On many occasions whilst doing ARES/RACES/RayNet type activities I've thought that it would be a good idea to record the proceedings. The problem is that the recording needs to be of the whole event which can be hours long and so wel out of the realms of a simple cassette recorder. Also, the recorder has to be placed in such a possition as to be able hear all the station involved in the event.

This need was demonstrated to good effect recently when my local ARES team was invovled with a Half Marathon event in Staten Island. One of the competitors dropped down dead of a heart attack. This resulted in much finger pointing at the various agencies whom together we very tardy in handling the call for help. If they had a recording mechanism ARES could have proved that they did their job in short order. Thankfully nothing became of the finger pointing.

One of the events that I'm involved in is the New York City Marathon which is held every year in (you guessed it!) New York City. The group I'm involved with handles all the "Start Event" comms within the confines of Fort Wadsworth on Staten Island where the Marathon starts. This year I was the Net Control Operator and handled about 15 Hams littered around the Fort and the Verazano Bridge Toll Plaza. I also had stations passing through whom were attached to various elements of the Marathon organisation, the Mayor of New York City, and the various chase and lead vehicles. So with the Net Control job in mind I set about constructing a recorder capable of recording the radio traffic for the entire operation.

The result is what you see on the left. Its basically a VCR with a Police type Scanner and a video overlay board attached. The VCR was a cheap and cheerful Sharp VC-A410 4 head device that I bought at a local Electronics store for $35. It is a mono device but is capable of Long Play/Record and so a T-180 video tape can be made to record for up to 8 hours with fairly low video quality. Added to this was a police type scanner radio. It was tuned to the Net frequency of 144.335MHz FM and the received audio was fed to the VCR's Line In port. It was at this point that I had 2 problems. 1) The VCR wouldn't record anything unless there was a picture present; 2) How would I know where in time I was when listening to the tape? So I set about building a time source that could be displayed as a picture thus fooling the VCR into recording something. I still have some of my old ATV gear kicking around and so I started with that. The picture you see on the left is actually made up of 2 devices.

The lower half of the picture is a video overlay board from icircuits.com. I can change the information on this device to say whatever I want. As you can see, I configured it to ident the tape with the event name, location, date and frequency information. The board is also configured to display the information on a blue background. Other options could be to have it superimposed upon an incoming picture such as a CCTV camera. I did briefly think about feeding the NBC coverage of the Marathon into the system but as we started at 0400EST and the coverage didn't start until 0800EST it became a mute point. The overlay board is programmed by a Windows application over the serial port. This poses me a problem as I'm a Linux user. I had to start a whole new adventure with an application called Wine that would allow me to run Windows applications on Linux. If icircuits.com are reading this please make note that you live in a multi OS world and please do some cross compiling (it works fine under Wine though).

The upper half of the picture is a GPS overlay board from blackboxcamera.com. When fed with a 4800bd NMEA GPS signal is produces the overlay as seen on the left. Position, altitude, speed, course, ident and of course the time/date. This device requires that it be fed by a picture as it must use the incoming sync pulses to output its bit train onto the picture. It has very few options and unlike the ident board it can be programmed by a Linux machine. It uses commands sent down the serial cable from a terminal program. I used Minicom and all was fine. The observant ones amongst you will have noted that there are 2 separate callsigns displayed in the final output above. The reason for this was simple. We use the club call when doing events such as the Marathon but it could be any one of us that operates the call. As I foresaw the tape being used as evidence I thought it useful to identify both the station and the operator. You never know ...

The project took a little less that 2 weeks to get together. I already had the boards and the VCR I just had to wire it all together. The icircuits.com board comes as a plain board but the GPS board comes in a box as shown in the picture. I chose to put both boards into a single housing that could sit on top of the VCR. Added to the mix was a 9 inch portable TV set so that I could see everything was working. The TV set had 3 purposes on the day. It allowed me to check on the recorder system as well as use the clock for the net time stamping. I could also watch the Marathon coverage on the TV. Net Control is a very disconnected job and one has no view of the event from within the Control caravan.

This is what happens when the GPS drops out.	And then it does this after 30 secs of no GPS.
This is the block diagram thingy-whatsit.	This is the whole shebang.

 Future improvements may include changing the mono VCR for a stereo one as there is a LMR net going on concurrently with the Ham Radio Net.

© & ® Mark A Phillips, G7LTT 1995-2005
This page was last updated Friday January 28, 2005 06:29 Eastern Standard Time