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  1. Fast Convolution Filtering with Teensy 4.0 and audio board

    To test T4 performance I extracted the fast convolution filtering code from my SDR and tested it with the Teensy 4.0 and the Teensy audio board. Both were connected with flying wires (MCLK with...
  2. Hi! it seems it does not work properly with...

    Hi!

    it seems it does not work properly with the library as it is at the moment.

    I used the SGTL5000 audio board, connected it to the T4.0 and used the guitar example. Additionally to the...
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    Thanks for your input! When using the DAC...

    Thanks for your input!

    When using the DAC alone, it works perfectly both ways: either with SCL connected to GND (PLL mode) or SCL connected to pin 23 (using MCLK from the Teensy 4.0).

    But when...
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    Oh, did not know that. I left SCL of the DAC...

    Oh, did not know that. I left SCL of the DAC unconnected.

    When testing with the Convolution object by DerekR I experienced strange crackling noises. Could it be that this is caused by this?

    I...
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    Thanks again for the hints! ADC works together...

    Thanks again for the hints! ADC works together with DAC !

    Connections for documentation:

    Teensy 4.0 with ADC PCM1808 module (line-in Input), running simultaneously with the DAC PCM5102...
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    Thanks for that hint! Is working now. Just for...

    Thanks for that hint! Is working now. Just for documentation for others to try:

    Teensy 4.0 and DAC PCM5102 module from AliExpress

    Vcc = Vin
    GND = GND
    FLT = GND
    SCL = floating
    BCK = BCK =...
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    Could you post your sketch for using the PCM5102...

    Could you post your sketch for using the PCM5102 with the Teensy 4.0? Or did you just use an example sketch? If yes, would be nice to know which one you used.

    Thanks a lot!

    Regards, Frank DD4WH
  8. Thread: Bat detector

    by DD4WH
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    Hi Edwin, thanks a lot! I will think more...

    Hi Edwin,

    thanks a lot! I will think more about that!

    However, adding additional hardware for features already implemented (built-in SD card) is a bit annyoing, and I think I read that the...
  9. Thread: Bat detector

    by DD4WH
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    well, then we will never know or solve the...

    well, then we will never know or solve the problem with the noise that you have . . .
  10. Thread: Bat detector

    by DD4WH
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    Hi Corbee, it could well be that the 23kHz...

    Hi Corbee,

    it could well be that the 23kHz noise is associated with the wrong connection of the central pad which must be left totally unconnected in single ended mode. But we do not know if you...
  11. Thread: Bat detector

    by DD4WH
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    Hi Corbee, as I stated, the spectrum is from...

    Hi Corbee,

    as I stated, the spectrum is from 0 to 250kHz (500ksps sample rate !), you have to multiply the frequency axis by 10 ;-).

    Your spectrum looks good, except for the peak at 23kHz.
    ...
  12. Thread: Bat detector

    by DD4WH
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    strange, I updated the spectrum, can you see it...

    strange, I updated the spectrum, can you see it now? Its visible here . . .
  13. Thread: Bat detector

    by DD4WH
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    Here is a spectrum of a recording with the...

    Here is a spectrum of a recording with the ICS40730 made in Audacity:

    17222

    As you can see, the scale is from -70 to -90dB on the y-axis, so there is no pronounced noise at a certain frequency,...
  14. Thread: Bat detector

    by DD4WH
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    Hi Edwin, sorry for being silent so long. I...

    Hi Edwin,

    sorry for being silent so long. I have some experience with the ICS40730 and can only say its the most powerful ultrasound MEMS I have ever seen . . . it can pick up ultrasound up to...
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    Hi Valeri, well thats explainable: * there...

    Hi Valeri,

    well thats explainable:

    * there are different options to use the oscillator chip Si5351: which clock output do you use? [CLK0, CLK1, CLK2] and which Xtal frequency did you install?...
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    Hi FrankB, thanks a lot for your simulations...

    Hi FrankB,

    thanks a lot for your simulations of the input filter!

    I am a little puzzled about that difference in comparison to my simulations with ELSIE . . .

    Will have to think about that...
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    It will probably take us a while to account for...

    It will probably take us a while to account for the changes in Teensy 4.0.

