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AM / FM tuner TEF6686 controlled from the computer

dktr 11142 19
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  • AM / FM tuner TEF6686 controlled from the computer

    Recently, you can buy interesting AM / FM tuner modules on the TEF6686 chip. Such a module costs about PLN 100 and is sold as an FM head for car radios. It has amazing possibilities, great sensitivity and selectivity, adjustable de-emphasis and filter. The module is already output analog audio L + R, or MPX, depending on the configuration.
    The device consists of a microcontroller atmega328 with a program that translates the i2c communication with the tuner and issues via uart. You can use the xdr-gtk program to control, I think that a lot will be explained by the movie on which I make a rather slow band-scan, in the background an open page maps.fmdx.pl where you can quickly and easily verify what and where it comes from.



    The antenna used in the film is a dipole installed in the V polarization on the roof of a four-story block, more precisely on a pipe from the former azart installation, plus a 40 m cable.

    The housing comes from an old, damaged vga-composite converter and the holes for the sockets fit perfectly.



    AM / FM tuner TEF6686 controlled from the computer

    AM / FM tuner TEF6686 controlled from the computer

    The tuner itself looks like this:

    AM / FM tuner TEF6686 controlled from the computer

    Wiring diagram:

    AM / FM tuner TEF6686 controlled from the computer

    There is also the possibility of remote operation of the tuner, you will additionally need a raspberry pi and a sound card with a line-in connector, then the tuner itself can be installed in a convenient location and used without delay via the Internet. I have such an installation on a 70 m chimney, the xdr itself is publicly displayed so everyone can have fun.
    The necessary programs are here: http://dktr.pl/XDR
    There is foobar2000 configured to have as little audio delay as possible and an item with stream address added. There is also the xdr-gtk program, to connect you need to enter the hostname dktr.pl and the password 12345 and you can shoot.

    Cool? Ranking DIY
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    About Author
    dktr
    Level 22  
    Offline 
    dktr wrote 601 posts with rating 332, helped 26 times. Live in city Ostróda. Been with us since 2003 year.
  • #2
    simw
    Level 26  
    Since you presented your solution in another thread, such a tuner has come to me.
    The cost is PLN 67 + PLN 15 per shipment.
    The module will now wait for its turn, perhaps for the end of the world, and a day longer than most procrastinating projects :)
    Thanks for sharing your solution.
  • #3
    Nepto
    Level 15  
    Nice! Where exactly did you buy this tuner module? Could you upload a more detailed photo of the module's board?
  • #4
    dktr
    Level 22  
    Aliexpress or other Chinese store and enter tef6686.

    Pictures, I also unsoldered the screen.

    AM / FM tuner TEF6686 controlled from the computer

    AM / FM tuner TEF6686 controlled from the computer
  • #5
    Nepto
    Level 15  
    Thanks a lot for the photo! It's actually interesting, in the TEF6686 datasheet from NXP they say that the housing is HVQFN32 and here you can see if it had feet.
  • #6
    dktr
    Level 22  
    The leg is not there, it's tin. Interestingly, the manufacturer of the module saved on ESD protection, which is probably why more is sold ;)
  • #9
    excray
    Level 40  
    dktr wrote:
    Recently, you can buy interesting AM / FM tuner modules on the TEF6686 chip. Such a module costs about PLN 100 and is sold as an FM head

    I prefer to buy a complete tuner with an amplifier, control and display for 1/3 of this:
    https://www.aliexpress.com/item/32816122408.html
    on some Chinese invention, which has such sensational sensitivity that without any antenna it already receives even medium-strong stations, and also offers good audio quality. Anyway, I plug it in, it works. For this it also has an RS232 input, which you can control the tuner in your own way and make your own interface.
  • #10
    dktr
    Level 22  
    This Chinese invention is QN8035 and there is no driveway to the TEF6686 chip from this thread. A completely different league of tuners.
  • #11
    excray
    Level 40  
    As for the quality of the FM stereo signal, it is too good. Anyway, in the era of DAB and streaming music, such tuners are like a cassette tape.

