OpenEar: An Easy to Use Windows TETRA Voice Decoder

A new TETRA voice decoder called "OpenEar" has just been released. The program is a standalone Windows app that directly connects to an RTL-SDR. Decoding a TETRA voice signal is as simple as opening the program, tuning to the TETRA frequency and clicking on the signal. With good signal strength voice comes through very clearly. CPU usage on our PC is also minimal. 

The program source is currently not available as the author notes that he only intends to release it as open source in the future once the project is completed, and right now this is only the first early release. Right now the program is just an .exe with a few .dlls. You'll need to first install the Microsoft Visual C++ Redistributable Package linked in the Git readme. Just in case, we virus scanned the exe and tested the program in Sandboxie. It appears to be clean, and it works as intended.

In the future the author hopes to support many more protocols such as DMR, MPT1327, ACARS, AIR, GSM and more. In order to support his work he is asking for Bitcoin donations, and the donations link can be found on the Git readme.

UPDATE 1: If you're getting missing dll errors and you already installed the Visual C++ Redistributable, try downloading the missing dll's from There should only be about 5 missing.

UPDATE 2: As pointed out in the comments by Steve M. from Osmocom, this software may be in violation of several GPL licences as no source code has been released and it appears to rely on GPL code and libraries. Please take this into account.

UPDATE 3: As per update 2, the author has decided to temporarily disable the TETRA functionality pending a rewrite of the code that he will complete within one to two months). Instead he has added DMR decoding.

OpenEar TETRA Voice Decoder Screenshot
OpenEar TETRA Voice Decoder Screenshot


    • moneriomaa

      If the problem persistsو you can take screenshot from OpenEar when you try for decode Pocsag (when pocsag is exist on spectrum)
      then send it for me, i see that you are in correct way or not
      or you can record baseband I/Q with sdrsharp and send it to me, i analyse signal and find what is the problem
      [email protected]

    • Greg Hefferon

      Pour moi le pocsag fonctionne parfait, et je n’ai pas besoin de décalage, je me cale directement sur la fréquence et les messages sont la

  1. thierry

    bonjour je n’est aucun message pocsag avec votre logiciel est-ce normal j’ai la trame sur 466.175mhz mais pas de message

    • moneriomaa

      don’t place your signal on center of spectrum! set 50KHz or 100KHz shift on main frequency
      (for you like 466.275 mhz)
      then click to signal then you can decode if it is pocsag, it is tested

        • moneriomaa

          in version 1.7.0 this problem solved, there is not place for inserting shift, but you can change main frequency for place signal 50k or 100k with shift for example if your signal frequency is 360 MHz
          then set main frequency 259.9 MHz it shifts signals to right 100k

  2. thierry

    comment ajouter les c+++

    3- Ajouter un démodulateur AM / FM de base à l’interface utilisateur pour une écoute de base des fréquences analogiques pour la première sortie vocale de l’interface graphique

    4- Tetra Decoder Conversion de codes en c ++ et test par signal I / Q et rtl-sdr

    5- Décodeur DMR Conversion de codes en c ++ et test par signal I / Q et rtl-sdr

    6- Décodeur Pocsag Conversion de codes en c ++ et test par signal I / Q et rtl-sdr

    7- Décodeur ADS-B 1090 (Mode S) Conversion des codes en c ++ et test par signal I / Q et rtl-sdr

    8- Décodeur AERO Conversion de codes en c ++ et test par signal I / Q et rtl-sdr

  3. landry telliez


    It would also be in the future to know if there will be the possibility of decoding the protocol (Antares and Acropol)? Its not bad either

      • moneriomaa

        if you download version 1.5.4 (last on github) it is decode tetra
        but read Note part on readme github before use

    • moneriomaa

      sorry i didn’t hear Antares and Acropol before!
      they are navy? give me more info please

      • RF Guy

        Antares/Acropol is the French Communication System for Police. Its based on Tetrapol Technology. The Air Interface is simple encrypted Tetrapol.

