What's the advantage of half band filter?

whats the advantage of half band filter over the normal one..
how is there frequency response (do they behave like complex filter).
How exactly they can be designed.

Amit

half-band filter

Half Band filters are used in splitting a full band signal of bandwidth W into two eqaul subbands each with bandwidth W/2. Since the bandwidth is the subband signals is now half, the sampling rate can also be reduced by a factor of 2.
For more information you may refer to QMF (Quadrature Mirror Filter) filter banks used in multirate signal processing.

octave band filter reconstruction

Thanks ramesh for your reply.
So how exactly we can split the bandwidth between two eqaul band.
can you suggest me some link or the paper where i can read about
the halfband filter and there implementation.

Amit

half band filter equation

...they have also half of coefs zero, and are usefull in interpolation
and decimation.

Regards,

--rs

halfband filter bandwidth

Yes, and H(w) = 1-H(Pi - w)
Save some computing power because lots of zero coefficient.

Ciao,
Dino

half band filter design

see my post:
**broken link removed**

and search internet you can find Matlab program on how to design the half band filter.

A simple but very good method:
1. Design a 2N+1 fir filter using REMEZ method
2: set coefficients (No. 2,4,6,8...) to zeros
3: set coefficient N to 0.5

Half band filters can also be used for signal oversampling by 2 (x2). The resulting signal contains the original samples and the interpolated point between the original samples are the original samples filtered by the non-zero coefficients.

T.

Re: Half Band filter?

The half band filter (QMF filters) are used in subband coding of digital video and audio signals. These filters are used for octave band spitting and reconstruction. Also used for digital interpolation and decimation in signal processing.

Re: Half Band filter?

Half-band filter play an important role in multirate digital signal processing. FIR half-band filters are easily designed to exhibit exactly linear phase, but IIR half-band filters provide higher computation speed at the cost of the phase nonlinearity. Hence, the advantage of IIR half-band filters is evident for the applications where the computation speed, low power consumption and miniaturisation are the main requirements.
A half-band filter transfer function has to satisfy the passband stop-band symmetry conditions . This implies the constraints in the choice of the filter parameters: pass- stop-band ripples and pass- stop-band edge frequencies. For the appropriate usage of a digital filter design software in half-band filter design, it is necessary to calculate the exact relations between the above mentioned parameters in advance