Entering P25 Trunked Tower Sites

[rbritton1201]

I have a Uniden SDS200, and it's programmed with several MOSWIN P25 trunked system towers programmed as depicted in the Sentinel software screen below. Notice how the tower sites (which contain the tower frequencies for each tower site) are independently programmed from the "TROOP C" and "REGION C INTEROPERABILITY" programming slots. I want to confirm that the P25 tower sites are supposed to be programmed as I have them below.


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[AC0RV]

For each tower site, I generally just program the controls for each site.

For the Talkgroups I have them listed for agency as Department (within the department then by use. (for example SO = Dispatch,Car to Car,etc)

Hope this helps you out,

 

[u2brent]

I have a Uniden SDS200, and it's programmed with several MOSWIN P25 trunked system towers programmed as depicted in the Sentinel software screen below. Notice how the tower sites (which contain the tower frequencies for each tower site) are independently programmed from the "TROOP C" and "REGION C INTEROPERABILITY" programming slots. I want to confirm that the P25 tower sites are supposed to be programmed as I have them below.

That is the way it should look, Sites are separate from Departments, As you've noted Sites have frequencies, Departments have the TGID's that are carried on the site frequencies (presumably). The scanner scans the sites looking for a control channel to decode, If it finds the CC for a site it will stop and decode and determine if a TGID is active. Then the scanner proceeds to the next site in range, If any. Rinse and Repeat.

 

[rbritton1201]

Why does the scanner show four full bars of signal strength when the tower site is scanned, without any traffic being present, and the signal strength shows only two bars from the same tower site when the scanner stops on an actual transmission being received (see the two shots below). Even the dBm readings don't correlate with the signal indicators. It seems like the dBm reading on the full four bars of deflection should be at -109dBm, and the two bars of deflection should be at -98dBm. Just trying to understand these indicators.

dB

 

[AC0RV]

It may be because of the Data Burts that are sent from the user's Radio (GPS location & IDs,etc)

 

[u2brent]

I don't think the bars can be correlated to a specific db level on the display, it's just a rough indicator of the signal currently received and can include interference as well, Also perhaps some of the voice channels may have lower power output than the CC. There are so many possibilities for the differences your observing..

 

[kruser]

Why does the scanner show four full bars of signal strength when the tower site is scanned, without any traffic being present, and the signal strength shows only two bars from the same tower site when the scanner stops on an actual transmission being received (see the two shots below). Even the dBm readings don't correlate with the signal indicators. It seems like the dBm reading on the full four bars of deflection should be at -109dBm, and the two bars of deflection should be at -98dBm. Just trying to understand these indicators.

The signal strength difference when a site switches to a voice frequency could also be because of physical antenna placement on the sites tower.
I see this pretty often on multi channel P25 sites of all types. And also when using other models than the SDS series.
Some antennas are often placed below another. You can see the difference in signal strength if you are a distance from the site as the sites controller picks different frequencies that may use different antennas.

Your SDS scanner could also be being influenced by other strong signals +/- of the control channel or voice channel frequency. Pretty much what @u2brent pointed out above. Not much you can do about that with the SDS models and their TV tuner chip they use which has an 8 MHz wide window open to interference about 4 MHz above and below the tuned frequency.
I totally disregard the dBm reading on the SDS display and only rely upon the D-ERROR reading for digital systems.
I find the dBm reading to be wrong near 90% or more of the time. I consider it useless for the SDS models.
In your screenshots, you show your model as an SDS200. You should get rid of the display field you have set for "Batt:" as the SDS runs off external power and replace that field with "D-ERROR:". The lower the D-Error reading the better! A reading of zero when they are talking is ideal.

 

[rbritton1201]

Hi Kruser,

When you get some time, can you advise exactly how to change from "BATT" to "D-ERROR" on the display? I'm not quite sure how to make those changes, but I would like to incorporate your suggestion into programming.

