## 1d correlation / convolution

Started by in comp.dsp6 years ago 1 reply

I have the absolute amplitude of a digital signal that I want to auto correlate with self , also cross correlate with a different digital...

I have the absolute amplitude of a digital signal that I want to auto correlate with self , also cross correlate with a different digital signal [ absolute magnitude ] . I'm using a complex 1d fft to implement this . I only have the absolute values of the spectra to work with ; where the absolute value is defined as : square root of (Real^2 + Imaginary^2). After multiplying the a...

## Averaging of phase noise?

Started by in comp.dsp6 years ago 4 replies

Hi all, My most basic question can be summarized as: "Can phase noise be averaged out?" And subsequentially, is there a difference if the...

Hi all, My most basic question can be summarized as: "Can phase noise be averaged out?" And subsequentially, is there a difference if the input signal is a sinusoid or wideband? What happens after averaging infinitely many times? My first reaction is: No, it can't (at least not in a similar manner as white noise where SNR is increased by 10dB for every additional 10x of averaging) becau...

## frequency measurement and time-frequency uncertainty

Started by in comp.dsp6 years ago 34 replies

We have a requirement to measure a 32.768 KHz TTL output quickly and with a certain accuracy. If one used an N-bit ADC sampling at F samples...

We have a requirement to measure a 32.768 KHz TTL output quickly and with a certain accuracy. If one used an N-bit ADC sampling at F samples per second, what is the relationship between T_m and F_delta, where T_m is the minimum measurement time (say, in seconds) for a maximum frequency error of F_delta (say, in PPM)? For this discussion assume the frequency is stable over the measureme...

## [FAR Off Topic] Backup email providder - Help please

Started by in comp.dsp6 years ago 9 replies

I am of opinion that "free" can "cost too much". My email provider is having 'problems'. I've dealt with them for decades - they were my ISP in...

I am of opinion that "free" can "cost too much". My email provider is having 'problems'. I've dealt with them for decades - they were my ISP in dial-up days. Their solar system headquarters is less than 5 miles from my home in rural SW Missouri. I just did not realize how much I would miss email. Are there any ethical free email providers. TIA

## Cool piece on Google's neural network engines

Started by in comp.dsp6 years ago 7 replies

## OT: Those arithmetic questions

Started by in comp.dsp6 years ago 25 replies

Often you see questions on social media such as - find the answer to 9/3(1+2) (they usually use the divide symbol which nobody uses of course...

Often you see questions on social media such as - find the answer to 9/3(1+2) (they usually use the divide symbol which nobody uses of course so= I have replaced it with a slash) and they spout on about order of operations and so left to right the answer= is 3x 3 =3D9 and the catch is that people answer 9/9 =3D 1. Ha, they don't= know their order of operations which was agreed by conve...

## Variable data rate PSK modem

Started by in comp.dsp6 years ago 9 replies

Dear All, I have a fixed data rate PSK receiver which works fine. Now I have to design a variable data rate PSK receiver. The Block Diagram...

Dear All, I have a fixed data rate PSK receiver which works fine. Now I have to design a variable data rate PSK receiver. The Block Diagram looks like this(Hope ASCII Art works): ADC-> AGC-> RRC-> Complex Mixer-> Coarse/Fine Carr.Recov-> Timing Rec-> BPSK/QPSK | | NCO---------------- When I try to add

## RF complex mixing

Started by in comp.dsp6 years ago 25 replies

Hello everyone. Could anyone explain please the next issues we know that there are no negative frequencies, so during real rf mixing the"-"...

Hello everyone. Could anyone explain please the next issues we know that there are no negative frequencies, so during real rf mixing the"-" frequencies fold back to positive F axis. so why during complex RF mixing the "-" Frequencies exist? I think that I understand that the complex signal can have "-" frequencies, but if we look at x(t)*cos and x(t)*-sin terms as ar real rf mixing

## replace zeroes with red noise before 2D FFT?

Started by in comp.dsp6 years ago 1 reply

I came across a claim in another forum for dealing with 2D FFT where there are dead traces (data is t-x domain before FFT). So if there is a...

I came across a claim in another forum for dealing with 2D FFT where there are dead traces (data is t-x domain before FFT). So if there is a dead channel, fill it with red noise whose amplitude matches roughly the other channels, then do the 2D FFT. Supposedly this minimises artefacts. Plausible?

## Frequency (Doppler) shift problem

Started by in comp.dsp6 years ago 7 replies

Hi all, I am processing satellite transmissions and assume no prior knowledge of the Doppler shift. Using a brute force technique I have been...

Hi all, I am processing satellite transmissions and assume no prior knowledge of the Doppler shift. Using a brute force technique I have been able to extract coarse Doppler and fit a polynomial. I wish to be able to use the polynomial to remove the Doppler components from the signal but have come up against a problem. Below is some (modified) code which illustrates the issue I'm