25 October 2015

Robust PACKET Radio

Robust PACKET  is  a  data  transmission  mode using eight carrier, pulse shaped OFDM (Orthogonal Frequency Division Multiplex), 60 Hz spaced and spreading a 500Hz bandwidth. Dependent on the user data rate (200 or 600 bps before AX.25 protocol overhead) each carrier is DBPSK (as in this sample) or DQPSK modulated at a constant rate of 50 Baud. The modulation type is automatically adapted to the propagation conditions. Just like ordinary PACKET RADIO, the AX.25 protocol is utilized as the Layer 2 protocol.
This sample has been heard on 10147.3 KHz (cf) on the Robust Packet Network operated bu HAMs: below teh demodulation of the messages received.

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