## PM demodulation

Started by in comp.dsp16 years ago 53 replies

Hello all ! I would like to know if there is a quite simple (but efficient) way to demodulate a PM signal who is digitalized. I have seen...

Hello all ! I would like to know if there is a quite simple (but efficient) way to demodulate a PM signal who is digitalized. I have seen some for FM demod, especially with CORDIC. Does something exist for PM as well ? Many thanks ! Sam

## What is x = I + jQ

Started by in comp.dsp16 years ago 11 replies

This is regarding the DSP math/equations in general. What is "x = I + jQ"? I know that j = 0 + 1i and i = sqrt(-1) and i^2 = -1. But what is...

This is regarding the DSP math/equations in general. What is "x = I + jQ"? I know that j = 0 + 1i and i = sqrt(-1) and i^2 = -1. But what is x = I + jQ, where x represents a form of the input data signal. I need this info to calc the atan(Q/I) for frequency demodulation purposes. Any help is appreciated.

## am demodulation algorithm

Started by in comp.dsp14 years ago 3 replies

can anybody suggest me a good algorithm for demodulating AM signals that can be implemented in VHDL.

can anybody suggest me a good algorithm for demodulating AM signals that can be implemented in VHDL.

## FM demodulation problem

Started by in comp.dsp14 years ago 2 replies

Hi, I've designed a FM demodulator with (IdQ-QdI)/(I=B2+Q=B2). My FM modulator is center on 70 MHz with 250 kHz deviation. The demodultor...

Hi, I've designed a FM demodulator with (IdQ-QdI)/(I=B2+Q=B2). My FM modulator is center on 70 MHz with 250 kHz deviation. The demodultor works fine from 10 kHz to 250 kHz (message)... but under 10 kHz I lost a lot of amplitude in my IdQ-QdI signal... Is it because i made the derivative by x[n]-x[n-1] ? Is it working better with a FIR filter with 3 taps (-1,+1,0) ? If yes what are...

## FM demodulation help needed

Started by in comp.dsp17 years ago 16 replies

Since everyone was so helpful with my AM problem, how about helping with FM? I have I/Q at baseband. I am not using an IF but translating to...

Since everyone was so helpful with my AM problem, how about helping with FM? I have I/Q at baseband. I am not using an IF but translating to 0hz, with sin/cos in hardware using a quad dds. Could this be a problem due to not getting the entire signal since the frequencies around 0hz are filtered and I obviously don't have a DC component??. I have tried the arctan(i/q) followed by a 1 tap...

## phase recovery

Started by in comp.dsp12 years ago 2 replies

Hi everybody, I am implementing a GMSK demodulator. To achieve coherent demodulation, I recovered the frequency with the power of 4 of the...

Hi everybody, I am implementing a GMSK demodulator. To achieve coherent demodulation, I recovered the frequency with the power of 4 of the signal. How can I recover then the phase? Can anybody give me any clue? Thanks mj

## How does PCM-Demodulation work?

Started by in comp.dsp12 years ago 13 replies

Hi: How does a PCM-demodulator work? Thanks, Radium

Hi: How does a PCM-demodulator work? Thanks, Radium

## Synchronous AM demodulator

Started by in comp.dsp15 years ago 16 replies

Greetings. I want to make a program that does synchronous AM demodulation. I can't seem to find any good descriptions on the net how this is...

Greetings. I want to make a program that does synchronous AM demodulation. I can't seem to find any good descriptions on the net how this is done. Could somebody please explain it, or point me to some resources? Thanks in advance. This message was sent using the Comp.DSP web interface on www.DSPRelated.com

## RE: FM Demodulation problem (Lyons Ch. 13.22)

Started by in comp.dsp15 years ago 18 replies

Rune -- what was the final result of this thread (posted Sep 19-22 2004)? Was your MATLAB implementation of the FM demodulator correct, did you...

Rune -- what was the final result of this thread (posted Sep 19-22 2004)? Was your MATLAB implementation of the FM demodulator correct, did you make any changes, or what? I couldn't find any later posts about it, and inquiring minds want to know! Thanks. cheers, jerry

## Hard Limiters

Started by in comp.dsp10 years ago 9 replies

Used in FM before demodulation. Do they actually do any filtering though apart from removing amplitude variations? What I have seen is that for...

Used in FM before demodulation. Do they actually do any filtering though apart from removing amplitude variations? What I have seen is that for low SNRs (carrier to noise ratios) you are better off without it! Many people have told me that too. For high SNRs they are fine ie if you are connected to the ariel. Hardy

## Sub : Help on FSK demodulation

Started by in comp.dsp17 years ago 13 replies

Hello I am using binay FSK. The symbol duration is 'T'. Let the two signal frequencies be f1 and f2. Ideally, we need to select f1 and...

