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Author Topic: Interference  (Read 197 times)
N9KZN
Member

Posts: 3




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« on: October 05, 2003, 01:22:02 AM »

Is there a way to identify an analog ham transmitter (any ham band) with an ID schema?
It’s rumored that there is test equipment that will identify such an analog transmitter.

It’s understood that one needs to identify per the rules, as the FCC requires.
Is there is an imbedded ID scheme within an analog transceiver?
Self-built kits, as I recall don’t have identities, how about manufactures?

The reason for asking, a local ham is claiming that he can identify an offending
transceiver for not  properly providing an ID as required.

It would be nice, but who’s charged in tracking ownership of transmission equipment.  A recorded audio signature may be useful in identifying an offender. A foxhunt is an alternative to find an offender. As always with interference one should file an interference report with their local repeater operator or FCC. Providing the time, date and frequency. If possible, listen to the input frequency on a repeater for more direct information.
--
de n9kzn@ hotmail.com
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K9KJM
Member

Posts: 2416




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« Reply #1 on: October 05, 2003, 02:06:45 AM »

There are lots of ways to get to those who would
fail to ID, Interfere, etc.  
http://www.motron.com/TransmitterID.html
Is one of many schemes to ID transmitters.
There are lots of others......   Fox hunting
is a great sport!
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RobertKoernerExAE7G
Member

Posts: 1435




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« Reply #2 on: October 05, 2003, 03:00:25 AM »

"The reason for asking, a local ham is claiming that he can identify an offending transceiver for not properly providing an ID as required."

Bad tranceiver!

Some hams will say anything.

Read a ham ad for a New Rig, it was only USED for 2 hours.

73
Bob
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AA4PB
Member

Posts: 12644




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« Reply #3 on: October 05, 2003, 11:11:59 PM »

No ham equipment in the U.S. is required to have an imbedded ID. There is software available that can analyze and record various characteristics of the transmitter (mostly key up characteristics). Using that you may be able to reasonably identify a transmitter that you have previously recorded. It's similar to a human fingerprint but not nearly as accurate because many of the signal characteristics can change with time and temperature.
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WB6BYU
Member

Posts: 12986




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« Reply #4 on: October 06, 2003, 04:01:43 PM »

The Motron units implement the "transmitter fingerprinting"
methods developed by K7PF (Huh). They plot the
frequency changes when a transmitter is keyed.  I saw
a demo at a hamfest, and you could generally tell
different models of the same rig apart when looking
at the plots on a scope.  (And in many case you could
identify that the plots were from different units of
the same model radio.)

This shouldn't be too difficult to do yourself by
hooking up a triggered sweep scope to the discriminator
output of an FM receiver.  The difficult part is trying
to digitize the result, store it for known users, then
automatically record the signature of an interfering
station and compare it against the stored records.

It certainly is not infallible, since there are a couple
ways to confuse the system.  (It must detect the
key-up to get a plot.)  But it can be useful in many
cases when someone uses the same radio for identified
and non-identified transmissions.

Just like everything else, you want to have a wide range
of tools at your disposal.  Fingerprinting is one of
them.  Foxhunting is another.  Both require practice
to be good at them.  It is sometimes amazing how many
repeater problems disappear when a local club starts
holding regular transmitter hunts, even when (as it
should be) no mention is made of interference tracking
in conjunction with the hunts.  For more information
or ideas about transmitter hunting try www.HomingIn.com
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