You should get rid of the display field you have set for "Batt:" as the SDS runs off external power and replace that field with "D-ERROR:". The lower the D-Error reading the better! A reading of zero when they are talking is ideal.

 

[scanman1958]

Also, you may get 3, 4 or five bars on the signal strength but if no one is talking you won't hear anything. The scanner will.move on to the next site you have programmed, that is if you have multiple sites programmed.

 

[rbritton1201]

Kruser prompted me to change the BATT indicator to the D-Error indicator. It can't be done within Sentinel, it has to be done from the display editor via the SDS200 itself. Not sure if Proscan provides a way to do it through programming or not, but if so, I expect it would be a little easier. I'll have to investigate that further when I have the time.

I notice that I get a D-ERROR "zero" reading consistently on all the tower control channels when the scanner scans through them, all except the Washington Tower, which show no signal strength indicator deflection, and no D-error reading. Seems like the Washington tower is turned off.

I get the following D-Error and Signal Bar readings:

Shirley Tower: D-Error = consistent "zeros" all the time, both when receiving voice transmissions, as well as when only the control channel signal indicator is present, 5 bars of signal strength at all times, control channel, as well as voice transmissions.

Imperial Tower: D-Error fluctuates between 0 and -15 (+)(-) a point or two, only one bar of signal strength.

St. Clair Tower : D-Error fluctuates between 0 and -5 (+)(-) a point or two, 2 bars of signal strength.

Weldon Spring Tower = D-Error fluctuates between 0 and -48, but often in the mid -30's, only 1 bar of signal strength.

Washington Tower = no readings either way, no control channel, no voice reception, and no bars of signal strength...is it turned off?

dBm is generally consistent with the signal bar indicators, the lesser the number of signal bars the higher the negative dBm number is.

I still get very good audio reception performance off of all the above MOSWIN towers, with the exception of the Washington Missouri tower, and even with the less than stellar D-Error and Signal Bar indicators showing on the scanner's readout regarding some towers, they all seem to be working equally well with respect to their audio reception.

But, I'm especially surprised that the best reception I seem to be getting with respect to signal bar indicator and D-Error indicator is off the Shirley tower in Washington County, better than the St. Clair tower, which is much closer to me versus the Shirley tower. The St. Clair tower is probably less than 2 miles away from me in Union, Missouri, whereas the Shirley tower's range circle on the MOSWIN map has me quite a distance outside the perimeter of the Shirley towers supposed maximum range.

I don't get it...

You should get rid of the display field you have set for "Batt:" as the SDS runs off external power and replace that field with "D-ERROR:". The lower the D-Error reading the better! A reading of zero when they are talking is ideal.

 

[kruser]

Kruser prompted me to change the BATT indicator to the D-Error indicator. It can't be done within Sentinel, it has to be done from the display editor via the SDS200 itself. Not sure if Proscan provides a way to do it through programming or not, but if so, I expect it would be a little easier. I'll have to investigate that further when I have the time.

You can definitely change the Display setting in Sentinel. I'm not good at explaining how to do it but that's exactly where I change mine. Or you can do it with the radios menu also but Sentinel is easier if you ask me. Look at the top row menus in Sentinel and you should see one for Display settings. Hopefully someone else will come along and explain these settings in Sentinel for you!

I notice that I get a D-ERROR "zero" reading consistently on all the tower control channels when the scanner scans through them, all except the Washington Tower, which show no signal strength indicator deflection, and no D-error reading. Seems like the Washington tower is turned off.

THIS is normal, the D-Error may not display errors until a voice channel is talking. This sounds like you have a decent signal of the control channels at least.

Washington Tower = no readings either way, no control channel, no voice reception, and no bars of signal strength...is it turned off?

The 700 MHz Washington site is definitely Online using 773.03125 for the control channel. It's possible they have it locked out for voice traffic though but you should still see the control channel signal if you are programmed correctly.

