SDS100/SDS200: Why are transmissions going digital and unrecognizable after a short time..

[RMason]

You can try turning on the attenuator for your 'local site'. You will want to do this only for the local site that is giving you issues - not the distant site. This might help if you are getting too strong of a signal with the REM 820S antenna.

There are a couple of ways to do this:
Site Attenuation - Press Func then Dept (softkey2) to hold on the Site.
Press Func then 4(ATT) to toggle attenuation. Press Func then Site (softkey2) to resume.

or
By setting the site options through the menu (or edit the site in Sentinel)

​ Press Menu then scroll to Manage Favorites and press E/yes. Scroll to the Favorites List and press E/yes. Scroll to Review/Edit System and press E/yes. Scroll to the System and press E/yes. Scroll to Edit Site and press E/yes.

To Edit an Existing Site scroll to the Site and press E/yes.

Scroll to Set Attenuator and press E/yes. Scroll to On and press E/Yes.

 

[chad_96]

You can try turning on the attenuator for your 'local site'. You will want to do this only for the local site that is giving you issues - not the distant site. This might help if you are getting too strong of a signal with the REM 820S antenna.

There are a couple of ways to do this:
Site Attenuation - Press Func then Dept (softkey2) to hold on the Site.
Press Func then 4(ATT) to toggle attenuation. Press Func then Site (softkey2) to resume.

or
By setting the site options through the menu (or edit the site in Sentinel)

​ Press Menu then scroll to Manage Favorites and press E/yes. Scroll to the Favorites List and press E/yes. Scroll to Review/Edit System and press E/yes. Scroll to the System and press E/yes. Scroll to Edit Site and press E/yes.

To Edit an Existing Site scroll to the Site and press E/yes.

Scroll to Set Attenuator and press E/yes. Scroll to On and press E/Yes.

Thank you for this. I did try turning on the attenuator for only my local site closest that seems to be the problem.

Unfortunately, it took the signal from full bars down to 1 and I lost the Data icon on that site as well. So I would assume that's going to be more harm than good?

 

[chad_96]

Thought I would share some stats I found from looking at another thread.

I have seen people mention the RSSI readings, and they mention that the LOWER the number, the better. I've also seen a mention that -60 and below is best.

While scanning the 2 sites ( just while scanning) the RSSI is showing on Site #1 -82dbm this is my local closest site. On Site #2 I show -96dbm and that is the farther away site, that I am getting a bulk of the traffic on that's not seeming to be an issue.

As for filters, I seen them, have no clue of they would be of any help, and have no clue what they do. I've tried reading some threads on them, but it's too technical to understand for me. If anyone knows a filter setting that I should attempt to try in this situation, I'm all ears.

When I turned on the attenuator for my local site that I'm having issues it took my signal strength from full bars and thr data icon displayed, down to 1 bar and flickering data icon with mainly not having a data icon, so I assume that's more harm than a help.

 

[RMason]

Gotta ask: what is your squelch set at? Improper squelch settings have been known to cause odd behavior. Most suggest setting squelch at 2.

As for filters, I seen them, have no clue of they would be of any help, and have no clue what they do. I've tried reading some threads on them, but it's too technical to understand for me. If anyone knows a filter setting that I should attempt to try in this situation, I'm all ears.

Finding the optimal filter is trial and error and is location dependent. You can select the filter setting in the site settings. You can choose between the various settings to see if there is one that works. Normal, Invert, Wide Normal, Wide Invert, Wide Auto, or Off. (Global will use the Global Auto Filter setting)

 

[chad_96]

Gotta ask: what is your squelch set at? Improper squelch settings have been known to cause odd behavior. Most suggest setting squelch at 2.



Finding the optimal filter is trial and error and is location dependent. You can select the filter setting in the site settings. You can choose between the various settings to see if there is one that works. Normal, Invert, Wide Normal, Wide Invert, Wide Auto, or Off. (Global will use the Global Auto Filter setting)

My squelch is at 2.

And oddly I just received a transmission on my fire departments TAC channel that lasted about 20 seconds and didn't go digital.

Makes me wonder if my scanner and the settings aren't the problem, and maybe if the departments radios/reception in their area they happen to be transmitting from is poor and causing the reception errors.

I do know the state trooper who was on town the other night had went digital ad well, which led me to believe what I've posted. But, I do recall him telling the dispatcher that his in car computer wasn't working properly due to poor reception where he was at.

So many technical things to question...

 

[RMason]

Makes me wonder if my scanner and the settings aren't the problem, and maybe if the departments radios/reception in their area they happen to be transmitting from is poor and causing the reception errors

That is certainly possible. If the units are having trouble getting into the system, there isn’t much you can do on your end.

