Modem Clock Option and Modem Bit Regenerator Option are still available.
The TAPR 9600bps modem is a full-duplex baseband modem compatible with K9NG and G3RUH standards. The TAPR 9600bps modem, like other 9600bps modems, requires an interface to your radio other than via the microphone and speaker jacks. The modem fits internally into the case of many popular TNCs and supports a 20-pin modem disconnect header which allows for a second external modem (such as the TAPR PSK modem) to optionally be connected.
The 9600bps modem uses a 4-layer PC board for minimum noise and utilizes a transmit waveform lookup table in ROM for minimum transmit distortion. The transmit path includes an independent watchdog timer. The modem selection logic correctly routes the PTT command from the TNC to prevent, for example, keying your 1200 baud radio when running 9600bps. The receive filter includes a compensation adjustment to tailor the modem to the radio receiver and AC-coupling to accommodate frequency drift on the channel. An improved state machine is used for clock recovery. The DCD circuit works on both signal quality and the presence of a signal.
9600bps Modem Clock Option
The clock option provides the necessary radio port clock for 9600bps operation. When you enable the external 9600bps modem on a TNC 1, TNC 2, or clone, your TNC will automatically be set up for the correct radio port speed. When you switch back to the TNC's internal modem, the TNC will automatically select its normal radio port speed again. Thus, you can switch between 1200bps and 9600bps operation with a single switch. The clock option is necessary if you wish to use your modem as part of a stand-alone full-duplex 9600bps repeater, in conjunction with the bit regenerator option. The clock option is also useful if you wish to operate at a non-standard data rate (say, 8700 bps) for backbone links that you don't want other users on. Note: You will have to replace the crystal in the clock option kit if you wish to use a non- standard rate.
The price for the Clock Option (for DCD or 9600b modem) is:
$ 5 US for members of TAPR
$ 5 US for non-members+ shipping/handling if applicable.
9600bps Modem Bit Regenerator Option
This option is intended only for use as part of a full- duplex 9600bps repeater. It is not suitable for use at a home station. The bit regenerator keys the PTT line of the modem whenever it receives an incoming signal (DCD is true). It stores the first 8 bits in a buffer, then starts sending the bits out again, resynchronizing them with its own crystal-controller clock to remove jitter and noise from the received signal. The buffer is 'elastic' so it can accommodate a slightly different '9600bps' data rate from the sending station and its own 9600bps clock. Full-duplex bit-regenerating repeaters for 9600bps are starting to be used in more and more locations. It truly makes 9600bps operation fast and friendly.
The price for the Bit Regenerator (for 9600b modem) is:
$ 9 US for members of TAPR
$ 10 US for non-members+ shipping/handling if applicable.
Documentation and Downloads
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