    At the moment I am not sure whether it will compile and/or work with the T4. I do not own a T4 yet, but the order is...
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    There have been several people with that plan....

    There have been several people with that plan. But as far as I know, nobody has published code for that.

    If you are interested in an SDR transceiver code, you might have a look at UHSDR (however,...
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    you seem to confuse the "Teensy SDR" with the...

    you seem to confuse the "Teensy SDR" with the "Teensy Convolution SDR".

    The former is using all 16-bit integer math and uses blocks as in the audio library. So your proposed way of using it should...
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    As far as I can see, there is no need for such a...

    As far as I can see, there is no need for such a large (and processor-intense) FFT. Of course the T4 could help you, but I am pretty sure that by reducing the load you can do that on a T3.6

    Your...
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    Hi gohlhausen, thanks for your work! Did...

    Hi gohlhausen,

    thanks for your work!

    Did you test, how your FFT performs if applied to audio? In my experience, when used for convolution (FFT --> complex-multiply with filter mask --> inverse...
  22. We now use a total of 12 microSoundRecorders for...

    We now use a total of 12 microSoundRecorders for recording nocturnal Crex crex (corn crake). Thank you again, Walter, for providing us with this Teensy 3.6 recording tool with your software!

    Our...
  23. Thread: Bat detector

    by DD4WH
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    deleted due to browser error.

    deleted due to browser error.
  24. Thread: Bat detector

    by DD4WH
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    Hi Edwin, what an impressive amount of...

    Hi Edwin,

    what an impressive amount of microphones!!! Looks like a lot of soldering fun ;-).



    This is wrong for single ended mode and is not stated in the datasheet, that is what my posts in...
  25. Thread: Bat detector

    by DD4WH
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    Hi Edwin, I feel that there are several people...

    Hi Edwin,

    I feel that there are several people having problems to understand how to use the ICS40730 in single ended mode for maximum performance ;-).

    Here is the <magic> with that MIC:

    GND...
  26. Thread: Bat detector

    by DD4WH
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    I initially thought you were looking for people...

    I initially thought you were looking for people reporting about their experience with the ICS40730. Thats what I did.



    I can highly recommend the ICS40730 which has proved to be of excellent ...
  27. Thread: Bat detector

    by DD4WH
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    Well, that is odd. How would you explain that...

    Well, that is odd.

    How would you explain that we use the ICS40730 in many devices with great sucess and in your setup the output is not clean?

    I am not sure what you mean with two outputs? The...
  28. Thread: Bat detector

    by DD4WH
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    Hi Remis, we use the ICS40730 as a standard...

    Hi Remis,

    we use the ICS40730 as a standard ultrasound microphone for our semiprofessional bat recorders (in single ended mode !):

    * it has a sensational frequency response up to 160kHz
    * it...
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    Hi Holger, give this a try also, its a very...

    Hi Holger,

    give this a try also, its a very nice filter designer and also plots the response and gives you the coefficients. Also helpful is the possibility to test the filters with different...
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    Hi Valery, 1.) sample rate: yes, that is...

    Hi Valery,

    1.) sample rate: yes, that is already implemented in the newest version of the software!

    2.) yes, that is also possible, but you would have to alter the function setfreq according to...
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    Hi Frank, I have no experience with PIN diode...

    Hi Frank,

    I have no experience with PIN diode switching, but they are said to have low resistance against IM3, which means that high signal levels can seriously distort your reception. Could be...
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    Hi Valery, please learn how to use the Arduino...

    Hi Valery,

    please learn how to use the Arduino IDE and Teensyduino in order to compile your programs by yourself!

    That is really vital and important and will help you a lot for your own...
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    Hi Valery, nice to hear from you and thanks...

    Hi Valery,

    nice to hear from you and thanks for your report!

    However, I tested the situation with the AGC and I cannot confirm the behaviour you describe. The AGC works fine and similarly in...
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    Hi Wolfgang, I am happy to help, but not in...

    Hi Wolfgang,

    I am happy to help, but not in "second hand mode", so Valery should post his questions here directly on the forum.

