PC generated 405 lines and more!

[PerdioPal]

Digital is getting so fast it will (probably is) be easy to generate 405 at RF from one pin of a chip, just add a low pass filter.

[ppppenguin]

That's sort of what a digital radio transmitter is. Except that mostly they use fast DACs.

Frank Cuffe did some experiments along these lines to generate the RF output directly from a FPGA. I've also done some very simple experiments. I got as far as a 1kHz tone on a 15MHz carrier. It proved that the ideas worked. I also sketched, but never implemented, a vestigial sideband digital modulator. This used the so-called "3rd method" of SSB generation, also known as the Weaver method after his paper from 1956. This method, designed to avoid difficult filter or phase shifter problems that afflict other SSB methods, is rather complex in analogue but pretty simple in digits.

[Mike Watterson]

Probably now something does it with the FPGA translated to an ASIC with 8 or 16 pins and 1/1000th or less power consumption. FPGAs are for prototyping and low volume. The designs can be automatically converted to a cheap, small package, small chip at low power. An FPGA has the wiring diagram in RAM tables and much of the logic in RAM tables. Some dedicated I/O and multipliers. An FPGA is expensive and takes a lot of power because it totally general purpose.

Over 10 years ago people were doing SVGA graphics from an FPGA using resistors as the DAC for each of the R G B. One wonders what is in the €15 approx magic boxes for component to HDMI or composite to HDMI and vice versa. Certainly not FPGAs at the power consumption and price? Probably prototyped on them.

The snag with cheap ASIC from FPGA prototype is that the setup cost might be $500,000! Then 50c each for the chips if you buy enough!

A €15 Dealz (Poundland) radio is using a dedicated ASIC ( probably prototyped in DSP on an FPGA). No tuned circuits at all. Whip via capacitor for VHF and SW. One pin for ferrite rod. A polymer pot "tunes" it. Works better than a cheap superhet.

[PerdioPal]

"a vestigial sideband digital modulator", that doesn't matter DSB will be fine, the set trims off the edge.

[Murphyv310]

The Hack RF will do it and apparently standards conversion.
Some 60s sets don't like DSB as it was shelved when Crystal Palace took over and used VSB.