Open Source DSP Audio Processor for FT-817

[gerryk]

Hi Frank...
Yes, I had a browse through your code. It's very comprehensive for sure.
How does the spectral NR sound? I believe that's what Yaesu use, and IMMO their NR is probably the best sounding in the industry.
I will be ordering a 3.6 in the very near future...
73
Gerry Ei8DRB

 

[DD4WH]

Hi Gerry,

most transceivers use the LMS algorithm in the time domain for noise reduction, which does a good job when your signal already has high SNR.

If your signal has a low SNR and you would like to "pull it out of the noise", LMS does not help very much. Here you need spectral NR in the frequency domain.

Only very few transceivers (most of them in the 2k$ range) have spectral noise reduction algorithms implemented. Even the Elecraft K3 has only got LMS.

I uploaded one short example of the software implemented noise reduction (collaboration with Michael, DL2FW) in the Teensy Convolution SDR, which is also implemented in the UHSDR software running on STM32F4 and STM32F7 processors.

https://github.com/DD4WH/Teensy-ConvolutionSDR/blob/master/example1.mp3

However, we have a diversity of different hearing habits and preferences, so I realized that some people like the NR for its strong noise reduction, some dislike it because it changes the sound of the speech. Your ears decide .

73 de Frank

 

[DB5FP]

Hello,

I red the article just last night and bought a teensy 3.2 on ebay. Verry nice work has been done!
But I think there has to be some improvemts :

- Samplerate has to be reduced 44kHz ist 5 times higher than needed
- reducing sample rate will give same extra power for noise canceling or / and auto notch or reducing CPU clockrate
- Some manual notch filtering should be added

Samplerate adjustment has to bee done in input_adc.cpp, I'll try my best after my teensy arrived.
I'll fit my boards into my old rigs IC-202 and TS-790. Afterwards I'll send some pictures of the migration progress.

73s Frank / DB5FP

 

[JimSheldon]

Hi Gareth,
Just came upon this thread. Wondering if you could contact me directly via email (w0eb [at] cox dot net) as I have some questions about the possibility of implementing your filter as a stand-alone, tunable filter using an encoder and a couple of selector push buttons with a small 1.44" Color TFT display to show the filter CF and Bandwidth graphically. A friend of mine is a super good programmer and between us it would be fun to get something like this working. Not to use commercially but as a good conversation point at ham fests.

Jim Sheldon, W0EB

 

[JimSheldon]

Hi Gareth,
I did find some more info along with some images of how you wired things up, but the way you have the various items soldered to the pins on the Teensy 3.2 don't seem to reconcile with the pin assignments in settings.h.

Also, there's an extra yellow wire coming off of pin 3 of the Teensy that doesn't have any correlation to either the encoder or the display.

Could you post some more detailed info on how to actually connect the display, encoder and any other things to the Teensy 3.2 so I can match it with your code and build a stand-alone filter?

Any help here would be much appreciated.

Thanks in advance,

Jim Sheldon, W0EB

 

[bejoysat]

Audio processing is fine, equalization is a MUST, but it would be a very nice addition for this project to also implement an RF compressor/clipper using the Hilbert transform, and a noise gate just like Voice Shaper. This means Microphone --> Equalization/noise gate ----> SSB modulation ---> SSB envelope compression/clipping ----> SSB Demodulation ----> Processed Audio sent to transmitter.

The three stages of SSB processing can be achieved digitally using the hilbert transform, but I don't know how far can you go with the teensy.

In my opinion, Voice Shaper is, by far, the most flexible and powerful speech processor available today for SSB. In the other hand, there is the need for a computer to run the software... so I see a lot of potential for an RF processing stage in this project. I guess this can be easily created in MATLAB.

73 DE LU6PSG

Is there any project that does this? Similar to Voice Shaper. I am keen on doing something on these lines so that I can learn some DSP stuff.

Thanks,
Bejoy VU3BOJ

 

[Alyosha_ag]

FT-817 CW SSB filter

Very nice project.

I am wondering why it is impossible to modify the board and put not only fiscally on the place of the original filter in the FT-817 but connect to the connectors of the mechanical filters.
With no modifications to the FT-817 radio. Or minimal.


Best regards

 

[pepelopez]

excellent project, although it seems a bit abandoned ...

Anyway, the problem would be manipulating / modifying the FT 817 for those which we do not have much experience with SMD devices, as is the motherboard of the FT817.

It would be very interesting to build a Teensy equipped speaker and a small audio amplifier (like the LM386) to make a kind of bhi type speaker (which are quite expensive!)
Therefore, could a scheme like the one in this image below work?



all the elements (teensy and amp) could be stuffed into a small speaker:

 

[pt9kk]

Hi there! Since it has been quite sometime since the last post, are there any changes, mods, improvements to that project. I'm interested in a good filter for the FT-817 and FT-890. Also, I would like to know if I may use the most recent Teensy 4.1 instead of the one mentioned on the project. Replies are appreciated!

 

[zarampano]

excellent project, although it seems a bit abandoned ...

Anyway, the problem would be manipulating / modifying the FT 817 for those which we do not have much experience with SMD devices, as is the motherboard of the FT817.

It would be very interesting to build a Teensy equipped speaker and a small audio amplifier (like the LM386) to make a kind of bhi type speaker (which are quite expensive!)
Therefore, could a scheme like the one in this image below work?

View attachment 26962

all the elements (teensy and amp) could be stuffed into a small speaker:

View attachment 26963

Hola pepelopez;

Indagando por la red, encontré este post que publicaste ya hace mucho tiempo... a dia de hoy estoy intentandolo con una Teensy 4.0 y con los componentes de tu ejemplo. Me falla la programación del código "GI1MIC-DSP-Filter.ino" a la hora de verificar con Arduino IDE.

Llegaste tu a montarlo y hacerlo funcionar? Gracias de antemano.

 

[BriComp]

Hola pepelopez;

Indagando por la red, encontré este post que publicaste ya hace mucho tiempo... a dia de hoy estoy intentandolo con una Teensy 4.0 y con los componentes de tu ejemplo. Me falla la programación del código "GI1MIC-DSP-Filter.ino" a la hora de verificar con Arduino IDE.

Llegaste tu a montarlo y hacerlo funcionar? Gracias de antemano.

View attachment 28567

Translation:

Hello pepelopez,

Searching the net, I found this post that you published a long time ago... today I'm trying it with a Teensy 4.0 and with the components of your example. The programming of the "GI1MIC-DSP-Filter.ino" code fails me when verifying with the Arduino IDE.

Did you get to assemble it and make it work? Thanks in advance.