# Tag Info

Accepted

### Transfer function of second order notch filter

For digital notch filters, I like to use the following form for a notch filter at DC ( $\omega$=0): $$H(z) = \frac{1+a}{2}\frac{(z-1)}{(z-a)}$$ where $a$ is a real positive number < 1. The ...
• 52.4k
Accepted

### Exponential moving average cut-off frequency

The discrete recurrence relation given on the linked page is $y[n] = (1-\alpha)y[n-1] + \alpha x[n]$ with $x[n]$ being the input samples and $y[n]$ being the output samples. So taking the Z-transform \$...
• 2,710
Accepted

• 90.5k

### What is the name of a low-pass filter that tracks rate of change?

I do not think that there's a specific name for this type of lowpass filter. There are indeed similarities between the cascade of two lowpass filters as suggested in the OP's answer, and a combination ...
• 90.5k
Accepted

### Filtering an acceleration signal

I believe the best strategy is to filter prior to calculating the magnitude. To see this easily, consider the low pass filtering as an averaging process and consider the noise as a zero mean Gaussian ...
• 52.4k