THE CGC COMMUNICATOR

                            CGC #485

                   Wednesday, November 7, 2001

                 Robert F. Gonsett, W6VR, Editor

     Copyright 2001, Communications General Corporation (CGC)



  A Letter to the Editor in CGC #484 reported that XM's
terrestrial repeaters work by overpowering the direct satellite
signals, "....swamping out receiver front ends with the stronger
local signal."  This, apparently, is not the case.

  Chriss Scherer, editor, BE Radio magazine, explains that the
terrestrial transmitters retransmit the satellite signal in a
different part of the spectrum.  The listener's receiver looks
for data in three different places (satellite 1, satellite 2 and
terrestrial) and, according to Chriss, reconstructs a single data
stream from the available pieces.  The July 2001 issue of BE Radio
explains the situation further.

  A diagram showing spectrum usage can be seen at:


  Thanks to Chriss for the clarification!



  Craig Caston (KCBQ/KPRZ) offers this link for updated northern
light photos:


  There has been a second solar storm - within days of the
one reported in CGC #484 - and Dennis Mammana was once again in
the right place at the right time to capture the effects on film.
_________________________    End   _______________________________