by Stephen » Sat Mar 31, 2007 12:03 am
According to the NBTVA Handbook, the ham radio transmission standards for NBTV signals are as follows:
AM
Polarity: negative, sync is the largest HF amplitude, white the smallest.
Mod. depth: 90%, white HF amplitude is 10% of max. HF amplitude.
Bandwidth: 20 kHz.
FM
Polarity: positive, white is the highest frequency, sync the lowest.
Deviation: 15 kHz peak to peak.
Bandwidth: 35 kHz, occupies 3 channels in the 12½ kHz grid.
As far as I know, these are permissible on any of bands that permit these modes. However, with respect to AM it would be more desireable to have an AM transmitter with a VSB modulator to achieve less bandwidth and better signal to noise ratio. It is my understanding that the 2003 75th anniversary transatlantic transmissions on 15 metres used AM transmitters with VSB modulators and a 12 kHz bandwidth.
Stephen