The Mysterious J-Cube
June 13, 2018 8:02 AM   Subscribe

How did this ca. 1995 illegal cable hookup in Brooklyn work?

In the mid-90s in Brooklyn my friend had a Cablevision box that received basic cable over coaxial. He also had a small black box (I think it was called a J-Cube) with a coax connector coming out that plugged into the coax line at the splitter between the line itself and the cable box, temporarily replacing the actual cable line. He would hit a combination on the remote, held down the button on the box plugged into the line, the LCD display on the cable receiver box would flicker, he would plug the cable line back in and then the premium channels would be unlocked for a certain (possibly random) period of time of anywhere from an hour to a couple of days. He referred to this as "charging" the box.

Anyone have an idea how this worked? I know the black box had a very small circuitboard inside and was definitely a made-to-order item.
posted by griphus to Technology (2 answers total) 2 users marked this as a favorite
 
You can read all sorts of stuff about how analog cable was scrambled here.
posted by uncleozzy at 8:19 AM on June 13 [3 favorites]


I can’t say for Cablevision specifically, but I worked for a while at a cable company with a similar setup so I can tell you about how ours worked. I imagine that this setup was similar as it was around the same time.

The set top box is not just a channel changer, it’s “addressable”, so it can receive and obey messages sent by the cable company. The company knows which customer has which set top boxes, and they can send a message out on the wire that says “Serial number 0011223344, you are now authorized for HBO.” Since the cable operator only has one data stream that goes to all their customers, they place the messages onto that stream and the boxes filter out ones that aren’t addressed to their serial number. The system would even work for pay per view, since you could send a hit to enable channel 139 at 8:00 and send another at 10:00 to disable it. We used to call it sending a box a “hit” - the signal to set up all its channels.

The system that sent out all the hits was called “Conditional Access”. It would handle any incoming requests from the PPV system, the call centre, etc, and when it had nothing else to do, it would do a “global refresh”. It kept track of all the set tops and their programming, and it would slowly work its way through the list, hitting each box one by one, then start again from the top. If, say, a customer canceled their premium channels, but one box was unhooked at the time, it would miss the hit telling it to downgrade, so the idea was that the global refresh would eventually get it once it was reconnected. Ours probably took 7 days or so to get through the list.

My guess for how the mysterious J-Cube worked is that it would send a hit to your box enabling all the premium channels. It’s possible for a hit to target every box in the system, so it could send a hit that would work on any box. Eventually a new hit would come down due to a global refresh and knock your channels out again, but the timing would seem random since it would be whenever the global refresh came around to your box.
posted by pocams at 10:44 AM on June 14 [2 favorites]


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