Recent content by DD4WH

Oh, very nice! I did not know about your extension, good to know!

WAV files have to be 44.1ksps sample rate. The audio library does not play files recorded at other sample rates.

Try these IRs: https://github.com/bmillier/FFT-Convolution-Filter-Uniformly-partitioned/tree/master/Example

Also, be sure that your IR uses minimum phase coefficients. Simply calculating linear phase coefficients works, but then the latency is still as long as the filter length/IR length. The whole trick of achieving low latency only works with minimal phase coefficients.

Thanks again, Bob for your efforts on FT8 Rx! I have now implemented it into Teensy Convolution SDR and it works very well: https://youtu.be/nKm-cLcOV94 Time can be synchronized by turning the encoder while in Time Set menu. This is totally sufficient, no need for GPS or internet server time...

Is there an upper limit to the Buffer size? I would like to use a large Buffer, because of the high latency of SD cards for recording.

There different types of compressor for you to test: https://github.com/chipaudette/OpenAudio_ArduinoLibrary

Hmm, I cannot reproduce a problem in playing the WAV files recorded with my code, they play correctly and smoothly with different players on different devices. You may be right that the chunk lengths are inconsistent, but the files are playing and sound nice . . . As you claim in various...

Hmm, I cannot reproduce a problem in playing the WAV files recorded with my code, they play correctly and smoothly with different players on different devices. You may be right that the chunk lengths are inconsistent (I am not a specialist in WAV headers), but the files are playing and sound...

Hi Bob, thanks for the motivation! :-) will try my very best, although time is quite limited at the moment. Yes, I totally agree, FT8 for emergency communication seems much more useful and interesting than semiautomatic collection of countries... Seems my message in the KeithSDR group was...

Bob, thanks a lot for your detailed answers! I will start my journey by building the original Charlie Hill pocket FT-8 and see how it works and how that deals with SNR. Have not yet looked too much into the code, though. OK, I was imprecise in my question on sample rate. I now understood how it...

after a restart of the Teensy, it seems the SNR readings are OK! = = = = = SYNC TIME 15 = = = = = FT8 Received TRansmissions, Noise Type=L 0 18:44:26 msg: CQ VU3FGJ MK65 dt=2.72 freq=1271 snr=-21 km=6606 az=104.2 1 18:44:26 msg: DM2DXA EB7DLN 73 dt=2.72 freq=2040 snr=-21 ft8_decode Time...

Mark & Bob, independently from our conversation, a few days ago I read about Farhans sbitx for the first time! Very exciting and also very interesting that the DSP-10 also follows a superhet approach. I read your DSP-10 papers many years ago (they are 24 years old now . . .) and had...

Just thinking loud: if I integrate the FT8 class as-is into the Teensy Convolution SDR, it would run all the time even if it is not used. And if the user increases the sample rate (I regularly use 256ksps), it could easily be too fast for the T4. Hmm, will think �� more.

Bob, tried today to receive and decode FT8 with your FT8Receive function. I use my Teensy Convolution SDR and a magnetic loop indoor antenna for reception and production of FT8 audio, and I feed the audio to another Teensy 4.0 with a PCM1808 ADC running your example code. Works perfectly...