AHP is???
AHP is Active Home Pro. The control software that is needed to use the CM15A.
BVC is???
BVC is Bills Voice Commander. This is a piece of software written by Bill Johns, one of the community members of this forum. It is for giving your X10 hardware voice control capability. If you want to know anything about this software, ask bill himself or Dave_X10_L, the biggest fan of BVC.
TM751 is??? (I think that this is the transceiver that sends the signal through the wiring to turn on/off the cameras??) and has a metal expanding anntenae.
You are correct to a point. The TM751 will take X10 RF signals and re-transmit them onto the power lines. It will not however take power line signals and convert them to X10 RF signals.
CM15A is?? (I think that this is the signal receiver that has a thin black vinyl covered wire antennae that sends a signal to the TM751 and receives the motion detector signals and plugs into my PC by USB.) How in the heck did you replace the thin wire anntenae with the expanding one?? (this assumes that I have the units numbers and function defined correctly)
The CM15A does not necessarily send signals to the TM751, although it can, but there can be issues with that. The CM15A is a programmable X10 controller that can do what the TM751 can and MUCH more. This is mainly used with the Active Home Pro software to use timers and macros to control your modules. The software can store the timers and macros directly in the CM15A and they can be run from the CM15A without the need for the computer to be on.
ACT234 phase coupler repeater is ?? I'm assuming that this is some sort of signal booster, but I'm not sure. Since searching on the x10 site by part number is almost useless I have no idea where to look or what it looks like or even if it is available via x10.
You are correct, the ACT234 is a phase coupler repeater. It is connected in your breaker panel to couple the X10 power line signals from one phase to the other. If a device like this is not used and you plug a device into an outlet on one phase and you have your CM15A or TM751 in an outlet on the other phase, your device will typically not function. The ACT234 on top of coupling the signal to the other phase, will repeat that signal in order to boost it.
IF you have questions on any of the X10 equipment and how it works, come to the forum and ask. DON'T rely on the X10 website. But I'm sure by now you already know that.