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

[Timothy Normand Miller]

On 3/5/07, Dieter <netbsd at sopwith.solgatos.com> wrote:

> > 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?

Ok, what we can probably do is use a fixed 330MHz and then, in the
amplifier, delay green by 1/3 and blue by 2/3 of a clock period
relative to red and then just add them together.  That gives us
effectively 990MHz.  Good enough?  Actually, it's not quite that
simple, but since everything is a smooth curve, I think we can fake
it.

> (Still low, but
> better than 330.)  And we lose half of that to Nyquest?

That loss is elsewhere in the problem, I think.  That is, we would get
the same loss whether we used analog or digital to encode the signal.

> > 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.

Tying the three channels together effectively triples that.

-- 
Timothy Normand Miller
http://www.cse.ohio-state.edu/~millerti
Favorite book:  The Design of Everyday Things, Donald A. Norman, ISBN
0-465-06710-7