The following article appeared in CGC #722:

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  SATELLITE RADIO INTERFERENCE TO BROADCAST SIGNALS

  Many XM & Sirius satellite radio receivers are more like
tuners because they lack audio amplifiers and speakers. In
these cases, mini FM transmitters are often used to send the
satellite audio to an FM broadcast receiver nearby. Of course,
it is a problem when the FM signal generated in some other
guy's car captures your FM receiver and jams out an authorized
broadcast station.

  Over the past few weeks, CGC has received a few listener
complaints where the FM signal generated in one car has apparently
captured the FM receiver in another car, disrupting licensed FM
broadcast signals. If you are associated with an FM station,
have any of your listeners complained about this happening? Do
you have any reason to believe that any of the mini FM
transmitters used with the satellite tuners are a bit too
powerful (they probably radiate too well if they can be heard
100 feet away on a vacant FM channel). One client asks this
specific question: "If a brand new Sirius Sportster tuner is
taken right out of the box, what FM frequency is preset by the
manufacturer?" (Sportster frequencies are user programmable.)

  Any and all comments are welcome at this time. Please send
mailto:r.gonsett@ieee.org, and be sure to indicate if you do NOT
want your name published.

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  CGC COMMUNICATOR READERS RESPOND

  In response to the above article, several notes and letters
were received.  The notes are summarized first, followed by the
letters.

  _____


  88.1 MHZ IS THE DEFAULT FREQUENCY FOR SIRIUS STARMATES
  AND SPORTSTERS

  The default frequency for the FM transmitter in a Sirius
Starmate satellite receiver is 88.1 MHz according to the
Starmate's instruction book (first URL below, pdf page 29).
This frequency was confirmed by Dave Rickmers in an accidental
listening test. The FM transmitter is turned "on" by factory
default settings, and the FM frequency can be user-adjusted by
those wishing to do so. Dave notes that his Starmate will only
transmit about 10 feet in stereo, or 30 feet max in mono,
strongly suggesting that the Starmate is Part 15 compliant.

  The Sirius Sportster satellite receiver is much like the
Starmate. The default frequency is 88.1 MHz (even though the
unit can be user-tuned from 87.7 to 107.9 MHz), and the FM
transmitter is once again turned "on" by factory default (second
URL below, pdf page 30). However, none of our readers submitted
data indicating whether the Sportster is Part 15 compliant, so
"DX tests" (can the unit be heard 100 feet away?) are encouraged.

  One reader wondered whether the external FM transmitters
sold as accessories to Sirius and XM receivers are Part 15
compliant, or if they could be mis-installed so as to make them
non-compliant (using the car antenna as a mini broadcast station).
These are great questions that remain unanswered.

  http://www.sirius.com/pdf/manuals/Starmate_ST1.pdf
  http://www.sirius.com/pdf/manuals/Sportster_PnP_User_Guide.pdf

  _____


  KKJZ, 88.1 MHZ, LONG BEACH, NOTES SATELLITE INTERFERENCE

  "It's funny you should ask about Sirius satellite on FM
frequencies. Here's an e-mail that I received this morning
from a KKJZ listener.

  "This is the first fixed-location complaint. I have received
at least 2-3 mobile reception reports over the last six months.
Additionally, one of our staff members has described interference
while driving an Orange County freeway that she initially thought
was pirate activity, but seems to fit the description of a mobile
low power FM retransmission."

  Ron Thompson, Chief Engineer, KKJZ
  January 18, 2006


  Following is the attached listener complaint letter entitled
"Signal Overlap in L.A.:"

  "For the past week or two, off and on, I've been getting
another station on your frequency. The weird thing about it is
that it's from satellite radio. And unfortunately it's always
"Howard 100," the Howard Stern station on Sirius. The signal
comes in loud and clear and I'm not a Howard Stern fan.

  "I called your front office last week to report it, but I
don't know if it ever got passed on to your engineers. It used
to only happen late at night - now it's happening as I write this
(7:39 am). I just thought I'd write and let you know."

  [Name and L.A. address were given - letter dated
  January 18, 2006]

  _____


  RELIGIOUS NETWORK NOTICES INTERFERENCE

  "We've had it both ways - listeners complaining that we're
interfering with their Sirius/XM as well as complaining that
Sirius/XM is interfering with their reception of our signal.
We even had one guy who apparently commuted at almost exactly
the same time as someone else most days, so he'd get random
interference along the drive whenever the other guy was close.

  "We've had similar (but fewer) problems with the CD players
that transmit to the car radio.

  "The challenge is worsened with fixed frequency transmitters
(or with ones where the listener isn't technically savvy enough
to know how to retune it). We have to persuade them to return
to the vendor for resolution. Can be quite the challenge."

  Paraphrased P.S.:  Most of the interference was reported on
88.1, 88.3 & 88.5 MHz. Once in a while other frequencies in the
non-comm band were mentioned. Some of the offending transmitters
only work in the non-comm band, much to my chagrin!

  [The author is the engineer in charge of a religious
broadcasting network and asked that his or her name be
withheld. Letter dated January 18, 2006.]

  _____


  KWVE REPORTS SATELLITE INTERFERENCE

  KWVE, 107.9 MHz, San Clemente (transmitter atop Santiago Peak)
reports being hit by satellite interference. The latest episode
was a one-time event involving a dedicated KWVE listener stuck
in a left turn lane for about two minutes in the Santa Fe Springs/
Downey area. Just as KWVE's Pastor was reaching his main point,
Howard Stern's audio jammed out the sermon, and the interference
continued until the traffic light changed and the vehicles began
moving again. The listener, involved with Childrens' Ministries,
was not amused.

 

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