DSDPlus Tait TIII system not showing CC number

[LA6FRA]

There is a Tait TIII system with multiple base stations in my area (Spain). I cannot follow the TG's because the system do not broadcast the CC Chanel number. Derfor a cannot allocate a frequency to the other channels. The only thing I know is the fequency of the CC channel. I have been asigning a chanel number and using the DMR_TIII_LxN_Freq_calc to fill up other chanel numbers. So far now luck. Any suggestions?

 

[mtindor]

I see multiple issues

1. Gain too high
2. Crappy signals on at least one of them
3. Wrong BW set in FMP* (should be 7.6, not 12.5)

Fix some of that so that you can get good signals.

The CC does show the channel number

You need to monitor the control channel long enough to obtain ALL of the Ch's

Group Call; TG=5046476 RID=5047800 Ch=1228

Then you need to determine all frequencies in use on that same site

Then you have to determine what Ch is assigned to what frequency

Looks like you are on the right track, at least somewhat. But fix that high gain (your dongle is overloading) and concentrate only on signals that are 20db or better above the noise floor. If you must work with weak signals, it's going to take longer. Increasing the gain doesn't always help (as can be seen in your screenshot).

In the screenshot on the right, it's probably being directed to the right channel, but the signal is too weak. Thus the ERR. You should strive to be ERR free.
Mike

 

[LA6FRA]

Thanks Mike. I am confuse about the BW. The system uses 12,5.
I have all the chanel numbers of this site. The cc frecuency is 172.1875. The I have ch 1227 1128 and 1233 and 1234


I have another system, about 30 kms away. This one gives me the CC number and the neigbours site CC number.
Everythings works OK with this.

 

[mtindor]

Thanks Mike. I am confuse about the BW. The system uses 12,5.
I have all the chanel numbers of this site. The cc frecuency is 172.1875. The I have ch 1227 1128 and 1233 and 1234


I have another system, about 30 kms away. This one gives me the CC number and the neigbours site CC number.
Everythings works OK with this.

No, the system does not use 12.5. ALL DMR is 7.6. The BW should be set to 7.6. No exceptions.

In your DSDPlus.frequencies file make sure 1227 is tied to the proper freq and 1233 is tied to the proper freq

On the system 30 km away, what does it say the CH is for the neighboring CC (this site) ? Does it say its 1227 or 1233?

 

[LA6FRA]

The first system is VHF. This is the one I do not find the CC number for the CC chanel, only CC frequency and all other chanel numbers associated to this site. No frequencies.

Current network: L1
Current site: L1-9.8
CC 172.1875 Unknown ch number
This system do not give the CC number. This is the one I try to find.


The other sytem, UHF, give thge following info in the cc chanel T12-2.1 neighbor: Site T12-1.2; CC=979 This one is not a problem!

 

[mtindor]

For L1-9.8 :

You are going to have to sit on the control channel until there are Group calls. You'll have to log all of the CH #s.

You said you have 1227/1228 and 1233/1234 but your screenshots show that you have:

1227/1228
1237/1238
1239/1240

Do you know all the frequencies assigned to this site? Or only some of them?

Sit on the CC. When it says there is a Group Call on 12xx, if you don't hear that group call on the CC (you likely won't), move to another frequency that you know is part of the site, as quickly as possible, to see if there is voice active on that freq. You are going to have do that until you can determine at least one voice frequency. You'll only be able to know the LSNs/LCN of the control channel if (a) a voice call occurs on it, which they never do on TIII CC's around me, or (b) you know the system's bandplan and can calculate it.

But you have to have at least one LSN <--> frequency confirmed 100% to even attempt to calculate the other frequencies, if a bandplan can be deteremined.

Mike

 

[mtindor]

In your first set of L1-9.8 screenshots, it shows :

1239 172.1875 CC on the right side
1237 172.1875 CC on the left side

Are you just guessing LSNs and inserting them into the DSDPlus.frequencies file? If so, don't guess.

You need to determine for certain what frequencies are part of Site L1-9.8. You know that 172.1875 is. Do you know of any others with 100% confirmation?

Recommendations: Try _not_ to provide screenshots that show "guesses". That doesn't help anyone on this forum to help you. We need to deal with only 100% factual information.

Mike

 

[mtindor]

Are you will to post (or email or private message me) your 1R-DSDPlus.Event log? Or any *DSDPlus.Event log?

That would be useful. Of course it might contain information about other systems that you don't want to post publicly about. But at least that would allow us to look through the log and see what actual LSNs were advertised as being in use on that site.

 

[cg]

There is the bandwidth or the space the signal occupies on the spectrum. DMR signal is 7.6KHz wide, P25 signal is 9.5 or 12.5 KHz wide, NXDN is 4KHz wide. Use the "B/b" key to change
And then there is the step, or how far apart each channel is from another one. Without knowing what the typical step for VHF is in Spain, I would guess it may be 12.5K. If so, the channels in your system would fit in a pattern something like:
1227 172.1125
1229 172.1250
1231 172.1375
1233 172.1500
1235 172.1625
1237 172.1750
1239 172.1875
1241 172.2000
1243 172.2125
1245 172.2250
1247 172.2375
This is what the calculating program you used is figuring. Do not worry about the even number channels in the Frequencies file, they are assumed to be there.

 

[mtindor]

FMP has autocorrection turned on. And in the first screenshot, lefthand side, it had to correct 835 hz or so. that's excessive. Either the freq on the left is not accurate, or the dongle needs some PPM adjustment. Given that, it's hard to say if the bandplan @cg posted above is right or not. In the screenshot, on the righthand side, I can't see how much correction had to be used. It may be autocorrecting enough that the frequencies we think are the frequencies are .00625 or .0125 off. Would be good to know that the dongle was tuned to the center freq of the CC and VC with a max autocorrection of around 100hz or less.

 

[LA6FRA]

I made a few DSDPlus.frequencies files and I activated recording. Then I just wait for the signal and check everytime if any recordings was made until I got recordings. Then I new the right frequency anc LSN.
I works perfectly now

 

[LA6FRA]

I pick up 12 sites from here from the same network, every site has a cc frequency + 3 more frequencies. I can see open and encrypted traffic.