Building a Standards Converter

[ppppenguin]

As we know, the modulator chips used in Hedghog (and Aurora) are obsolete and the grey market suppliers are getting down to the floor sweepings. I don't see any hope of a new chip doing anything similar as analogue RF inputs to TV are also obsolete. So we will need a new approach:

1: External modulator. Several traditional designs have been published. Not multichannel.

2: Direct Digital Synthesis (DDS). Frank and I have done limited experiments. Making a Ch1 signal directly in digits isn't hard. Needs a more modern FPGA and a good high speed DAC. Direct to Band III isn't feasible. A Band I signal can be heterodyned up to Band III but you also a get a mirror signal which may not matter.

3: DDS at IF. Perhaps in the 15 to 20MHz range. As above but heterodyned up to all channels. Reduces the DAC and FPGA requirements a little.

4: VSB may be possible quite easily using the Weaver or 3rd method for SSB generation.

5: Sound also fairly simple. Added to vision in digits before DAC.

Any RF/DSP/DDS experts here? I know some of the basics - certainly no trouble to make a basic DDS for DSB vision plus AM sound. But I'm not an RF expert by any standard.