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  • DD4WH's Avatar
    07-02-2020, 11:45 AM
    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 high/critical (could lead to...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    07-02-2020, 10:28 AM
    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 -125dBm of noise in...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    07-02-2020, 10:10 AM
    Excellent work! Really looking forward to testing and comparing :-)
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    07-02-2020, 10:09 AM
    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 also NO dBm-display....
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    07-02-2020, 10:02 AM
    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 with such a low no. of...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-11-2020, 11:03 AM
    @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 am asking because I...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-11-2020, 10:57 AM
    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 :-).
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-11-2020, 07:58 AM
    @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 soldering ;-) and it...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-08-2020, 01:46 PM
    OK, understood! However, I think the limiting factor will not be the noise of the OP-Amp (most QSDs use low noise types, e.g. the LT6231 has 1.1nV/sqrt Hz), but the noise coming from the fast updates of the spectrum...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-08-2020, 11:05 AM
    @Les, @Karlchen: for ICs with higher frequency capability, maybe you can find something useful here: http://www.potatosemi.com/ They have 7474, 3253 and alike with switching frequencies up to 1GHz ! They have been...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-04-2020, 09:14 AM
    Congratulations! Very nice! I think the filters can be built with SMD components. Use good (and expensive) NP0 capacitors. The coils are more critical, those with high Q are bigger and cost more . . . Bob Larkin...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-04-2020, 09:02 AM
    I have to read a lot, because as a biologist many of this electronics / DSP stuff only becomes clear to me by reading the references :-). As far as I understand it, by using one ADC for the I signal and another ADC...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-03-2020, 10:11 AM
    Nyquist always plays a role ;-). We are using two ADCs with 256ksps each and we digitize I AND Q, so the resulting bandwidth is 2 x Nyquist == 256kHz bandwidth. That is the reason why we can display a full 256kHz...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-03-2020, 08:26 AM
    Hi WH7U, very interesting simulations and figures! However, I do not understand your scaling of the axes very well. Is the y-axis linearly scaled? Would be good to see a dB scale. And x-axis is frequency in MHz? But...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    06-03-2020, 08:14 AM
    Hi Esteban, thanks for the information! How did you measure sensitivity? And which bandwidth/demodulator did you use? Standard sensitivity measures are usually made in SSB with very narrow 500Hz bandwidth. If I...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-27-2020, 03:37 PM
    Hi Esteban, that looks really great! And it will be a great help for anyone trying to build a Teensy Convolution SDR (or any other QSD-based SDR). I am really curious about the Msi001 performance and would love to...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-27-2020, 03:16 PM
    How about this "ready-to-use" solution on the Teensy? https://forum.pjrc.com/threads/60332-High-quality-audio-streaming-using-NRF24-(working)-Sample-rate-synchronization?p=234918&viewfull=1#post234918
    5 replies | 224 view(s)
  • DD4WH's Avatar
    05-20-2020, 02:19 PM
    I can confirm, it seems Italy is a little special concerning highly exaggerated shipping costs. Here, in Germany, ordered at exptech: two T4.1 did cost 63,28€ == 31.64€ for ONE Teensy 4.1 including shipping BTW, my...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-18-2020, 08:20 PM
    Hi Bob, really struggling here with the OpenAudio lib . . . there are several issues: * the codec code for tvl320 seems redundant, it is present in the standard audio lib AND in the OpenAudio lib, one of them has...
    15 replies | 347 view(s)
  • DD4WH's Avatar
    05-18-2020, 02:02 PM
    @WH7A: great to hear that! Could be an option to lower the SPI speed for the TFT (70MHz), see one of my posts above. The QRP labs receiver is great! But it uses an audio transformer after the OP amps which will...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-18-2020, 09:42 AM
    Very interesting! Would be nice of you could post some more information, eg. name of the NGO or some preliminary details about the ventilator? You probably know this Arduino-based design?...
    2 replies | 221 view(s)
  • DD4WH's Avatar
    05-18-2020, 09:23 AM
    Hi Bob, thanks for the code on your homepage! However, I cannot manage to run it. I have the following problems: * I copied OpenAudio_ArduinoLibrary from chipaudettes github to my Arduino lib folder * I copied the...
    15 replies | 347 view(s)
  • DD4WH's Avatar
    05-18-2020, 08:27 AM
    ... mine left PJRC on April, 21st, spent 18 days in San Francisco and has now been held in customs in Frankfurt for two days, we´ll see when it arrives ;-). I purchased two T4.1 with exp-tech, which arrived the next...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-17-2020, 06:12 PM
    Excellent to hear! Have fun with it, thats the goal ;-) Does it work with the original tft.begin settings (70MHz) ?
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-17-2020, 06:10 PM
    Hi Bob, excellent work! Very nice and easy to use! As you requested, some first observations of a test with Teensy 4.1 & Teensy audio shield rev. D: * I had to adjust the input and volume levels of the codec * I...
    15 replies | 347 view(s)
  • DD4WH's Avatar
    05-17-2020, 04:59 PM
    Sounds exciting! I have to read more about that in order to understand what you did in the code!
