## Forums Search for: Demodulation

## CORDIC BPSK demodulation

Hi all, I would like to know how we can demodulate a BPSK signal with CORDIC algorithm. How can we (with CORDIC) make the phase acquisition...

Hi all, I would like to know how we can demodulate a BPSK signal with CORDIC algorithm. How can we (with CORDIC) make the phase acquisition and tracking due to an IQ conversion without a Costas Loop... Thanks...

## Re: OT: Tubes (was PM demodulation)

Randy Yates wrote: > Steve Underwood writes: > > > [...] > > What's this about old tube technology? What do big FM transmitters use >...

Randy Yates wrote: > Steve Underwood writes: > > > [...] > > What's this about old tube technology? What do big FM transmitters use > > today? Only the exciter has changed since the time Jerry was talking > > about. > > > Do you doubt that a freshly-graduated BSEE of the day would > most likely know little-to-nothing about tubes? When I was > going to DeVry in 1976, I was

## Mapping MSK ? How to regain the information from I and Q ?

Hello , I despair on how to regain the initial information from the seperate I and Q bits after MSK modulation/demodulation. If d(t) is...

Hello , I despair on how to regain the initial information from the seperate I and Q bits after MSK modulation/demodulation. If d(t) is the data, a sum of delta pulses g(t) is the frequency response (MSK: REC) and c(t)=g(t)*d(t) (* convolution !) then phi(t) is the phase , which is calculated by cumsum(c(t)) (MSK:"linear ramps up and down according to the bit") an...

## Box car filter

inHello, I've got after the FM demodulation (by derivative : (IdQ-QdI) / (I=B2+Q=B2)) a low pass filter. This filter is a IIR Butterwoth 4th...

Hello, I've got after the FM demodulation (by derivative : (IdQ-QdI) / (I=B2+Q=B2)) a low pass filter. This filter is a IIR Butterwoth 4th order. But I know that I can use a box car filter. But what is a box car filter ? Is it a FIR filter with rectangular window ? Or FIR filter with all the coefficients to value one ? I think that I just need to make an integration of my FM demo...

## qpsk demodulation questions

inHi, I'm currently working on a QPSK demodulator, but I'm seeing some things that don't look right, and I wanted to run them by some of...

Hi, I'm currently working on a QPSK demodulator, but I'm seeing some things that don't look right, and I wanted to run them by some of the people in this group. Is there a site where I can post up some screenshots to show you what I'm seeing 1...The recovered signals on the I and Q branches are the inverse of the actual transmitted data. A transmitted '1' is received as a zero. Is this ...

## Need of Eqaulization ?

inDear Members, I am experimenting on digital 4-FSK (orthogonal) communication system. On the demodulation side, I am using AGC and then 4...

Dear Members, I am experimenting on digital 4-FSK (orthogonal) communication system. On the demodulation side, I am using AGC and then 4 filters to detect tones and then using symbol timing. My question is how can I know that I need equalization looking at the signal if I transmit and receive the signal over the air? How can I verify that my signal is being affected by multipaths ? ...

## Urgent help neede

inHello People I need some help in understanding and implementing Digital FM -Modulation and Demodulation using digital signal...

Hello People I need some help in understanding and implementing Digital FM -Modulation and Demodulation using digital signal processing techniques. References to related links is required. or If you have any papers related to this topic- please email it to parth175@yahoo.co.in Thanks in advance Bye Parthasarathy

## your intuition: 16MHz MIPS for tri-band SSB Demod at 44.1 KHz???

inHi! to expand on the subject briefly: I'm experimenting with mechanical television a la Baird televisor. I think it would be neat to...

Hi! to expand on the subject briefly: I'm experimenting with mechanical television a la Baird televisor. I think it would be neat to encode three channels of color (YIQ) into one audio channel. I would like to use a fairly cheap microcontroller for demodulation because I have lots of experience with it (Atmel Atmega32). Thus far, SSB AM has been the most straightforward approach. On...

## Re: PM demodulation

On Fri, 05 Nov 2004 10:11:08 +0800, Steve Underwood wrote: > Allan Herriman wrote: > > > > > All "solid state" finals for broadcast FM...

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. > > > > Regards, > > Allan > > > > > I said big FM transmitters.

## ADSL Demodulation

inHello, In every book and article aobut ADSL processing the A/D and D/A sample rates are given as 2.208 MHz. For a transmitter implementation...

Hello, In every book and article aobut ADSL processing the A/D and D/A sample rates are given as 2.208 MHz. For a transmitter implementation at this sample rate you would get the conjugate symmetric image spewing out of your D/A since one may use up to bin 255 and there is absolutely no oversampling, and no analog filter in the world can cut-off that fast. Likewise for the receiver, any si...

