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General Scanning Discussion For general questions not specific to a model of scanner or general discussion of use of a scanner. Location specific posts should be directed to the regional forums listed below.

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  #1 (permalink)  
Old 08-27-2014, 8:11 PM
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Default Police (UHF) Frequencies -- What is their repeater offset??

Recently became interested in listening to local law enforcement frequencies. It seems that all the frequencies listed in various online databases are the repeater input frequencies, as all I can hear are dispatch. Not individual officers.

This is in the UHF band.

Does anyone know what the offset is? I am trying to hear the repeater output frequency.

I thought it was 5 mhz, but don't hear anything so could be wrong.


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Old 08-27-2014, 8:56 PM
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In the UHF band, the lower of the listed frequencies should be the repeater output. Thus 453.300 and 458.300 as a pair, you should be listening on 453.300 mhz.

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Old 08-27-2014, 9:25 PM
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Quote:
Originally Posted by rescuecomm View Post
In the UHF band, the lower of the listed frequencies should be the repeater output. Thus 453.300 and 458.300 as a pair, you should be listening on 453.300 mhz.

Bob
Thanks Bob. Guess I'm not seeing a range in any listing of police frequencies. So is it safe to assume the offset is always 5mhz?
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Old 08-27-2014, 10:08 PM
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453.0125-453.9875 and 460.0125-460.6375 are the outputs of typical UHF public safety radio system repeaters. The inputs are 5 MHz higher, at 458 and 465 MHz respectively.
That said, some agencies (L.A. County Sheriff comes to mind, who are in the UHF-T band at 483 and 486 MHz IIRC) use a two-frequency simplex system, or have the capability to disable the repeat function, where you have to have both the output and input frequencies programmed in, and be within range of the officers mobile and portable radios, in order to hear both sides of the conversation.
Another possibility comes to minnd. Is it possible that that agency has both an older UHF system that the dispatchers still multicast on, as well as a newer 700 or 800 MHz trunked system that does not patch the officers back to the older UHF system?
What radio system(s) are you trying to listen to?
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Old 08-28-2014, 12:14 AM
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Quote:
Originally Posted by KB7MIB View Post
453.0125-453.9875 and 460.0125-460.6375 are the outputs of typical UHF public safety radio system repeaters. The inputs are 5 MHz higher, at 458 and 465 MHz respectively.
That said, some agencies (L.A. County Sheriff comes to mind, who are in the UHF-T band at 483 and 486 MHz IIRC) use a two-frequency simplex system, or have the capability to disable the repeat function, where you have to have both the output and input frequencies programmed in, and be within range of the officers mobile and portable radios, in order to hear both sides of the conversation.
Another possibility comes to minnd. Is it possible that that agency has both an older UHF system that the dispatchers still multicast on, as well as a newer 700 or 800 MHz trunked system that does not patch the officers back to the older UHF system?
What radio system(s) are you trying to listen to?
LA Sheriff is a good example. I am in LA, have attempted to figure out their system. I thought they use the usual repeater system. What I thought were the inputs being listed on all the different LE frequency listings... it would be easy to find where everybody is being repeated... just add 5 MHz and whalaaa... I have the output. But it wasn't working. So... what you suggest might be reality. They might be using a simplex system and/or using a newer trunked system that doesn't patch the officers back through what dispatch is using.

Hmm...

I'll try again tomorrow. Thought it was simpler.
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Old 08-28-2014, 5:34 AM
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Offset - The RadioReference Wiki

Maybe your Agency disables the Repeater?
If you are hearing Dispatch then you have the Output

What Agency/Frequencies?

Quote:
Originally Posted by drew4392 View Post
Recently became interested in listening to local law enforcement frequencies. It seems that all the frequencies listed in various online databases are the repeater input frequencies, as all I can hear are dispatch. Not individual officers.

This is in the UHF band.

Does anyone know what the offset is? I am trying to hear the repeater output frequency.

I thought it was 5 mhz, but don't hear anything so could be wrong.


Thank you!
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Old 08-28-2014, 9:01 AM
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Originally Posted by ecps92 View Post
Offset - The RadioReference Wiki

Maybe your Agency disables the Repeater?
If you are hearing Dispatch then you have the Output

What Agency/Frequencies?

Thanks for the link. It seems 3MHz could be it, as well.

My thought was since I was hearing dispatch, perhaps I was only hearing repeater input. Dispatch probably has stronger base stations.... or I am more line-of-sight with them and not patrol units. Otherwise, if I was listening to the repeater output frequency, I'd hear everybody. No?

LA Sheriffs -- https://www.radioreference.com/apps/db/?ctid=201

482.9125, specifically.

Thanks for the help, guys
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Old 08-28-2014, 12:03 PM
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Quote:
Originally Posted by drew4392 View Post
Thanks for the link. It seems 3MHz could be it, as well.

My thought was since I was hearing dispatch, perhaps I was only hearing repeater input. Dispatch probably has stronger base stations.... or I am more line-of-sight with them and not patrol units. Otherwise, if I was listening to the repeater output frequency, I'd hear everybody. No?

LA Sheriffs -- https://www.radioreference.com/apps/db/?ctid=201

482.9125, specifically.

Thanks for the help, guys
It looks like the whole system is explained here:
Los Angeles County, California (CA) Scanner Frequencies and Radio Frequency Reference
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Old 08-28-2014, 3:12 PM
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Yup, Repeaters are Disabled

NOTE: Mobile traffic is not rebroadcasted over the output frequency of the dispatch channels. Instead, only a beeping tone is broadcast to signify to the field units that someone is talking. To monitor units in the field you must program in the input frequencies also. The corresponding L-TAC channel is included in brackets.

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Old 08-30-2014, 8:58 PM
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As others have said, plug in the input frequencies for LASD and you'll hear the officers talking. Well, only if you're close enough to hear.


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Old 08-31-2014, 3:35 AM
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And yes, it's a 3 MHz split in the UHF-T band between 470-512 MHz.
It's 5 MHz between 450-470 MHz.
If we had know what agency or specific frequency band you were asking about, you probably would have had the correct answer a little quicker
Just for future reference.
Good luck now that you have the answer!
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