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@DM5SG: EER transmission/polar transmitter is exactly the idea that came to my mind when FrankB wrote that excellent FM transmitter code! Would be nice to hear more on your developments! Maybe it...

[EDIT: crossposted! Thanks Mark !]

fixed link:

https://www.ap.com/blog/fft-spectrum-and-spectral-densities-same-data-different-scaling/

@Paul: your link is broken and seems to produce SPAM !?

@jonr: Ah, my fault: I was talking about underclocking from 150MHz up to 600MHz, that works properly!
But setting it to > 600MHz with the Teensy Convolution SDR causes big problems, thats true! But...

@jonr: no audio glitches here while changing CPU freq while audio is playing. I am using I2S audio with ADC PCM1808 and DAC PCM5102 with the Convolution SDR code.

Hi JayShoe !

excellent, just what I need !

I tried to participate in Kickstarter, but it did not work out, maybe because of problems with overseas credit cards / payment . . . it seems...

@AC8GY, @KD9JCD, @DH1AKF: I will try to answer your questions below:

Sorry for my late reply!

Teensy Convolution SDR & T3.6:
* I am afraid I ruined the T3.6 support in one of my last additions...

Hi Uli,

very nice project, it would be great to have the Teensy generate accurate signals for phase and amlitude in order to drive a Class E polar transmitter!

Generally, I think it is feasible...

@KD9JCD: sorry for the late answer: I will have to look at the new Teensyduino version, which could potentially make problems because of the SD lib change. So I still need some time to dive deeper...

Thanks a lot, Walter, for your quick response and the clarification!

I misunderstood the MDEL parameter, which seems to be a compile time define and not (as I wrongly assumed) a parameter that is...

Hi Brian, nice to hear that you are still working with Teensy and SDR!

As I wrote earlier in several posts in this forum:

The twinpeak problem (problem of random order of samples at startup of...

Hi Walter,

after a long time, I tried to upload the software to a newly built recorder.

However, it does not work any more.

* it seems the triggered recording mode is always enabled
* it is...

Hi Rudolf: no, there is no complete schematic / es gibt keinen kompletten Schaltplan. Its the very nature of the project that the Teensy Convolution SDR can cope with every I & Q input from many...

maybe you would like to try to disable the digital highpass filter of the codec. This has caused trouble in other setups. Search the forum for the actual code line to do this. I am away from my PC,...

Sounds good!

Have a look at the function switch_RF_filters() in the code and alter it according to your needs and pin selections! Do not forget to define the Band1, Band2 etc. pins to your...

Hi Hubert,

the software switches seem correct. But you configured it as "No Teensy audio board", because my T4 hardware has no audio board, but external ADC and DAC.

if you use the #define...

hi Hubert,

please let us know what you are using, how your hardware looks like, what kind of preselector you would like to switch etc.

otherwise it is difficult to answer your questions.

Hi!
The Teensy Convolution SDR code works with many hardware configurations including different I2S codecs, I have built and tested a few of those types:

* T4.1 & audio shield rev D
* T4 &...

You are probably right . . . I remember fiddling around a lot about this when I wrote the code . . . I need to have a look into my handwritten archive for the initial preparations/thoughts on that.
...

I think, I have to correct myself (although I am not so sure, do not have the time at the moment to test this or properly think about it):

* the code as it is, does in fact offer the possibility...

Maybe we should open a separate thread with this phenomenon?

* Windows 10, Arduino 1.8.13 TD 1.53
* Teensy 4.0 with Teensy audio shield REV D
* USB - Audio in / I2S Audio out
* Compiling with...

Inside the Convolution loop, we are doing a complex FFT / inverse FFT routine. The real part of the input is one channel, the imaginary part of the input is the other channel. So in one loop, BOTH...

good that it works for you now!

Very interesting!

Would you be willing to prepare a very short How-To for your room correction for speakers somewhere?


EDIT: Strangely, USB audio seems to...

Tested the USB_Passthrough example with Teensy 4.0 & Audio board Rev D, Arduino 1.8.13 TD 1.53, but I cannot get it to work.

