: X-10 2.4GHz Video :

X-10 2.4GHz Video
by: dosman



    Anyone that has surfed the web recently will get one of those annoying X-10 pop-under adds. I must say that I am ashamed of them, and had I not already been familiar with X-10 before their advert tirade I would have never bought their video equipment. Anyway... What is it exactly? X-10 is actually a spec for automated house control. It uses your house power wiring to signal devices to power on and off. Generally this is a small module that has a lamp or something plugged into it. Nice add-ons are RF transceivers (RF remote control) so that you have a wireless interface to this. Now, what is the X-10 wireless video setup about? Basically it's just a poor mans microwave video receiver and cameras with a twist. It should interface with other, more expensive microwave video systems in the 2.4GHz range. What they do is have all the cameras transmit on the same frequency. Then, you use the X-10 home power control to power on only one camera at a time. You can then flip through all your cameras on one monitor. It works quite well for what it was intended. So, for really cheap you get a 2.4GHz microwave video receiver that you can drive around and spy with :-).  Here I will present some pictures and other things that I have done to my receiver and cameras.

    Anyway, I have used X-10 house control for some time now, and I decided it was time to play with the wireless video. When I got mine, it was $135 for 3 cameras, 1 receiver, 1 full remote control, 1 battery pack for a camera, and one keychain remote. All the cameras are color, have sound, and use X-10 power supplies with built-in X-10 power control. Radio Shack has the same hardware, but they want $130 for just one camera and one receiver. The top left picture also shows my Hauppauge USB TV tuner behind the camera (Not included with the standard X-10 kit, I had this previously). I am impressed with it, they even include a programming API kit with it on the bundled software CD. It will accept coax as well as S-video. They even include a S-video to composite adapter (S-video to RCA jack) which I used for the first time down the page in my camera experiment('s).


War Driving Pics

I also have an 802.11b WiFi network around here, so interference is a concern of mine. I run on the common channel 6 for now and so far I have not had any problems between that and X-10 channel A.


X-10 channels from 2.411 to 2.473 GHz
channel A = 2.411 GHz
channel B = 2.434 GHz
channel C = 2.453 GHz
channel D = 2.473 GHz


802.11B channels in the 2.4GHz spectrum
13 US Channels from 2.412 to 2.462 GHz.
channel 1 = 2.412 GHz
channel 2 = 2.417 GHz
channel 3 = 2.422 GHz
channel 4 = 2.427 GHz
channel 5 = 2.432 GHz
channel 6 = 2.437 GHz
channel 7 = 2.442 GHz
channel 8 = 2.447 GHz
channel 9 = 2.452 GHz
channel 10 = 2.457 GHz
channel 11 = 2.462 GHz
channel 12 = 2.467 GHz
channel 13 = 2.472 GHz

Microwave oven: 2.450GHz



    Current experiment: broadcasting my own video over the X-10 transmitter. I have 3 cameras, so I have room to screw one up. One nice thing about X-10 is that all their junk is very modular. The video camera has a self-contained video unit with a cable connecting that to a self-contained 2.4GHz transmitter. So, why not remove the low quality camera and input a nice video signal from my DVD player :-). Shouldn't be that big of a deal. First, we need to do some experimenting and make sure which wires are which. At first glance it looks like they are being nice and are using yellow for video and white for audio. Before I blast my poor little transmitter with raw output from my DVD player I want to see if I can directly view the signal coming out of the camera.

   I did 40 hours of work in 2 shifts this week, so I have the day off. This morning I was able to pull some composite video directly off the camera and feed it into my USB TV tuner's S-video jack. Now I know I can feed a line-level composite signal directly into the transmitter.

My scope hooked directly to the camera output signal before it reaches the transmitter




The video signal




Close up view of the disassembled camera. I was really impressed, they actually tried to make it water resistant with rubber washers and sealant around the hole the cable comes in.


    During my experimenting, I learned some things that make me a little concerned. With the X-10 video power supply, power is constantly being feed to the camera. There is a separate power line for the transmitter. When you power the "unit" on and off, only the transmitter is being powered on and off. Anyone familiar with RF emanations may be concerned about the tempest issues this raises... The cable and housing of the camera unit is not shielded, so it is surely leaking the video and audio signals into the surrounding areas. What this means is that while you may only have one camera "on", someone could still be picking up every one of your camera's signals and watching you. While most morons probably don't even realize that people can pick up their 2.4GHz X-10 video signals from the street, this makes the problem even worse. If you use camera's to keep tabs on children or the like, you may have camera's installed in places like your own bedroom. While you probably don't leave that camera on very often, you are still exposing yourself and your loved ones to intrusion now that this tempest issue lurking. Or maby that kind of thing turns you on, but personally I don't care for it ;-).

    I may investigate the power supply and see if I can "patch" it so the camera is turned off as well. There must be a reason for them to have done this, I am curious now. I could maby see them having interference problems from the transmitter and needing a separate power line, I will post more if I look into this further.


    Did some war driving last night/this morning, found 112 AP's in my town. That's double what we had over the summer, these college kids will make the winter interesting :-). We also found 3 X-10 transmitters in town. One was probably spying on a neighbors window, another was a store security camera, and the last one was possibly operated by the town as it was mounted in public view and observed traffic in a congested area. We managed to record some video of ourselves driving through the intersection, and also noticed that it could swivel. We now have to investigate what freq's control its movement :-).

    Ok, back to business. Here are the wires as they exist in my camera/transmitter:

        Yellow = video
        White = audio
        Red = camera positive
        Blue = ground
        Black = ground

    Black and Blue are ground wires, but I don't know for which signals. They are soldered together on the same pad so it shouldn't make any difference.

    I have managed to send video from my DVD player over the transmitter. It works pretty well, however don't expect DVD quality on the receiving end. Below are some snaps from my test signal with WinTV. Of course, nothing else but War Games could be a proper video signal for this project ;-)




I am having trouble with the audio though. I was able to see the audio signal on my scope coming out of the camera, but for some reason I can't feed it directly into the transmitter from the DVD. The line-level for the video out of the DVD player is fine as-is, maby the line-level audio signal isn't powerful enough to register with the transmitter.


More coming as I actually do it...



Other projects coming in the near future

I want to attach a better antenna to the receiver unit. It looks like there has already been a lot done with this, so my work is mostly follow-the-leader here. I will probably be using the Pringles Can methodsince it's very close to the frequencies X-10 uses, plus I'm a cheap bastard ;-).

More coming as I actually do it...

Other good resources of info for stuff like this

Antennas: http://www.gladwyne.com/Antennas/

Microwave Video Scanning: http://www.geocities.com/ResearchTriangle

Other microwave video products: http://www.supercircuits.com

General S-band fun: http://ourworld.compuserve.com/homepages


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