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Old 02-07-2013, 12:27 AM
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Default BCD 996XT Control Channel Drops.

Question I have A BCD 996 XT and I programed in Our Counties New P25 System and I just noticed today that the Control channel seems to drop and NFM apears where the control channel usually is. Then the control channel comes back and then stays off again. When this happens it seems that I don't get any transmissions again till the control channel comes back. Any Ideas why this is happening? Any help with this would greatly be appreciated.

Thanks,

jludlow
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Old 02-07-2013, 1:54 AM
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It sounds like you may be getting a low signal level which an outdoor or band specific antenna could help or you may be experiencing interference from something else that is overloading the front end and that can cause the control channel to drop.
The Uniden models usually do pretty good as far as rejecting interference from other signals though but all radio's are prone to what is call desense. GRE's are famous for that problem in the VHF high band mainly.

My guess is you are working with a weak signal. What does the little signal level bar graph show when you are or are not getting the control channel?

Also, make sure you don't have any priorities turned on that may be causing the 996 to tune away from the control channel while checking the priority channel or systems. I think there may be more than one type of priority check that can be enabled on the 996 so you may need to wade through the menu's and check everything if it is a priority problem. I think the Close Call feature can also run kind of like a priority so that would cause the radio to tune away from the control channel for a while.

It could also be the infamous multipath distortion problem that can affect all scanners and even commercial radios. This happens on sites that are simulcast sites meaning a system that has multiple towers all sending out the same signal. Your scanner can't deal with them as the signals hit your scanner a few milliseconds apart and that confuses the heck out of the scanner. The 996 will go back to just showing NFM when that happens as it is no longer decoding CC data. A loss of signal from a weal signal will also cause it to display NFM. There are ways to try and improve reception of simulcast systems that involve experimentation on your part. There is no one proven method that works for all. Sometimes using less of an antenna fixes it as the lesser antenna may prevent one of the towers signals from reaching your scanner. Some (myself included) have had luck using a Yagi (directional) antenna aimed at one tower only which causes the scanner to capture the signal from that one tower. Sometimes it is nearly impossible to fix. Some have better luck using a GRE scanner for simulcast sites.
The system I monitor works better on a Uniden for me. Some days my GRE will not pickup the system at all.

Post back your signal level first though. I'll see if I can find what state the county you mention is in as the database for the system will usually say if it is a simulcast site or not. Or if you get this, copy and past the link to the database page for that county system. I have no idea where Geauga County is located yet!
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Old 02-07-2013, 7:25 PM
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I have noticed on my 396 that I have issues with the control channel "dropping off" if I'm dealing with a multi path issue on a true P25 system. I haven't been able to come to any other conclusion because if I use a directional antenna (i.e. Yagi) and point it towards a known area where the closest transmitter is then it stops and all works as it should.
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Old 02-07-2013, 11:34 PM
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Quote:
Originally Posted by jludlow View Post
Question I have A BCD 996 XT and I programed in Our Counties New P25 System and I just noticed today that the Control channel seems to drop and NFM apears where the control channel usually is. Then the control channel comes back and then stays off again. When this happens it seems that I don't get any transmissions again till the control channel comes back. Any Ideas why this is happening? Any help with this would greatly be appreciated.

Thanks,

jludlow
Make sure you have the latest firmware v1.07.03. It has a fix for P25 distortion issues.
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Old 02-08-2013, 4:41 AM
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kruser,

Hi sorry it took so long to get back to you. The singnal levels never really seemed to drop by all that much 1-2 bars but right back to 5 bars. The state that I live in is Ohio and the county is Geauga. The system is The Ohio MARCS-IP Multi-Agency Radio Communications (P25) system. It is a Simulcast system I tried to copy and paste the info but for some reason it didn't work.

Thanks Again for your help,

jludlow
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Old 02-08-2013, 4:48 AM
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W8RMH,

Did that when it was released.

jludlow

Last edited by jludlow; 02-08-2013 at 4:50 AM..
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Old 02-08-2013, 5:24 AM
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I monitor MARCSIP off the Franklin and Fayette County sites with my BCD396XT with no problems. If you use FreeScan you can download it directly to FreeScan then to your scanner. No copy/paste needed. Also I strongly suggest using a 700/800 Mhz antenna.
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Last edited by W8RMH; 02-08-2013 at 5:27 AM..
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Old 02-08-2013, 6:14 AM
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W8RMH,

I have a 396xt also haven't had any problems with it at all. It's just my 996xt.

jludlow.
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Old 02-08-2013, 8:08 AM
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Default Re: BCD 996XT Control Channel Drops.

OK, since my last post I updated the firmware on my 396 and it seems to have resolved the issue on mine.

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