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  • 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...
    402 replies | 73871 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...
    402 replies | 73871 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...
    402 replies | 73871 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...
    402 replies | 73871 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...
    402 replies | 73871 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...
    402 replies | 73871 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 | 188 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...
    785 replies | 28494 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 | 247 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...
    402 replies | 73871 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 | 202 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 | 247 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...
    785 replies | 28494 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) ?
    402 replies | 73871 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 | 247 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!
    402 replies | 73871 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...
    402 replies | 73871 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 . . . *...
    402 replies | 73871 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...
    402 replies | 73871 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 | 134 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...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    05-16-2020, 12:17 PM
    I do not know what that means . . . "time-reversed order"?
    402 replies | 73871 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...
    402 replies | 73871 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 | 201 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 | 979 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 | 979 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 | 979 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 | 979 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...
    785 replies | 28494 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 | 979 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...
    785 replies | 28494 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 | 785 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...
    785 replies | 28494 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...
    785 replies | 28494 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...
    785 replies | 28494 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...
    785 replies | 28494 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...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    05-04-2020, 08:21 PM
    works very well with Windows 10 and Teensy Convolution SDR. Special thanks to you, Paul, for fixing the daylight saving issue ;-) ! Central European Summertime seems to be supported by T1.52 beta-4 in combination...
    38 replies | 1866 view(s)
  • DD4WH's Avatar
    05-02-2020, 10:12 AM
    Thanks Paul, for that quick and important info about the difference between T4 and T3.6 RTC setting on upload. I can report that the bug is still there with Windows 10 and Teensyloader 1.52 beta3 in time zone Berlin...
    20 replies | 662 view(s)
  • DD4WH's Avatar
    05-02-2020, 09:18 AM
    Is there any way to fix the annoying bug that causes the (S)RTC to lag one hour behind when I load a program into my Teensy? This one hour lag bug has been reported quite a few times in different threads, but to...
    20 replies | 662 view(s)
  • DD4WH's Avatar
    04-30-2020, 05:42 AM
    Yes, the paper has already been submitted some months ago to the German speaking HAM Radio journal "Funkamateur", BTW: the author is active on this forum :-). My plan was to take that paper (which will deal with DSP...
    785 replies | 28494 view(s)
  • DD4WH's Avatar
    04-24-2020, 07:36 PM
    Works on Windows 10 Tested with Teensy 4.0 Convolution SDR using latest ili9341_t3n lib, Etherkit_Si5351 lib and FrankBs audio codec lib. Excellent! Can´t wait to test it with T4.1
    67 replies | 3009 view(s)
  • DD4WH's Avatar
    04-23-2020, 11:22 AM
    @Xtian: which Teensy? which Arduino version? which Teensyduino version? Its hard to guess that. If you are using T3.6: Did you follow the given instruction to manually install ALL the CMSIS files to the right...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-21-2020, 09:18 AM
    @Tihomir: you are right, it is a bit cryptic and not readily useable with T4 & Teensy audio board. HARDWARE_DD4WH_T4 means: T4 plus ADC PCM1808 & DAC5102 So, you should comment that #define out and make your own...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-21-2020, 09:13 AM
    @Renzo: maybe you can be a little more specific with your question. I am sorry I cannot help with the current version of your question as in post #310
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-15-2020, 02:13 PM
    Renzo, sorry, but I could not understand what your question is? Maybe you post here your question in French AND the English translation with DeepL https://www.deepl.com/translator]
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-15-2020, 09:58 AM
    I am a little puzzled why you use TWO interrupt routines, the queue in the audio lib and an additional one!? But maybe I am misunderstanding your approach. I use the record and the play queue with great success with...
    8 replies | 251 view(s)
  • DD4WH's Avatar
    04-14-2020, 11:35 AM
    Thanks very much, that sounds really good! However, I am a bit puzzled about the syntax. If I try to substitute: uint8_t val = psram.psread(i); would I put in this instead? psram_read_n(i, val, 8); What is the...
    26 replies | 2082 view(s)
  • DD4WH's Avatar
    04-10-2020, 08:08 PM
    probably, if you can ensure that the signal level is somehow constant. 49m: can you receive a station on 5970kHz right now? And how about 6110kHz? If you do not receive CRI on 6020, something is wrong.
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 06:58 PM
    Frank: I suspect your main interest is to improve WFM radio reception. I will be experimenting with the AD8331 as a VHF variable gain preamp in the next weeks with exactly your aim in mind and will report back my...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 03:55 PM
    Frank: thanks for your code regarding PLL and spread spectrum! I do not have the time to test it thoroughly now, but I will do so in the next days!!! It potentially collides a little bit with my intention to adjust the...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 03:41 PM
    Hi Frank, sorry, I had some easterly distraction and also I had to think a bit more about your problem. You have to convince me, that you have a problem with high noise in the preamp. I do not see that yet, but I am...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 11:24 AM
    Frank, probably we are talking about very different things. I dont get your problem, I think. We seem to be using different meanings of the word "noise". For example: How did you measure the noise of the "input stage...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 11:18 AM
    Maybe I misunderstand your approach: If you short R6, you short the input to the QSD. And you also short Vdd to GND through the FET, but I may be wrong. That means, your input signal must be zero, and so the signal...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 10:57 AM
    the next step is: Connect your antenna and measure the SNR: * inject an RF signal with constant signal level (or use a radio signal that does not change signal level in time, for example ground wave reception of...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 10:48 AM
    Frank, I am pretty sure the AGC produces the noise that you hear. Could you do the following: * USB demodulation, filter bandwidth 2.4kHz * measure the noise with the dBm display for the situations that you...
    402 replies | 73871 view(s)
  • DD4WH's Avatar
    04-10-2020, 10:29 AM
    Frank, how did you measure the noise? What do you mean by "too much of noise"? What is your noise benchmark? Did you measure in an EMI-free situation? Also one has to be careful not to be fooled by the AGC, because...
    402 replies | 73871 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) 06-04-2020 09:14 AM
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10-25-2015