Re: [Discuss-gnuradio] Software Analog TV (SATV) ...

[Eric Blossom]

On Tue, May 25, 2004 at 07:02:49AM -0700, Saeed Beyty wrote:
> dear GNUs' 
> Hi
> as a complementary to our SDR project we stareted developing a
> software TV, like the one you did in software HDTV.  but there is no
> digital TV transmitter station here, so the choice is to use the
> analog TV signals, and decode them to get the picture snapshots
> using a analog controled TV tuner from samsung in addition with some
> side elements just as Eric had in his board, i'm trying to connect
> the tuner to parallel port and feed data to the DAS4020 card.
> So...
> what should i do?

I sugggest that you first get broadcast FM reception working.  This
will allow you to check out your tuner and the interface to the 4020
card.  http://comsec.com/wiki?HowToFM gives the basic outline.  The IF
of the samsung tuner is probably different than 5.75 MHz.

> is there any written code for analog TV or must i do it myself?

There's some old code that came from MIT that doesn't work with the
current system that may be useful as a source of signal processing
ideas.  The code is pretty nasty looking, but I suspect that at least
at some point in the past, it worked.  Receiving analog TV shouldn't
be too tricky.  We've dropped the file from the distribution, but this
link will get you a copy of it:

http://savannah.gnu.org/cgi-bin/viewcvs/gnuradio/gnuradio/src/pspectra/lib/vrp/needs-work/VrTV.h?rev=1.3&content-type=text/vnd.viewcvs-markup

I suggest that at least until we release the next tarball, you work
with the CVS tree to develop the NTSC TV receiver.

Directions for accessing CVS can be found at:
http://www.gnu.org/software/gnuradio/

After checking out the tree, be sure to read the README in the top
directory and make sure you've got the proper versions of the
autotools and other dependencies.

> is the idea correct? isn't there any technical problem?
> any one intrested in this project ? 
> i'm waiting to hear from you
> kind
> --Saeed

After getting FM reception to work, I'd start by a recording a couple
of seconds of data to disk, and then making sure that the spectrum
looks like what you expect.   You should be able to demod the TV audio
using the broadcast FM demodulator. 

Eric