        • moneriomaa

          thanks, yes, i found some info about it on book
          “Mobile Telecommunications Standards: GSM, UMTS, TETRA, and ERMES”

    • moneriomaa

      about tetrapol i think more than 98% is encrypted and i like spend time for protocols with more reachable outputs (but tetrapol is interesting and can’t be forgotten)
      about gsm, it is time consuming with few output (voice is encrypted (in offline can be decrypted by kraken) and hopping signals)
      but interesting and maybe done in near future

      • RF Guy

        for the 2 % unencrypted Tetrapol Transmission its worth to design a windows decoder.
        there are some complete unencryptet Tetrapol Networks out there.
        maybe some users can provide signal samples of unencrypted Tetrapol.
        please don’t forget TETRAPOL !

        • moneriomaa

          yes everything that never be heard before could be interesting, on near future try for more studding about tetrapol vocoder part

        • didier

          bonjour je pense que les pompier ne sont pas crypter en France du coter tetrapol
          super boulot et j espère que tu va y arriver sa serai super au moi de savoir se qui si passe dessous et merci bien

    • moneriomaa

      adding more hardware support is in plan but no release time specified (it is in six months plan)

  4. echelon

    I’m waiting for a version that supports the Airspy R2. The program sounds very promising!

    Will there be a way to decode Tetra encryption TEA 1,2,3?
    Or is this technically not possible.

    • moneriomaa

      you’re welcome
      multi hardware support yes is in plan
      Anyone interested can send an empty e-mail to [email protected]
      for notifying release update and details

      about Encryption, it is interesting field, about DMR encryption some works done and about Tetra some study started but documentation is not public, i try be more focused in this field

  5. MACNZ

    Author, impressed with DMR decode Audio quality, for my ears significantly more intelligible audio decode than DSD+ 1.01.

    Suggest keep working through the issues and improvements.


    • moneriomaa

      about quality there is so many reason can be there
      but when i heard ” significantly more intelligible” there is maybe another reason that must checked
      cause as like you i compared it before by dsdplus and when is comparable quality i released that
      i think there is another problem!
      about working for better quality, yes after current works (DMR Bp, EP decryption), i review that

  6. Walid

    now my computer is working fine , I am working with OpenEar v1.5.4
    I can report that Tetra is working as instructed by shifting the center frequency about 100 KHz it decodes but a lot of breaking occuring
    DMR no decoding
    Hopefully the new release will come up soon addressing those issues as this is a very promising project

    Thanks for the good work

    • moneriomaa

      you’re welcome
      about this problem you said
      ” a lot of breaking occurring, DMR no decoding”
      about breaking accruing please describe more your meant
      was the crash happened? or other meant about breaking?!
      about DMR no decoding did you see Sync word when click on DMR or not?

      • Walid

        thanks for the reply
        On Tetra I receive the Voice but the audio is breaking a lot
        On DMR no Sync

        Thank you

        • moneriomaa

          you’re welcome
          audio qulity is more depend on two thing in my mind
          1- demodulator output quality
          2- data loss
          for 1 check the constellation graph in normal it must 8 point in 4|4 arrangement
          Better separate points give better quality it reachable by more gain and snr (if i remember correct, 20 db or up must be has good constellation)
          2- if in decoding process, point have so many rotation or distribution it is maybe for data loss in path
          i saw it so rare,some times in old cpu but for most currently cpu it must work fine

          about dmr try click on center of signal that red cover all the DMR signal it must shows sync (I imagined that as you said you shifted DMR )
          if you again see no sync you can record I/Q baseband signal on 1.024 by sdrsharp and send to my e-mail for more process by me (no need big size it is enough for 5 or 10 seconds and if you decide to do this please don’t forget that signal not placed on center, thanks)

  7. vselic

    Any news, if there Will be a way, to listen to the encrypted traffic? The program is useless for most of european users…

  8. Moray

    Just a quick note to say thanks Moneriomaa ?

