Thanks, Ian, you are right, the cortex m3 is a small processor unit, and no DSP extension like the f4, the main reason was the price of midules, I got one module for less than 2 dollars, and the challenge start. The cmsis library help a bit also if you can see the processor load for massive processing. But the simple fir run not bad. After fir I started to do some experience on Noise Reduction, I worked in time domain using simple smoothing algorithms. The processor has not enough power to make Spectrum subtraction methods but I plan to make other tests maybe using a cortex m4 processor, it is not a full DSP but I'm curious to see how it works. I found some modules at cost of 7 dollars with stm32f407. Feel free to use share and cobtribcon on project, I have a bitx40 and plan to add as external module or internal unit using existing onboard lm386. I calculate the filters with online calculator (I put the address on GitHub), I have not Matlab ( use more years ago at the University ) a simulation or calculus of filters could be usefull, for the ssb I build small fir with few taps 9 or 11 to have no audio distorted, for the CW I worked with over 60 taps, I compared more calculator online and this was the best results .? Thanks for help.?
The filters for CW are 300 hz width centered to 700 hz and 700 hz (circa) centered to 700 hz, these are band pass.
For ssb we have two lpf of 2200 and 3300 that I used in both with the cw bpf as decimator and they sounds better.
Bye ik8yfw.
