Oh, I understand that most folks here wouldn't have the skills needed to design the circuit, but some could do so, and simply copying a design is within the ability of many. I think most of the information is already out there on the signal and it wouldn't be too terribly hard to simply record the data stream that a TIU or DCSRC spits out on power up, and use a micro-controler to spit the same 1's and 0's out on command, however Stan's solution is just a simpler way to go. (assuming we're talking about the couple folks that do have the skills and equipment needed)
Now, it might be worth it for MTH to sell a ready to go box that provides a watchdog on command, or on a timed repeat.
JGL
