Tetra Signal Scanner

[oe5kbo]

hallo my friends i come with a problem and hope for interesting discussion.

I try to track the tetra uplink signal 380 to 385 mhz uplink . with my spectrum analyzer. How strong must be the signal if it is by 5 watt about 500 meters away.

Can you sent me a picture if you have track a uplink Signal from Tetra. Please make a test with emercency cars fire cars. Report me i will do the same and report you.

Ore it is better with openear software to track the uplink ?????? and the RTL SDR ????



Thanks karl

 

[Ubbe]

You can have a RTL-SDR or equal to scan the 380-385MHz range and set its gain to a very low value and an antenna tuned to the band to minimize out of band interferences. Then the software, perhaps in a RaspberryPi, would filter the result and check the timing for the pulses to correspond to the tetra protocol, and trigger some sort of attention device.

The TTT software can decode tetra uplink and I think you can do attention tone if it decodes a call, even if its encrypted and uplink, at least with the older versions. You would then probably use the scanner plugin in SDR# to cover a frequency range.

/Ubbe

 

[oe5kbo]

´hallo ubbe thanks for replay. first a question is see in your underline a lot of transceivers MD 380 and CS 750 do you work DMR ????
If yes fine. ??

Now i need your help. yes because i am not so long on SDR. I use SDR Studio 1.0.0. 1832

TTT will not run i make something wrong. see my pictures maybe we bring it to run!!!!

 

[oe5kbo]

another picture

 

[oe5kbo]

one picture more

 

[Ubbe]

I only listen DMR and have programmed some systems in them that are scanned. CS750 are working OK but MD380 are much better. Stay away from CS580, it is terrible and are a Baofeng radio.

Your first picture show a receive quality of 72% which is bad. It has to be 90% or better. Other picture with TTT show 92% but the problem are that your SDR dongle are not calibrated in frequency in SDR# and when TTT sends a frequency to the dongle it will be off frequency with bad reception.

Start only SDR# and not TTT. Tune to the correct frequency 392.1375 and then go into the cogwheel for settings and adjust "Frequency correction ppm" until you see the received signal exactly in the middle of the marked bandwidth in the bandscope. You can zoom in and adjust the bandwidth to match the signal exactly when adjusting ppm. Then TTT and other programs will send the SDR dongle to the correct receive frequency.

/Ubbe

 

[oe5kbo]

ok i have the 95 % but TTT is still not working what is wrong. ......

 

[oe5kbo]

hi ubbe is this a upload signal i think it is a download signal. How i can different the upload to a download signal and how i can check up how near in db is this signal ????? How is to decide a upload signal and a download signal ????? How you can decide this in the waterfall signal ????

 

[oe5kbo]

First i have to find out what is a upload signal and what a download. How you can do this. ????? with the signal strange because a Base station will not change the signal strange correct, ore other way ???? Is the upload Signal other frequencies as a dowload ???

 

[Ubbe]

Upload to the basestation are always a pulsating signal that sounds like a machinegun. Downlink from the basestation transmitter are always a continous carrier with digital modulation.

You will normally only see uplink signals if you are very close to anybody transmitting and the transmission are only temporary for a couple of seconds. Downlink from a basestation are always transmitting and not stopping.

You are still low in frequency. Increase the ppm setting by 2.0

Start SDR# and TTT and then stop TTT and download my IQ recording and load that wav file instead of RTL-SDR and play it as the Source in SDR#.
Click the Demodulator and Auto and also NetInfo and you should see calls being done at other frequencies and you will also hear one call if you have the volume slide turned up.
If you start TTT if will immeditaly go to the control channel that are not part of the recording and it will not work.

15-03-24_427750kHz.wav

drive.google.com

/Ubbe

 

[oe5kbo]

hallo my friend ubbe. I do wrong. Can you help me with a Teamviewer Session. If you have time please give me a timetable if you can config my
SDR. Thank you for helping .

 

[oe5kbo]

my email kbrand0777@gmail.com sent me email if you have time

 

[oe5kbo]

Halo ubbe ok this was working i bring your file from 240 sweden to listen super fine

now i find another wav file on my laptop is this from you with tetra modulation decrypted or this from me ?????? stored ???

 

[oe5kbo]

will you sent me an email i sent you this file back kbrand0777@gmail.com this is a file to decode

 

[Ubbe]

If you can't decode it then I cannot either. My email provider usually stops files attached so might not work. Use google drive, its free.


/Ubbe