Bulletins from the Pacific Packet Radio Society - page 153

Signaling format:

** Preamble ** SYN1 ** Packet **

Preamble: At least 20 transmitted consecutive '1's corresponding to 40 zero-crossing on the channel

SYN1 At least 3 ASCII SYN characters

Packet Any number of bytes less than 256

Transceiver control and measurements:

Transmitter control:

Power controllable in 16 5-dB steps. Range: -20 dBm -- 55 dBm (4 bits) Transmit / receive switching (switch time less than 1 ms)

Receiver output:

Slow SNR reading (Channel quality check): Received (S+N/N) IN 16 3-dB steps. Time constant | 10 ms (1 packet) Range: 0 dB -- 45 dB (4 bits)

Fast SNR reading (Channel busy check): Received (S+N/N) threshold detector (1 bit) (Tc [ 50 us). Threshold presentable in 16 steps (4 bits) of 3dB each. Range: 0 dB -- 45 dB

Received SNR (S+N/N) measured at data detector.

LINK programming environment

The LINK programming environment consists of a FORTH dictionary with two vocabularies, the LINK vocabulary and the LFORTH vocabulary. When a packet enters the LINK machine interpretation is commenced with the context pointer pointing at the LINK vocabulary. The LINK vocabulary can be said to represent the programming environment for non-privileged users. In this vocabulary only a few words are available. These are listed below. Among them are the so-called format words, which define the access algorithm and the format of the packets used. The standard system has at least to contain the two standard format words IF' and "A" described below.

2.1 The LINK vocabulary

F ---
A ---

Together 'F' and 'A' describe the basic Softnet channel-access algorithm. The following is a description of this algorithm.

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