Before you read the title of this thread and say "Oh this guy programmed his scanner wrong or oh the antenna is probably shot", I am reaching out to this form because that does not appear to be the issue. I have programmed several of these scanners for the same system with no problems using ARC XT as well as freescan. This scanner, despite having great signal strength and proper programming, will not decode the control channel. I have tried control channel only, programming all the site frequencies, adjusting gain, P25 settings, etc.. I am starting to think there is something defective in the unit itself. Has anyone ever had something like this happen? Open to anything. Thank you!
BCD996XT Finding Cntrl Chan
- Thread starter jovitt
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doctordialtone
Member
Welcome to the
The 396XT does not handle P2 transmissions You need a P2 scanner to do that.
Are you sure you are monitoring a P1 system?
Please post a link to the system.
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This is for a P25 Phase 1 system. It worked fine on this system before, I was then contacted about how it stopped working and now here we are. I have done a reset on it, reprogrammed it a thousand times and have had no success. https://www.radioreference.com/apps/db/?sid=5298
tvengr
Well Known Member
If you have programmed other 396/996XT scanners on the system and they work, it cannot be a P25 Phase 2 system. The XT scanners are only capable of Phase 1. Please let me know which system you are attempting to monitor. I use ARC-XT for my programming. It is also possible that you have a simulcast problem, receiving several towers at once. If you have plenty of signal strength, try removing the antenna and inserting a paper clip or other short piece of wire into the antenna connector to reduce signal strength. You can also try turning on the attenuator.
tvengr
Well Known Member
Which specific talkgroups are you attempting to monitor. That is a Phase 2 capable system and some of the talkgroups are using Phase 2 which your scanner cannot receive. It is possible that the talkgroups you want switched to Phase 2 (showing a "T" in the Mode column) and that is why your scanner quit working.
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doctordialtone
Member
Yes, as tvengr stated, the system you are trying to monitor is partially Phase2,
You'll need a newer scanner to monitor them.
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Only the Oneida cell and associated talkgroups are Phase II on that system. If the OP is monitoring other county cells, Phase II is not the issue.
In addition, P25 systems use the same FDMA (Phase I) control channel regardless of whether or not the talkgroups are Phase II. The scanner would not display Finding Ctrl Chan even if the system were 100% TDMA; it would still be able to lock onto the control channel, it would just not tune to any voice frequencies.
As @tvengr mentioned, I suspect that this is a simulcast distortion issue, assuming there is no issue with the scanner itself. All five sites of the CNYICC are simulcast cells.
In addition, P25 systems use the same FDMA (Phase I) control channel regardless of whether or not the talkgroups are Phase II. The scanner would not display Finding Ctrl Chan even if the system were 100% TDMA; it would still be able to lock onto the control channel, it would just not tune to any voice frequencies.
As @tvengr mentioned, I suspect that this is a simulcast distortion issue, assuming there is no issue with the scanner itself. All five sites of the CNYICC are simulcast cells.
This scanner is going to be for a firehouse in Onondaga County and only needs a couple of talkgroups. Onondaga Fire Control, TAC 3, TAC 4, and CMD 5 which are all FDMA. I also suspected simulcast distortion being an issue. The antenna is on a mast on the roof of the firehouse and is performing great so that isn't an issue. The Onondaga County 911 center is about half a mile away. The 911 center is one of the sites in the system. I have tried programming the control channel only (460.500) and it would lock onto it for a minute then drop it again. It did pick up a fragment of a conversation before it dropped the control channel. I have been testing the scanner alongside a county portable so I can tell if there is radio activity. I also tried some alternate control channels with no success. I have found that the scanner will lock on to and hold the control channel if I set the control channel only to a frequency from a tower on the other end of the county. Scanner shows only 2 bars and it misses just about all traffic but it stays on that specific control channel. That's the farthest I have gotten with the thing.
tvengr
Well Known Member
If control channel locks and then drops out, it sounds like a simulcast problem. Try moving the scanner to different locations around the room and see if that makes any difference. Also vary the antenna length and orientation.
doctordialtone
Member
Jovitt says, " The antenna is on a mast on the roof of the firehouse and is performing great "
I have tried a rubber duck antenna and moved it around with no improvements. Unfortunately the antenna is not variable in this case. The antenna to be used is a roof mounted Laird on top of the firehouse. It is either that, or use another rubber duck or telescoping antenna that came with the scanner. I cannot install any new equipment on the roof unfortunately. This scanner will be in an equipment rack with not a lot of room.
If the 911 center a half-mile away is one of the transmitter sites then you almost certainly do not need to use a rooftop antenna. In fact you could very well be getting too much signal, which these radios don't always handle well. I would first try enabling the Attenuator for the site. That will cut the signal strength down considerably. If that doesn't help try using the back-of-set telescoping antenna that comes with the 996XT instead of the rooftop antenna, and collapse it to its shortest length.
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tvengr
Well Known Member
What is the firmware version in the scanner. Did you check the hidden P25 Adjust Mode and the P25 Adjust Level and what are their values?
Attenuator enabled reduces the signal strength to 3 bars on the scanner, but still will not lock on to the control channel. The stock telescoping hasn't given me any better results either.
Firmware is what I believe is the latest, 1.07.03. I did check the hidden adjustment mode. I have just factory reset the scanner so currently it is at the default.
tvengr
Well Known Member
That is the latest firmware. What are the values in the P25 settings?
P25 LP Filter is off, P25 Adjust Mode is 11, and P25 Adjust Level is 50
tvengr
Well Known Member
Those are the correct settings. Some systems vary from the default settings. Try varying the P25 Adjust Mode setting. The reason I asked about the firmware version is that on old firmware you had to change the Adjust Level to 200 from the default 50 for the control channel to lock. I agree that if the firehouse is just a half mile from the site that you should try using the rear of scanner antenna and not the rooftop. That would reduce the chance of receiver overload and possibly eliminate receiving other towers contributing to the simulcast issues. I am going through my 996XT to see if I can find anything else that could cause the problem.
Ok with some tinkering, the scanner now holds on one of the alternate control channels! The bad news is it misses every single transmission on the system. I set it to ID Search and it never picked up any chatter. I had a county portable next to me the whole time to confirm. The LP Filter is ON, and P25 Adjust Mode set to 8. I'm not sure if this is progress or not. Suggestions?
doctordialtone
Member
Is there any way for you to take it somewhere closer to the transmitter temporarily to test it out?
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