Good evening everyone. First of all, I am new to posting here, as well as very new to this scanner since I recently just got it, I had a Whistler 1040 before so this is definitely a learning curve. I will start with what I got set up so far, I got the scanner, updated it and everything and updated the database. I set up some favorites off of that database and there is a P25 Phase II local site that supports PD, FD, etc. Well when I hold on a specific talkgroup within that site, I will get signal bars and "NFM" appears along with "DAT" but the strange thing is, the signal bars fluctuate along with "DAT" fluctuating then it all completely drops out. I will hear transmissions when there's signal and "DAT" is displayed. When the signal drops out, I will switch the modulation between auto, NFM and FM and when I get back to auto, the signal picks back up and I can listen to it again then the same cycle repeats with the signal going out after a while. Does anyone know what is going on and why the signal does this but works when I switch between the modulation types? Hopefully this makes sense to someone, I am very new to this type of scanner and learning as I go and would greatly appreciate any advice or tips anyone can provide. I do apologize to anyone if I am not explaining things properly since I am new to this. Thanks again to anyone that can help.
BCD436HP/BCD536HP: BCD436HP Questions
- Thread starter gillen122
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It's working correct. Leave it on Auto. The DAT and LNK is normal. There is other information that is sent to they're in car CAD system or radio. That is what the other terms mean. Someone will chime in soon and explain it better than me.
That somewhat makes sense. I appreciate it, now another question I have is, do you know anything about the digital threshold level and if I should switch it to manual rather than auto?
From the manual:
LNK Displays when data is received on a voice channel in Receive/Hold Modes.
DAT Displays when data is received on a control channel in Receive/Hold Modes.
P25 Displays if the channel is receiving digitalized voice in Receive/Hold Modes.
So DAT means the scanner is "listening" to the Control Channel and is receiving control channel data. LNK means the scanner is on a Voice Channel and it is receiving "carrier" on that channel (not voice though). P25, something else you'll notice, means it is receiving digital voice traffic on a voice channel.
The business of the signal strength indicator fluctuating is normal behavior. The Uniden folks have said "it is normal housekeeping" with trunked systems. (Probably didn't want to get too specific because of secret engineering "stuff".)
The digital threshold is a little more difficult to explain. Most importantly, there is no one configuration that fits all (just like a pair of shoes). It is so specific to system and your location with respect to transmitters. You probably may want to try different combinations if you are having garbling or no audio issues that are commonly associated with simulcast. (I can use one combination and my next door neighbor uses something different.)
The threshold is more or less of a starting point for the brains of the scanner when it comes to decoding a digital signal. Auto more or less means the scanner is trying to achieve the lowest bit error rate possible. It is all done very quickly and involves that threshold. Manual means, more or less, than scanner won't try to tweak the bit error rate. It uses the threshold value and "lets it ride".
For me and "what's pleasing to my ears" I leave it on manual. I'm thinking (and could be wrong) transmissions are too short for the scanner to get a real good "fix" and is trying too hard to perfect the bit error rate to where it actually sounds worse.
The bottom line is feel free to tinker with different combinations, but be patient when you do so. It will take some time to hit the sweet spot. Also keep good notes so you can go back to what you think is the best.
LNK Displays when data is received on a voice channel in Receive/Hold Modes.
DAT Displays when data is received on a control channel in Receive/Hold Modes.
P25 Displays if the channel is receiving digitalized voice in Receive/Hold Modes.
So DAT means the scanner is "listening" to the Control Channel and is receiving control channel data. LNK means the scanner is on a Voice Channel and it is receiving "carrier" on that channel (not voice though). P25, something else you'll notice, means it is receiving digital voice traffic on a voice channel.
The business of the signal strength indicator fluctuating is normal behavior. The Uniden folks have said "it is normal housekeeping" with trunked systems. (Probably didn't want to get too specific because of secret engineering "stuff".)
The digital threshold is a little more difficult to explain. Most importantly, there is no one configuration that fits all (just like a pair of shoes). It is so specific to system and your location with respect to transmitters. You probably may want to try different combinations if you are having garbling or no audio issues that are commonly associated with simulcast. (I can use one combination and my next door neighbor uses something different.)
The threshold is more or less of a starting point for the brains of the scanner when it comes to decoding a digital signal. Auto more or less means the scanner is trying to achieve the lowest bit error rate possible. It is all done very quickly and involves that threshold. Manual means, more or less, than scanner won't try to tweak the bit error rate. It uses the threshold value and "lets it ride".
For me and "what's pleasing to my ears" I leave it on manual. I'm thinking (and could be wrong) transmissions are too short for the scanner to get a real good "fix" and is trying too hard to perfect the bit error rate to where it actually sounds worse.
The bottom line is feel free to tinker with different combinations, but be patient when you do so. It will take some time to hit the sweet spot. Also keep good notes so you can go back to what you think is the best.
