SDS100/SDS200: P25/Squelch
- Thread starter Dexter2
- Start date
- Status
It shouldn't be "rotating" through frequencies. Once it locks on to the control channel, the data transmitted will assign it a frequency. If you're seeing "rotating frequencies", then the scanner is losing the control channel data stream, which would be causing loss of signal.
Ubbe
Member
The c are the normal control channel and a are alternate control channels if the normal one have some problem. Maybe it's their site that are problematic and it's nothing wrong with your scanner.
Those frequencies without any letter can only be used as voice channels and the ones with an a can also be used but are only taken in rotaion when both voice channels are occupied with conversations, as they are reserved for dual duty as both control channel and voice channel usage.
Can you do a longer video of 2-3 minutes when there's some activity in the system? And you could set the SQ to 1 or 0 and use detailed display to show the frequencies.
When the SQ are open at setting 1 or 0 it detects that as a carrier and it will slowly go thru all the frequencies in the site to try and find any control data info.
/Ubbe
Those frequencies without any letter can only be used as voice channels and the ones with an a can also be used but are only taken in rotaion when both voice channels are occupied with conversations, as they are reserved for dual duty as both control channel and voice channel usage.
Can you do a longer video of 2-3 minutes when there's some activity in the system? And you could set the SQ to 1 or 0 and use detailed display to show the frequencies.
When the SQ are open at setting 1 or 0 it detects that as a carrier and it will slowly go thru all the frequencies in the site to try and find any control data info.
/Ubbe
Last edited:
Yeah most likely tomorrow and particular Hold, Filter, or TG Delay? Since today is Sunday its little to no activity. I've left it on my desk for the past three hours with SQ on 2 and Wide Invert Site Filter and everything has remained constant DATA, full signal bars, D-ERROR - 0, NOISE- 3digits, RSSI: -50/-60, frequency has stayed on 859.1125. I've only heard one transmission and that was about two hours ago but again its Sunday and I moved it out of the living room, as I noticed it stopped working and NOISE went through the roof out of no where.
Based on those findings, you are receiving an excellent signal.
Good Afternoon, I hope this is helpful. In this video the SQ is 2, Site Filter is Wide Invert, System Hold is 255, TGID's 17-20 has a 10 sec Delay, the rest were left at 2 sec. I happen to notice while watching that you don't see NFM on the 859.1125 frequency. The only two frequencies IFX is applied are the two voice channels. Though it appears any activity only comes up on 857.0625 and 858.6875a. Since the video was created at 2:42pm and its now 4:26pm there has only been two broken vocal conversations similar to what you hear in the video. As always, thank you for your help.
drive.google.com
IMG_1099.MOV
drive.google.com
Good Afternoon, I hope this is helpful. In this video the SQ is 2, Site Filter is Wide Invert, System Hold is 255, TGID's 17-20 has a 10 sec Delay, the rest were left at 2 sec. I happen to notice while watching that you don't see NFM on the 859.1125 frequency. The only two frequencies IFX is applied are the two voice channels. Though it appears any activity only comes up on 857.0625 and 858.6875a. Since the video was created at 2:42pm and its now 4:26pm there has only been two broken vocal conversations similar to what you hear in the video. As always, thank you for your help.
IMG_1099.MOV
It's hard to see, but is that a Close Call or Weather Alert indicator below the channel name? If it is, turn it off.
That's the Unit ID. I never turned on a Close Call or a Weather Alert so I'm not sure how to turn it off, I don't think its on though.
Just above the UID...I can't tell if that's an air bubble or a Close Call indicator?
Ubbe
Member
In the beginning of the video you are able to recieve a conversation although the noise level are at 15000. Later it goes to the same voice channel but the the squelch doesn't open and it goes back to the control channel. The voice channels seems to be the worst ones, but the signal strenght are usually very good at -50dBm but still high noise level and often high data errors. Sometimes even the control channel are affected by this.
There are some tough interferencies you have to fight there.
Is that a Remtronics antenna? What happens when you use the standard antenna that has less gain in the 800Mhz band?
