FACSIMILE STANDARDS

For facsimile transmissions in the Amateur Service the following characteristic values are preferred:

1. The video (picture) modulated signal is generated at the audio frequency level, similar to the technique used for SSTV. The edge frequencies for "black" and "white" are 1500 Hz and 2300 Hz respectively ; the frequencies corresponding to the half-tones are between these two frequencies. The audio frequency bandwidth is maximally 3000 Hz.

2. The rotation speed of the picture drum is switchable between 60, 90, 120, 150, 180 and 240 rpm, with 60, 120, 180 and 240 rpm being the preferred values.

3. The index of co-operation shall provisionally be 288, in accordance with CCIR recommendation. Minor deviations from this value are permissable.

4. Phasing-in signals and end-of-picture signals will be chosen at a later stage, taking into account practical considerations based on the state-of-the-art.

5. All Amateur Service allocations should be open for this mode of transmission. Operation via repeaters and amateur satellites should also be allowed.

6. For the transmissions F1C should be used. ( e.g. frequency shift keying of an audio frequency sub-carrier, which modulates the main carrier in SSB, or direct FSK (shift-keying) of the main carrier by the modulating signal.)

Additionally, on frequencies above 144.5 MHz mode F2C, i.e. FM/AFSK modulation of the RF carrier by a frequency-modulated sub-carrier, is permitted.