how to capture digital T.V signal

J-M-L:
You can't do that with an arduino - not fast enough.

i don't want to do it with any special hardware ! this forum is the nearest forum related to this topic i found...
delay is not matter, if i be able to read signals with my own computer, any idea is welcome!
there are some kind of data logger, but they are so expensive for an student like me ( they are the last choice )

J-M-L:
I'm surprised you say you can't buy those components in your country

if i want to order something i need to know what exactly i need, something like datasheet (map of the electrical circuit) or something, because any wrong order can be expensive !

J-M-L:
what do you think is embedded in the decoders attached to televisions?

hmmmm
analog signal -> antena -> Amplifier ( i think ) -> band-pass filter -> digitizer

in this case band-pass filter must pass more frequency range...