    My suspicion is that he operates the Teensy Convolution SDR...
  35. https://framagit.org/PiBatRecorderPojects/TeensyRe...

    https://framagit.org/PiBatRecorderPojects/TeensyRecorders/blob/master/PassiveRecorder/Fabrication/Souder%20c'est%20facile%20-%20Voici%20comment%20faire.pdf
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    Hi Mike/bicycleguy, integrated your eePROM...

    Hi Mike/bicycleguy,

    integrated your eePROM code into the current version today. It now works properly, I think! I used a brandnew fresh T3.6 to test this and everything worked out nicely (after I...
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    Hi Mike, thanks for your pull request treating...

    Hi Mike,

    thanks for your pull request treating EEPROM.

    Sorry, I messed up the github (github is not one of my strengths, I must admit . . .).

    There seem to be problems with your code:

    *...
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    Awesome!!!! That specific atan2 approximation...

    Awesome!!!!

    That specific atan2 approximation lowers the processor load in FM demodulation from 40.6% to 28.15% (234ksps sample rate) and in the first tests I cannot hear the difference between...
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    Hi Walter, hi Frank, yes, I can confirm: ...

    Hi Walter, hi Frank,

    yes, I can confirm:

    SGTL5000 overclocking with 234ksps and 281ksps works nicely [I use those sample rates frequently for receiving wide band FM stereo broadcast stations...
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    new version of Teensy Convolution SDR is on...

    new version of Teensy Convolution SDR is on github

    https://github.com/DD4WH/Teensy-ConvolutionSDR

    new:

    * new excellent SDR hardware by DO7JBH supported
    * bugfixes (thanks bicycleguy!)
    *...
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    bicycleguy, thanks for your very good and...

    bicycleguy,

    thanks for your very good and precise observation!

    Probably my fault, sorry!

    It could be that this odd behaviour is caused by a buffer overflow (that is my fault!):

    please...
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    Hi bicycleguy, sounds good, would like to try...

    Hi bicycleguy,

    sounds good, would like to try to integrate your code into the script, if you allow!

    However, calibration_factor has to be type unsigned long long, please change that in your...
  43. Thread: Bat detector

    by DD4WH
    Replies
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    31,503

    Hi Alain, the datasheet of the ICS40730 states...

    Hi Alain,

    the datasheet of the ICS40730 states that the mic has a sensitivity that is 6dB lower in single-ended mode vs. differential mode. However, the high SNR of 74dBA is the same irrespective...
  44. Thread: Bat detector

    by DD4WH
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    Salut Alain, Edwin, Cor, Jean-Do. and all others...

    Salut Alain, Edwin, Cor, Jean-Do. and all others interested,

    Darras et al. (2018) in their paper use the ICS40720, which is an older version of the MEMS. Also they do not describe any frequency...
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    Hi bicycleguy, thanks for the suggestion! I...

    Hi bicycleguy,

    thanks for the suggestion!

    I do not understand the code fully yet, so I will take some more time to digest it. However, a couple of things to comment on:

    - calibration factor...
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    Hi Derek, thanks for your clarifying reply! ...

    Hi Derek,

    thanks for your clarifying reply!

    I had to read over that again in my favourite book (Rick Lyons "Understanding Digital Processing") and one of my favourite papers on Fast...
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    Hi Derek, sounds very interesting, looking...

    Hi Derek,

    sounds very interesting, looking forward to it!

    Sorry for my potentially silly question, my approach to DSP is more a way of trial and error than really having available any formal...
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    Martin, yes, we thought about this. I am not...

    Martin,
    yes, we thought about this. I am not sure whether the actual 12bit resolution of the ADCs (even if you set them to 16bit) will be sufficient for a high quality radio, but who knows whether...
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    hi Martin, what Thierry probably meant was this...

    hi Martin, what Thierry probably meant was this method by Frank B:

    https://forum.pjrc.com/threads/38753-Discussion-about-a-simple-way-to-change-the-sample-rate?highlight=change+sample+rate
    ...
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    Derek, thanks a lot for the detailed...

    Derek, thanks a lot for the detailed explanations!



    excellent! Thats totally new to me, I thought you had to rotate the frequency bins of the FFT output (and not the coefficients) for frequency...
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