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Old 01-21-2014, 10:19 PM
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Default Missed transmissions during 'scan'? - BCD396XT

Please bear with me, I'm not a radio nerd so I'll try to explain this the best I can.

I have a BCD396XT, and have it setup with only one channel, a trunked system (Maricopa County Trunking System, Maricopa County, Arizona - Scanner Frequencies)

I have only one "site" as well, Central Court/Downtown Phoenix Site Details (Maricopa County), the closest site to my location. That site has 15 different frequencies, if that matters.

Therefore, there should be nothing to 'Scan' to look at other channels, it's a single channel that I listen to 24/7. I have the scanner in 'Hold' mode as well, if that makes a difference.

The problem I have is that if there's a period of time with no audio, let's say 15-20 seconds, it seems the scanner will start scanning again, perhaps the other 15 frequencies in that 1 site. During this time, my signal bars go from 3-4 to 0-1. Eventually, when people start talking on that channel again, it'll lock back in but it may miss the first second or so of their transmission. As long as there's there's constant radio 'chatter', the scanner behaves fine, the signal stays at 3-4, no audio is dropped and you can listen to it just fine.

I assume that when it detects no audio, it goes and scans the other 14-15 frequencies, which I'm not sure is needed since I'm only listening to 1 channel? Is there a way to stop this or atleast tell it to wait a longer period of time to start 'searching'?

Thanks in advance!
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Old 01-21-2014, 11:17 PM
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lep lep is offline
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I don't believe your understanding of a trunked system is correct. As I understand it, your receiver listens to the control channel for a channel grant. When received, it switches to the correct frequency until the transmission series is completed. Then it resumes listening to the c.c. for more instructions in the form of more channel grants. It does not listen for "audio" nor does it scan the working channels. It only listens to the c.c. You may wish to adjust the 'delay', that is, the wait-time or the MOT end code detection and see if those help.
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Old 01-22-2014, 6:54 AM
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Just like "lep" said in the hold mode the scanner stays on the control channel listening for channel grants. Also from your description it sounds like the control channel strength decreases below what the scanner can decode and it starts scanning through the channels trying to find another control channel even though it is in the hold mode. As soon as it finds a control channel it can decode it returns to the hold mode listening for more channel grants. This loss of the control channel could be caused by many things including propagation, interference or maybe simulcast distortion.
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Old 01-22-2014, 8:02 AM
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In Control Channel Only mode, you should only enter these frequencies: 866.7750 and 868.8250
Those are the only 2 freqs listed as control channels for the site you are monitoring.
Danny Harp Jr.
HAM Radio Operator: N4YEK
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remember, Jesus loves you.

Last edited by n4yek; 01-22-2014 at 8:05 AM..
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Old 01-22-2014, 2:27 PM
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Don't confuse "channels" (which are called TalkGroups on a trunked system) with frequencies. Are you trying to listen to a single TalkGroup? If so, I'd recommend programming only that TG rather than use hold mode. The the scanner SCAN (the control channel[s])
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