Hello everybody! I'm trying to remove power line hum from a signal and have two questions concerning this. 1. How high do the harmonics go?...

Hello everybody! I'm trying to remove power line hum from a signal and have two questions concerning this. 1. How high do the harmonics go? (In general, round numbers) 2. How much frequency variations (+/-) should I expect in the fundamental 50 Hz component? The reason for asking these questions is that I am having a hard time choosing between a fixed comb-notch filter and someth...

Hello sorry to bother you again but I am confused. What I understand from the threads I read is that a comb notch filter is a good choice to...

Hello sorry to bother you again but I am confused. What I understand from the threads I read is that a comb notch filter is a good choice to remove power line interference, assuming that the frequency is stable... But say that the frequency fluctuates significantly, some say that there is no use to go adaptive, while some claim that it should work... I don't see why the suggestion of m...

Hi all, I have a question about computing LLR values from M_QAM symbols to be used in LDPC decoding. I have seen some formula in text books that...

Hi all, I have a question about computing LLR values from M_QAM symbols to be used in LDPC decoding. I have seen some formula in text books that require noise power (e.g. y=2*r/sigma^2 for BPSK, where r is the received symbol). What about when the noise power is not known? Should it be estimated in the receiver from the complex baseband symbols? Best, HCH.

I'm trying to find a good reference on creating a Winograd FFT for small powers of two (

I'm trying to find a good reference on creating a Winograd FFT for small powers of two (

Okay, I have a Matlab exercise I've been working on. I've been stuck on something peripheral to the main problem. It gives two channels, each...

Okay, I have a Matlab exercise I've been working on. I've been stuck on something peripheral to the main problem. It gives two channels, each with its own attenuation coefficient in dB/km. As well, there are repeaters with a minimal signal power requirement, given in dBm. Basically, for this part of the problem, we have to figure out which channel gets the signal across 100 km with the least ...

Hi, I have a question concerning the exact definition of the one-sided Power Spectral Density (PSD): Usually it is defined as 2 times the...

Hi, I have a question concerning the exact definition of the one-sided Power Spectral Density (PSD): Usually it is defined as 2 times the two-sided PSD, but only for frequencies f > = 0. Then I found one definition which said that the one-sided PSD is 2 times the two-sided, but for f > 0 only ! For f = 0, this definition said, that the one-sided PSD equals the two-sided PSD. Intuitively

I'am studying robust methods for processing power electrical signals in non-Gaussian noise. I know the mostly used method is M-Estimator and...

I'am studying robust methods for processing power electrical signals in non-Gaussian noise. I know the mostly used method is M-Estimator and have already implemented an algorithm to analyze power harmonics. But how can I evaluate it and compare it with other non-robust methods. Besides impulsive noise, is there any other non-Gaussian noise? How can I simulate them? Thanks in advance!!!!!...

I'm getting a puzzling result from trying to look at the spectral content of noise and am wondering if someone could shed some light. I'm...

I'm getting a puzzling result from trying to look at the spectral content of noise and am wondering if someone could shed some light. I'm probably missing something very simple. Suppose I take a length N stationary signal and look at the normalized power at the lowest non-zero frequency, f=1/N, of the dft. By normalized, I mean using Parseval's relation and also dividing by the length of th...

I plotted the power spectrum density of a signal and I am trying to get a conversion scale that will give the magnitude(amplitude) of the...

I plotted the power spectrum density of a signal and I am trying to get a conversion scale that will give the magnitude(amplitude) of the original signal in time domain. I am entirely new to this.

Dear All, I have built an OFDM transmitter with 0dbm output power. If my receiver needs 20 db of SNR to work properly, what would be the...

Dear All, I have built an OFDM transmitter with 0dbm output power. If my receiver needs 20 db of SNR to work properly, what would be the range of my transmitter. The noise figure of the receiver is 5 dB. (In my experiments, the range is roughly 2 feet. So i want to know if it is a valid figure). Thank you, Aitezaz

Hi all I m trying to fix this weird behavior that I see from a data obtained from a terahertz spectroscopy analysis. The final data generated...

