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  1. Thread: Bat detector

    by DrMikeG
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    Hi DD4WH, thanks for sharing your work. Is...

    Hi DD4WH, thanks for sharing your work.

    Is there enough data collected in the recordings to do visual display of specific calls - something like this:
    ...
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    Hi Franck - thanks for pointing me towards your...

    Hi Franck - thanks for pointing me towards your project - I never knew you got ultrasound from jangling keys! (I'll test that later...)

    I recently demonstrated my mark1 Teensy bat detector at a...
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    Hi Defragster! What a good memory you have -...

    Hi Defragster!

    What a good memory you have - this thread has been quiet for a long time (like my bat detector).

    By a strange coincidence, I was discussing this project at a raspberry pi event...
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    Hi shinji - no i've not checked. I think you are...

    Hi shinji - no i've not checked. I think you are correct, the range sensor emits 8 pulses - but I believe they are sufficiently close together that I'm only identifying them as a single signal on the...
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    Ok. So my better fake bat arrived today - hc-sr04...

    Ok. So my better fake bat arrived today - hc-sr04 ultrasonic range finder.
    I have connected it up to another teensy, and it is giving me reasonable distances. (Very cool BTW).
    5216

    I use the...
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    That's a great suggestion! :-> For 2.50 I could...

    That's a great suggestion! :-> For 2.50 I could produce a test a signal that is actually in the bat audio range!
    It's hard to find next-day parts here in the UK, but I should have one by the...
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    Ok - so I think that video (from a couple of...

    Ok - so I think that video (from a couple of weeks ago) shows the limits of what I could achieve using floating point based FFT. (I could JUST make 122Khz sampling rate)

    In order to perform a...
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    So, I've had some success - but I'm struggling...

    So, I've had some success - but I'm struggling with the signal to noise ratio in the FFT-based solution. (I can convince myself there is something there other than noise, but it's not very...
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    Ok - I'll have a go at stripping it down. ...

    Ok - I'll have a go at stripping it down.

    Thanks
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    It might be incidental, but a int...

    It might be incidental, but a
    int SAMPLE_RATE_HZ = 66666; works ok.
    Where as
    int SAMPLE_RATE_HZ = 66667; breaks it.
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    Thanks WMXZ - the problem I have is that if I...

    Thanks WMXZ - the problem I have is that if I comment the graphics operations, for some reason the sampling seems to stop working.
    It's as if it needs throttling to avoid something bad happening....
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    Ok. So I have a working pitch shifter. The...

    Ok.
    So I have a working pitch shifter.

    The problem I have now is that I am reaching a speed limit.

    I have other sketches with higher sampling rates that work, so I should be able to raise the...
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    Ok. So, I bought a spare microphone - and it...

    Ok.

    So, I bought a spare microphone - and it behaves exactly the same as the one I was hoping was 'broken' :-(

    The passthru example doesn't work for me - I hear something, but with no...
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    Ok - so in the process of double checking...

    Ok - so in the process of double checking everything - I think my microphone might be damaged.
    It seems to register either almost nothing, or clipping.

    I have at one point had the Audio Mono Pass...
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    1) Does the ADC will return 2 unsigned or a...

    1) Does the ADC will return 2 unsigned or a signed bytes?

    2) A couple of days ago you suggested that it could "be improved a little bit by not reflecting the frequencies but by setting negative...
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    Hi WMXZ - I took a diversion into magnitudes,...

    Hi WMXZ - I took a diversion into magnitudes, which was a mistake.

    The original application I'm adapting uses the magnitudes of a f32 FFT to drive a really nice visual spectrogram.
    So, I...
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    [ Edit: Sorry, just found this thread which I...

    [ Edit: Sorry, just found this thread which I need to read... https://forum.pjrc.com/archive/index.php/t-25290.html - it might answer my questions...
    Thanks. ]

    I'm really struggling with the...
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    Ok - sorry, so I figured out the output from the...

    Ok - sorry, so I figured out the output from the q15 fft is in 11.5 format to prevent overflow.
    So, I need to shift it into 1.31 before I iFFT with q31.

    Thanks.
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    Okay - I'm struggling with the integer based FFT...

    Okay - I'm struggling with the integer based FFT / iFFT.
    I can see Paul has it the FFT working in analyze_fft1024.h, so I have hope - but I can't get it to round trip my data...

    I think the...
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    WMXZ - Thanks again - it's going to take me some...

