Marshall Co - 156.1800

[eea123]

Hello,

We have been having an ongoing problem with a periodic unknown transmission interfering with our radios at 156.1800. Our local radio provider has not been able to track the transmission source.

I wanted to see if this group might be able to help. I logged the following this morning on 9-23-11:

8:09 am - 2 sec burst
8:13 am - 3 to 5 sec burst
8:14 am - 3 sec burst

I have been told that this is interference is occurring on most all of the local 15X frequencies. I have heard that it is "skip" from other towers, but also that it could be a local GPS signal?

Thanks,
Ed Andrews, County Engineer

 

[N9JIG]

Ed: Is it coming thru the repeater? If so is it coming thru all the satellite receivers (if you have more than 1...)

If it is coming thru a single receiver could be crosstalk on the phone lines or a too tight squelch.

 

[eea123]

We are certain it is coming through multiple receivers: all of the trucks hear it regardless of where they are deployed, as well as the base radios in the shop & office. We have also verified the interefence with multiple departments within the County, as well as even to some of the surrounding ones.

I'll have to check on the repeater and any satellite connections. I understand we have two towers in the County. This is where my knowledge starts to tap out.

 

[N9JIG]

If it is coming thru multiple receivers then it is probably an RF signal on the input frequency, and, assuming the receivers are PL protected (they almost certainly are) the signal has to have the same PL. This rules out random RF noise, so it is likely one of several issues:

Rogue radio (intentional or not). Sometimes a low voltage or other electrical issue in a car will cause a radio to transmit.
Outside users on the same freq (Check for other users of that freq and PL). If conditions are good they can be from hundreds of miles away.
Adjacent channel users with the same PL.


My family had quite a bit of farmland in and around Varna, spent a lot of time riding horses there and biking over to Lacon. Had a lot of fun there as a kid!

 

[Starcom21]

IF the actual input tone is 206.5, then:

Search Results for 159.075 in (the Entire Database) with Tone: 206.5 PL

Freq Out Freq In Tone Callsign Description Category Agency/County State
154.74750 159.07500 206.5 PL WPXB827 Bullhead City FD - Tactical Bullhead City
Mohave County Mohave
AZ
154.98000 159.07500 206.5 PL WPQI653 Butler Co Fire Dispatch Fire
Butler County Public Safety Butler
KY
The actual license: http://www.radioreference.com/apps/db/?fccCallsign=WPQI653
is for wideband DATA/Digital only, no voice.

155.02500 159.07500 206.5 PL WQEA497 Fire/Rescue - Dispatch Smith, County of
Smith County Smith
TN
156.16500 159.07500 206.5 PL KVZ585 Beckley Street Department Public Works
Public Service Raleigh
WV

If input is 88.5 then
Search Results for 159.075 in (the Entire Database) with Tone: 88.5 PL

Freq Out Freq In Tone Callsign Description Category Agency/County State
156.10500 159.07500 88.5 PL WPJU572 DeSoto Parish Road Department De Soto, Parish of
De Soto Parish DeSoto
LA
156.18000 159.07500 88.5 PL KNCS266 ESDA / Highway Department / Sheriff Alternate (206.5 PL on input?) Marshall County 911 / ESDA
Marshall County Marshall
IL
156.18000 159.07500 88.5 PL KSD543 Highways Green, County of
Green County Green
WI

The only adjacent channel problem (according the the DB) would be:
151.18250 159.06750 206.5 PL KFI652 Beloit FD Local Fire Departments
Government and Safety Services Mahoning
OH