Hi all I m trying to fix this weird behavior that I see from a data obtained from a terahertz spectroscopy analysis. The final data generated out of the spectrometer software and i have perform some analysis on them. The first step I need do is take fft of the data to able to see its features in frequency domain but i observe a bizarre pattern. The power spectrum shows echo type of patterns . T...

Hello all, I have an audio app which generally displays dB levels as SPL calculated using dB = 20 * log10(p/p0) But I want to also display RMS...

Hello all, I have an audio app which generally displays dB levels as SPL calculated using dB = 20 * log10(p/p0) But I want to also display RMS levels. Is it more typical to calculate these values as a pressure level (using 20*log...) or as a power(intensity) level (using 10*log...) Any help, thoughts or opinions much appreciated. Cheers, Ben

Hi, I have a power spectrum and I want to get the frequency bands. Should I use a band-pass filter first to get the bands, or can I simply...

Hi, I have a power spectrum and I want to get the frequency bands. Should I use a band-pass filter first to get the bands, or can I simply divide the PSD data at needed frequencies? Than you..

Hi, How can I visualize the one and two-sided power spectral densities? As I can see, the former is for the real signal and the latter is for...

Hi, How can I visualize the one and two-sided power spectral densities? As I can see, the former is for the real signal and the latter is for the complex, but why are these values No/2 and No, respectively? Thanks.

Let's say there is a sine wave signal, and an amplifier with limited output amplitude. To produce maximum output power at fundamental frequency,...

Let's say there is a sine wave signal, and an amplifier with limited output amplitude. To produce maximum output power at fundamental frequency, the sinusoid could be clipped into square wave. So far so good. What if the input is a short burst of a sum of several unrelated sine waves with different amplitudes and the goal is to match given amplitude spectrum and generate maximum power? ...

I've got an upcoming application where I'm going to be looking to use some multiplexed ADC channels to do power supply monitoring. This is...

I've got an upcoming application where I'm going to be looking to use some multiplexed ADC channels to do power supply monitoring. This is a side function, a nice-to-have rather than core functionality. I'd like to be able to report as a running thing for each rail monitored both the DC value and peak-to-peak ripple. Reporting speed doesn't matter. Algorithmic complexity only matters inso...

I'm creating an FFT-based real-time analyzer for audio (i.e. live sound,) and have pretty much everything figured out except for this one thing:...

I'm creating an FFT-based real-time analyzer for audio (i.e. live sound,) and have pretty much everything figured out except for this one thing: should I plot the power spectrum (log of the _square_ of the magnitude of FFT outputs,) or the amplitude spectrum (log of the "plain old" magnitude of the FFT outputs)? (I think I'm using these terms correctly; correct me if I'm wrong.) Every desc...

Friends, In the field of switching power supplies or other power supply architectures in which a switching signal is used, and a...

Friends, In the field of switching power supplies or other power supply architectures in which a switching signal is used, and a signal (output voltage) is sampled and used for control, the prevailing wisdom is that the ADC sample clock should be synchronized so that it samples "between" the switching clock edges and thus avoids coupling the switching noise into the samples. I say this ...

I'm measuring V and I instantaneously and feeding them into a computer for an ac motor. Is there an easy way to find the Power Factor ie...

I'm measuring V and I instantaneously and feeding them into a computer for an ac motor. Is there an easy way to find the Power Factor ie the cosine of the angle between V and I ? I suppose there is zero crossings but there will be some noise of course. H

Hi Since the power is more relevant to analyze than the amplitude I have come up with the idea of using signed square ss(x) = x^2 for positive...

Hi Since the power is more relevant to analyze than the amplitude I have come up with the idea of using signed square ss(x) = x^2 for positive x and -x^2 for negative x or ss(x) = (x^2)^(1/2)*x = sgn(x)*x^2 Instead of analyzing the power as the square of the amplitude the signed power could be used instead. This would preserve more information of the original signal. The or