Tetra decoding

[ET-NL]

thanks for the report!
do you get more SSI info for calls in the new version?
..

On the the private call's I now also see the ISSI of the mobile unit. With the previous versions of Telive I only saw the ISSI of the office unit.

ET

 

[grosminet]

funcube GRC

I prefer my previous method . In GRC you have to search for the right signal wich is often boring . With QTHID , you put the exact frequency and Tetra decoder is running .

I succeed in 1.8 with SDRPLAY by using my own osmosdr-tetra_demod_fft.py .It is working fine also with RTL SDR KEY

I tried 1.8 with funcube pro plus and GRC changing in grc frequency and hardware hw:2 to hw : 0 but can't decode . I found hw is 1 but grc is in 96k and I should de 192K for funcube pro plus

Maybe you can manage to contact GQRX people in order to make GQRX working with telive

 

[sq5bpf]

I prefer my previous method . In GRC you have to search for the right signal wich is often boring . With QTHID , you put the exact frequency and Tetra decoder is running .

same here. either you put the frequency in the running flowgraph, and it works, or you open the flowgraph in gnuradio-companion, change the parameters (frequency, offsets, ppm etc), and save it as some other filename. then either open it in gnuradio-companion and run it, or compile it into python (click run->generate) and run the resulting python file without using gnuradio-companion

I succeed in 1.8 with SDRPLAY by using my own osmosdr-tetra_demod_fft.py .It is working fine also with RTL SDR KEY

but this is only 1 channel. why use a receiver with only one channel when the rtl dongle and sdrplay have several MHz of bandwidth?

I tried 1.8 with funcube pro plus and GRC changing in grc frequency and hardware hw:2 to hw : 0 but can't decode . I found hw is 1 but grc is in 96k and I should de 192K for funcube pro plus

that flowgraph uses the funcube source, which isn't that flexible (osmocom source would be better). i've just added telive_1ch_simple_gr37_slow_udp.grc , which is the flowgraph used on my bootable image. this uses a rtl-sdr with 256kHz sampling rate to save CPU. you can use it for the funcube dongle +. just change samp_rate to 192000, and change the osmocom source properties to fcd=0,device=hw:1 . i don't have a funcube dongle + , but this should work (maybe with a few other minor tweaks)


btw it's hard to support receivers which i don't own. hint, hint

 

[sq5bpf]

i've commited a small change to telive to disable audio buffering. this may be a fix for the problem reported by drmaligno

could you update telive and test? the old behaviour can be toggled by pressing ! (this is active only for new calls, not for the ongoing call)

i think it does sound slightly better (less hickups), but would like others to test

 

[drmaligno]

Sorry, i do not note any change,

my better option is with
demod/${GR_DIR}/simdemod2.py -o /dev/stdout -i $FIFO | ./float_to_bits /dev/stdin /dev/stdout | ./tetra-rx /dev/stdin


Thank you

 

[Greg94430]

tetra

Hello, excuse my English but I use a translator I have the same problem as drmaligno. I did all the test as you indicated sq5bpf but micro cuts are always the voice. My setup is a 3.6GHz AMD Phenom quad core with 4g of memory so I do not think it comes from my material. Hoping that you find a solution and thank you for your superb work sq5bpf

 

[mrscanner2008]

saw this on another forum.

A new TETRA voice and multiframe SDS decoder - rtl-sdr.com





Is that 2 software have the same function to decode the tetra?

We don't have Tetra here in Quebec, Canada to test the 2 software.

 

[sq5bpf]

Is that 2 software have the same function to decode the tetra?

similar

but it is much better, because it does reassembly of fragments for SDS, which tetra-rx doesn't do right now. so it will work in case of long SDS (here these are ignored or show up as garbage)

i will look into it once i get some free time (not soon unfortunately)

 

[drv73]

Hello from Spain.
I 'm using Debian Telive 8 get to see all the information in " receiver1 1" terminal and also on screens Telive , but I do not see A_play in Telive .
Maybe I need another codec ETSI for my area en_30039502v010301p0.zip ??

Thank you very much and congratulations to the creator this software

 

[grosminet]

State of art in TETRA decoder

After already 4/5 years of Tetra decoding experience, I can give some feed back

- For me the best configuation , stable , low cpu and low memory is Funcube pro + and QTHID 4.1 and fcdp-tetra-demod.py

No graph , you put the exact frequency in QTHID and go

- second good configuration is working with osmosdr-tetra-demod (original version not the one in s5bpf package ) Working fine with RTL SDR key

-other results :

SDRplay is working with sort of clamping with osmo-tetra-demod . There is sort of interference in the signal that make lost of tetra decoding . Less result than funcube pro +

AIRSPY isn't working with osmo-tetra-demod because of over buffuring USB and "ooooooooooooooo" result after 1 minutes .very high CPU usage crash computers

I never succeed with GRC , It is too boring trying to set the exact frequeny with GUI .

That the reason I did some test with GQRX and CubicSDR . I think it is the best way to try on with tetra decode and high speed SDR (airspy and sdrplay)

Tests made with UDP and Gqrx aren't good because GQRX isn't sending the right format

I was unable to make tests with cubicsdr because IQ output isn't documented . I made many requests on github (no answer)

For me the best way is the usage of a good GUI linux interface (GQRX or cubicsdr) and adaptation to telive . (multiples graphical VFO ) could allow to monitor plenty of TETRA signals .

sorry for mistakes , english isn't my native language

 

[sq5bpf]

I never succeed with GRC ,

the remaining 99% of users succeded with this method, maybe you're doing something wrong?