An antenna has it's least gain in the direction it points, now that is straigh up in the sky. If you could try and have the antenna horisontal and point it around the clock when you notice that it tries to receive a voice channel, perhaps with the SQ at 0. At some point you might be able to get a good signal with less noise and no d-error and the antenna will then point in the direction of the interfering source.
It seems that there's an interfering signal that comes and goes, probably a voice channel of another system, that are too strong to be able to be blocked out by the scanners own filter settings. The system you are receiving seems to have a general -50dBm signal strenght which is extremly good, so you probably have to instead focus on how to reduce the strenght from the interfering frequency. Using attenuator on the frequencies and then test all the filter setting are probably the only thing that are left to do.
If it where a faulty scanner it should also be noticed with other systems. But it has been noted that faulty SDS100 scanners have been showing extreme signal strenghts that are bogus and still have receive problems, but it should be evident on other systems as well.
/Ubbe
There are some tough interferencies you have to fight there.
Is that a Remtronics antenna? What happens when you use the standard antenna that has less gain in the 800Mhz band?
An antenna has it's least gain in the direction it points, now that is straigh up in the sky. If you could try and have the antenna horisontal and point it around the clock when you notice that it tries to receive a voice channel, perhaps with the SQ at 0. At some point you might be able to get a good signal with less noise and no d-error and the antenna will then point in the direction of the interfering source.
It seems that there's an interfering signal that comes and goes, probably a voice channel of another system, that are too strong to be able to be blocked out by the scanners own filter settings. The system you are receiving seems to have a general -50dBm signal strenght which is extremly good, so you probably have to instead focus on how to reduce the strenght from the interfering frequency. Using attenuator on the frequencies and then test all the filter setting are probably the only thing that are left to do.
If it where a faulty scanner it should also be noticed with other systems. But it has been noted that faulty SDS100 scanners have been showing extreme signal strenghts that are bogus and still have receive problems, but it should be evident on other systems as well.
/Ubbe
I was also thinking using the NAC Code if it isn't enabled. I was looking at the video again and wondered if the interfering voice channel was the result of an adjacent trunking system?
The only thing I can think of is laptop, phones, fax machine. But then again, this also happens outside too. When I first purchased the radio and used the standard antenna I was surprised I automatically picked up the neighboring counties sheriffs system but couldn't get this transit system no matter what I did, that's when I tried the Remontronix. Another reason why I'm leaning towards the system and not the radio because when the radio was new, I was able to recieve this system without any problems or any manipulations on my part, thats why I was like I can't stay here I have to go all the way back home haha. When I did Analyze, I got more signal strength on the Police system and little to none on the Transit system. But both systems still worked.
I kind of don't understand the antenna direction part, you want me to like lay the radio down in different directions and watch the NOISE levels. How do you do attenuator on individual frequencies? You want me to put the original antenna back on?
When it comes to interference I can only think of other electronics, for example, this system would never work in my living room or my office, either my bedroom or bathroom window were the best places. But then I figured out, if I put the radio above my office desk over the electronics it was another good spot, but then it doesn't explain why it doesn't work outside or in the car.
Awhile back, I remember one time dispatchers weren't able to respond to drivers, drivers could RTT, and dispatchers could hear them but wouldn't be able to respond and so the talkgroup which switched to another.
Oh my haha, sorry that was smudge I needed to wipe off and I will check NAC in the morning.
Ubbe
Member
NAC and subtones and color codes have nothing to do with reception quality. It's just another filter that the sanner has to check until the conversation can be monitored. Try and use as few resctrictions as possible in a scanner. It only takes one of the restrictions to temporarely fail and your monitoring are gone. If you are able to receive the same frequency from two different systems that use different NAC or color codes then it wont magicly make the interference dissapear, it only makes reception sporadic and probably worse than without any NAC or color settings.
