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  • DD4WH's Avatar
    04-28-2019, 06:03 PM
    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 experiences ! I have...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-27-2019, 04:45 PM
    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 the situations you...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-25-2019, 08:11 PM
    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 without an antenna or...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-17-2019, 01:51 PM
    https://framagit.org/PiBatRecorderPojects/TeensyRecorders/blob/master/PassiveRecorder/Fabrication/Souder%20c'est%20facile%20-%20Voici%20comment%20faire.pdf
    1 replies | 95 view(s)
  • DD4WH's Avatar
    04-14-2019, 10:43 AM
    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 eliminated some bugs...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-13-2019, 01:41 PM
    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: * some variables that...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-12-2019, 08:51 PM
    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 atan2f and...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-12-2019, 08:13 PM
    Hi Walter, hi Frank, yes, I can confirm: SGTL5000 overclocking with 234ksps and 281ksps works nicely . However, the processor load is about 79% when using stereo FM radio reception and 234ksps. With 281ksps, only...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-11-2019, 05:26 PM
    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!) * sample rates up to...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-11-2019, 08:07 AM
    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 change this in function
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-10-2019, 06:51 AM
    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 code. --> the Si5351...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    04-05-2019, 10:44 AM
    DD4WH replied to a thread Bat detector in Audio Projects
    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 of the sensitivity...
    223 replies | 23577 view(s)
  • DD4WH's Avatar
    04-05-2019, 08:32 AM
    DD4WH replied to a thread Bat detector in Audio Projects
    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 response higher than...
    223 replies | 23577 view(s)
  • DD4WH's Avatar
    04-05-2019, 07:58 AM
    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 does seem to be used...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-29-2019, 10:28 PM
    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 Convolution Filtering by...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-29-2019, 04:17 PM
    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 math . . . Why do...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-27-2019, 07:54 PM
    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 the SGTL5000 is so...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-26-2019, 03:28 PM
    DD4WH replied to a thread Change SampleRate in Audio Projects
    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 Discussions on changing...
    11 replies | 348 view(s)
  • DD4WH's Avatar
    03-24-2019, 01:17 PM
    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 translation!? And...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-24-2019, 12:54 PM
    DD4WH replied to a thread biquad output noise in Audio Projects
    Sorry, my mistake, I thought "int" was 16bit. So the coeffs have 32bit precision, I agree. So, we boiled the problem down to the internal precision of the calculations: The link you mentioned states: So, I...
    10 replies | 343 view(s)
  • DD4WH's Avatar
    03-24-2019, 10:38 AM
    DD4WH replied to a thread biquad output noise in Audio Projects
    Summarizing the main points from the links given above and summing this up with my own experience with IIR filters on the Teensy and having read pages 280ff in the excellent book by Rick Lyons (Understanding Digital...
    10 replies | 343 view(s)
  • DD4WH's Avatar
    03-23-2019, 05:28 PM
    Hi Martin, not sure if this is the same problem (that we have called "twin peak problem", because in an SDR spectrum display you see twin peaks from one carrier), but you could have a look here: ...
    2 replies | 100 view(s)
  • DD4WH's Avatar
    03-23-2019, 09:40 AM
    @Frank: OK, did not know that, I thought the FPU of the new T4 would handle double as fast as float ;-) @Rob: if you use the Si5351 directly, your need for 4x higher LO frequency is avoided, so you can directly...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-22-2019, 09:39 PM
    Ah, OK, now I understood! For AM & SSB reception up to 30MHz I use sample rates of 96k or 100k, that seems quite clean of spurs in the range that the SDR uses (as we use an intermediate frequency of sample rate / 4,...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-22-2019, 09:02 PM
    Thanks Frank for the Si5351 link. Yes, confirmed, I have never experienced problems with phase noise in the Si5351 and also never had problems with slow lock of the Si5351 or Si570 which I have both been running in...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-22-2019, 03:39 PM
    Hi Rob, thanks for your comments! As a biologist, I may not be up to the latest developments in the RF engineering field. Why would you think the DDS AD9850 is "much faster" ? It goes up to only 125MHz -as far...
    196 replies | 47086 view(s)
  • DD4WH's Avatar
    03-21-2019, 03:22 PM
    DD4WH replied to a thread Bat detector in Audio Projects
    Hi Polly, I do not think that it is possible to record ultrasound files to SD with a sample rate of 1.8MHz with the Teensy 3.6 . . . We use a maximum sample rate of 500kHz with 12bit resolution (internal ADC) and...
    223 replies | 23577 view(s)
  • DD4WH's Avatar
    03-21-2019, 12:24 PM
    Hi Derek, unfortunately I can confirm that the WM8731 (together with an STM32F4 / STM32F7) has exactly the same problem of an occasional random one sample delay. You are right, that is not very nice in the context of...
    38 replies | 932 view(s)
  • DD4WH's Avatar
    03-20-2019, 12:50 PM
    Try the Iowa Hills IIR Filter designer http://iowahills.com/8DownloadPage.html For each filter stage you need a 2nd order filter and you need to specify the sample rate, cutoff frequency and the filter order....
    2 replies | 148 view(s)
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About DD4WH

Basic Information

About DD4WH
Location:
Central Europe
Interests:
Software Defined Radio, Digital Signal Processing, Bat detection & bioacoustics

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Teensy Convolution SDR (Software Defined Radio) 04-28-2019 06:03 PM
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04-28-2019 06:03 PM
Join Date
10-25-2015