I can't claim any originality for this project but I can claim to have improved upon it and given some folks a bloody good laugh at the same time. "What's an ATV HatCam?" you ask. Well, its a camera on a hat that uses Amateur Television to send its pictures to a TV set. Amateur Television is part of Amateur Radio. Hams have been sending pictures to each other for over 50 years.
OK, lets get to it. Firstly take a look at this PDF document from PC Electronics. These guys probably didn't come up with this idea either but this is where I started. As you'll see from the document its quite a simple setup. BEWARE! Whilst its simple to make its not cheap. If you have to buy everything it'll set you back about $200. Mine cost $250.
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So here it is. The KC2ENI variant ATV HatCam. As you can see
its just a construction hat with a camera and an antenna on top. I used the wide brim
"Pith Helmet" type that you can get from most Do-It-Yourself stores like Home
Depot (B&Q to us Brits). Inside the hat is a Video-Lynx 100mW TV transmitter which you can also get at MFJ and some other places. It outputs the picture on 433.97MHz so it can be used the world over on 70CMs. This also works out to be cable TV channel 59. Also included is a caption generator or "Down Stream Keyer" that puts my callsign and the time and date onto the picture. This is especially useful as the law here in the States requires the picture to be visually identified. Normally one would do this by holding a card up with one's call letters in front of the camera at the appropriate time but I can never remember to do this. The transmitter has no audio facilities so Morse ident is out of the question. This is the caption generator |
So why does mine vary from the original document? For a start mine has the DSK added. But it also has some other abilities. The picture on the left shows the buttons, switches and sockets on the back of the HatCam. To the left is the power switch with its light. In the middle are a switch, a phono socket and a 5 pin DIN socket. The switch selects the picture source. This can be from the built-in camera or from the phono socket. It allows me to use a camcorder instead of the built-in camera. The 5 pin DIN plug allows me to supply external power for longer periods instead of using the internal batteries. It also allows me to charge the internal batteries too. The buttons on the right allow me to program the DSK with the time and date plus whatever message I want to have on the screen. Mostly it'll display my callsign. |
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The camera is a CCTV camera that I got from Ebay. It needs a 5VDC power supply which is a problem as the rest of the HatCam runs at 9VDC. You'll notice a screw head on the right of the camera. This is holding down a 7805 regulator to convert the power from 9 to 5VDC. Power is supplied by 2 PP3 type 9VDC batteries wired in parallel. The 2 batteries give me extra current which should sustain the operating life of the HatCam. I can get about 24 hours out of the HatCam on a fully charged set of batteries. On the top of the hat I installed a BNC antrenna connector so that I could fit a Rubber Duckie antenna. In an effort to get the most out of the antenna I lined the inside of the hat with tin foil so as to create a "ground plane" for the antenna to work against. This can add as much as 3db's to the signal level so its worth the hassle. I said earlier that it cost me about $250 to build. Why so much? Lets take a look. I had to buy everything from scratch apart from the switches and sockets etc.
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© & ® Mark A Phillips, G7LTT 1995-2004
This page was last updated Saturday October 09, 2004 12:24 Eastern Daylight Time
