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...

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

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...

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 ...

Dear 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 ? ...

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

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...

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...

Im a little confused about how you employ coherent demod in OFDM. After the FFT at the receiver, how do I perform a coherent demodulation-dont I...

Im a little confused about how you employ coherent demod in OFDM. After the FFT at the receiver, how do I perform a coherent demodulation-dont I need a carrier for phase estimation in case of BPSK, QPSK etc. Also this is what coherent OFDM is, right?

I'm working with a customer to design a system. The preferred development model seems to have settled into one where I do all the heavy...

I'm working with a customer to design a system. The preferred development model seems to have settled into one where I do all the heavy lifting mathematically, and they implement the algorithms that I cook up. Their software guy is willing, but we both think he'd benefit from a tutorial or three, and perhaps a book on basic data communications. Does anyone have any recommendations? A...

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...

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...

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...

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...

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...

Hi All, I have been working for some time now on making a multichannel FM demod / remod, and I have finally gotten my hands on some test...

Hi All, I have been working for some time now on making a multichannel FM demod / remod, and I have finally gotten my hands on some test equipment to put this design through its paces and have found that I have a strange problem. To start with I will outline the design that I am using.. I undersample the FM signal at 80MSPS using a 12bit ADC, this signal is then mixed down to baseba...

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 ?

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 ...

Hi Guys, I am doing a project on Software Defined Radio receiver.. I have generated a AM signal which is coming from a microphone and it goes...

Hi Guys, I am doing a project on Software Defined Radio receiver.. I have generated a AM signal which is coming from a microphone and it goes to a signal mixer. I have a local oscillator and the two signals are mixed (Superhet). The output from the mixer forms the IF(Intermediate Frequency).Now what I have to do is to demodulate the signal and feed it to the speaker using a AF Amplifier. So...

In 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.

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...

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...

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...

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...

There are communication systems with orthogonal multitone physical layer. That is, one of N frequencies in the set is sent at a time. An example...

There are communication systems with orthogonal multitone physical layer. That is, one of N frequencies in the set is sent at a time. An example of such system is "Olivia": http://en.wikipedia.org/wiki/Olivia_MFSK . In the systems like that, they usually demodulate signal by incoherent detector. The loss due to incoherent demodulation is 1dB ballpark. There are, of course, technical reaso...

I 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?

Hi everybody, I demodulate a FM signal with this : IdQ - QdI But in a paper I see that after this, we have to add an Integrate and Dump !!...

Hi everybody, I demodulate a FM signal with this : IdQ - QdI But in a paper I see that after this, we have to add an Integrate and Dump !! But for this operation, we need and integrate clock time over the symbole to demodulate.... If I don't put this Integrate and Dump block I think that in presence of noise the demodulator works bad !!! Do you have suggestions ? Thanks.