spread spectrum, as well as the cessation of weak signal activity. We are certain that no such eventualities represent the Commission's intent in proposing these rule changes.
CSVHFS feels that a way must be found to foster the development of spread spectrum techniques and still prevent potential serious harm being caused to existing weak signal activities. We believe that these, seemingly contradictory, objectives can be met with the establishment, in any new rules which the Commission may invoke, of provisions prescribing certain frequency segments, in which the kinds of spread spectrum being addressed in the NPRM, shall not be allowed. We will outline our recommendation for these prescribed frequency limits later in these comments.
Automatic Power Control
The NPRM includes a requirement for automatic power control for spread spectrum stations running more than 1 Watt. While CSVHFS applauds the apparent Commission intent of minimizing interference to other amateur operation, we believe that automatic power control will be ineffective in materially reducing spread spectrum interference. We believe that much of the time the spread spectrum stations will be running as much power as they have available, especially if they are sharing spectrum with other stations using other modes - particularly if those stations are running considerable power, as many weak signal operators do.
Two Kinds of Spread Spectrum
In a paper given at the our 1996 Conference, Tom Clark W3IWI and Phil Karn KA9Q presented a case for the use of spread spectrum-like techniques for enhancing weak signal communication such as EME and long haul terrestrial. CSVHFS believes that the types of techniques discussed in this paper may have potential for the kind of work our members, and other weak signal operators, do. We would like to see the rules written so as to permit experimentation with these kinds of spread spectrum. We feel that this can be accomplished while not allowing spread spectrum operation to materially impact other operation. To do this, we suggest that the Commission define two types of spread spectrum. One type might be called "Broad Band" and the other "Narrow Band".
The bandwidth of spread spectrum being proposed in this NPRM appears to be undefined but CSVHFS believes what the Commission is proposing would occupy bandwidths considerably greater than that of "conventional" modes such as voice FM, AM and SSB. Hence, we would proposed it be termed "Broad Band". The "Narrow Band" type of spread spectrum such as that discussed by Clark and Karn in their paper, might occupy a bandwidth of perhaps 10 kHz. Since it would occupy such a relatively narrow band of frequencies, it is reasonable to believe that it can be accommodated on the VHF, UHF and microwave amateur bands without materially impacting existing weak signal operation.
CSVHFS Proposal
In light of the above, the CSVHFS proposes that a "Narrow Band" version of spread spectrum be defined and authorized on all of the amateur bands above 50 MHz presently open to SSB and AM, so long as the bandwidth of the transmitted signal does not exceed that of an AM voice signal, e.g. 10 kHz or less. We also propose that, until more data on the impact of "broad band spread spectrum operation on other modes becomes available, spread spectrum should be prevented form causing potentially harmful interference to existing weak signal operations. Therefore, we propose that the rules state that no Broad Band spread spectrum emissions shall take place in the following segments.
50.0 - 50.5 MHz*
144.0 - 144.5 MHz*
222.0 - 222.15 MHz*
431.5 - 432.5 MHz
902.0 - 903.5 MHz
1295.5 - 1296.5 MHz
2303.5 - 2304.5 MHz
3455 - 3457 MHz
5759 - 5761 MHz
10367 - 10369 MHz
* These segments are included in case the Commission should decide to authorize
spread spectrum on frequencies below 420 MHz.
Conclusion
CSVHFS believes that spread spectrum operation should be encouraged. It may eventually prove valuable for a variety amateur applications. However, we contend that, until more information is available on its impact on existing amateur activities, spread spectrum operation should be allowed only on band segments that will not significantly impact weak signal operation and perhaps render such operation untenable.
CSVHFS contends that, provisions limiting the frequency segments on which spread spectrum is authorized, is consistent with existing Commission policy in the Amateur Service, and cite, as examples, the fact that voice operation has been limited to certain segments in the HF and VHF amateur bands for many years. In addition, unattended digital operation is restricted to certain small segments of the HF bands and Unattended Beacon Operation is allowed only in small segments of the 10 meter, 6 meter, 2 meter, 1-1/4 meter and 70 cm bands. Also, repeaters are allowed only in certain band segments.
It is recommended that the Commission incorporate these suggestions in formulating new Rules designed to foster widespread use of spread spectrum among amateur radio operators. In addition CSVHFS proposes that the Commission authorize two types of spread spectrum. One that could be termed, "Narrow Band", would be authorized anywhere above 50 MHz where SSB and AM are allowed, as long as the transmitted bandwidth does not exceed 10 kHz. The other, that could be called "Broad Band", would be authorized anywhere, except in the segments listed above. We believe that this course will allow amateurs to develop spread spectrum technology and continue to do other notable work to further develop all facets of the radio art.
RESPECTFULLY SUBMITTED,
Gerald Handley WA5DBY Board Chairman
May 2, 1997
Appendix A
Part 97 of Chapter 1 of Title 47 of the Code of Federal Regulations is proposed to be amended as follows:
Part 97 Amateur Radio Service
All other provisions contained in NPRM rm8737 are retained except as noted:
97.305 Authorized emission types
SS (spread spectrum) emission with bandwiths wider than 10 kHz are prohibited from the following frequency segments:
50.0 - 50.5 MHz*
144.0 -144.5 MHz*
222.0 - 222.15 MHz*
431.5- 432.5 MHz
902.0 - 903.5 MHz
1295.5 - 1296.5 MHz
2303.5 - 2304.5 MHz
3455 - 3457 MHz
5759 - 5761 MHz
10367 - 10369 MHz
(* These frequencies included only in case the Commission should decide to
authori