        Aerial Video Services, out of Burbank, California, is
     major supplier of the in-car cameras, wireless cameras
     and communications links for the television coverage of
     auto racing and other sporting events. During a recent
     racing series at the Texas World Speedway, AVS provided
     the microwave and communications equipment for the Prime
     Network television coverage of the races. I had a chance
     to work with the AVS crew, and check out their radios.
     If you get to attend a sporting event where wireless
     cameras or mics are in use, you might check out some of
     these frequencies.

       Let me explain a little about the equipment they are
     using, and what you might hear. Any time there is a
     wireless camera in use, they will be sending the
     pictures from the roving camera location to the TV
     remote truck on a microwave link. They may use the
     2 to 2.5 gHz or 7 gHz microwave bands. In addition to
     pictures from the camera, there has to be voice
     communications to the cameraman, and sound from the
     announcer's microphone, who may appear on camera, and a
     cue channel to the announcer, so he knows when he is on
     the air. The communications from the TV director to the
     cameraman are usually referred to as the "PL". This
     stands for "party line", and is a two-way communications
     link with the director and the camera operator. It is
     usually set up as a low-power repeater, so you will
     always hear the directors calls, and the camera
     operators replies. The cue channel to the announcers is
     called the "IFB", which stands for "interrupted feed-
     back". This is usually the audio from the program that
     is being produced, along with the director or producer
     interrupting the program feed, in order to give cues to
     the announcers. This transmitter will be on as long as
     the TV production truck is operating.

        AVS uses mostly I-COM programmable radios. Here are
     frequencies that are programed into the units...

        Channel   Frequency
           1       457.525 - This ch.used for IFB 10/18,19
           2       457.550
           3       457.575
           4       457.600
           5       467.750
           6       467.775
           7       467.800
           8       467.825 - Car camera control data
           9       467.850
          10       467.875
          11       467.900
          12       467.925 - AVS tech communications
          13       467.7375
          14       467.7625
          15       467.7875
          16       467.8125

     They also have radios programed in the 450 - 455 mHz
     Broadcast Remote Pick-up bands. At the racing I attended
     they used 455.350 as the P.L. communications to the pit
     camera. 450.350 was the input frequency to the repeater.
     Why they used the frequencies "backwards" from what the
     normal repeater frequency scheme would be isn't known.
     The car camera control data uses a 10-watt base station
     that transmits control tones to the cameras in the cars.
     You will hear a continuous carrier with DTMF (Touch-
     Tone) audio tones as the commands are sent. The
     microwaved pictures and sound from the in-car cameras
     are beamed up to a helicopter that has a microwave
     receiver on board, and then re-transmitted back down to
     the TV production truck on another microwave frequency.
     The TV truck used 123.050 to talk with the helicopter.

       The wireless mics that the roving announcers may use
     are Sony UHF mics in the 950 mHz band. Here is the
     channel allocations for the USA.

        Channel   Frequency
          11       947.250
          12       948.250
          13       950.250
          14       951.750
          15       949.000
          21       947.750
          22       949.750
          23       950.750
          24       951.250
          25       948.500
          31       949.250
          32       948.750
          33       950.000
          34       951.500

       Also, for you race fans who may end up at some SCCA
     racing events, here are some assorted track frequencies
     in use at the Texas World Speedway, in College Station,
     Texas.
        151.625 - SCCA Race Control Primary
        151.685 - SCCA Secondary
        151.715 - SCCA
        464.500 - Texas World Speedway
        464.550 - Texas World Speedway

       To sum up, check all of the above frequencies for
     activity next time you are at the races, or any other
     major sporting event where there might be some wireless
     cameras wandering around!
