"Hans Summers" wrote in message news:bmj291

Interesting ideas Len. I guess the idea of an all-digital spectrum analyser
is similar to that of an all-digital HF amateur radio tranceiver. It can be
done but at the current state of the art, it's a difficult proposal for the
hobbyist and certainly difficult to obtain the same level of performance as
the equivalent analogue device for the same amount of cost and/or effort.

I have a PC-based oscilloscope that does something pretty close. It
digitizes at the rate of 4ns per sample (taking 8bit samples
unfortunately) and generates an FFT display of magnitude/power
spectrum/power density).

I think it is feasible to use an analogue RF front end under computer
control, the a PC controlling the VCO and sampling the logarithmic output.
In essence just replacing the oscilloscope as the display system.

I guess, it is not necessary to PC control the VCO. Sweep generators
are easy to come by. probably, if there is a way to feed the sweep
into the PC to generate the X-axis, then that might be a better
alternative.

- farhan