DuPage County frequency changed?

maredzki

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Hey Guys!

In the last week or so all of my OP25 radios tuned to 773.84375 have stopped receiving. Could anyone check if that frequency is active still? I've tried multiple backup frequencies and still hit nothing. I've tried several different SDR dongles as well.

Here is an example from the output. I should be seeing a spike to tune into. I have nothing. Any ideas?
1607312235173.png
 

boatbod

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Did your control channel move to an alternate frequency?
Try turning on the fft plot (#1) to see if there are any signal spikes nearby.
 

werinshades

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Hey Guys!

In the last week or so all of my OP25 radios tuned to 773.84375 have stopped receiving. Could anyone check if that frequency is active still? I've tried multiple backup frequencies and still hit nothing. I've tried several different SDR dongles as well.

Here is an example from the output. I should be seeing a spike to tune into. I have nothing. Any ideas?
View attachment 95042
They've been on an alternate control channel..
 

maredzki

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Did your control channel move to an alternate frequency?
Try turning on the fft plot (#1) to see if there are any signal spikes nearby.
Here is what I get tuned to the primary channel:
1607313917976.png
 

maredzki

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They've been on an alternate control channel..
Any ideas what channel they are now on?

And besides the obvious indication of no-audio, outside of scanning each frequency listed for DuPage county we can’t really tell what they’ve switched to?
 
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boatbod

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RRDB usually lists the known alternate control channel freqs for each system. That's a good place to start the hunt.
 

Patch42

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I've definitely heard traffic from the DuPage site in the last couple days. I can't answer the question about the frequency because the scanner deals with that and I can't figure out how to get it to indicate what frequency it's picking up the control channel on. It flashed over to the talk frequency too fast.
 

maredzki

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I've definitely heard traffic from the DuPage site in the last couple days. I can't answer the question about the frequency because the scanner deals with that and I can't figure out how to get it to indicate what frequency it's picking up the control channel on. It flashed over to the talk frequency too fast.
Patch42, are you using your own p25 scanner to listen instead of the stream?
 

maredzki

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RRDB usually lists the known alternate control channel freqs for each system. That's a good place to start the hunt.
I might have to spend sometime tomorrow to tune into each one of them unless there is a better way to see which one indicates a spike?
 

Patch42

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Patch42, are you using your own p25 scanner to listen instead of the stream?
Yes. Just got a SDS100 last week. I just checked and it appears the scanner is programmed with every frequency listed for each site so I'm not sure how to go about telling what channel it's getting control data on.
 

Johnnydollar2

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I did it with my Whistler WS1080 by punching in the frequencies as conventional channel/object browsing objects in the scan-list and pausing, monitoring that frequency. That's how I find the Nac of a SITE too. You'll hear the noise/data and see what it says on the screen. There must be a similar way to monitor the control channels on those SDS100s. There are only 4 frequencies listed as CC and alternates for Starcom21 DuPage County SITE
 

werinshades

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Any ideas what channel they are now on?

And besides the obvious indication of no-audio, outside of scanning each frequency listed for DuPage county we can’t really tell what they’ve switched to?
I program the control and alternate control channels which I obtained from the database. DuPage site is active this morning. Maybe check the database?
 

RBMTS

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The active control channel this morning is 774.43125 . It's strong and working fine from Naperville.
 

RBMTS

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As of 11:23 the Dupage 1-01 site is still showing an active CC on 774.43125 and comms are being heard/tracked.
 

maredzki

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RBMTS, that is interesting. I adjusted the frequency in my Carol Stream location and it is picking up the signal. My location in Addison, where I think the FCC antenna is by I355 cannot tune to that frequency. I assume the backup antenna is somewhere in Wheaton and it makes the reception a little more difficult. What do you think?
 

RoninJoliet

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I'm in Joliet and I always had trouble getting T101 DP , now they changed to he Alt CC and I now have 5 bars and very good coverage on it ???
 
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