But, I'm especially surprised that the best reception I seem to be getting with respect to signal bar indicator and D-Error indicator is off the Shirley tower in Washington County, better than the St. Clair tower, which is much closer to me versus the Shirley tower. The St. Clair tower is probably less than 2 miles away from me in Union, Missouri, whereas the Shirley tower's range circle on the MOSWIN map has me quite a distance outside the perimeter of the Shirley towers supposed maximum range.

The Shirley tower site is using 171.26250 MHz for its control channel. If your scanner is displaying Shirley but with a different frequency, you are not hearing the Shirley site! It's easy to have mistakes with this statewide system as a lot of frequencies are reused across the state. What frequency is displayed when your scanner says it's on the Shirley site?

The two sites you are having issues with are both 700 MHz sites. All the other sites you mentioned are VHF.
Even though the St Clair site is close to you, how's your antenna for 700 MHz? What are you using for an antenna and is it indoors or outdoors? If outdoors, how high and what type and length of coax are you using?

I forget your location exactly but Shirley is probably not out of the question for you. Verify you are on that frequency for Shirley I listed above though. I can hear all the sites you mention but not always. It can be very band opening dependent for me. I'm using various antennas up about 40 feet. A 12 element yagi for the 700 MHz sites and an old antenna specialists VHF Hi/Low band for the VHF sites. And I'm located up high in the eastern part of Chesterfield very near the old St Louis County EOC bunker and county police radio towers on Olive and Ladue.

One other thing, for the 700 MHz sites, set the Filter setting for those sites to Off unless you have a ton of other 700 MHz towers very near your location but I don't think you do.

I don't get it...

 

[u2brent]

Kruser prompted me to change the BATT indicator to the D-Error indicator. It can't be done within Sentinel, it has to be done from the display editor via the SDS200 itself. Not sure if Proscan provides a way to do it through programming or not, but if so, I expect it would be a little easier. I'll have to investigate that further when I have the time.

I don't get it...

FYI,
If the profile being used does not point to (Target) an SDS100 or SDS200 the Edit Display functions will be disabled.

Located just under the scanner menu button, It should look like this..

 

[kruser]

FYI,
If the profile being used does not point to (Target) an SDS100 or SDS200 the Edit Display functions will be disabled.
View attachment 111852
Located just under the scanner menu button, It should look like this..

That's a very good point that the Target Model must match!
The target model choice is actually under the "Tools" menu though.

 

[kruser]

I don't get it...

I missed your screenshot earlier showing reception of the Shirley site. If the signal strength readings are true, Shirley is giving you a very nice signal considering the distance!
I'm still wondering about your antenna type and coax etc.. for the problems you seem to be having with 700 MHz sites.
Something seems to be going on in the antenna part of your setup.
VHF and 700 MHz UHF is also a factor. VHF usually wins.

The St Clair 700 site tower is just west of St Clair along I-44. Regardless, you should get a decent signal from that site even if they are using some form of directional antenna on that 700 MHz site. I think are using the standard 700 MHz omni antenna they use around the state however.

I'd take the SDS200 dBm and signal bar meter readings as well as the RR range ring estimations with a grain of salt. The SDS models can be influenced by many external factors as far as the signal strength meters go and the RR range rings are also just a best guess estimate based on site location and antenna height and ground elevation plus transmitter power.

For the Display Settings, as long as Sentinel is set to one of the SDS models, under the screenshot that @u2brent posted, look under the Edit menu for Display Settings.

One thing I did notice this evening is Washington, MO PD has been heard on the Weldon Spring tower a lot more than what seems like normal.

 

[teknishun]

Changing the battery voltage label to digital error count is simple.

Open Sentinel
Click on Tools and make sure Target Model = SDS200
Click on Edit Display (the little rainbow box that has 3 colors)
Two new boxes will open up
Click on the Detail Trunk Tab
Click on the area of the display that currently shows "battery voltage"
You will notice the title of the other (color) box changes to "Battery Voltage" also. This is a DROP DOWN LIST.
Using the drop down list scroll key, scroll down to "Digital Error Count"
On the display where "battery voltage" was you will see it change to "Digital Error Count"
SAVE your changes and exit.
Download to your scanner.

