September 5-7, 2014, Austin, Texas
High-Speed Wireless Networking in the UHF and Microwave Bands
By David Bern, W2LNX and Keith Elkin, KB3TCB
Abstract: This paper discusses building an amateur radio wireless network using commercial off the shelf wireless networking equipment that is currently available. As an example, four Ubiquiti NanoStation M3 3.4 GHz digital radios are used to assemble a demonstration network of two wireless network links that operate on two different frequencies. In conclusion, the paper invites the amateur radio community to build a nationwide highspeed amateur radio wireless backbone network to connect all local amateur radio area community wireless networks.
Proceedings Paper – Presentation
Clarifying the Amateur Bell 202 Modem
By Kenneth W. Finnegan, W6KWF and Bridget Benson, PhD
Abstract: Since its inception more than three decades ago, packet radio has seen several significant changes in technology and applications. Despite its age, the 1200 baud Bell 202 modulation used in some of the earliest packet systems still enjoys a wide user base in several of the major amateur packet networks. Oddly, despite being one of the longest-lived amateur packet modulations in use, the amateur radio community seems to have neglected to write a detailed specification document for this integral part of so many packet systems. This paper presents information gathered from network protocol specifications and amateur packet radio articles to assist other amateur radio operators implementing modems for this prototypical modulation.
The Stream Control Transmission Protocol (SCTP) and Its Potential for Amateur Radio
By Eduardo Gonzalez , Dr Stan McClellan and Dr Wuxu Peng
Abstract: The Stream Control Transmission Protocol (SCTP) provides several unique features not found in TCP (Transmission Control Protocol) and in UDP (User Datagram Protocol) while maintaining the useful aspects of both. This paper provides an introduction to SCTP and several features that should be very attractive to the Amateur Radio Community. These features are particularly useful with the rise of Software Defined Radio which use network interfaces to provide both control and data streams. The main features explored are multi-homing, multi-streaming and the ability to select reliable vs unreliable and ordered vs non ordered delivery of application messages.
SDR-based DATV-Express Exciter for Digital-ATV
By Ken Konechy, W6HHC
Abstract: The DATV-Express project was formed to create low-cost solution for Digital-ATV transmission. The open-source project was first announced and described at the TAPR Digital Communications Conference (DCC) in 2011.
The project’s hardware board design has the capability to go well beyond just DVB-S transmission. The design should be able to transmit any waveform of up to 8 MHz bandwidth using SDR techniques; including DVB-T, DVB-S2, ATSC and SSB. The current product utilizes Ubuntu OS running on a PC. The presentation also describes work being done to use the design on GNU Radio. Future plans include making the exciter more portable by using an ARM-based ODROID U3 Single-Board-Computer. The current product is in production.
A Radioteletype Over-Sampling Software Decoder for Amateur Radio
By Joseph J. Roby, Jr, K0JJR
Abstract: A radioteletype (RTTY) over-sampling software decoder for amateur radio is described. Using computationally inexpensive software techniques, including over-sampling with the Goertzel algorithm, a reliable, self-synchronizing decoder can be created.
An HF Frequency-Division Multiplex (FDM) Modem
By Steven Sampson, K5OKC
Abstract: A popular new digital voice mode has been FreeDV designed by David Rowe, VK5DGR. This paper is about an FDM modem implementation, but in order to test the modem, I also translated the Codec2 speech vocoder into Java. That left a simple GUI design to finish the prototype.
Modulation – Demodulation Software Radio
By Alex Schwarz VE7DXW and Guy Roels ON6MU
Abstract: How to upgrade and connect an analog RF transceiver to a computer for full IF-SDR operation (RX and TX). Installation procedures for FT-950, IC-756 as addendum.
A Software-Based Remote Receiver Solution
By Martin Ewing, AA6E
Abstract: Need to get your receiver off site to avoid interference? Here is how one amateur connected a remote radio to a club station using a mixture of Linux, Windows, and Python.