Start by doing one test. Hold you scanner horisontal with the base at your stomack and the antenna pointing away from you and then slowly turn around while there's a conversation taking place to see if the reception clears out at some direction. You can also do a search between 855MHz-860MHz to see what other transmitters you can find that have high signal strenghts that might be the problem. It wont solve anything but will probably reveal what system, if any, that are the culprit in your area.
But what you could do to rule out most scanner problems are to post a debug log file that we can study to see if you have the cold solder joint problem of J401 that seems to be the most common problem.
a) Isolate your scan list to the bare minimum needed to demonstrate the issue.
b) Hold AVOID while powering on the scanner.
c) MENU --> SETTINGS --> SET Debug Log Mode --> SD Card (File)
d) Let the scanner scan long enough to catch the issue.
e) MENU --> SETTINGS --> SET Debug Log Mode --> Off
The resulting log is in the scanner's debug folder that can be zipped and posted to the forum.
/Ubbe
Start by doing one test. Hold you scanner horisontal with the base at your stomack and the antenna pointing away from you and then slowly turn around while there's a conversation taking place to see if the reception clears out at some direction. You can also do a search between 855MHz-860MHz to see what other transmitters you can find that have high signal strenghts that might be the problem. It wont solve anything but will probably reveal what system, if any, that are the culprit in your area.
But what you could do to rule out most scanner problems are to post a debug log file that we can study to see if you have the cold solder joint problem of J401 that seems to be the most common problem.
a) Isolate your scan list to the bare minimum needed to demonstrate the issue.
b) Hold AVOID while powering on the scanner.
c) MENU --> SETTINGS --> SET Debug Log Mode --> SD Card (File)
d) Let the scanner scan long enough to catch the issue.
e) MENU --> SETTINGS --> SET Debug Log Mode --> Off
The resulting log is in the scanner's debug folder that can be zipped and posted to the forum.
/Ubbe
From what I saw on the video which would lead me to believe an offending signal is coming in on the voice channel. By detecting and using the NAC, this "might" isolate it to the system in question similar to assigning a CTCSS or DCS tone to an analog signal.
But really...holding the scanner at the base of your scanner and rotating like a beam antenna? The SDS scanners are very sensitive to receiving not only simulcast, but any digital system that others couldn't. My suggestion was a simple option that the op could try in his attempt to alleviate any interference?
Ubbe
Member
It does nothing for radio interference problems. It only blocks out other signals not matching the tone or data filter you have set, which makes it harder to troubleshoot RF interference problems where several signals are mixing.
One test method could be to enter the most troublesome voice frequency into quick save and configure as analog only and open squelch and listen to the raw signal, if there's some other signals sounding slightly different that appear on the frequency.
The rubber antenna on portable scanners are highly directive if using it where it has its least gain, in the direction where it points, and you can null out a signal, just like a loop antenna, to find the direction to the source. It will give two nulls in the opposite direction to each other but by having you body behind the antenna it will block the signal even more and the best null with the lowest signal level will have the source coming from behind, in the opposite direction of where the antenna points. It's a very effective way to find the direction to a radiosignal that I have used numerous times.
/Ubbe
I will do the debug, when in my bedroom I did what you mentioned before and I noticed away from the window it works better facing horizontally and closer to the window standing up as normal. I remember I had it clipped to my headboard and it worked perfectly (best place in my entire home) so I left it there for a couple months but it became an annoyance to charge and listen being I'm not a hermit haha. Though I am considering leaving it there again and purchasing the bluetooth adapter for my ear pieces.
As of right now, I turned SQ to 0 and I noticed that NFM now shows at the bottom for frequency 859.1125 but it just disappeared again , and being I'm receiving all transmissions now the only frequency that shows during transmissions for both dispatcher and operator is the 858.6875 and depending on the unit/vehicle 856.7875.
I will try and dig out the original antenna today. Do you want me to debug with SQ on 2 or leave it at 0?
From what I saw, the interference "might" be an offending signal or a trunking system. Give it a try, won't hurt.
Does that mean put NAC as SEARCH? Its currently as Set and then the code that's in the database.
Under Settings...Site NAC Operation, is it set to Use Site NAC?
- Status