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-17-2020, 04:23 PM
    One recommendation: * Do NOT mess with any of the calibration variables before you are perfectly sure, that everything is working correctly. Leave every calibration variable as it is ! * the frequency calibration is...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-17-2020, 04:13 PM
    @WH7U: I guess you are nearly there :-). * it would be best, if you have the latest Teensyduino software 1.52 and use that for compiling * the TFTs behave differently, even if they all say they are ILI9341 . . . *...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:44 PM
    Excellent! It should not have an influence on the sound quality, but only on the ability to reproduce Stereo signals accurately, I think. Edit: "time division multiplexing": not sure, what that is ;-). If you have...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:32 PM
    The PJRC Teensy 4.1 page lacks some detail about the pins between the processor and the SD card (the backside of the pinout card is missing). Would be good to have them included on this page:...
    2 replies | 155 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:25 PM
    Hmm . . . 1.) the main filter is a complex convolution filter which calculates the coeffs with a function in the sketch. It does NOT use the CMSIS FIR filter function 2.) the CMSIS FIR filter is used in the following...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:17 PM
    I do not know what that means . . . "time-reversed order"?
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:11 PM
    Hi Les, nice to hear that you had success in building the SDR! * with T4.0/T4.1, you do not need to install a newer version of CMSIS. This is only necessary with Teensy 3.6 * I would strongly recommend to use the...
    464 replies | 78776 view(s)
  • DD4WH's Avatar
    05-16-2020, 09:32 AM
    My recommendation would be not to use rev B/C with wires and T4.x. It will create all sorts of problems, I spent a lot of time on this and did not manage to get T4.0 & audio shield to work properly with wires longer...
    8 replies | 261 view(s)
  • DD4WH's Avatar
    05-15-2020, 06:15 PM
    Thanks Kurt, thanks Michael! Excellent! Plugged out the Teensy and beginning to read now :-).
    32 replies | 1184 view(s)
  • DD4WH's Avatar
    05-15-2020, 05:08 PM
    Need to read something about "cache" and how it works for the different RAM regions including EXTMEM. Do you have any suggestions where I could find something (beginners level, please :-) . . .)
    32 replies | 1184 view(s)
  • DD4WH's Avatar
    05-15-2020, 04:39 PM
    Win10, T4.0 with ADC PCM1808 and DAC PCM5102a and Ili9341_t3n (@70MHz) runs well with TD 1.52 beta6. Same setup also plays mp3 from SD card (flying wires soldered to a µSD-card adapter) with FrankBs codec lib .
    32 replies | 1184 view(s)
  • DD4WH's Avatar
    05-15-2020, 04:35 PM
    @FrankB: * the sketch is for guitar cabinet emulation: combines applying large impulse responses to audio together with minimizing latency. (and it consumes a lot of processor power and a lot of memory, so is ideal...
    32 replies | 1184 view(s)
  • DD4WH's Avatar
    05-15-2020, 01:25 PM
    @manitou, @mjs513: thanks for pointing me to the speed change code for PSRAM SPI! I tried using T4.1 plus two soldered PSRAM chips and Teensy audio shield with partitioned convolution filtering @44.1kHz sample rate...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-15-2020, 12:42 PM
    Win10, Arduino 1.8.12, TD 1.52 beta6, T4.1 and Teensy audio shield version D, 2 PSRAM chips, using EXTRAM as part of the audio buffering --> works with partitioned convolution filtering /* * (c) DD4WH 15/05/2020 ...
    32 replies | 1184 view(s)
  • DD4WH's Avatar
    05-14-2020, 08:34 PM
    at the moment I am experimenting with using 2 PSRAMs with T4.1 for audio processing (guitar cabinet impulse - partitioned convolution filtering). However, it seems the PSRAM is too slow for large filters. (I use TD1.52...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-13-2020, 08:17 PM
    Win10, Teensy 4.0, Teensy Convolution SDR, works well! Win10, Teensy 4.1, 2 PSRAM chips, tried several example sketches, including PSRAM memory display ("16MB"), works well so far, however the T4.1 does only program...
    13 replies | 999 view(s)
  • DD4WH's Avatar
    05-13-2020, 07:43 PM
    Excellent! :-) FLASH: 36048 0.44% of 7936kB (8090416 Bytes free) FLASHMEM, PROGMEM ITCM: 24288 74.12% of 32kB ( 8480 Bytes free) (RAM1) FASTRUN PSRAM: 16 MB OCRAM: 524288 Bytes (512 kB) - 12384...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-13-2020, 07:22 PM
    Soldered a second PSRAM chip to the Teensy 4.1 underside and updated to Teensyduino 1.52 beta5. Using Pauls´ sketch from #478 it detects both chips: External RAM test PSRAM size is 16 Mbyte myint = 123456...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-13-2020, 01:31 PM
    I received my two Teensy 4.1 ordered from ExpTech two days after the order! My beta T4.1 sent from PJRC on April 22nd still seems to circle around somewhere in San Francisco . . . Some questions: * ExpTech did not...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-11-2020, 09:08 PM
    My T4.1 beta test board also is stuck with USPS in San Francisco since April 24th . . . I just ordered two T4.1 at exp-tech (32 EUROS each, thanks for the hint, sstaub & Michael), I bet those will be here quicker...
    797 replies | 33228 view(s)
  • DD4WH's Avatar
    05-10-2020, 06:12 PM
    Hi Keith, not sure how your frontend looks like, but a standard quadrature sampling detector does not need standard SBL-1 mixers and a splitter with the associated high losses. Do you use a "Tayloe" type of frontend to...
    464 replies | 78776 view(s)
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About DD4WH

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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) 07-02-2020 11:45 AM
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10-25-2015