## Forums comp.dsp

## Low-overhead high quality sine wave generation

inResonant filters are often used for this purpose, but with a remark that they need some way of amplitude control, because the numeric errors can...

Resonant filters are often used for this purpose, but with a remark that they need some way of amplitude control, because the numeric errors can make it rise without control (gain > 1) or decay to 0 (gain < 1). I don't know about you, but for me it was a great surprise to discover that for certain "magic" values of amplitude the error integrated over the entire period is *exactly* 0, which

## Precise and repeatable delay generation

inHi all, I am faced with the following problem. I need to generate 1MHz square wave where the phase delay has to be controlled precisely and...

Hi all, I am faced with the following problem. I need to generate 1MHz square wave where the phase delay has to be controlled precisely and repeatedly. The duty cycle of this signal can be anywhere between 40%-60%. The delay should be able to be incremented in approx. 10ps steps and the resulting 1MHz square wave jitter needs to be around 100fs or better. I was thinking about usin

## machine learning vs interpolation

inGreetings. I have been using neural networks and other machine learning tools for sometime time. Yesterday the following question popped up in...

Greetings. I have been using neural networks and other machine learning tools for sometime time. Yesterday the following question popped up in my mind however: Why do we use machine learning tools when we could achive similar results with plain interpolation? Let's assume a noise free regression scenario (not classification and no measurement errors). In the case of infinite samples and...

## DSM integrator - how many bits?

inI'd like to implement a first-order delta-sigma power amplifier in Verilog. The input stream is N=16-bit wide (signed). How many bits should the...

I'd like to implement a first-order delta-sigma power amplifier in Verilog. The input stream is N=16-bit wide (signed). How many bits should the integrator have? Common sense says it would be enough for the worst-case delta (=N+1) + the actual content (also N+1), so N+2 bits. Is it correct? Can it be done with just N? Best regards, Piotr

## Low memory footprint decimation

Hello, so I finally have some time to return to the problem of the multichannel decimation on PSOC5LP. The situation is as follows: there are...

Hello, so I finally have some time to return to the problem of the multichannel decimation on PSOC5LP. The situation is as follows: there are 8 channels of 12 bits@100kHz each and a single digital quadrature mixer running at 310kHz, also 12 bits. The hardware is an 80MHz ARM CortexM3 equipped with a coprocessor called DFB, running at the same speed, with single-cycle 24x24-> 48-bit MAC an

## Finding maximum of sinc in 0..1

inHi folks, the audio world is sort of obsessed with sort of "true peak level". Unfortunately it is rather tricky to calculate, so it is...

Hi folks, the audio world is sort of obsessed with sort of "true peak level". Unfortunately it is rather tricky to calculate, so it is calculated by oversampling to about 192kHz and taking the normal peak level. Sadly that's really not true peak level. So how about the (nearly) correct value - if we take say 2 * N + 1 samples around each sample S[0] (hence S[-N] .. S[N]), we can calculate ...

## How can a filter impulse response be interpolated?

inHi, I know how to interpolate a digital signal. It is first interpolated by inserting 0's. For example, one can add 4 0's to each data for a...

Hi, I know how to interpolate a digital signal. It is first interpolated by inserting 0's. For example, one can add 4 0's to each data for a 5 times interpolation. Then, a low pass filtering to eliminate the aliasing frequency. Now, I have a low pass filter from 0 to 10 MHz pass band with a sampling rate of 40 MSPS. I want to get the same 0 to 10 MHz response (it is not a flat pass band...

## Why is there a spurious component in this resampling process?

inHi, Thank all of you for replying to my previous post on filter impulse response. One of the replies said to directly calculate the fir coef...

Hi, Thank all of you for replying to my previous post on filter impulse response. One of the replies said to directly calculate the fir coef as the original filter. I considered this method. The only problem is too time consuming. As it is not a general FIR design, I have to find the background information to write the code from the bottom. OK. I have solved the problem with all of your in...

## 6dB/oct butterworth crossover doesn't have flat response

inHi folks, sorry if I'll be asking a dumb question :). I'd like to build a 6dB/oct crossover (with variable number of bands and crossover...

Hi folks, sorry if I'll be asking a dumb question :). I'd like to build a 6dB/oct crossover (with variable number of bands and crossover points). First order butterworth LP and HP filters seem to be working fine and provide nearly flat magnitude response IF the crossover point isn't high enough, hence close to the nyquist, then it starts forming something that looks like a high-shelf of +6dB. ...

## Kalman filter estimator for Gyro and accelerometer

inI am using a fairly standard approach to estimating angular pitch using a KF. It uses both accelerometer and Gyro angle data. Now it estimated the...

I am using a fairly standard approach to estimating angular pitch using a KF. It uses both accelerometer and Gyro angle data. Now it estimated the angle fine enough and I implement the steady-state KF. Never tried this before but then put a PID or lag-lead controller on this measurement. I find that the Kalman filter bandwidth is stuff all and severely reduces the bandwidth of my cl

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