CWT filter bank 3 dB bandwidths

returns 3 dB (half-power) bandwidths for the wavelet filters in the filter bank
`bw`

= powerbw(`fb`

)`fb`

. `bw`

is a *Ns*-by-4
MATLAB^{®}
`table`

, where *Ns* is the number of wavelet
bandpass frequencies (equal to the number of scales). For every filter in
`fb`

, the table contains the corresponding bandpass
frequency, the 3 dB bandwidth, and the lower frequency and upper frequency limits of
the 3 dB bandwidth.

The 3 dB bandwidth limits mark where the filter power is half its peak value. The
magnitude frequency response at the limits is equal to 1/√2 times the peak
magnitude. Since the passbands in `fb`

are normalized with peak
magnitudes approximately equal to 2, the magnitude frequency response at each limit
is approximately equal to 2/√2. The 3 dB bandwidth is also known as the half-power
bandwidth because $$20{\mathrm{log}}_{10}\frac{1}{\sqrt{2}}\approx -3.$$