STANDARDS FOR DIGITAL COMMUNICATIONS

1. Modulation methods

- FM/AFSK (where allowed in the bandplans)

- FSK : at speeds below 300 bit/s FSK is preferred

- PSK : at speeds above 300 bit/s PSK is preferred

General Applications :

Shifts for FSK and FM/AFSK :

at 1200 bits per second -1 kHz

below 1200 bits per second-850 Hz, 170 Hz (preferred)

Mark is always the higher frequency.

Note.For FM/AFSK the audio frequencies are :

- space1275 Hz

- mark1445 Hz or 2125 Hz, depending on shift

Packet-Radio Applications: ¹)

for 300 bit/s transmissions using FSK a shift of 200 Hz should be used;

for 1200 bit/s transmissions using FM/AFSK audio frequencies of 1200 and 2200 Hz should be used (as in the Bell 202 standard).

On the bands below 30 MHz the signalling speed shall not be more than 300 bit/s.

2. Coding/bit- rates ¹)

- Baudot :45.45, 50, 100 bits per second (50 bit/s preferred)

- ASCII :1 start bit, 7 data bits, 1 parity bit, 1 stop bit.

Parity:if generated -even parity

if not generated -parity bit set to space

110 bits per second preferred.

3. Protocols

- Packet Radio :AX-25 as published by ARRL

- AMTOR :CCIR 476-1, modes A and/or B.