Repeater Question

[cookiend15]

Hello fellow scanners. I'am looking for some input on a question. My question is when there are 2 or more frequencies assigned how do you know if one of them is a repeater frequency. Case in point below.

Amsterdam Fire Department

453.3875 (203.5 PL) Amsterdam Fire Repeater
458.3875 (203.5 PL) Amsterdam Fire Input

So only the repeater frequency needs to be monitored and you will still hear all of the action.

State Police Troop G Zone 3 Princetown

154.680 (167.9 PL) Car-To-Base
155.445 (167.9 PL) Base-To-Car

Now with the state police having 2 frequencies you will need to monitor both frequencies in order to hear all of the conversation, however with the Amsterdam Fire Department you only need to monitor the repeater frequency of 453.3875 (203.5 PL) and you will hear both ends of the conversation mobiles-to-base and base-to-mobiles. So my question is when 2 or more frequencies are used how do you know if one of them is a repeater.

Thank you.

[jim202]

The normal way of doing things at UHF are input high, repeater output low. You
listen to the repeater output.

At VHF it's any ones guess what channels are the correct one to listen to are. If
you get a split channel operation like your showing for troop G, you will need to
try and grab both channels. Many times these split operations don't always use
a repeater.

Jim

Originally Posted by cookiend15

Hello fellow scanners. I'am looking for some input on a question. My question is when there are 2 or more frequencies assigned how do you know if one of them is a repeater frequency. Case in point below.

Amsterdam Fire Department

453.3875 (203.5 PL) Amsterdam Fire Repeater
458.3875 (203.5 PL) Amsterdam Fire Input

So only the repeater frequency needs to be monitored and you will still hear all of the action.

State Police Troop G Zone 3 Princetown

154.680 (167.9 PL) Car-To-Base
155.445 (167.9 PL) Base-To-Car

Now with the state police having 2 frequencies you will need to monitor both frequencies in order to hear all of the conversation, however with the Amsterdam Fire Department you only need to monitor the repeater frequency of 453.3875 (203.5 PL) and you will hear both ends of the conversation mobiles-to-base and base-to-mobiles. So my question is when 2 or more frequencies are used how do you know if one of them is a repeater.

Thank you.

[cookiend15]

Originally Posted by jim202

The normal way of doing things at UHF are input high, repeater output low. You
listen to the repeater output.

At VHF it's any ones guess what channels are the correct one to listen to are. If
you get a split channel operation like your showing for troop G, you will need to
try and grab both channels. Many times these split operations don't always use
a repeater.

Jim

Jim,

Thanks for your input to my question. Yeah my main problem is with the 150-160 Mhz VHF frequencies in trying to find out what frequency is the repeater and which frequency is the input. Like in the case of the Montgomery County sheriff, there input frequency is 156.090 (127.3 PL) which you can hear only when the MCSO mobiles are close enough to you, and there repeater frequency is 154.785 (127.3 PL) which you can hear both the mobile-to-base and the base-to-mobile end of the conversations on clear as day. Now on the other hand with the Mid County Ambulance there input frequency is 151.415 (151.4 PL) which you can only hear when the mobiles are close enough to you, however there repeater frequency is 158.760 (151.4 PL) which you can hear both ends of the conversation on clear as day. so it seems to me that with regards to the 150-160 Mhz VHF frequencies the repeater frequency can either be the higher or lower frequency, and thats my main problem (trying to figure out which frequency is the repeater, and which is the input frequency. It does not seem as simple as you stated with the UHF frequencies, the input being the higher frequency and the repeater being the lower frequency. I'am just trying to make sense of the whole thing with trying to figure out which frequency is the repeater when 2 frequencies are used in the 150-160 Mhz Range.

Chris

[silverbk]

There is no set standard in the vhf portion of the spectrum.

Methods I have used:

Look up the station in the FCC ULS database. There you will see which frequency is licensed for mobiles and portables and which is licensed for a high power base.

Listen to both freqs, your scanner will stop on the repeater freq way more often. You will be able to hear the repeater (with practice). They hum, kerchunk and sometimes have courtesy tones.

Take a frequency counter and have a cop or FF key up their radio. The reading you get will be the input.

You generally only need to monitor the output of the repeater, unless you have a situation like FDNY where you would want to monitor a mixer off message, in this case you need the input freq.

[902]

Originally Posted by cookiend15

Now with the state police having 2 frequencies you will need to monitor both frequencies in order to hear all of the conversation, however with the Amsterdam Fire Department you only need to monitor the repeater frequency of 453.3875 (203.5 PL) and you will hear both ends of the conversation mobiles-to-base and base-to-mobiles. So my question is when 2 or more frequencies are used how do you know if one of them is a repeater.

UHF and 800 MHz usually use repeaters for their communication, unless it's for fireground or other local application.

There is no guarantee on VHF that an agency with two frequencies is using a repeater. State Police agencies seem to be comfortable with using semi-duplex, which is a mode where the base is on one frequency and the mobiles on another. St. Louis (city) Fire Department uses that, too. So do some taxicab fleets. The dispatcher parrots what someone says on the "talk-back" channel. I can't for the life of me figure out how, exactly, removing the emphasis of an original speaker's voice enhances safety, but it makes sense to someone (and that doesn't have to be me).

The definitive way to tell if someone is using a repeater or not is to go into the FCC database and see if there is an FB2 (a repeater) or an FB (just a regular base station) licensed. The thing is that with console patches and other temporary patching stuff, you can hear what you think may be a repeater, but is only a function of a console or matrix. Those do not need to be licensed as FB2. There are also special types of repeaters, like FB6, FB8 and similar.

[studgeman]

The short answer of how do you know what to listen to? LISTEN TO IT, find out how the system acts then go from there. FCC license infromation should always be taken with a grain of salt.