794 MHz ARMER?

[baboehrs]

Last Friday, I was in downtown Minneapolis waiting for my wife to finish her dentist appointment. I was parked in an underground parking ramp waiting for her, but I thought I would do some searching around just to see what hits I could get. I stumbled upon a pair of frequencies in the 794 MHz range that sound like they are part of a trunking system. Since then, I have been receiving several hits on the one (the other could be a control channel) that sound amazingly part of the ARMER system. Sure enough, today I heard teh Minneapolis fire department paged on the one frequency. I just checked the database, and there aren't any frequencies that I could see that get out of the 800's. So what gives? Is this some testing being done on 700 MHz public safety when the TV signals are gone? Give a listen to the following:

794.559375
794.059375

-Bruce

 

[unclebubba]

700 MHz freqs are a part of the ARMER system.
http://www.srb.state.mn.us/pdf/ARMERProject-PlanExhibit-7-FreqAssignments.pdf

 

[baboehrs]

But you're missing my point, unclebubba. I know that ultimately the frequencies are moving to the 700MHz range due to TV vacating the spectrum. However, the official TV switchover date in next February, and all (at least according to my quick inspection) official ARMER frequencies are in the 850MHz +/- range. Why did I find one at 794? Is this some sort of advanced testing? Is RadioRefernce behind (I have found several dozens of talkgroups that aren't identified in the database)? Does anyone know? -Bruce

 

[Raven95150]

According to the FCC database, most of the counties in the metro area are licensed on frequencies in the 750-800 range for public safety use, so it's very possible they are using some of these for testing or other purposes.

http://wireless2.fcc.gov/UlsApp/UlsSearch/searchAdvanced.jsp

 

[mikey60]

But you're missing my point, unclebubba. I know that ultimately the frequencies are moving to the 700MHz range due to TV vacating the spectrum. However, the official TV switchover date in next February, and all (at least according to my quick inspection) official ARMER frequencies are in the 850MHz +/- range. Why did I find one at 794? Is this some sort of advanced testing? Is RadioRefernce behind (I have found several dozens of talkgroups that aren't identified in the database)? Does anyone know? -Bruce

I'm guessing that you have a Pro-96 or Pro-2096? If so, you're likely receiving an image. The Pro-96 tends to do this in that frequency range.

Mike

 

[baboehrs]

Nope, I have a PSR-500. I'm convinced at this point the state radio board folks are testing out new frequencies. -Bruce

 

[mikey60]

Nope, I have a PSR-500. I'm convinced at this point the state radio board folks are testing out new frequencies. -Bruce

Odd, Typically in the 700Mhz range the base frequencies are in the 764 MHz range, and the inputs are in the 794MHz range...

Mike

 

[stmills]

Most likely you are hearing images from Metro ARMER 101 off City Center in Minneapolis.
The IF frequency of the PSR 500 is 21.4 Mhz.
794.559375+21.4+21.4+21.4= 858.759375 858.7625 Tower 101 Frequency
794.059375+21.4+21.4+21.4= 858.259375 858.2625 Tower 101 Frequency

700 Mhz band
763-768 Base/repeater 793-798 Mobile Nationwide Broadband license
769-775 base/repeater- 799-805 mobile Narrowband

The County Licenses for the metro counties are for a data network, except for 2 Hennepin Licenses for low power on scene channels and nationwide Itinerant channels.

Steve

 

[mtindor]

I'll have to agree with Mike and stmills. The PSR-500 is definitely prone to receiving images in the 79x mhz range. I see it happen all the time. What you are hearing is going to be what stmills indicated.

Mike

 

[baboehrs]

Aha! That's what I was hoping to see from this group - some long-time scanner experience coupled with some analysis! Thanks, guys, for doing some deep thinking. -Bruce

 

[mmtstc]

ARMER began migrating some of its assets to 700 MHz just prior to the RNC... There are some SOA frequencies in that range (but i wont be sharing them with everyone unfortunately...) that are starting to see some intermittent usage...