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  1. Hi Dirk, when I changed the code to work with...

    Hi Dirk,

    when I changed the code to work with T4.1, I also used two PSRAM chips and checked whether that would work.

    it does not work!

    The reason is not the CPU power, which the T4 has more...
  2. :-) Well, it is a matter of definition of your...

    :-)
    Well, it is a matter of definition of your goals!

    You mention three different of your goals in this thread:

    * pitch shifting
    * playback rate adjustment
    * crunchy and lovely audio...
  3. In the context of Software Defined Radio dealing...

    In the context of Software Defined Radio dealing with analytical (complex) signals, builders often use an IF at exactly samplerate-divided-by-4, ie. in your case 192ksps / 4 = 48kHz

    Then you are...
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    I am not at all familiar with FAUST, but by...

    I am not at all familiar with FAUST, but by looking at the webpage it seems that there are things that can be very easily done with a T4.1 (all the filtering stuff) and more complex/demanding things...
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    Could you specify your project and the kind of...

    Could you specify your project and the kind of DSP you are planning? Otherwise there is no chance anyone could help you with an idea.
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    ??? Could you be a little more specific in your...

    ??? Could you be a little more specific in your question?

    I think the T4.1 is more than capable of doing complex DSP.
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    Bob Larkin provided very nice code for an Audio...

    Bob Larkin provided very nice code for an Audio Equalizer (https://forum.pjrc.com/threads/60928-Audio-Equalizer-using-FIR?highlight=audio+equalizer), which I implemented as a 9-band graphical EQ in...
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    Yes, the Malahit is a nice receiver, but...

    Yes, the Malahit is a nice receiver, but unfortunately closed source.

    If you port the software to the STM32F7 or H7, please keep it open source and it would be very nice if you posted a link to...
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    Yes. At the moment it is programmed like that....

    Yes. At the moment it is programmed like that. Synch is not a problem, because both, the ADC and the DAC use the same master clock MCLK provided by the Teensy.

    Paul, did you already build a Teensy...
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    Not sure what you mean exactly? What are "valid...

    Not sure what you mean exactly? What are "valid channels"?

    Do you want an automatic frequency scan search for stations and save their frequencies in memory?

    That is not implemented at the...
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    I hope, the new version solves this problem. ...

    I hope, the new version solves this problem.

    73 Frank
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    Thanks for pointing me to that, You are right, I...

    Thanks for pointing me to that, You are right, I built that bug. Will try to solve that this evening.
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    Bill, I tried to exactly reproduce the situation...

    Bill, I tried to exactly reproduce the situation you described:

    * 50 Ohms resistor on the antenna input

    21537

    So, the spectrum looks similar, BUT: the birdies are very very low signal...
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    Yes, fully agreed! :-) AM mediumwave stations...

    Yes, fully agreed! :-)

    AM mediumwave stations do not pose problems any more here in Central Europe, because most countries have shut down all or many of their transmitters! (eg. Germany, the...
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    Just to let you know I uploaded a new version of...

    Just to let you know I uploaded a new version of the software to my github.

    * Teensy 4.1 support with DO7JBH hardware (and a self-built T4.1 to T3.6 adapter)
    * Menu Assistant by tisho (thanks a...
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    for wideband transformers, I have good experience...

    for wideband transformers, I have good experience with FT77 ferrite material ring cores and also with binocular cores 73-202. Using this ferrite material leads to better results in the VLF range...
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    Hi Bill, good to hear your setup works with...

    Hi Bill,

    good to hear your setup works with higher drive strength. I use the default 2mA and it works, but could have to do with shorter wires.

    You made a very good point in discussing the...
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    Hi! that looks like you have some sophisticated...

    Hi!
    that looks like you have some sophisticated plans, very interesting!

    Si5351:
    * maybe you could experiment with the drive strength of the Si5351 which is software controlled?...
  19. Workaround1: * Restart the Codec once you...

    Workaround1:
    * Restart the Codec once you detected twinpeaks
    Workaround2:
    * Shift your Sample Buffer by one Sample once detected

    I use the DAC PCM5102 for my setup
    You do Not need two Teensy...
  20. This specific bug made me crazy a few years ago...

    This specific bug made me crazy a few years ago while programming SDR radio software.

    We termed it "twin peak syndrome", because in an SDR, you have to have a strict 90 degree phase difference in...
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    It seems I had a combined hardware and a software...

    It seems I had a combined hardware and a software bug that prevented mirror rejection. Now it runs and the mirror rejection seems normal! Excellent.

    Also, the mirror rejection seems to be highly...
  22. Thread: Bat detector

    by DD4WH
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    Deleted due to possible misunderstanding

    Deleted due to possible misunderstanding
  23. Thread: Bat detector

    by DD4WH
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    Yes, exactly. An ultrasound signal ZoomFFT...

    Yes, exactly.

    An ultrasound signal ZoomFFT example with real figures:



    with the original routine in the software, 256 samples are taken as input for the FFT [the internal routine uses an...
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    Regarding the non-existing mirror rejection with...

    Regarding the non-existing mirror rejection with the Msi001:

    * Do you experience also missing mirror rejection?
    * in your video, Esteban, I can see that there is some mirror rejection on...
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    @tisho, @Esteban: I have a bugfix for the...

    @tisho, @Esteban:

    I have a bugfix for the tuning step / AFC


    int64_t DeltaF = p.freq - Flo; //Calculate the diference between the "set" and the "result"(without fine correction)...
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    0xf380 does not make sense to me at all:...