* Compiled the sketch with USB type: Audio
* compiled fine
* PC...

Hmm, strange.

I have never used USB audio with the Teensy and have no hardware compatible with SPDIF, so I cannot test that.

One idea is the sample rate: why did you comment out the I2S setting...

Not sure if I understand what the problem is. I use Teensy audio lib in many projects only as a queue in - queue out helper.

Maybe you would like to have a look at an example which works:
...

Very good to hear! Have fun with your SDR!

Perfectly OK :-).
Its just that I cannot help you with the Msi001 version of the Teensy Convolution SDR!

No, it seems you completely misunderstood me! There is NO roadmap, not even a hidden one.

And there already is existing code for the Msi001 which allows for the VHF/UHF bands you are looking for...

Iñigo,
it is already possible with the Msi001 chip! Ask tisho and Esteban! I do not have working hardware with the Msi001, so I cannot contribute to that part of the software (yet).

Henk, try to uncomment:
#define USE_W7PUA

Yes! But it is defined in different ways, depending on which hardware you have defined at the beginning of your sketch!

Which Hardware did you define in the very first lines of the sketch?

Hi Henk,

you have to keep an eye on which #define you uncomment/comment at the beginning of the .ino-file.

Probably you have too many #define uncommented, so that the program initializes a very...

Very easy: buy a Teensy 4.1 (SD card slot) with a Teensy audio board and use the LINE IN. The audio from the LINE IN is sampled by the codec and no effect is added.

Hi Dirk,

when I changed the code to work with T4.1, I also used two PSRAM chips and checked whether that would work.

it does not work!

The reason is not the CPU power, which the T4 has more...

:-)
Well, it is a matter of definition of your goals!

You mention three different of your goals in this thread:

* pitch shifting
* playback rate adjustment
* crunchy and lovely audio...

In the context of Software Defined Radio dealing with analytical (complex) signals, builders often use an IF at exactly samplerate-divided-by-4, ie. in your case 192ksps / 4 = 48kHz

Then you are...

I am not at all familiar with FAUST, but by looking at the webpage it seems that there are things that can be very easily done with a T4.1 (all the filtering stuff) and more complex/demanding things...

Could you specify your project and the kind of DSP you are planning? Otherwise there is no chance anyone could help you with an idea.

??? Could you be a little more specific in your question?

I think the T4.1 is more than capable of doing complex DSP.

Bob Larkin provided very nice code for an Audio Equalizer (https://forum.pjrc.com/threads/60928-Audio-Equalizer-using-FIR?highlight=audio+equalizer), which I implemented as a 9-band graphical EQ in...

Yes, the Malahit is a nice receiver, but unfortunately closed source.

If you port the software to the STM32F7 or H7, please keep it open source and it would be very nice if you posted a link to...

Yes. At the moment it is programmed like that. Synch is not a problem, because both, the ADC and the DAC use the same master clock MCLK provided by the Teensy.

Paul, did you already build a Teensy...

Not sure what you mean exactly? What are "valid channels"?

Do you want an automatic frequency scan search for stations and save their frequencies in memory?

That is not implemented at the...

I hope, the new version solves this problem.

73 Frank

Thanks for pointing me to that, You are right, I built that bug. Will try to solve that this evening.

Bill, I tried to exactly reproduce the situation you described:

* 50 Ohms resistor on the antenna input

21537

So, the spectrum looks similar, BUT: the birdies are very very low signal...

Yes, fully agreed! :-)

AM mediumwave stations do not pose problems any more here in Central Europe, because most countries have shut down all or many of their transmitters! (eg. Germany, the...

Just to let you know I uploaded a new version of the software to my github.

* Teensy 4.1 support with DO7JBH hardware (and a self-built T4.1 to T3.6 adapter)
* Menu Assistant by tisho (thanks a...

for wideband transformers, I have good experience with FT77 ferrite material ring cores and also with binocular cores 73-202. Using this ferrite material leads to better results in the VLF range...