FM Demodulation

Started by Henry VIII in comp.dsp12 years ago 15 replies

I have an application where I need to detect an unmodulated tone at a fixed baseband frequency on an FM carrier. The mod index of the tone is...

I have an application where I need to detect an unmodulated tone at a fixed baseband frequency on an FM carrier. The mod index of the tone is quite low, such that only the first Bessel pair of FM sidebands is significant. Can I demodulate the tone by directly detecting its Bessel components (the first two sidebands) at RF without first passing the composite FM signal through a discrimi...


Soft QAM demodulation

Started by Crisanquito in comp.dsp11 years ago 1 reply

Hello I guess it is one of the most basic topics, but I am not able to understand this topic, mainly because I have not found yet any...

Hello I guess it is one of the most basic topics, but I am not able to understand this topic, mainly because I have not found yet any reference explaining it: I am trying to understand the iterative turbo decoding, but I am still trying to understand the APP decoding part. The computation of gamma implies to find gamma(s',s)=P(yk|xk), being yk the received codeword and xk the transmitted code...


Approaching QAM256 demodulation

Started by haxorcize in comp.dsp8 years ago 14 replies

Hi! I am trying to write a demodulator for a 6MHZ-wide QAM256 signal. I have captured a sample file with the aid of a USRP, and I carry on...

Hi! I am trying to write a demodulator for a 6MHZ-wide QAM256 signal. I have captured a sample file with the aid of a USRP, and I carry on the rest in Matlab. [Question regarding sampling frequency]: I get max 8MS/s from the USRP (although the spec says it should support 16MS/s - I can't seem to get that for some reason). It seems like I should take > 12MS/s to avoid aliasing for a 6MHz si


ADC and DAC for modulation and demodulation

Started by chess in comp.dsp5 years ago 4 replies

Hi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous...

Hi I have written Matlab script for BPSK modulation. The way my code works is as follow: series of 0 and 1----> NRZ data (continuous rectangular pulses with amplitude -1 and 1)---> multiply by carrier----> add noise--> multiply by carrier---> integration---> detection---> Bit Error collection? I would like to know can anyone tell me where I should apply DAC and ADC ? I am wondering shoul


FM demodulation phase unwrapping

Started by mans-34 in comp.dsp13 years ago 24 replies

Hello, I did some simulation to develop an FM demodulator. I used Simulink for modeling. I create a 40 MHZ carrier signal...

Hello, I did some simulation to develop an FM demodulator. I used Simulink for modeling. I create a 40 MHZ carrier signal modulated with 1K data signal and sampled at 102.4 M sample per cycle. The signal is then feed into a FIR filter to make IQ signal. I used Atan and unwrap and differentiator to demodulate the signal and I was able to successfully demodulate it. ...


Re: PM demodulation

Started by Steve Underwood in comp.dsp15 years ago

Allan Herriman wrote: > On Fri, 05 Nov 2004 10:11:08 +0800, Steve Underwood > wrote: > > > > > Allan Herriman wrote: > > > > ...

Allan Herriman wrote: > On Fri, 05 Nov 2004 10:11:08 +0800, Steve Underwood > wrote: > > > > > Allan Herriman wrote: > > > > > > > > > All "solid state" finals for broadcast FM have been around since the > > > '80s. At the time, they were better in terms of reliability, but not > > > initial purchase price. > > > > > > I don't know how the comparison stands today. > > > > > > Regar


Synchronous AM demodulation (again...)

Started by AlanWrench in comp.dsp9 years ago 27 replies

Hey there I am the new one and I am from Germany. Currently I am in the USA writing my Bachelor Thesis. I have the following issue: I have...

Hey there I am the new one and I am from Germany. Currently I am in the USA writing my Bachelor Thesis. I have the following issue: I have an AM modulated signal with a carrier voltage about 100V to 500V and a message voltage of about 250mV. This signal is out of a coil which is part of an RFID reader (more MCID - magnetic coupling... that's why the voltage is so high). The carrier has a fr...


Newbie: CW demodulation

Started by EA7FNJ in comp.dsp15 years ago 8 replies

Hi guys, I'm newbie in those groups. I tried to make a CW demodulator (Telegraphy). I would like to make this because it's the simplest signal. I...

Hi guys, I'm newbie in those groups. I tried to make a CW demodulator (Telegraphy). I would like to make this because it's the simplest signal. I have somes algorithms about USB/LSB/AM/FM demodulators, with theis I/Q signals, but what do I have to use to try it? or are there any simple solution?. In tha analog world, it's only IF-LO= CW Audio, but in the digital world, is is simpler than analog?. ...


equalizer in matlab

Started by Peter Simpson in comp.dsp10 years ago

It seems that the training symbols have to use the same modulation as the data symbols. Is there any way that I can use different modulations? ...

It seems that the training symbols have to use the same modulation as the data symbols. Is there any way that I can use different modulations? say QPSK for training and 16QAM for data. I tried equalizing the two parts separately with a constellation change in between. The shape of the equalized constellation seems correct, but it is compressed. Of course the demodulation result is wrong. ...


PAM DEMODULATOR

Started by vimmi in comp.dsp11 years ago

To all the guardians of signal processing, iam writing a matlab code for the pulse amplitude modulation and demodulation. i have done in the...

To all the guardians of signal processing, iam writing a matlab code for the pulse amplitude modulation and demodulation. i have done in the following way 1.a sine signal with 1000Hz frequency. 2.then a square wave(carrier) of 10000Hz frequency. 3.multiplied these 2 for sampling. 4.quantized the resultant signal. 5.i have added some noise by using rand() fn. 6.at the receiver side i corr...