    I’ve been testing your programme for a few hours now, and it’s so much easier to use than the various windows and linux apps that can’t do as much as yours! I hope development continues into the future ?

  9. Tom

    Not working also here, with same 0xc000007b error on differents computers
    Any solutions!? Nothing worked so far for me, what i found on the internet.

    Thx! Tom

  10. Ondrej

    Hello, is it possible to add “generic” nput devices? I use ICOM R8600 which has both IQ output through DLL library and IF output as a 12,5 kHz as a “sound card”. Is it possible to add fuctionality to select the signal source? Thanks.

    • moneriomaa

      yes it is possible but currently rtl hardware like security dongle for running.
      but more hardware will be supported in Pro version in future with more software features and different UI
      Pro version is currently under development and no release date specified

  11. dxon2m

    Thank you for the good work!
    I am patiently awaiting the TETRA decoder to be active. Would I be able to see the information broadcasted on the TCCH? (ie. Location Area, Security Class, MNC/MCC, etc)

    Also I have been using the DMR function on a local Capacity Plus system, but nothing is showing except for the word “Sync”.

    • moneriomaa

      you’re welcome
      about tetra network info yes i add some features in future.
      about DMR and any other protocol (expect ADS_B)
      note that i wrote on Notes part that there is center known issue that i try to solve this but before i solve the issue, for decoding signal it must be some shifted from center not more but about 50 or 100khz to right or left then click the center of signal, sample of this description showed on github readme image

  12. walid

    I downloaded the latest version of the OpenEar project placed it on a known DMR frequency At the same time I placed the AOR AR-DV1 on the same frequency , I can see the signal but no Sync achieved via OpenEar while I can get a clean decode from the AOR receiver, same applies for Tetra.
    At the end I hope you can add a squelch function for the AM and NFM mode.

    Thank you for all your efforts and patience

    • moneriomaa

      you’re welcome
      please, check this notes “” as i said

      -fix issue for clicking center of spectrum (some ddc simple problems)

      currently you can’t receive signal on center of main spectrum you must shift signal 100KHz or more from center to right or left then you get clear output, as i show it on my sample picture on github,
      this is known issue and i solve in next releases
      but currently solution is that i describe above
      about squelch i add in next version

      • walid

        Thanks for your reply I can confirm , after shifting the signal that
        Tetra is working although my old computer audio breaks up
        DMR decoding very poorly and sometimes not decoding at all

        • moneriomaa

          you’re welcome
          about minimum snr needs for getting clear voice 22 db for tetra and 18 db for dmr is minimum
          but i work for using better demodulator for improving performance

      • George

        I am unable to get OpenEar working with windows 7 64 bit
        Is it that normal ? I noticed you mention testing on windows 10 and 8.

        Thank you

        • moneriomaa

          i have not system with windows 7, for testing, but from users that used the software only one person gave feedback that error like “The file version is not compatible with the running Windows version…” has been you have same error like this or another one?

  13. Anonymous

    Hopefully frequency field gets more decimal places, now it has three … you can enter e.g. 434.562 but not 434.5625.

    • moneriomaa

      i updated this on v1.5.4 and now you can enter e.g. 434.05625
      and note that Fs is 10240000 and this fft resolution is 4096 so you get 1024000/4096 = 256 Hz resolution
      adding more precision (5 or 6 floating digit) currently is not useful

  14. moneriomaa

    one people on forum said that with avast virus scanning, received “idp.ares.generic virus detected”
    i searched and find this link about some reason for this mistake on detection
    maybe useful for some one that use AVG and Avast antivirus software.

  15. landry telliez


    I just tested the pocsag in the 466Mhz awesome reception 512 Bits on the other hand I realized that the frequencies of the firefighters are at 1200 Bits and the function is not activated a solution will be found for the 1200 Bits ???

