CATV Descramblers??

[doanster]

I was looking in the basement and I found a home-made cable tv descrambler... a friend made it gave it to my dad a decade or two ago...

So, does anyone know how one of these things would work? Looking at the circuit, it contains three variable capacitors and three inductors, nothing else. Seems too simple to believe, but it actually worked way back then!!

 

[jmcoreymv]

If I remember (and I could easily be wrong), one simple method used to scramble analog channels was to remove the vertical sync pulse. So all the descrambler had to do was recreate the sync pulse and its done. I'm sure there are also other more complex scrambling techniques used as well.

 

[doanster]

that's it? interesting...

 

[dkozloski]

Our local cable company inverted the video so all that was required was an inverting video amplifier and a DC restorer. I use an old VCR for a tuner to get audio and a video signal to work with. I used a gamesters modulator fron Radio Shack to get a channel 3 signal I could tune with the TV. If you got caught with a pirate descrambler you were billed for every pay per view event and movie that was offered on any channel during the time period you had it. Bills in the $50,000 range were not unknown. If you couldn't pay you went to the slammer. Only a few of the worst offenders were ever prosecuted.

 

[MAW1082]

get a spectrum analyzer and a crystal oscillator then go down into your basement and start having fun

 

[seanp789]

See but now people use free to air satellite boxes with a bit of reprogramming. Probably safer than trying to pirate domestic cable.

All digital signals now use various encryption keys. The longer the key, the harder it is to crack. Broadcast keys are usually leaked by employees as opposed to cracked as I believe they are now using 128-bit encryption. The days of analog are coming to an end.

 

[doanster]

Originally posted by: MAW1082
get a spectrum analyzer and a crystal oscillator then go down into your basement and start having fun

And blow a hole in my wallet at the same time... hehe

 

[JTWill]

Originally posted by: doanster

Originally posted by: MAW1082
get a spectrum analyzer and a crystal oscillator then go down into your basement and start having fun

And blow a hole in my wallet at the same time... hehe

The unit you are describing was the first type of de-scrambler used. The cable company had the pay channel broadcast with a pulse that messed up both picture and sound. the pulse was in between the picture and sound signal and what you have is a tunable notch filter for the channel that was used filtering the pulse out. The pulse was also called a Bullet or a Chirp signal.