    WMXZ - Thanks again - it's going to take me some time to work through your suggestions. I don't fully understand your first sentence yet (give me a minute).

    Jp3141 - I may well have to fall back...
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    Thanks for the help everyone! Setting the...

    Thanks for the help everyone!

    Setting the read/write resolution back to normal got me back on track... Thanks to WMXZ.

    Jp3141 - The continuity check on my multimeter makes a really handy tone -...
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    Thanks WMXZ. I'm running the headphone through...

    Thanks WMXZ.

    I'm running the headphone through a 10uF capacitor, and the samplerPlayer example and a tone synth example both produce good sounds for me.

    I guess as you say, my input might not...
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    I rebuilt the audio input circuit. I changed the...

    I rebuilt the audio input circuit. I changed the voltage divider to 10k-10k to give 1.65V DC bias.
    So I should be able to read the full +/-1V audio swing from the microphone.

    5068

    Using the...
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    Thanks for the suggestions WMXZ - I will get to...

    Thanks for the suggestions WMXZ - I will get to your suggestions (I'm not ignoring them, you just got me thinking about the problem...)

    The microphone I'm using is described as having output 2Vpp...
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    If I turn the Poti on the Mic right down the...

    If I turn the Poti on the Mic right down the noise gets quieter, but there is still some a pretty constant crackle.
    I'm running it off 3AA batteries so the power should be pretty clean.

    If I...
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    Hi all, My big bundle of bits arrived in the...

    Hi all,

    My big bundle of bits arrived in the post yesterday, so I could finally solder up the recommended input circuit.
    My audio source is a microphone board with a preamp, so I've wired it up...
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    Thanks for the advice Jp3141 - I think I...

    Thanks for the advice Jp3141 - I think I understand what you're saying about the twin shielded cable.

    I'm still reading through the various links above. The one WMXZ posted does explain about...
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    Thank you again WMXZ, I'll have a read. Please...

    Thank you again WMXZ, I'll have a read.

    Please don't have the impression that I'd not already tried google - but without the magic phrase "grounding single ended audio connection", there is an...
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    Hi WMXZ, any specific tips on grounding, anything...

    Hi WMXZ, any specific tips on grounding, anything I can read? Thanks.
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    Hi Paul, thanks for the input, but do you mean...

    Hi Paul, thanks for the input, but do you mean you'd need me to provide more details of the circuit before you could comment on whether the wire length would necessitate a change?
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    So, I have a rather basic question... If I...

    So, I have a rather basic question...

    If I attach my microphone / preamp to my teensy with really long wires (say, 2 meters) will it have any appreciable effect on my circuit?

    Can I dangle it...
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    Ok, so I've been trying to do too many things...

    Ok, so I've been trying to do too many things this evening, but I did have some time to look at this.

    Having got a better handle on setting up the ADC, outputting analog, and the FFT, I've got the...
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    Thank's WMXZ. I know very little about bats - I'm...

    Thank's WMXZ. I know very little about bats - I'm basing this work on the information here (nice example processed sounds) http://www.skillbank.co.uk/bat_detectors/tech.html

    The echolocation rep...
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    Oh I'm also totally in favor of simple solutions...

    Oh I'm also totally in favor of simple solutions - but if I'm going to slow the signal down, I need to only play it back selectively?

    If I'm playing back at 1/10th speed, I can only play 1/10th on...
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    Hi Theremingenieur. Thanks for the input - I...

    Hi Theremingenieur.

    Thanks for the input - I think what your suggesting is broadly the 'heterodyne' technique, which would produce a series of clicks?

    With the FFT, I can theoretically...
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    Hi WMXZ - thanks ever so much for your input! ...

    Hi WMXZ - thanks ever so much for your input!

    You are quite right, there are certainly bat call frequencies which will be way above what I can reach - and I'm not a bat expert, but I am an...
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    Thanks for the response Paul, I'm honored :-) ...

    Thanks for the response Paul, I'm honored :-)

    I've just found the thread discussing Pedvide's ADC library - I'd better have a read though that too before I post any more questions.

    Thanks for...
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    Oh, and sorry if these points are covered in...

    Oh, and sorry if these points are covered in other threads - I've done my best to search.
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    Bat Detector - 96khz sample, FFT and iFFT?

    So, the bats that live in my garden (and scare my Son) make calls in the range 20-60khz.

    I have an adafruit electret microphone, which is spec rated up to 20khz, but I've heard can give some...
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