So when it comes to the signal fluctuation, is it normal for the signal to just completely drop out? I'm assuming the reception isn't the best if that's the case, I haven't got a new antenna yet but I have one on the way that should hopefully help. Like I said though, I'm very new to this type of scanner and I do appreciate the response and explanation on everything.
What system are you trying to monitor not knowing will only lead to guessing.
With that said sounds like 1 of 2
1 Simulcast
2 Strong signal near by AM FM TV PAGING CELL or other 2WAY
With that said sounds like 1 of 2
1 Simulcast
2 Strong signal near by AM FM TV PAGING CELL or other 2WAY
It's a P25 Phase II system. It's in Abilene, TX if that helps.
The fluctuating and momentary disappearance of the signal strength bars is absolutely normal. The x96, x36 and SDS lines of scanners all do it. Nothing to fret over. Usually this only happens at the end of a transmission and the carrier drops. However during transmissions, the indicators hold steady.
This system appears to be a simulcast system, though the database does not specifically say it is. Sometimes a real good antenna/antenna system is the worst thing for simulcast. A poorer antenna is best because you don't want the scanner to be receiving multiple sites and garble the 0s and 1s of the digital signal.
Signals from two or more sites can arrive at your scanner nano-seconds apart. Sort of like an echo. The scanner has trouble decoding these out of sync signals and that can translate into garble or no audio. Being really close to one site and being on the outer fringes can improve simulcast distortion when it happens. Interestingly, at my home, I get clearer audio by removing the antenna when monitoring my simulcast system.
This system appears to be a simulcast system, though the database does not specifically say it is. Sometimes a real good antenna/antenna system is the worst thing for simulcast. A poorer antenna is best because you don't want the scanner to be receiving multiple sites and garble the 0s and 1s of the digital signal.
Signals from two or more sites can arrive at your scanner nano-seconds apart. Sort of like an echo. The scanner has trouble decoding these out of sync signals and that can translate into garble or no audio. Being really close to one site and being on the outer fringes can improve simulcast distortion when it happens. Interestingly, at my home, I get clearer audio by removing the antenna when monitoring my simulcast system.
I live right behind the local PD here and by their building is a big tower, I'm not sure if it's one of the sites transmitting or not. As for simulcast, how exactly can you tell that's the kind of system they have? I ask because I'm still learning this stuff. I grew up listening to the old analog frequencies so P25 systems, digital, etc is still fairly new to me.
In my area when things are slow, LEO will initiate a communication with voice and finish the communication on their CAD system. You will think that the conversation was dropped but not the case. When things get busy or something important is happening, all communications will be voice and you will hear the complete conversation. North of me in Miami where there is nonstop crime action, I will hear complete detailed conversations on voice all day long. Other information like the GPS location of the crime, details of the suspect and other data is still being sent to their CAD systems at the same time.
My city is pretty calm most of the time so I can see why I might not be hearing much. The most I've heard so far is dispatch checking status but I do know when things go down, they are pretty busy based on when I've listened to the scanner radio app on my phone. I might just have to wait on a busy day or night to listen in and see what happens. I think I may just have reception issues where I live.
Depending on the city size and radio system, that radio tower may not even be part of their current system and/or is just a transmitter site for a repeater system.
What city and state?
Abilene, Texas
It's P25 conventional system. The repeater output is on 155.45250 MHz
While not noted specifically in the database, the Abilene system is indeed Simulcast.
If I am reading the map correctly, it appears that the tower at the PD's location is not one of the transmit locations for the simulcast site.
Simulcast can be an issue for scanners other than the Uniden SDS100 & SDS200. As already mentioned above by ofd, sometimes less antenna is better for simulcast. More on Simulcast in the Wiki.
Simulcast digital distortion - The RadioReference Wiki
That's the Texas Department of Public Safety, the state police & highway patrol. Abilene uses the trunked system for PD, FD, & various other city departments.
As @hiegtx corrected, Abilene PD (vs TxDPS) is a separate system... APD shows only 1 site (with lots of frequencies) but also shows that pretty much everything on the police side is encrypted and no scanner will receive them.
I believe you are correct, I can hear the dispatch for PD and FD but that's about it. I think I found my issue though and reading on another post on here, I turned modulation to FM and it works way better
An update for anyone that's curious. I believe I found my issue related to the signal bouncing back and forth, I checked other posts on the forums here and found that switching modulation to FM and that helped keep the signal somewhat steady and able to hear more. Also related to the signal is my reception, I found a cheap magnet antenna on Amazon, Tram 1089-BNC Scanner Mini-Magnet... https://www.amazon.com/dp/B01DY8FOK0?ref=ppx_pop_mob_ap_share. That antenna seems to have helped wonders as I can attach it to any metal surface in my house and the signal I get it almost perfect that way. Hopefully this info could also help someone else out if need be and I also appreciate any help anyone has given me.
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