    By the way, I compared several parameters such as sensitivity, SNR or THD and both systems are practically the same. So I have no idea on the basis of what you concluded that the layout you are writing about is better. As for me, it is an ordinary system dedicated to Car Audio, i.e. rather not very sophisticated equipment.
  • #12
    dktr
    Level 22  
    I tested tuners made on the qn8035, si4703, tea5767 chips on the same antenna. Only tef6686 can handle, for example, the reception of radio 7 at -94dB at 88.0, where on 88.1 I have + PLUS + with the signal -65, there was chaff on the other tuners, similarly with VOX FM 94.7 and Jedynka at 94.8. This is equipment for listeners and not for radio listeners, the quickly refreshed and accurate signal indicator nicely visualizes, for example, the signal reflection from the plane, support for rotors gives the opportunity to outline the directional characteristics of the antenna, and after scripting, you can set an alarm when the conditions for good propagation begin tropospheric ;)
  • #13
    sq3evp
    Level 29  
    How is the sensitivity of TEF6686 compared to others? There are a lot of descriptions on the Internet, but I did not find a strict comparison of parameters and subjective assessment "by ear".
  • #14
    dktr
    Level 22  
    It all depends on the level of interference. With the antenna input shorted, the signal indicator shows -120 dBm. In my location, three shielded cat6 twisted pairs go to the roof along with the coaxial cables, when all devices have a fastened link at the end, the noise level increases to -95 dB in the entire range. Under such conditions, the stereo jumps at -91 dBm and the RDS at -75 dBm. The antenna is an ordinary dipole in V polarization on the roof of a 4-story block, for example RMF from Koszalin on 89.3 I receive a 60 kW transmitter at -92 dBm - 210 km.
  • #15
    sq3evp
    Level 29  
    These are nice results. From what you write, the audio quality is not great, but the selectivity is better?
    I wonder how it would perform on something better than an ordinary dipole.
  • #16
    William Bonawentura
    Level 33  
    dktr wrote:
    Recently, you can buy interesting AM / FM tuner modules on the TEF6686 chip

    How about AM reception? Can you upload our 225kHz recording?
  • #17
    dktr
    Level 22  
    On AM it is surprisingly good, in the middle of the city, the antenna is a dipole 88-108 with a balun, so not quite for this band.
  • #18
    William Bonawentura
    Level 33  
    Thank you very much. You've just found a "word-music" broadcast :D

    I will ask 2 more questions.
    1) Do I think that as a PC driver - a module, an Arduino board should be suitable?
    2) In the case of using Rasbpers, connect the I2C directly from the GPIO connector of the board?
  • #19
    dktr
    Level 22  
    Atmega328 (arduino) is there to translate commands from uart and pass them via i2c to the tuner. If you compile on rpi then there is a chance to run everything without atmega - it might be useful, but only for remote listening. Then somewhere far away in the rpi + tef6686 box and the audio card from line_in, rpi locally is not needed, because analog audio is straight from the tuner and you don't have to push it through the network. In the case of local control everything will work atmega and a computer from usb uart. Currently, I put such a tuner together with an atmega and a VFD display in the housing from the Denon tuner, you only need to make a hole for the USB socket, local control is already working - tuning from the buttons. Now I have to finish parsing RDS, I already have PI :)



    So it will be in the housing.

    AM / FM tuner TEF6686 controlled from the computer

    Edit, the whole thing was closed in the housing ;)
  • #20
    delta221
    Level 1  
    In the Netherlands Sjef has made a TEF V2 and also V1 tuner for AM and FM, all info is here: search : pe5pvb
    I can not post now a link, there are also lot of video's see on Youtube:
    TEF V2 reciever LW MW and SW
    You can get it on GTK by Wifi and audio also by BT
    AM / FM tuner TEF6686 controlled from the computer