frequency measurement and time-frequency uncertainty

Started by Randy Yates in comp.dsp8 months 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 Richard Owlett in comp.dsp8 months 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 Rob Gaddi in comp.dsp8 months ago 7 replies

Linked 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

Started by Anonymous in comp.dsp8 months 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 Mehtap özkan in comp.dsp8 months 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 Anonymous in comp.dsp8 months 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 Anonymous in comp.dsp8 months 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 Anonymous in comp.dsp9 months 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


charge pump related loop simulation in PLL

Started by fl in comp.dsp9 months ago 2 replies

Hello all: Though my question is not in the strict DSP, I cannot find another appropriate forum to discuss about it. As a hobby, I am interested...

Hello all: Though my question is not in the strict DSP, I cannot find another appropriate forum to discuss about it. As a hobby, I am interested in a PLL simulation. On numerous tutorials, I know there are current sources in a charge pump type phase detector. I realize that the current source makes the voltage cross the capacitor linearly increase. It is seen the Laplace transform of the RC ...


Does decimating after Sampling mean loss of data?

Started by Mehtap özkan in comp.dsp9 months ago 1 reply

Dear All, I use an AD9371 board and on it the ADC samples the input at 1228 MHz, then the sampled data is decimated by 5 and a downsampling FIR...

Dear All, I use an AD9371 board and on it the ADC samples the input at 1228 MHz, then the sampled data is decimated by 5 and a downsampling FIR filter reduces the output rate to 122.8 MSPS. This is what I have as an input to the FPGA where demodulation occurs. The signal to be demodulated is an 80 MHz wide QPSK modulated one. For ideal demodulation I need a 320 MSPS (x4 symbol rate). My quest...


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