 

[rbritton1201]

Thanks, I did find it last evening when I was messing with it, and noticed how you can name the various windows, etc...Appreciate the help!

Changing the battery voltage label to digital error count is simple.

Open Sentinel
Click on Tools and make sure Target Model = SDS200
Click on Edit Display (the little rainbow box that has 3 colors)
Two new boxes will open up
Click on the Detail Trunk Tab
Click on the area of the display that currently shows "battery voltage"
You will notice the title of the other (color) box changes to "Battery Voltage" also. This is a DROP DOWN LIST.
Using the drop down list scroll key, scroll down to "Digital Error Count"
On the display where "battery voltage" was you will see it change to "Digital Error Count"
SAVE your changes and exit.
Download to your scanner.

 

[rbritton1201]

I missed your screenshot earlier showing reception of the Shirley site. If the signal strength readings are true, Shirley is giving you a very nice signal considering the distance!

Yes, I'm impressed by the signal reception I'm getting off the Shirley tower, but maybe it's just a straight shot to the Shirley Tower, no obstructions from geography, but yeah, it seems pretty extraordinary to me too! I checked all the frequencies that are entered into the scanner for each of the towers entered into the scanner, and they all match the listing of tower frequencies listed in radio reference for each respective tower.

I'm still wondering about your antenna type and coax etc.. for the problems you seem to be having with 700 MHz sites.
Something seems to be going on in the antenna part of your setup.
VHF and 700 MHz UHF is also a factor. VHF usually wins.

I have a Diamond Discone Antenna, mounted in the attic, about 20 feet off ground level. The coax is RG8/U mini foam, not the thick stuff, a little larger diameter than RG58/U mobile coax. It runs about 60 feet up to the attic from the shack. The frequency range of the Discone antenna is 25 - 1300 MHz, so it should receive the full range of frequencies.

The St Clair 700 site tower is just west of St Clair along I-44. Regardless, you should get a decent signal from that site even if they are using some form of directional antenna on that 700 MHz site. I think are using the standard 700 MHz omni antenna they use around the state however.

I'll bet I'm not probably more than two or three miles from that tower...I don't get it either! Doesn't make sense that the signal from the Shirley Tower appears to be superior to the signals from the St. Clair tower. Both towers seem to deliver that same quality of audio, the only discrepancy is the statistical readouts I'm seeing on the scanner, but I don't notice any better performance by the ear between St. Clair tower and Shirley tower.

I'd take the SDS200 dBm and signal bar meter readings as well as the RR range ring estimations with a grain of salt. The SDS models can be influenced by many external factors as far as the signal strength meters go and the RR range rings are also just a best guess estimate based on site location and antenna height and ground elevation plus transmitter power.

For the Display Settings, as long as Sentinel is set to one of the SDS models, under the screenshot that @u2brent posted, look under the Edit menu for Display Settings.

Yes, I was able to mess with it very early this morning, and found the area where I can make those display adjustments via Sentinel after all. I did check to also make sure that the program points to the SDS200, and it is correctly programmed with respect to that setting.

One thing I did notice this evening is Washington, MO PD has been heard on the Weldon Spring tower a lot more than what seems like normal.

I still receive no signals off the control channel or voice reception via the Washington tower, and I double checked specifically to make sure the frequencies are all within programming for the Washington tower, and they are there in programming. Not sure what's going on with that. But, if I'm only getting about two bars off of St. Clair, even though t it's not a reliable indicator, then maybe geographically reception is impaired by geography? But, I get between two and three bars off the Weldon Spring tower. So, who knows...