Hello I am using binay FSK. The symbol duration is 'T'. Let the two signal frequencies be f1 and f2. Ideally, we need to select f1 and f2, such that (f1-f2)= k/T; {k=1,2..}. Both my frequencies are less that 2kHz. 'T' is in the order of 20 micro secs. My question: 1.In a practical scenario, do we have to choose f1 and f2, that precisely satisfies the above equation? If not, w...

## I-Q vs PLLs

Started by in comp.dsp15 years ago 15 replies

Which gives best performance, a Phase-locked-loop (say all digital - software) or I-Q (ie using arctan and then...

Which gives best performance, a Phase-locked-loop (say all digital - software) or I-Q (ie using arctan and then differentiating) demodulation.Reason I am asking is that a PLL is supposed to be the best - is it better than just the pure number crunching.It woudl appear to me that when you differentiate you introduce noise and the whole point of a PLL is that it a servo which tracks rate of cha...

## Looking for Rune Allnor

Started by in comp.dsp14 years ago 3 replies

hi, Rune Allnor, you had the same problem than me on the I=B2+Q=B2, this implies ripple on the FM demodulation with you 128 taps filter......

hi, Rune Allnor, you had the same problem than me on the I=B2+Q=B2, this implies ripple on the FM demodulation with you 128 taps filter... do you found why ? thanks

## why DFSK?

Started by in comp.dsp13 years ago 9 replies

DFSK (differential frequency shift keying) performs worse than FSK, then why DFSK is also applied in practice? what's the common demodulation...

DFSK (differential frequency shift keying) performs worse than FSK, then why DFSK is also applied in practice? what's the common demodulation method for DFSK, especially when channel coding is also used? thanks!

## CORDIC based FM demodulation

Started by in comp.dsp14 years ago 28 replies

Hello, I know that it is possible to demodulate an FM signal using a CORDIC ATAN core and the subtracting the current ouput of cordic...

Hello, I know that it is possible to demodulate an FM signal using a CORDIC ATAN core and the subtracting the current ouput of cordic from the last one. But I can not understand how carrier frequency and sampling rate would change it? What are the requirements? Where are the limitations? Regards

## fsk demodulation

Started by in comp.dsp15 years ago 7 replies

I am a novice in DSP.I am trying to demodulate a FSK signal wherein the mark and space frequencies are 16MHz and 24MHz respectively.I am...

I am a novice in DSP.I am trying to demodulate a FSK signal wherein the mark and space frequencies are 16MHz and 24MHz respectively.I am thinking of using delay and multiply method.Can this be implemented using an ADSP-2181?More specifically will the DSP be able to handle the high throughput involved?Please correct me if I am conceptually going wrong somewhere. This message was sent using the...

## fh fsk over non flat band

Started by in comp.dsp13 years ago

Hello, I am using a slow FH bfsk communication system. to demodulate I use a bank of correlators (non coherent demodulation). But my problem...

Hello, I am using a slow FH bfsk communication system. to demodulate I use a bank of correlators (non coherent demodulation). But my problem is when I emit and when I receive the gain is not the same over the whole bandwidth. In all the papers I have found it is assumed that the energy send and received is the same for each tone. How to take into account the different gains associated with...

## demodulation problem

Started by in comp.dsp16 years ago 3 replies

Hello. I am working on a software demodulator and have a few questions. First off let me say that I am just getting into this DSP...

Hello. I am working on a software demodulator and have a few questions. First off let me say that I am just getting into this DSP stuff. Anyways... I have a file of samples representing a bpsk modulated wave. The popular method of demodulating seems to be through I/Q channels so that the phase and magnitude can be detected. Is there a way to convert my non complex samples to an I/Q fo...

## AM demodulation using DSP

Started by in comp.dsp13 years ago 41 replies

hi! i want to demodulate AM signal digitally... i want to use a digital filter to separate the carrier and the information signal. i've searched...

hi! i want to demodulate AM signal digitally... i want to use a digital filter to separate the carrier and the information signal. i've searched a lot...and i haven't found the answer. can anyone help?please... thx... -chris(c1910)- _____________________________________ Do you know a company who employs DSP engineers? Is it already listed at http://dsprelated.com/employers.php ?

## FSK Demodulator

Started by in comp.dsp12 years ago 14 replies

Hi folks, I manage a hardware engineering group for a telcom company and I am beginning to look around for FPGA IP to implement both FSK...

Hi folks, I manage a hardware engineering group for a telcom company and I am beginning to look around for FPGA IP to implement both FSK modulation and demodulation. I am wondering if any of you have any experience with any of the IP around today. The demodulator is the most difficult part and I believe the following list of requirements is fairly close: * 300 KHz bandwidth * 5-21 MHz ...