Equivalent noise bandwidth of filter

```
bw = noisebw(num, den, numsamp,
Fs)
```

```
bw = noisebw(num, den, numsamp,
Fs)
```

returns the two-sided equivalent noise bandwidth,
in Hz, of a digital lowpass filter given in descending powers of z
by numerator vector `num`

and denominator vector `den`

.
The bandwidth is calculated over `numsamp`

samples
of the impulse response. `Fs`

is the sampling rate
of the signal that the filter would process; this is used as a scaling
factor to convert a normalized unitless quantity into a bandwidth
in Hz.

This example computes the equivalent noise bandwidth of a Butterworth filter over 100 samples of the impulse response.

Fs = 16; % Sampling rate Fnyq = Fs/2; % Nyquist frequency Fc = 0.5; % Carrier frequency [num,den] = butter(2,Fc/Fnyq); % Butterworth filter bw = noisebw(num,den,100,Fs)

The output is below.

bw = 1.1049

[1] Jeruchim, Michel C., Philip Balaban,
and K. Sam Shanmugan, *Simulation of Communication Systems*,
New York, Plenum Press, 1992.

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