 

[chad_96]

Does anyone have any tips on adjustments to use to get lower RSSI numbers?

Currently, while scanning my local site I'm getting -82dbm and when someone is talking it is staying around -85dbm. This is my local departments and closest site.

On my 2nd site I am sitting at -96dbm while scanning and -105dbm while someone is talking.

I understand that -60dbm and below to be the target area. However, what setting/adjustments would one tinker with to try and get those numbers down? Especially the local site/depts?

Thanks!

 

[buddrousa]

Outside Antenna

 

[Ubbe]

Does anyone have any tips on adjustments to use to get lower RSSI numbers?

Currently, while scanning my local site I'm getting -82dbm and when someone is talking it is staying around -85dbm. This is my local departments and closest site.

Your receive levels seems fine at -85dBm. When you enable the attenuator it will reduce the signal around 22dB for a 800MHz frequency making that -85dBm signal go down to -107dBm which is right over the squelch level and one bar indication, so seems to work as it should, but do not use it as the signal are then too weak to be decoded properly.

You shouldn't really aim to get the highest possible RSSI signal with Unidens SDS scanners as the signal meter measures both at the frequency you monitor and any interferencies. If going by signal strength you should aim your setting changes to get the lowest possible signal, the least added interference level.

If the signal are digital then enable one field in the display to show digital error count and then try and get as few errors as possible. This is the preferred method as you then only maximise the received signal and not the added RSSI signal level that comes from interferencies.

If you where a HAM radio amateur you would know what filters do as it is an IF shift function, but just try different filters and keep an eye on the data errors when a TG call goes digital. The errors probably sky rockets and the decode stops and goes digital and that are probably the result from a strong interference from another frequency. The IFX setting or one of the filter settings might prevent that from happening. If the site are busy you can make a hold on it, function+middle button that says Site, to make it easier to just test that single site and catch all calls on it while trying out different settings.

The receiver quality in SDS scanners are terrible so Uniden had to add all this extra settings that don't exists in other scanners, so it can be a handfull trying to get the scanner to work properly if you are unlucky to have too much interference from other transmitters in your area.
At -60dBm and stronger the receiver really goes bad with a lot of issues so try and keep any signal around -80dBm or weaker.

The level decrease in dB from the attenuator taken from the user manual.
14. Attenuator
ITEM UNIT NOMINAL
(NFM) 40.840 MHz 33dB
(FM) 72.515 MHz 33dB
(AM) 127.175 MHz 33dB
(NFM) 161.985 MHz 31dB
(AM) 272.950 MHz 27dB
(NFM) 406.875 MHz 24dB
(NFM) 857.150 MHz 22dB

/Ubbe

 

[chad_96]

Your receive levels seems fine at -85dBm. When you enable the attenuator it will reduce the signal around 22dB for a 800MHz frequency making that -85dBm signal go down to -107dBm which is right over the squelch level and one bar indication, so seems to work as it should, but do not use it as the signal are then too weak to be decoded properly.

You shouldn't really aim to get the highest possible RSSI signal with Unidens SDS scanners as the signal meter measures both at the frequency you monitor and any interferencies. If going by signal strength you should aim your setting changes to get the lowest possible signal, the least added interference level.

If the signal are digital then enable one field in the display to show digital error count and then try and get as few errors as possible. This is the preferred method as you then only maximise the received signal and not the added RSSI signal level that comes from interferencies.

If you where a HAM radio amateur you would know what filters do as it is an IF shift function, but just try different filters and keep an eye on the data errors when a TG call goes digital. The errors probably sky rockets and the decode stops and goes digital and that are probably the result from a strong interference from another frequency. The IFX setting or one of the filter settings might prevent that from happening. If the site are busy you can make a hold on it, function+middle button that says Site, to make it easier to just test that single site and catch all calls on it while trying out different settings.

The receiver quality in SDS scanners are terrible so Uniden had to add all this extra settings that don't exists in other scanners, so it can be a handfull trying to get the scanner to work properly if you are unlucky to have too much interference from other transmitters in your area.
At -60dBm and stronger the receiver really goes bad with a lot of issues so try and keep any signal around -80dBm or weaker.

The level decrease in dB from the attenuator taken from the user manual.
14. Attenuator
ITEM UNIT NOMINAL
(NFM) 40.840 MHz 33dB
(FM) 72.515 MHz 33dB
(AM) 127.175 MHz 33dB
(NFM) 161.985 MHz 31dB
(AM) 272.950 MHz 27dB
(NFM) 406.875 MHz 24dB
(NFM) 857.150 MHz 22dB

/Ubbe

Understood, thank you for the advise.

