I was listening to close to two hours of traffic on a FBI channel and realized that I could only hear the street agents. They would be responding to a dispatch which I couldn't hear but I could hear the rest of the agents no problem. The last time I got traffic on this frequency, I could hear everyone. Maybe that was just because it was all street agents that time?
Only the agent side?
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DiGiTaLD
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Sounds to me like you may have been listening to a repeater input frequency. Often times, dispatcher consoles are hard-wired to repeaters, so the only frequency the dispatch operator hears is the input channel, and the only frequency they transmit on is the output channel. If you were listening to the input channel in such a situation, the only traffic you'd here would be the mobiles and portables in the field, and not the operator on the console.
Was it analog or digital? Was it all in-the-clear?
Was it analog or digital? Was it all in-the-clear?
Analog. Didn't check the tone because I know the frequency from a reliable source. I'm pretty sure this is the repeater output. That's what had me perplexed. I didn't search for an output because I didn't want to miss anything. Either way, there was a lot of good action even without it.
I remember last time on the same frequency, they were using simplex without repeater because after they left 20 blocks or so from my house, the signal faded to zero. This time, they were in a whole other borough and I could hear them loud and clear. More evidence that this was repeater output.....
I remember last time on the same frequency, they were using simplex without repeater because after they left 20 blocks or so from my house, the signal faded to zero. This time, they were in a whole other borough and I could hear them loud and clear. More evidence that this was repeater output.....
N1BHH
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Sometimes they run split frequency operations, where the agents on the street operate on one frequency and their dispatch point is on another frequency, but it's most likely you were hearing the repeater input. There is also some operation which uses numerous input frequencies to cover a wide area. In the Boston area this is prevalent where one frequency south of the city is used as an input, compared with another one north of the city.
Only the agent side
My old local FBI system used 163.8375 for the input frequency and 167.2375, 167.3625, 167.4125 and 167.6875 for the repeater outputs. Depending on where the agents were, you could always hear them on all the output frequencies. But only 167.6875 had the Kansas City Regional dispatch center on it because it was hard wired using telephone lines directly to that repeater. So if you were listening to 167.2375, 167.3625 or 167.4125 you would only hear the agents in the field but not the KC dispatch center unless you had 167.6875 in your receiver. I suspect that was going on during your monitoring. Next time try searching 162.6 through 174.0 MHz and see if you can find other frequencies that are associated with the operation. Good luck and have fun!
Signal500
My old local FBI system used 163.8375 for the input frequency and 167.2375, 167.3625, 167.4125 and 167.6875 for the repeater outputs. Depending on where the agents were, you could always hear them on all the output frequencies. But only 167.6875 had the Kansas City Regional dispatch center on it because it was hard wired using telephone lines directly to that repeater. So if you were listening to 167.2375, 167.3625 or 167.4125 you would only hear the agents in the field but not the KC dispatch center unless you had 167.6875 in your receiver. I suspect that was going on during your monitoring. Next time try searching 162.6 through 174.0 MHz and see if you can find other frequencies that are associated with the operation. Good luck and have fun!
Signal500
jmm346
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Which frequency?
FireBuff44
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shell - if my memory serves me, they have the repeater channel and then a simplex/direct channel (repeater output) programmed in there radios. they were probably using simplex if everyone was in the general area, although if someone keys up the repeater you still hear it on the simplex side. i know philly used to make B3 Repeater and B4 Direct, etc.
ecps92
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SCANdal
Silent Key
B3: 172.475r (167.9)
B4: 172.475s (167.9)
B4: 172.475s (167.9)
jmm346
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My guess is at least one of the units was operating simplex (B4) and you were out of range of that unit.
I believe 165.975 is the input to B3
ampulman
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I'm in the Philadelphia area and have the same situation where I hear the mobiles only.
Sometimes I'll hear a base station on the same frequency; other times an encrypted tnx on another frequency (don't know if it's a response).
Mostly, just hear one on a single frequency in the 163 mhz region.
Anyone?
AM
Sometimes I'll hear a base station on the same frequency; other times an encrypted tnx on another frequency (don't know if it's a response).
Mostly, just hear one on a single frequency in the 163 mhz region.
Anyone?
AM
ecps92
Member
Your situation tells me that Dispatch [we call it Central here in New England] is remoted to another Repeater. The Resident Agents [RA's] were Desktop RF units
As Clyde mentioned , many of the Repeaters use a Common Input with Multiple outputs.
HQ aka Central will Wireline/Microwave remote to the Actual Repeater in-use vs the way the
users access via RF on the input.
My old Office was across the way from Central and unless someone was using a Portable Radio I never heard Dispatch on the inputs, since it was Microwave and/or LandLine remote.
As Clyde mentioned , many of the Repeaters use a Common Input with Multiple outputs.
HQ aka Central will Wireline/Microwave remote to the Actual Repeater in-use vs the way the
users access via RF on the input.
My old Office was across the way from Central and unless someone was using a Portable Radio I never heard Dispatch on the inputs, since it was Microwave and/or LandLine remote.
ecps92
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Back to basics question.
a.) Where you running CTCSS locked into 167.9 Hz ?
or
b.) Searching for CTCSS Tones and noticed 167.9 Hz
a.) Where you running CTCSS locked into 167.9 Hz ?
or
b.) Searching for CTCSS Tones and noticed 167.9 Hz
ecps92
Member
Well to know it was 167.9 you must of been in search.
What I was going to go for, was using 167.9 Hz this will block out the DVP/DES
and you will only hear the CLEAR transmissions, which might explain why you
only heard One Side of the Conversation. Dropping the 167.9 you would end up
hearing the White-Noise of the DVP/DES, just a thought, along with the other multiple
possible answers.
What I was going to go for, was using 167.9 Hz this will block out the DVP/DES
and you will only hear the CLEAR transmissions, which might explain why you
only heard One Side of the Conversation. Dropping the 167.9 you would end up
hearing the White-Noise of the DVP/DES, just a thought, along with the other multiple
possible answers.
Something to consider: Maybe the Dispatch Console in in Mixed mode (P-25/Analog) and the Dispatcher is answering on the Digital side. This is some what common here in Texas with Agencies that have one dispatch console but have both Police and Sheriff on Analog and P-25. Drop the PL tone and go to Controlled Squelch and that will determine that. Additionally, The Repeater might be in Closed mode or half Duplex. Dispatch being on a repeater may have their side closed as to not interfere with other Stations using the same repeater pair.
Just a thought.
Just a thought.
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