It is too boring trying to set the exact frequeny with GUI .

but you don't have to do this. instead of clicking you can input the ppm and frequency into the text boxes. also you can hardcode the frequency, ppm and other parameters in the grc file (and have different grc files for different networks). i've written about this multiple times.

an advantage of the rtl-sdr (and airspy and sdrplay) is that they can monitor several MHz at once, and the grc scripts allow monitoring multiple channels at the same time. the funcube and funcube dongle+ have only 96kHz or 192kHz of bandwidth, so this is only good for 1-2 channels.

 

[grosminet]

for sure

For sure I m doing something wrong in GRC . Maybe due to airspy and sdrplay wich are much more very good SDR . I m looking for an airplay.grc from 1.8 version but with settings of 1.5 version

I didn't understand what is the best between grc with UDP or GRC with fifo .

I' ll succeed

 

[webexcel82]

Raspberry

Proud to announce that I have just got the following working:

0. gnuradio-3.7.9
1. receiving data from an osmosdr source directly on the RPi2 (rtl-tcp)
2. getting it to work with Gnuradio-Companion on the host system
3. compiling the grc script modify it to run headless on the RPi2
4. running grc headless on the pi with direct hardware access (hence not using rtl-tcp)
5. running telive on the Rasberry Pi
6. encoding sound with opus
7. broadcasting metadata & voice to zeromq

Load average: 1.71, 1.79, 1.65 [verbose messages off in telive]

Indication of the cpu usage across the different components;

root     16485 71.0  7.0 204992 66796 pts/3    Sl+  23:33  16:34 python2 top_block.py
root     16491 12.8  7.2 221248 68912 pts/1    Sl+  23:33   3:00 python demod/python-3.7/simdemod2.py -o /dev/stdout -i /tmp/fifo1
root     16492 17.2  0.1   2856  1624 pts/1    R+   23:33   4:01 ./tetra-rx -a -i /dev/stdin
root     16581 11.2  0.6  25520  6080 pts/5    Sl+  23:41   1:47 ./telive

If people are interested I am happy to write up an in depth tutorial on this specific project. But I want to focus on the bigger picture

For now a small picture

Hi skinkie, I tested the installation with automatic script raspbian (did not work), in lubuntu, and ubuntu mate. In the last two, it works properly until it starts to decode voice, at which spend 4 or 5 seconds and the Xterm window ./rxx process stays blocked.
As you've accomplished it work? Thanks in advance

 

[grosminet]

I succeed

I succed running airspy single GRC and airspy . I have just a question . I don't know why the standard display sometime switch to AFC display like

**** AFC : 0.0002 (any value)

then re switch to decode

On what parameter could I play to suppress this ?

 

[grosminet]

sdrplay

I tried to clone airspy GRC to use sdrplay with tetra . I replace rtl sdr block by osmocom source .

full spectrum is good but channel 1 FFT has clamping display

I changed many parameters but no change . Anyone with a sdrplay and gnuradio radio could make a proper working grc ?

 

[webexcel82]

Hi skinkie, I tested the installation with automatic script raspbian (did not work), in lubuntu, and ubuntu mate. In the last two, it works properly until it starts to decode voice, at which spend 4 or 5 seconds and the Xterm window ./rxx process stays blocked.
As you've accomplished it work? Thanks in advance

Responding to myself, the problem is not the rxx, but the raspberry 3 model B soundcard. I put a external usb soundcard and...thas it!! Tetra PI mobile scanner whith a external battery accomplished!

Thanks to all

 

[grosminet]

airspy decode

After tests with internal antennas , I installed a pro yagi 420 MHz band (made for TETRA) .

I noticed that rxx is changing to all knows tetra frequencies in my 425 -430 Mhz range . rxx is swiching to another frequency after displaying AFC series then synchronize to another frequency and decode again

What rxx dont respect the frequency I put in grc ?

 

[sq5bpf]

I didn't understand what is the best between grc with UDP or GRC with fifo .

with pipes you need to launch receiver1 first, and the grc flowgraph second.

with udp you can use whatever order, you can turn receiver1 off (but leave the flowgraph running) and run at again, and also the flowgraph will work wiithout he receiver.

 

[sq5bpf]

I noticed that rxx is changing to all knows tetra frequencies in my 425 -430 Mhz range . rxx is swiching to another frequency after displaying AFC series then synchronize to another frequency and decode again

the AFC is not really AFC (i will have to call it something different). it just tries to be smart about the offset for the bit levels after the qpsk decoder. this allows receiving a more mistuned signal. it will receive a signal mistuned 1.5kHz, but not 25kHz.

What rxx dont respect the frequency I put in grc ?

rxx shows you the decoded control channel frequency (and other frequency data if you press t). it doesn't even know what frequency you put in grc, because this is a separate program.

these are possible explanations:

- you have the gains set too high, there is a lot of signal from the yagi, and the receiver is overdriven. this will cause receive errors, and garbled data. and some of this garbled data will be frequency data.

- the airspy receiver has some image frequencies, and you're receiving two stations at the same time because of this. this can be caused by a lot of things (like a bad antialiasing filter before the ADC, bad I/Q balance etc)

- there are several stations on this frequency, sometimes you're receiving one and sometimes the other


i don't have an airspy, so it's hard to give any more specific suggestions. you can try to play with the gains and with the IQ balance options. if you want to see image frequencies, get a signal generator, tune it around the band and check when it is seen on the receiver spectrum.

 

[grosminet]

airspy

The quantity of received datas with airspy is much more imortant than any others like funcube or rtl sdr

Maybe 10 times more .

If I set the right level rxx doesn't change frequency