Paolo Martinetti (@PMartin)


Re: C5505 eZdsp - reproducing wav file

Reply posted 5 years ago (11/29/2017)
Thank you Cedron. My file is Mono mode. It is very interesting what you say.The problem i think is endianity. Wav data is stored in little endian format and my...

Re: C5505 eZdsp - reproducing wav file

Reply posted 5 years ago (11/29/2017)
Thanks a lot Cedron,this is very helpful!Best RegardsPMartin

Re: C5505 eZdsp - reproducing wav file

Reply posted 5 years ago (11/29/2017)
Hi Benoit,thanks a lot for your suggestions.For example, i haven't considered the data endianity, but i created a tone signal (1Khz sine wave) and it is emitted...

C5505 eZdsp - reproducing wav file

New thread started 5 years ago
Hi, on my c5505 eZdsp i have configured the codec at 192 Khz recording / playback frequency.I'd like to reproduce a 8 Khz wav file, saved in 16 bit PCM format...

Re: Frequency shifting with FFT

Reply posted 5 years ago (11/09/2017)
Thanks, but I think i'll first try the analytic signal strategy. I think it is more efficientRegardsPMartin

Re: Frequency shifting with FFT

Reply posted 5 years ago (11/09/2017)
DSB-SC demodulation in real time is not so simple because you don't know the phase of the carrier of the received signal.RegardsPMartin

Re: Frequency shifting with FFT

Reply posted 5 years ago (11/09/2017)
Hi,my sampling rate is 192 Khz.I have to demodulate a DSBSC signal with carrier 32768 Hz.I want to use FFT because my SOC has a built-in FFT Hw accelerator.I have...

Re: Frequency shifting with FFT

Reply posted 5 years ago (11/07/2017)
Thanks.I'm a newby...could you provide an example?I'd like to demodulate only one band, not bothThanksPMartin

Frequency shifting with FFT

New thread started 5 years ago
Hi,i'd like to shift the frequency of a signal that is modulated DSBSCThe problem is that the I FFT the signal, but the carrier frequency is not integer multiple...

Re: DSBSC Demodulator

Reply posted 5 years ago (11/03/2017)
Hi David, solved:sum and products in iSin and iCos overflowed:Here's the solution:Int16 iSin(Int16 angle){    Int16 cc;  // cosine course    Int16 cf;  //...

Re: DSBSC Demodulator

Reply posted 5 years ago (11/03/2017)
Hi David, there is something wrong in my implementation. I'd like to ear your opinion, please.I tested the algo calculating sine and cosine of 5/6*pi.If 2*pi =...

Re: DSBSC Demodulator

Reply posted 5 years ago (11/02/2017)
Yes, a lot is gained from sums and multiplications too...apart the fact of overflows and underflows said before...

Re: DSBSC Demodulator

Reply posted 5 years ago (11/02/2017)
Yes,6000 cycles is an important gain. I gain them in a 384 loop, so i gain, at 120 Mhz about 19 msec only by sine and cosine.Thanks a lotPMartin

Re: DSBSC Demodulator

Reply posted 5 years ago (11/02/2017)
Hi David,i've implemented sin and cos and i gained 6000 cycles!I need to exercise in Fixed Point arithmetic to proceed...I have overflows and underflows in my algorithm,...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
Thanks!I'll try to implementBest Regards,PMartin

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
Very clear.Obviously, i must use fltoq15 of DSPLIB to convert of the course and fine tables to Q15 format.Now, how can i apply sin(a+b) = sin(a)cos(b) + sin(b)cos(a),...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
David, i have some questions:"Calculate a table for the sin(a) and cos(a) (remembering that cos(a) = sin(a+pi/2)), where "a" is the upper 8 bits of the angle. ...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
David, you are very very helpful!I'll try to implement then i'll make you to knowThanks you so much!PMartin

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
Thanks David,I'm passing from fp to 32 bit integer operations.How can i convert a float into Q31?Reasoning it should be:Q31 = float * 2^31, so Q31 = float <<...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/31/2017)
Hi David,I measured a lot of time spent in cos(), sin() and atan2.Furthermore, I'm implementing my algo with float data, instead of using integers. Being a newby...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/30/2017)
Yes, I done, but the time gain is not enough.I decided to maintain an input queue and an output queue.When there is a new frame in the input queue, i process it.Then...

Re: DSBSC Demodulator

Reply posted 5 years ago (10/30/2017)
If i create a receive buffer, long enough, and elaborate then transmit,i'll transmit with 45 msec delayed, and this isn't a problem. Agree?

DSBSC Demodulator

New thread started 5 years ago
Hi,I implemented a dsbsc demodulator using 2nd order costas loop on SoC c5505 eZdsp.My demodulation functions takes about 45 msec of cpu time, while data arrive...

Re: DSB-SC demodulation

Reply posted 5 years ago (07/12/2017)
Ok, but if i multiply a real signal by a complex signal i obtain a complex signal....so how can i get the demodulated real signal

Re: DSB-SC demodulation

Reply posted 5 years ago (07/12/2017)
dudelsound, i thank you a lot. I'm totally out of road.I'm developing Costas loop in order to demodulate my signalThanks you so muchRegards,Paolo

DSB-SC demodulation

New thread started 5 years ago
Hi, i'm trying to demodulate a DSB-SC modulated received signal.I acquire the signal without any problemthen i want to FFT the signal with 1024 point FFT (using...

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