Could you possibly tell me where to find the "IFX" setting on the SDS100?

Also, I have seen previous talk of the digital errors code method. I just don't know or understand how or what to do to get to that.

That being said, I appreciate the help and will try to locate the IFX setting, and run it and see if it helps out. And see what I can find on how to use the digital code error method.

And just to clarify the overall understanding. Essentially what I would be aiming my focus at is trying the filters, and cleaning up the signal more than anything, if I am understanding the overall advise you have given? Does that seem correct?

Thank you for the advise and help.

 

[chad_96]

Your receive levels seems fine at -85dBm. When you enable the attenuator it will reduce the signal around 22dB for a 800MHz frequency making that -85dBm signal go down to -107dBm which is right over the squelch level and one bar indication, so seems to work as it should, but do not use it as the signal are then too weak to be decoded properly.

You shouldn't really aim to get the highest possible RSSI signal with Unidens SDS scanners as the signal meter measures both at the frequency you monitor and any interferencies. If going by signal strength you should aim your setting changes to get the lowest possible signal, the least added interference level.

If the signal are digital then enable one field in the display to show digital error count and then try and get as few errors as possible. This is the preferred method as you then only maximise the received signal and not the added RSSI signal level that comes from interferencies.

If you where a HAM radio amateur you would know what filters do as it is an IF shift function, but just try different filters and keep an eye on the data errors when a TG call goes digital. The errors probably sky rockets and the decode stops and goes digital and that are probably the result from a strong interference from another frequency. The IFX setting or one of the filter settings might prevent that from happening. If the site are busy you can make a hold on it, function+middle button that says Site, to make it easier to just test that single site and catch all calls on it while trying out different settings.

The receiver quality in SDS scanners are terrible so Uniden had to add all this extra settings that don't exists in other scanners, so it can be a handfull trying to get the scanner to work properly if you are unlucky to have too much interference from other transmitters in your area.
At -60dBm and stronger the receiver really goes bad with a lot of issues so try and keep any signal around -80dBm or weaker.

The level decrease in dB from the attenuator taken from the user manual.
14. Attenuator
ITEM UNIT NOMINAL
(NFM) 40.840 MHz 33dB
(FM) 72.515 MHz 33dB
(AM) 127.175 MHz 33dB
(NFM) 161.985 MHz 31dB
(AM) 272.950 MHz 27dB
(NFM) 406.875 MHz 24dB
(NFM) 857.150 MHz 22dB

/Ubbe

Alright, for some reason I couldn't edit my previous response to you.

I found the D-Error option and added it to my display screen to monitor. I see that while just scanning it is showing different error counts, but I'd imagine from the previous responses I've gotten it is the error value while someone is physically talking that's what I want to look for, as well as testing the different filters while there is chatter going on to see what filter, if any, gets the lowest number on the D-error rate.

As for the IFX setting, I'm having a hard time with figuring out how to use it. I've found that pressing func + 4 on the keypad should enable it. However, when I try it gives me rapid beeps and doesn't work. I'm sure that's because I'm not using it properly.

Anyhow, just thought I would share what I've found and am currently testing out and see if it sounds like I'm on the right path.

Thank you

 

[Ubbe]

the error value while someone is physically talking that's what I want to look for, as well as testing the different filters while there is chatter going on to see what filter, if any, gets the lowest number on the D-error rate.

Correct

pressing func + 4 on the keypad should enable it. However, when I try it gives me rapid beeps and doesn't work.

It can only be toggled on or off when you stop scan, push the Channel button, on a conventional channel. To do IFX on a trunked channel you'll have to enter the frequency manually to do it, push Channel then enter the frequency, then push Channel button again and then do Function+4. Continue scan using the To Scan button. There is also a place in Sentinel where you can enter IFX frequencies but then you'll have to program your scanner each time you want to toggle IFX.

So you will have to know the frequency that are in use for that trunked call that goes digital and probably have to configure your display to show it, if not using the Detailed Trunked display setting that I anyhow recommend to use while figuring out issues.

/Ubbe

 

[chad_96]

Correct


It can only be toggled on or off when you stop scan, push the Channel button, on a conventional channel. To do IFX on a trunked channel you'll have to enter the frequency manually to do it, push Channel then enter the frequency, then push Channel button again and then do Function+4. Continue scan using the To Scan button. There is also a place in Sentinel where you can enter IFX frequencies but then you'll have to program your scanner each time you want to toggle IFX.

So you will have to know the frequency that are in use for that trunked call that goes digital and probably have to configure your display to show it, if not using the Detailed Trunked display setting that I anyhow recommend to use while figuring out issues.

/Ubbe

Thank you, I couldn't find any threads describing that info. I appreciate it.