Digital 'scope & spectrum analyzer Re: [Open-graphics] PCIe know-how?

[Dieter]

> > Will OGC be able to output arbitrary waveforms, or only video?
> > If OGC can generate sine waves, square waves, triangle, etc.
> > it would be very useful as a piece of test equipment.  It
> > could be a tracking generator for the spectrum analyzer?
> 
> I thought it would be interesting to generate RF signals entirely in
> the digital domain and use a video DAC to turn it into analog.  For
> instance, you can have a sine-wave generator, that's completely
> digital, and it has parameters that you can use to adjust the
> frequency, within a band.  BOOM.  You have an FM transmitter.  Attach
> an amplifier, and you can send audio to a nearby radio.

I forgot to mention this, but I recall reading that someone did this
using a video card.  I don't recall if it was AM or FM.

> If the granularity of our control of the signal is 330Mhz,

Ouch, that's a bit of a limitation.  I don't suppose the two heads
could be interlaced together somehow to get 660 Mhz?  (Still low, but
better than 330.)  And we lose half of that to Nyquest?

> can we
> encode all of the information in the TV signal?  Would the steps
> between digital levels (1024 of them) be too noisy?  Could we fix that
> with a low-pass filter?

Does 1024 levels imply a S/N of 30.103 dB?   If so, that would be plenty
for ATSC, but IIRC a bit low for good quality NTSC.  I haven't seen numbers
for PAL, SECAM, or DVB-T.