## Forums More comp.dsp

## 1d correlation / convolution

inI 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?

inHi 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

inWe 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

inI 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

inLinked in today's Ganssle. Interesting...

Linked in today's Ganssle. Interesting stuff. https://cloud.google.com/blog/big-data/2017/05/an-in-depth-look-at-googles-first-tensor-processi ng-unit-tpu -- Rob Gaddi, Highland Technology -- www.highlandtechnology.com Email address domain is currently out of order. See above to fix.

## OT: Those arithmetic questions

inOften 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

inDear 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

inHello 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?

inI 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

inHi 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

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