    • moneriomaa

      it must works for pocsag 512,1200 and 2400 bits, did you test for 1200 Bits and no detection?
      i tested it for multi bitrate and messages detected, you can help for better improvement with recording I/Q
      by sdrsharp and give it to me for further review

  16. Ronen

    The Software is only for 64 bit it would be nice to have a 32 bit version
    also a PPM frequency compensation parameter for the dongle would help to tune to the correct frequency

  17. moneriomaa

    its depends that which organisation used tetra, anyway using tetra with encryption is a more power consumption for handheld unit, Anyway, I haven’t taken the time to review it yet, but it’s an interesting subject to consider in the future, although it may seem a bit difficult to get to

    • moneriomaa

      its depends that which organisation used tetra, anyway using tetra with encryption is a more power consumption for handheld unit, Anyway, I haven’t taken the time to review it yet, but it’s an interesting subject to consider in the future, although it may seem a bit difficult to get to

      • vselic

        police, road services and other public services based on law&order… it’s a shame that even single burst can’t be heard. I believe it’s most likely the same all over Europe. Hacking the traffic is illegal anyway, but if somebody just “catch” the traffic, demodulate it and than bypass the encryption in smoe way, it should not be illegal – shure – if you do not share the data with public. I belive it already exists, but for private or. government purposes, so it’s not reachable for public online.

        • Anonymous

          Even listen to such freq is illegal to in the most european Country.
          Depend where you are life there are here 3 different Tetra systems:
          380 – 400mhz
          1) Police, Fire,… -> encrypt
          2) “other” Customer -> may not encrypt
          other freq:
          3) often not encrypt

          • vselic

            Not true… if you “catch” the traffic, which is on air – which you can hear with any radio reciever (rtl sdr, mobile station etc.), it is not illegal! What you do with the captured traffic is your bussines. You haven’t stolen anything, which is on air. So if you get modulated encrypted traffic, demodulate and decrpyt it, it’s your thing – but it’s illegal, that you share traffic with public.

            Other thing would be, if you hack the base stations, steal mobile stations, disturb the traffic and so on.

  18. landry telliez

    Hello everyone I have a quick question how should I proceed to have the audio of my DMR communications I don’t receive anything?


    • moneriomaa

      i will soon add the invert (DMR-) option maybe it help you, of course this is the standard implemented version on ETSI that mostly used by Motorola, maybe other manufacture change some implementation especially on vocoder , With all these explanations you should be able to mess up the sound with a encryption or change in the vocoder or even see the “sync” word on software. non of them?!

  19. moneriomaa

    Hi all
    i try to answer all comment but some times my post sent but not shown i don’t now why!
    about performance of Tetra in previous release that i disabled it temporarily (its hard to say for me after six months of day-night trying to make c++ class for Tetra) yes some improvements (on affect of center frequncy and snr) in demodulator for reach better performance, is in my job and release it on next two months.
    about error that you get on start point of running, i compiled it with static option, for remove needs to msvcr dlls but if any other error happened, it’s maybe about systems, so reason maybe different then solution is different.
    I will decide on adding protocols after the current phases and the protocol most likely to be in the comments will probably be chosen

  20. GiamMa-based researchers

    Nice, it works in TETRA under certain conditions but with different anomalies.
    It is still a good job if not excellent!
    Today we try the DMR.
    Someone asks if there are similar decoders for POCSAG / FLEX, the answer is yes, just search online…

    • moneriomaa

      you’re welcome
      i try to reach better performance by replacement of demodulator (improvement of output for input center frequency and snr) and other improvement on next release
      for pocsag / flex and tetrapol and other protocols after current phases, i decide to new plan

    • moneriomaa

      three days before, there is no tetra version of openear
      please be patient for 1 or 2 months for new version that much better of previous version

          • RF Guy

            yes, please try it so hard as you can…There are no working Tetrapol decoder for voice, you are a GENIUS when you can make a Decoder for Windows..

