I have a satellite receiver (or set-top-box) as shown below and I want to connect it to my computer in order to view digital TV on my computer. It has and is232c port and an AV port as seen from the figure. How should I connect this to my computer in order to watch satellite TV on computer? Can I use the its rs-232c port for this purpose?
No.
RS232 would be used to maintain the device - eg upgrade the firmware on it. Most RS232 Ports are limited to 115400 baud (I know there are exceptions, but thats relevant) - At less then 128k, that is nowhere enough to send video and audio in the general case, and definately not the digital DVB transmission you would receive.
At a guess, if you really wanted to hook it up, you could get an AV capture card, and the appropriate AV cable. This would be a cludge though.
A much better solution would be to get an appropriate DVB-T capture card. You can get cheap USB "DVB-T" tuner devices for about US$10 - just make sure it is compatible with the signal from your region.