    0xf380 does not make sense to me at all:
    1111001110000000 --> so reg0, no RF synthesizer enabled??? [bit 10]

    and then, reg0 is written again?
    0x6280
    --> 110001010000000

    and then, which...
  27. Thread: Bat detector

    by DD4WH
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    Ivano, * is there a similar ADC with 500ksps...

    Ivano,

    * is there a similar ADC with 500ksps that could be powered on a single 3V3 supply? That would enable users to power them with a single 3V7 lithium 18650 cell. The ADS8685 seems to be using...
  28. Thread: Bat detector

    by DD4WH
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    Hi Ivano, just a comment on the codec: *...

    Hi Ivano,

    just a comment on the codec:

    * the first version of the Bat detector of this thread (four years ago ;-)) had a codec because I had a Teensy audio board at hand and it was easier to...
  29. Thread: Bat detector

    by DD4WH
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    Hi Edwin, thanks for your correction! That was...

    Hi Edwin,

    thanks for your correction! That was my fault, I altered my post accordingly!

    Yes, you are right, depending on the gain of the preamp, you will get a lot of noise anyway and the...
  30. Thread: Bat detector

    by DD4WH
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    Hi, it is really fantastic to follow the...

    Hi,

    it is really fantastic to follow the developments by you, Cor & Edwin. This is a superb project!

    Just my subjective view on the question which microphone to use [my experience from the last...
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    @Esteban, @tisho Thanks again, to you, Esteban...

    @Esteban, @tisho
    Thanks again, to you, Esteban and your colleague EA7GIB for your kindness to send me a Msi001 board for integration into the Convolution SDR software!
    I am working hard to get it...
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    Thanks a Lot! Will Take a Look in August, sorry,...

    Thanks a Lot! Will Take a Look in August, sorry, that its Not possible earlier!
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    Fantastic developments! I am really impressed!...

    Fantastic developments! I am really impressed!
    @tisho: the menu looks excellent! I would really like to include it into the main code. Is it possible that you submit a pull request to my github? it...
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    Bill, exactly, you got it, excellent! Some...

    Bill, exactly, you got it, excellent!

    Some further comments on the signal flow:

    * I & Q samples coming in with user-defined sample rate (as an example, lets take 96ksps)
    * spectrum display...
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    Excellent! Thanks a lot for trying this and sorry...

    Excellent! Thanks a lot for trying this and sorry to see it took so much of your time. Thats pretty close to my experience. It took my computer even 50% longer for the computation. However, I did not...
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    @WH7U: not sure how the sample & hold in the...

    @WH7U: not sure how the sample & hold in the Tayloe frontend will react exactly. You made a lot of good points there.

    I am not sure -however- about the causes for your birdies, the cause might...
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    Bill, here is an example of an SDR built with...

    Bill,
    here is an example of an SDR built with the AD8333:
    https://www.helitron.de/dj0abr/german/technik/dds/sdrrx.htm

    The builder states that it works very well, but it needs a lot of preamp...
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    Frank, Les, Bill, I will check what difference...

    Frank, Les, Bill,

    I will check what difference the calibration factor makes in my build. But I remember that using a linear equation of the form y = factor * x + constant worked better than just...
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    @WH7U: Congrats to you for your working SDR! I...

    @WH7U: Congrats to you for your working SDR!

    I would suggest to use the latest firmware version of the Teensy Convolution SDR! You seem to have an old version, where the calibration constant was...
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    @jonr: not sure about your statement on the...

    @jonr: not sure about your statement on the "correction file, which contains nothing after 30msec": could you explain which file you mean and what is lacking after 30msec? It seems I did not get the...
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    Chip, you already answered part of your own...

    Chip,

    you already answered part of your own question. Some add-ons from my personal view:

    * commercially distributed guitar cabinet impulses have different lengths, some of them up to 0.5...
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    Uniformly Partitioned Convolution may be useful...

    Uniformly Partitioned Convolution may be useful to reduce latency for large FIR filters.

    You can find Teensy 4 code for that in my github, the link is here:
    ...
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    Hi Esteban, while looking at your video, I...

    Hi Esteban,
    while looking at your video, I realized the rather high temperature of the T4 processor, if I read correctly it is 58 degrees C in the enclosure.

    That seems to me rather...
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    hi Tisho, very nice you got your SDR to...

    hi Tisho,

    very nice you got your SDR to work!!!

    I am also very impressed about the noise floor figures.

    When comparing with Sherwoods figures, here: http://www.sherweng.com/table.html
    ...
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    Excellent work! Really looking forward to testing...

    Excellent work! Really looking forward to testing and comparing :-)
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    Hi Les, * in WFM, the default is NO spectrum...

    Hi Les,

    * in WFM, the default is NO spectrum display (because of the high processor load at 256ksps sample rate), so this is intended behaviour
    * without a spectrum FFT being performed, there is...
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    Hi Joe, there are several aspects with this...

    Hi Joe,
    there are several aspects with this according to my experience:
    * convolution filtering is computationally less intense if you substitute FIR filters from about 60 taps onwards, so even...
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    @Karlchen: did you test one of the 2xfo-setups...

    @Karlchen: did you test one of the 2xfo-setups you posted in #403 in a real SDR frontend? I would be very interested in your experiences and the performance differences compared to a 4xfo setup!
    I...
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    Oh, thats a pity. A few years ago I purchased...

    Oh, thats a pity. A few years ago I purchased that chip in SOIC package, so at least they used to produce them for some time in history :-).
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    @Karlchen: you are right: switching time !=...

    @Karlchen: you are right: switching time != bandwidth of the chip.
    All recent designs for QSD frontends I know of now use the 3253 instead of the 4066. Potato offers a 3253 in SOIC16 package (easy...
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