            • moneriomaa

              After 10 years of experience in comint, these things have become a personal favorite for me, and I do my best to add more protocols. thanks a lot, Everyone is GENIUS and just have to believe it 😉

  21. Anto

    After put mscvr120d.dll into the same folder then it’s works flawlessly receiving tetra TMO (OS windows 7 SP 1 64bit). Still further works to be done to distinguished between 4 time slot to listen. Hopefully it can be done for future release (with auto or manual choice among 4 time slot) and put other decoder such as P25 Phase 1 and DMR.

    • moneriomaa

      As I understood this error can have many causes
      For example:
      -Your operating system should be x64 for this software
      -check compatibility option on properties
      -run as administrator
      and some other solutions that you can easyly find on youtube by searching this error

  22. Steve Markgraf

    I don’t see what’s “Open” about this. There is no published source code for this program, thus it violates the GPL of librtlsdr and the AGPL of osmo-tetra.

    The readme states:
    “4- Convert all code in Tetra protcol on osmocom tetra to c++ objective code.It is a complete conversion from the I/Q acquisition stage to Voice and other data decoded by osmocom-tetra (more than 5000 lines of code only for tetra have been rewritten for better performance and objective usage features)”

    Of course you can not simply “rewrite” code so that you can publish it under a different license, this would require blackbox-reverse engineering.

    • moneriomaa

      the Open word i used for three reason, no limitation of protocols, no limitation for use and finally open source (with condition)
      if i set osmocom-tetra on my read me this is not meant that i use exactly that, i said rewrite coz it rewrited in 6 month of time,
      software is not one part that named tetra, it have more modules and parts that currently i cant realese the code as opensource with any licence.
      i think only way that i correct my readme file for pereventing make mistake

    • moneriomaa

      “Not working?!”
      how i can take screenshot when not working?!
      or maybe you must describe your problem

      “lots to be done” yes i agree with this

    • moneriomaa

      “Not working” !?
      How i can take screenshot, if it is not working?!
      or maybe better that you describe your problem more

    • Scanner

      msvcrt120d.dll is a “debug”-version of the file msvcrt120.dll
      Release versions should not make use of debug dll files

  23. walid

    the program asked for MSVCR120D.dll in order to start , after I installed the MSVCR120D.dlle , the program will not start
    any help please

    • Chris

      I tested this decoder with my main computer, got that error massage with the missing msvcr120d.dll. After I replaced that dll, I got the same problem you get. I tried a different computer and then it worked just fine.
      It works, but under specific circumstances. Sadly, I don’t know why it doesn’t start on some computers.

      • moneriomaa

        i compiled it with static link library again and uploaded it, download openear again and try to run, tell me result thanks

    • moneriomaa

      I tried tetrapol decoding but couldn’t get the clear sound so I’m waiting for the desired sound output then to use it in this software

  24. Remon

    I think it still needs a lot of work but no mention in readme:

    Tetra has 4 time slots, nothing in the GUI.
    DMO support?
    External audio support?

    • moneriomaa

      Yes there is a lot more work to be done to make it more desirable, but it will be done gradually.

      1-for multiple slots, currently last call-id selected and send to vocoder but coz code is objective in future 4 vocoder path is replaced and can listen to all 4 slot voice.
      2-about DMO support: answer is no
      3-for external audio:
      This request has two parts
      his request has two parts
      The simplest part is to add the reading data from the audio device where this is applicable
      The second part, this protocol is pi/4DQPSK the input data must be raw(I/Q) and may be slightly different with the standard audio rate for specified demodulator that i used
      I’m trying to find a better demodulator that has a lower error rate for improve performance for weaker signal. After finding this demodulator I will definitely add a feature that is not too far off, maybe in the 3 month period.

Post a comment

You may use the following HTML:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>