Rob Dekker wrote:

"Doug McDonald" <mcdonald@SnPoAM_scs.uiuc.edu> wrote in message news:dilv1a$4h3$1@news.ks.uiuc.edu...
[...]

greg

An interesting point. Digital TV (8VSB) signals are ideal for
moonbounce IF you don't want to decode, just receive. Since they
are mostly random sequences (with some pseudorandom parts) with
a flat frequency spectrum they are ideal for doing autocorrelation
analysis. The minimum period is about 80 nsec and the maximum is infinite. The powers are very high. OF course, you would want
transmitter and receiver to be far enough apart that the
moon was near the horizon at the transmitter and near the zenith at
the receiver.

Doug McDonald

Hi Doug,

Well, but what is the bandwidth of this signal ? Most be like 5-10 MHz or so right ?
So, the total power per Hz is spread out over this bandwidth.
This makes the signal very hard to detect when compared to the CW analog TV carriers.
The CW carrier of TV signal contains a considerable (10-20%?) amount of transmission power,
and it is concentrated in a very narrow bandwidth (0.1 Hz or less).

This is the same with ATSC: about 10% of the power is in the
residual carrier.

So digital TV signals will be a factor of a million less power per Hz of bandwidth, and
are thus much harder to detect than the analog TV carrier.

No, because the ATSC digital signals do contain a CW carrier. It's the
exact power ratio, which I forget, that matters. Remember that NTSC
signals are rated on peak power and ATSC signals on average power.

I am suggesting in my original post not that the ATSC signal
is "easy to decode" but that it is near-ideal as a "freebie"
signal for mapping the surface of the moon by using autocorrelation
analysis.

Doug