 

[scanman1958]

I have a question for you. Are you south of Hwy 44 from the St Clair site? If so the could be a reason you don't get the Washington site signal. I was in Washington a few months ago looking for the tower location ( which I narrowed down but did not exactly locate) and the signal is not a strong one and has trouble getting up and over 44. In my car I really had a ton of signal loss once I got up to the highway.

And from numerous trips up and down 44 to and from Bennett Spring I too can pick up the Shirley tower pretty darn good in my car. That site seems to have great coverage.

And if you don't live south of 44 then all that can be thrown out the window. Just trying to help.

 

[kruser]

I have a Diamond Discone Antenna, mounted in the attic, about 20 feet off ground level. The coax is RG8/U mini foam, not the thick stuff, a little larger diameter than RG58/U mobile coax. It runs about 60 feet up to the attic from the shack. The frequency range of the Discone antenna is 25 - 1300 MHz, so it should receive the full range of frequencies.

You don't have a metal roof by chance do you? That would surely kill some signals but I'd think it would totally wipe out the reception from the Shirley site!

The average Discone usually has the typical 25 to 1300 range claim but in reality, they start doing a poor job somewhere around 400 MHz or higher. Their radiation angle starts looking more and more up at the sky instead of out to the horizon where you get the signals from mostly.
They do make discones that are truly rated for 700 MHz+ but they are usually military and not cheap!
The RG-8U coax does have about 7 dB of loss at 780 MHz over a 60 foot length so you are loosing a fair amount of signal there. Every 3 dB of loss halves your available signal.
I'm not sure what the loss of the discone could be considered at 780 MHz as a discone is a unity gain (0 dB gain) antenna. I guess it could be a negative gain as it starts looking towards the sky for the higher frequencies above 400 MHz or so. I'm not sure how that would be calculated if it even can!
You will also get some loss being in an attic even if you don't have a steel roof.
How's your physical homes elevation compared to other homes, buildings or structures nearby and the height of the average terrain around you? Especially if you were to draw a line towards Washington city as well as the St Clair site along I-44. Anything blocking signals from either or both of those sites?

With all that figured in but not knowing about your roof construction, I'd think you should still be able to pull in the St Clair 700 MHz site very well using what you have now!

The Washington site could be a different story as it does not seem to have great coverage to the south of Washington. It's almost like they used directional antennas to contain that sites signal within the city of Washington itself but not much else once you travel out of the city.
@scanman1958 just posted similar findings about the Washington site while driving out I-44.

I do know the Washington did provide great coverage to the north down into the river valley north of Washington the last time I drove out to Washington via highway 94 from I-64. I've often wondered if they are using directional antenna for that site though. Especially if the sites purpose is to serve the city of Washington only but not really provide coverage for the county.
As noted, the sites signal really seems to drop off fast as you travel south out of Washington.

Did you once say you did get the Washington site before?
If so, I'd take a close look at your coax connections and connectors as well as the coax run itself and make sure you don't have any sharp bends or even kinks in the run or a connector that may be pulling apart. Sharp bends in coax can ruin it internally. Sometimes immediately and sometimes over a period of time before it fails.
The system techs could have also tuned the coverage of the Washington site since it went on the air to provide max coverage in the city but not the areas outside the city. I've seen that happen several times with today's trunked sites before but not so much, if ever, with Moswin sites.

I can't think of anything else that gives a red flag.

 

[rbritton1201]

I'm North of the St. Clair Tower location, near the East Central College...

I have a question for you. Are you south of Hwy 44 from the St Clair site? If so the could be a reason you don't get the Washington site signal. I was in Washington a few months ago looking for the tower location ( which I narrowed down but did not exactly locate) and the signal is not a strong one and has trouble getting up and over 44. In my car I really had a ton of signal loss once I got up to the highway.

And from numerous trips up and down 44 to and from Bennett Spring I too can pick up the Shirley tower pretty darn good in my car. That site seems to have great coverage.

And if you don't live south of 44 then all that can be thrown out the window. Just trying to help.