Matlab simulation of beamforming

Started by jaheti in comp.dsp12 years ago 5 replies

Hi all, I would like to know how I could model the effect of beamforming in a monte carlo simulation (running Matlab). A simple simulator...

Hi all, I would like to know how I could model the effect of beamforming in a monte carlo simulation (running Matlab). A simple simulator structure for the beginning could be something like: 1.random bit input 2.modulation (M-PSK or M-QAM) 3.beamformer 4.channel 5.demodulation 6.error counter, calculate BER as a function of SNR So, how to implement the beamforming part? Can I do the si...


Digital FM Demodulation

Started by Jon in comp.dsp16 years ago 3 replies

Hi all, After seaching the comp.dsp archive for FM demod I did not find anything on the case where there is a frequency offset between...

Hi all, After seaching the comp.dsp archive for FM demod I did not find anything on the case where there is a frequency offset between the transmitter and receiver. Is there a reference that explains how the frequency offset between the transmitter and reciever effects the performace of the demodulator? I assume that a digital PLL implementation would be required or would the method in t...


fm-demodulation on an FPGA

Started by in comp.dsp16 years ago 6 replies

Hi all, I have created an FM-receiver which is implemented on an FPGA (Virtex-II)= =2E After the FM-demodulator (currently I'm subtracting...

Hi all, I have created an FM-receiver which is implemented on an FPGA (Virtex-II)= =2E After the FM-demodulator (currently I'm subtracting the phase of the=20 previous sample from the phase of the current sample) I have to put a=20 highpass filter removing the lower 300 Hz of the output signal,=20 otherwise I have a tone on approx. 250 Hz. The funny thing is that the=20 250 Hz tone only s...


FSK Versus OOK Demodulation

Started by Randy Yates in comp.dsp9 years ago 24 replies

With the right filtering, an FSK signal can be viewed as two complementary OOK (on-off keyed) signals. Is the optimal FSK demodulator more...

With the right filtering, an FSK signal can be viewed as two complementary OOK (on-off keyed) signals. Is the optimal FSK demodulator more optimal, less optimal, or equivalent to two optimal OOK demodulators with their outputs combined? -- Randy Yates % "Watching all the days go by... Digital Signal Labs % Who are you and who am I?" mailto://yates@ieee.or...


implementing blind scanning in receivers

Started by prabu_cc in comp.dsp12 years ago 5 replies

hello everyone.. I am a student working on this project...to design dvb-s cards..I am new to DSP and MATLAB..have spend so much time to find a...

hello everyone.. I am a student working on this project...to design dvb-s cards..I am new to DSP and MATLAB..have spend so much time to find a way to implement,but unsuccessful.. and finally came to this forum for help.. i am using a particular demodulator chip ..If I input the centre frequency, the chip start the demodulation process without any problem. But i need to perform the blind scanning...


Converting I and Q to real signal

Started by micdahl in comp.dsp13 years ago 21 replies

Hello, I am a Mech Eng, so I'm not exactly a ninja at quadrature demodulation, and I have a problem that i've been trying to figure out for a...

Hello, I am a Mech Eng, so I'm not exactly a ninja at quadrature demodulation, and I have a problem that i've been trying to figure out for a while. Some background on the system: I am measuring vibrations using doppler ultrasound, vibrations induced by an actuator at around 200 Hz. The Doppler ultrasound setup I have spits out pulses of 5MHz at a frequency of 1563 pulses per sec. The mac...


GSM channel filter

Started by friedman in comp.dsp11 years ago 3 replies

Hi, Suppose I have to extract a single 200kHz channel from the GSM band and I'd do it using a non-linear phase response filter. Could someone...

Hi, Suppose I have to extract a single 200kHz channel from the GSM band and I'd do it using a non-linear phase response filter. Could someone give me an idea or a reference on how to evaluate the impact of the phase distortion? I mean how the GMSK demodulation process will be affected. Any advice or reference regarding this would be appreciated. thank you, friedman


FM demodulation at high frequency - technology limitations?

Started by Bernhard Holzmayer in comp.dsp13 years ago 6 replies

Hi fellows, since I appreciate very much your opinion and expertise, I'd launch some brainstorming around a future project we plan. This is...

Hi fellows, since I appreciate very much your opinion and expertise, I'd launch some brainstorming around a future project we plan. This is the idea: We have a sine wave signal @ 1MHz which carries analog modulation and - naturally lots of unwanted noise etc. Frequency of the unmodulated signal is known, the phase however isn't (might vary but can be assumed as stable, but unknown). We'...


AM digital demodulation using the absolute value

Started by Benjamin Couillard in comp.dsp9 years ago 9 replies

Hi everyone, I have a question. Assuming we have a band-limited signal from 10-20 MHz with a sampling frequency of 100 MHz. Let's say I want...

Hi everyone, I have a question. Assuming we have a band-limited signal from 10-20 MHz with a sampling frequency of 100 MHz. Let's say I want to obtain the envelope of this signal. One method would be to use a Hilbert filter, to obtain the quadrature signal and then do the whole envelope = sqrt(I^2 + Q^2). However, let's assume that I need to use the absolute value instead. What would happe...


4FSK blind Demodulation

Started by mani.rahnama in comp.dsp4 years ago 1 reply

Dear all, I am working on a four-FSK blind demodulator, and there are some problems, I can't resolve very well. The first one pertains to...

Dear all, I am working on a four-FSK blind demodulator, and there are some problems, I can't resolve very well. The first one pertains to the Frequency Offset Of the received Signal. The algorithm which is implemented uses energy per tone to decide which symbol is transmitted. Timing offset is calculated the same way, by finding the sample offset (within the symbol) that yields maximum...