## OFDM Question

inI was wondering about demodulation. We woudl need phase coherence of both the main carrier and the sub-carriers. I assume the main carrier can...

I was wondering about demodulation. We woudl need phase coherence of both the main carrier and the sub-carriers. I assume the main carrier can be locked onto with a PLL but what about the sub-carriers? Do they use a pilot sequency of some sort when multiply up to get the other frequencies? Thanks Tom

## What kind of filter is this?

inHi, This is my first post to comp.dsp. I found the filter below but I haven't been able to identify the type of filter it is (so I can...

Hi, This is my first post to comp.dsp. I found the filter below but I haven't been able to identify the type of filter it is (so I can understand and modify its parameters, properties, look for the theory, etc). It is used to separate U and V color components of chroma prior to demodulation by rotation according to the phase of the carrier. Using a sine as input, the output of y is 23 ...

## Is it difficult to do FM demodulation digitally?

inI've been looking at making an FM demodulator for a software defined radio. In principle at least this is trivial if you have a complex signal...

I've been looking at making an FM demodulator for a software defined radio. In principle at least this is trivial if you have a complex signal (I and Q), as you can compute the phase (atan(Q/I), then the modulation amplitude is just the derivative of phase with time. As far as I can see, this is should trivially easy, though the lack of arctan function might be the stumbling block on a fixed ...

## general fsk question

inI am trying to understand fsk demodulation in general. Is there an industry standard set of specific demod schemes or just classes of particular...

I am trying to understand fsk demodulation in general. Is there an industry standard set of specific demod schemes or just classes of particular methods (i.e. matched filter, correlation, coherent vs non-coherent) that are invoked on a project by project basis?

## Phase modulation and badnwidth

inHi everyone, say that we have a signal of this kind x(t) = A*cos(2*pi*f*t + B*y(t)); say that f is 1 kHz. If y(t) has a low frequency...

Hi everyone, say that we have a signal of this kind x(t) = A*cos(2*pi*f*t + B*y(t)); say that f is 1 kHz. If y(t) has a low frequency content compared to the carrier frequency, I find that it easy to extract the B*y(t) signal either using quadrature demodulation or the Hilbert transform. However, in the case where y(t) has a high bandwidth, for example a wideband signal with frequen...

## Another DMT Q: 180 degree phase reversals

Hi all, Ive come to another promblem with the project I'm doing on DSL. I can't seem to figure out if a 180 degree phase reversal (hardware...

Hi all, Ive come to another promblem with the project I'm doing on DSL. I can't seem to figure out if a 180 degree phase reversal (hardware inversion) will make the demodulation of the DMT signal impossible. As I see it there will be a problem with phaseshifts that holds the carrier waveform "positive" for more than a half period, like the QAM modulation on the picture. http://www...

## Digital FM demodulation

inHi all, I have a question, I have a wav.file, which is a FM modulated signal. It has 3 channels. I want to demodulate them, in Signal...

Hi all, I have a question, I have a wav.file, which is a FM modulated signal. It has 3 channels. I want to demodulate them, in Signal Processing Toolbox of Matlab. (but just the first and second channel (not the third one)) I used "demod" function, but it functions very bad and the problem is that, i need to demodulate both channels at the same time (mixed), in order to have both of the...

## baseband tasks - newby question

inIn a baseband processor, 802.11b 1Mb/s (bpsk) for example, what are the tasks done? For receive, I am guessing a) demodulation b)...

In a baseband processor, 802.11b 1Mb/s (bpsk) for example, what are the tasks done? For receive, I am guessing a) demodulation b) sync Is there source code somewhere for an audio bpsk modem somewhere to inspect? Something that might be compiled for a blackfin and used to play on a test bench... TIA.

## IQ Demod Questions

inHey guys, I have a few questions regarding digital I/Q demodulation that I can't seem to figure out on my own. I notice that if you sample at...

Hey guys, I have a few questions regarding digital I/Q demodulation that I can't seem to figure out on my own. I notice that if you sample at 4 times the carrier frequency you can essectially get the I/Q channels for free. This is due to the fact that the samples are 0,90,180,270 etc. (Note: of course this is only for the carrier frequency and other frequencies will not have the correct phase...

## PM demodulation

inFor my final project at university I'm working on a special measurement hardware. I've a tone at a certain frequency. I want to analyze the...

For my final project at university I'm working on a special measurement hardware. I've a tone at a certain frequency. I want to analyze the phase noise which is present in a bandwidth of 1 MHz around the tone. For doing that, stated that I'm using an FPGA with an ADC and given that the frequency of the tone is known, I demodulate the tone, getting I and Q and then I take the atan of thei...