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                      THE CGC COMMUNICATOR

                            CGC #432

                   Thursday,  February 8, 2001

                 Robert F. Gonsett, W6VR, Editor

     Copyright 2001, Communications General Corporation (CGC)

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  SAN DIEGO MICROWAVE INTERFERENCE ALERT

  Cox Cable/San Diego is taking interference hits about once
every 15 seconds on their C-band satellite downlink receiver
in El Cajon (relatively low elevation site).  The interfering
pulses unlock reception of certain digital TV channels which are
carried on the Cox system.  Initial reports indicate that C-band
equipment at Time Warner Cable and KUSI(TV) is also being
adversely affected by the pulses.

  Work by Cox suggests that the pulses, as viewed from El Cajon,
are coming from the direction of San Miguel Mountain and that they
are in the 5 GHz region.  The interference has been received
intermittently over the past week and is usually present in the
noon to 3 PM time frame.  (On Wednesday, February 7, the pulses
were still on at 5 PM.)

  Anyone with information to add to this case is asked to
contact Robert Lonn at Cox by e-mailing:  Robert.Lonn@cox.com 
Please include your telephone number.

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  FURTHER INFORMATION

  While the above account is the "official version" of the
interference episode, other opinions exist.  The report from
one Cox engineer who observed something different is as follows:

   "The interval of repetition is around 10-15 seconds.  I
   haven't observed (the interference) personally on 5 Gig,
   but on 1.5 Gig last Friday."

  Sometimes in microwave cases, the frequency of the
interfering signal can at first be difficult to determine.
For example, observing the interference through a LNB can
give one result (consisting possibly of image products), while
observing the unwanted signal directly can lead to another
result.

  One way or the other, we are dealing with a serious ongoing
interference situation, and all input is welcome at this stage.
Please reply to Robert Lonn as indicated above.

  -Ed.
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