RECCOM: Recording Communications



Radio Shack PRO 2042 1000 channel base unit     and    Uniden 55XLT

MADAR HQ uses a Radio Shack PRO 2042 1000 channel base unit, scanning 24/7, 10 specific aircraft frequencies (local approach & departure), Indianapolis Center, Memphis Center, Kansas City Center. This covers our region very well. We also use a hand-held Uniden 55XLT  scanning 24/7 the local law enforcement frequencies. Audio feeds from both units are fed into a Teac dual cassette recorder with the rec button depressed and the power cord plugged into the new Adafruit/Memorex Power Center set-up. When MADAR trips, the MPC turns on and records transmissions until the anomaly is over, plus an additional 5 minutes (command is built into MADAR s/w). To playback into computer we utilize the Audacity program to fast-forward the communications and/or record any important transmissions. The beginning of the tape is also time-stamped in UTC by the recorded time of the Alert Start on the MADAR Site spreadsheet.

Of course the beginning of a great monitoring system is the antenna. We made an indoor folded dipole (24") and tee'd it off for both scanners and get fantastic reception. If you have a way of putting up an external antenna, that would be much better but the indoor FD works very well. But the idea to build one in an area where there was no option to put one on a roof led us to these products. The first one I purchased (2) worked well, VERY well, for MADAR and the Lunascan Project.  The antennas pull out and were mounted vertical. One was mounted in the house near the MADAR equipment, the other inside the Lunascan trailer. The second link explains how to measure the lengths and build a folded dipole.

Bet you've seen one of these!

These were push-on connectors that were matching transformers for 300 ohm flat antenna wire to 75 ohm coax. They slid over the male coax connector on the back of the VCRs, but few ever used them. By putting two 24.5" solid wires on these and having them verticle, and sliding a coax coupler into it, the other male coax connects to a normal TV cable which runs to the scanners. If you work with scanners you know how to make a "Y" at the end and have two lines go out to the bayonet connections.

Since the two audio feeds are running live 24/7, we split the feeds into two each and run the second set to a pc. At any time we can watch and graph using the free Audacity program. And since the pc audio has wireless headphones, this can be done without disturbing anyone in the room.