Smoothed Symbol Transition Modulation Digital Signal Processing Algorithm
By Patrick Jungwirth, PhD
Abstract: We present a new, patent pending, modulation technique called smoothed symbol transition modulation (SSTM). Smoothed symbol transition modulation removes the rectangular windowing function limitations present in conventional modulation techniques. Conventional modulation is limited by the instantaneous step changes between symbols. In binary frequency shift keying (FSK), for the message {0, 1,}, there is a step change in transitioning from 0 to 1. In quadrature amplitude modulation (QAM), each in-phase, I, and quadrature phase, Q, symbol is transmitted for 1 symbol time. For the symbol transition, I(n-1) to I(n), assuming I(n-1) .. I(n), there is also a step change. The same step changes also occur in the quadrature channel. The embedded rectangular windowing functions present in conventional modulation are from the instantaneous step changes. The step changes always occur at multiples of the symbol time. Conventional modulation is also limited by the modulator.s dynamic behavior during a symbol transition.
Smoothed symbol transition modulation replaces the step changes with smooth, zero slope transitions between symbols. For smoothed symbol transition modulation, a symbol transition occurs over 1 symbol time; not an instantaneous step change. Smoothed symbol transition modulation uses half cycle raised cosine waveforms, and zero slope line segments to create a smooth waveform with zero slope symbol transition points. The smooth waveform and zero slope symbol transition points reduce channel bandwidth. SSTM offers opportunities for improved performance under intersymbol interference, multipath signal conditions, dispersive channel conditions (arctic flutter), and timing jitter conditions.
We present simulations comparing conventional FSK and QAM to smoothed symbol transition modulation FSK and QAM respectively. We show considerable improvements in bandwidth and power spectral density. SSTM is a general concept that can be incorporated in any digital modulation system. Potential applications for SSTM include narrow band systems, multi-channel DSL modems, crowded frequency channels, and urban multipath environments.
The European HAMNET – A Large Scale High Speed Radio Network
By Jann Traschewski, DG8NGN
Abstract: The HAMNET is a high speed amateur radio multimedia network based on commercial wireless devices using mainly the 6cm band. It covers mostly the German speaking region in Europe and is about to grow over the language border. It is using the international coordinated IP-address space of the AMPRNet (44.0.0.0/8) and AS numbers out of the 16-bit and 32-bit private AS number space to interconnect active regions by external BGP routing. This paper documents how this network has been deployed and how it is interconnected with the international AMPRNet and the Packet Radio World. It will show which tools have been developed and customized for link planning, spectrum and network management. Moreover it will show the challenges we meet with authentication, spectrum regulatory questions and non-line-of-sight wireless user access. Finally the vision of a huge intranet for radio amateurs with end-to-end communication capabilities will be presented.
Implementation of Basic Analog and Digital Modulation Schemes using a SDR Platform
By Jose M. Valencia and Omar H. Longoria
Abstract: Traditional radio communications systems ( hardware based operation) have been displaced by radio systems whose functionality is totally (or almost) software dependent, these kinds of systems are called Software Defined Radios (SDR). SDR systems are present in many commercial devices (cellular phones, tablets, notebooks, modems etc.), therefore it is important for people related with electronic communication systems to know how these systems works.
This paper describes fundamental concepts and basic mathematical theory used in SDR systems, and shows how to implement basic analog (amplitude and frequency ) and digital (binary shift keying) modulation schemes using the Universal Software Radio Peripheral (USRP) platform.
Digital-ATV – Digital Video Broadcasting-T for Ham Radio
By Mel Whitten, K0PFX
Abstract: This is an introductory presentation on DVB-T including topics on analog to digital data compression (MPEG), Forward Error Correction (FEC), and modulation. Reasons for using DVB-T over analog and other DATV modes are given. New and relatively low cost transmitting and receiving DVB-T consumer equipment from HiDes developed for ham radio is shown. ADTV stations utilizing HiDes equipment including the author.s home station is described. A list of resources is provided to help the get started in ADTV.
