## Forums comp.dsp

## Accurate frequency measurement problem

inHi all, Recently I've been faced with a problem of very accurate sine wave frequency measurement. Let me give you some details: I've got a...

Hi all, Recently I've been faced with a problem of very accurate sine wave frequency measurement. Let me give you some details: I've got a sensor which outputs measurement result as a frequency of a sine wave. The frequency of the signal is within 149.4kHz - 150.6kHz range and is very stable, as sensed parameter changes very slowly. Say the frequency can change no more than tens of

## Adding noise given by Noise Factor

inHello, For a system level simulation of an RF receiver in MATLAB I would like to specify Noise Factor (NF) and IIP3 for a block (e.g. the...

Hello, For a system level simulation of an RF receiver in MATLAB I would like to specify Noise Factor (NF) and IIP3 for a block (e.g. the complete receiver). My signals are represented as vectors of real numbers, heavily oversampled. I am confused: Is it best to represent the signals as voltages, currents or powers? In terms of IIP3 this is rather straight forward: My signals are vol...

## puzzle: Cross the desert

This group is comprised of mathematicians, who enjoy puzzles, so... You are stranded in a desert, at a base station, looking to get home. ...

This group is comprised of mathematicians, who enjoy puzzles, so... You are stranded in a desert, at a base station, looking to get home. There's a rescue truck, 11 miles away. Along the route, there is a series of rest stations, one at each mile. To make this long trip, you need water. You have a wagon, which can carry up to 7 liters. You drink one liter of water during the hik...

## Confused with digital modulations

inHello, I am studying implementation of a BPSK modulator and demodulator for radio applications and I am very confused. From what I have...

Hello, I am studying implementation of a BPSK modulator and demodulator for radio applications and I am very confused. From what I have read, in the transmitter section, the binary data is given to a BPSK mapper, which maps to bits to one symbol ( 0 =cos(wt), 1=-cos(wt) ). But I had read we are doing pulse shaping because we cannot transmit square pulses through the channel, but we are n...

## Android phone sample rate DSP puzzle

inI have a DSP puzzle that has to do with Android phones. I developed an Android app that I sell to piano tuners. It samples the...

I have a DSP puzzle that has to do with Android phones. I developed an Android app that I sell to piano tuners. It samples the microphone audio at 44100 samples per second and performs typical frequency analysis with an FFT, which is actually graphed for the user to see, to assist in piano tuning. The problem is that on a very few devices (actually only one model that I know for sure: t...

## Turing and Godel

inPresumably, most here are familiar with the concept of undecidability. My question is simple, though perhaps not the answer: Godel published...

Presumably, most here are familiar with the concept of undecidability. My question is simple, though perhaps not the answer: Godel published his results first, hence does Turing's non-computability theorem (the halting problem), follow as a corollary? What is the relationship between these seemingly parallel theorems? -- Rich

## [OT] I'm Available for Work

inIf anyone feels this is an unacceptable misuse of one of these groups -- speak up, I'll take it into account next time. I'm down to just one...

If anyone feels this is an unacceptable misuse of one of these groups -- speak up, I'll take it into account next time. I'm down to just one customer, with a couple of possibilities in the future but nothing certain. I vastly prefer to have two or three at a time, to fill my time in the natural pauses that happen in any project, and to keep a variety of work in front of me. So if you'...

## Nyquist and Shannon

inProbly been asked many times, but - Why is the sampling theorem called Shannon-Nyquist? Nyquist published his paper in 1924, what was...

Probly been asked many times, but - Why is the sampling theorem called Shannon-Nyquist? Nyquist published his paper in 1924, what was Shannon's contribution? Where was the original's deficiency? -- Rich

## cic interpolator filter in floating point vs fixed-point

inwould like to share one thing i learned in a hardway about CIC interpolator. many of us do matlab model before trying any fixed-point coding....

would like to share one thing i learned in a hardway about CIC interpolator. many of us do matlab model before trying any fixed-point coding. incidentally, i had no fixed-point tool set with my matlab. this forced me to write a plain (floating point) code for my CIC integrator an comb. implementing this was straight forward. i also implemented fixed-point code in C. interesting observation w...

## Hanning window - I/Q signal

inHi everybody, I have implemented Hann windowing function as follows: var N = samples.Length / 2; for (int i = 0; i < samples.Length;...

Hi everybody, I have implemented Hann windowing function as follows: var N = samples.Length / 2; for (int i = 0; i < samples.Length; i++) { samples[i] *= 0.5 - 0.5 * Math.Cos((2 * Math.PI * i) / (N - 1)); } Samples field consists of varying real and imaginary values. When i apply Hann window my signal mirrors every time at negative frequency, ergo the peak shoul

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