Android phone sample rate DSP puzzle

Started by in comp.dsp7 hours ago 11 replies

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...

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

Started by in comp.dsp14 hours ago 6 replies

Presumably, 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

Confused with digital modulations

Started by in comp.dsp2 days ago 2 replies

Hello, 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...

[OT] I'm Available for Work

Started by in comp.dsp3 days ago 58 replies

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...

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

Started by in comp.dsp4 days ago 6 replies

Probly 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

Started by in comp.dsp4 days ago 2 replies

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....

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

Started by in comp.dsp5 days ago 1 reply

Hi 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

OT more than one Matrix

Started by in comp.dsp6 days ago 1 reply

I have always said two Matrices. I heard somebody say two Matrixes which I thought must be wrong

I have always said two Matrices. I heard somebody say two Matrixes which I thought must be wrong

Oversampled dft filter banks

Started by in comp.dsp6 days ago

Hi guys, i need help from you. I've an ADC with 16 outputs lines, so i have 16 samples in parallel each time. Example: S16 S0 S17 S1 S18...

Hi guys, i need help from you. I've an ADC with 16 outputs lines, so i have 16 samples in parallel each time. Example: S16 S0 S17 S1 S18 S2 ... ... S31 S15 Each line has 300 MHz of sampling rate, therefore its bandwidth is 150 MHz. Now i would obtain 32 channels from these 16 but at same frequency..so i would have 32 channels with 75 MHz of bandwidth. Is possible for you? Have i alia...

Channel Estimation in the frequency domain

Started by in comp.dsp6 days ago 4 replies

Hello, I am using the ifft for the typical channel estimation in the frequency domain, in this case using 64 carriers: ChannelEst= ifft(...

Hello, I am using the ifft for the typical channel estimation in the frequency domain, in this case using 64 carriers: ChannelEst= ifft( Y./X , 64); Y is the FFT of RX signal X is the FFT of TX signal When all the 64 FFT points are filled, the channel estimation is perfect. But if i only TX some carriers: [12:50] and the rest of carriers are zero, then the estimation channel ha...