Sound Card As Tv Signal Decoder ?

[klain]

what if i build a simple vhf receiver that receives

from 50+ mhz to 155 mhz. it covers the

first tv channels 2-6, fm band and air band etc.

then connect the audio output to the mic of

the sound card. tune the receiver on the

frequency of tv carrier of a channel

and use the sound card to decode the tv signal ?

there are some utilities in linux that decodes morse

code captures, fax via the sound card.

is there a utility to do the same job for the tv signal ?

sorry for my bad english.

[digip]

I thought most of that stuff was dead, no longer broadcasting in standard def but everything is now HDTV signals. What stations are still carrying uhf/vhf that a rabbit ear TV can see?

What you can do though, is if you have something like a radio/police scanner that handles the right frequencies, you can pick up satellite video from weather stations and NASA. I was never really successful with it, but I think that was partly due to the scanner I was using. Its pumped through the sound card and decoded into images by software on the pc.

Edited September 25, 2010 by digip

[klain]

digip,

analog tv is not dead in the rest of the world.

it will be in a few years.

i'm trying to find a way to do this using the sound

card for educational reasons.

[digip]

digip,

analog tv is not dead in the rest of the world.

it will be in a few years.

i'm trying to find a way to do this using the sound

card for educational reasons.

I'm not knocking what you are doing, or trying to discourage you, but maybe the two things aren't mutually exclusive. I think in part, the showing of imagery from satellites might be along the same lines of what you are after and could help shed some light on your project. You'll need software to do the forming of the data, the sound-card more or less is just the capture device that will receive the radio stuff, like an audio out jack on a radio scanner (which is how its done for the Satellite images over radio frequencies).

In fact, might become more useful, not just for TV and Satellite, but there are also ways to intercept other types of communications, send and receive like walkie talkie/ham radio type stuff, using the soundcard to capture the radio stuff, and a separate transmitter to send back to the other party, you can share physical files over radio, etc. You can also probably intercept CCTV or Wifi Video Cameras given the right equipment too.

BSOD TV even did a few episodes on how to share files over radio and demonstrated the software that did it in the episodes. That should be something to look into if you want to get started with this stuff.

[moonlit]

Unfortunately what you propose isn't possible, a TV channel sucks up about 6MHz while your sound card can only handle about 100kHz (give or take a few Hz) so there's no way to cram enough data into the line-in on a sound card to see the video signal.

You can do what digip suggests though, receiving and decoding certain types of amateur radio data encoding (such as slow scan TV or PSK31), you can also use a soundcard as an extremely basic oscilloscope which allows you to see the signal from an infrared TV remote, for example, using an IR receiver hooked up to the line-in.

Edited September 26, 2010 by moonlit