# v_potsband

## PURPOSE

V_POTSBAND Design filter for 300-3400 telephone bandwidth [B,A]=(FS)

## SYNOPSIS

function [b,a]=v_potsband(fs)

## DESCRIPTION

    V_POTSBAND Design filter for 300-3400 telephone bandwidth [B,A]=(FS)

    Input: FS=sample frequency in Hz

    Output: B/A is a discrete time bandpass filter with a passband gain of 1

    The filter meets the specifications of G.151 for any sample frequency
    and has a gain of -3dB at the passband edges.

## CROSS-REFERENCE INFORMATION

This function calls:

This function is called by:

## SOURCE CODE

    0001 function [b,a]=v_potsband(fs)
    0002 %V_POTSBAND Design filter for 300-3400 telephone bandwidth [B,A]=(FS)
    0003 %
    0004 %Input: FS=sample frequency in Hz
    0005 %
    0006 %Output: B/A is a discrete time bandpass filter with a passband gain of 1
    0007 %
    0008 %The filter meets the specifications of G.151 for any sample frequency
    0009 %and has a gain of -3dB at the passband edges.
    0010
    0011
    0012 %      Copyright (C) Mike Brookes 1998
    0013 %      Version: $Id: v_potsband.m 10865 2018-09-21 17:22:45Z dmb $
    0014 %
    0015 %   VOICEBOX is a MATLAB toolbox for speech processing.
    0016 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
    0017 %
    0018 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0019 %   This program is free software; you can redistribute it and/or modify
    0020 %   it under the terms of the GNU Lesser General Public License as published by
    0021 %   the Free Software Foundation; either version 3 of the License, or
    0022 %   (at your option) any later version.
    0023 %
    0024 %   This program is distributed in the hope that it will be useful,
    0025 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
    0026 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    0027 %   GNU Lesser General Public License for more details.
    0028 %
    0029 %   You can obtain a copy of the GNU Lesser General Public License from
    0030 %   https://www.gnu.org/licenses/ .
    0031 %
    0032 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0033
    0034 szp=[0.19892796195357i; -0.48623571568937+0.86535995266875i];
    0035 szp=[[0; -0.97247143137874] szp conj(szp)];
    0036 % s-plane zeros and poles of high pass 3'rd order chebychev2 filter with -3dB at w=1
    0037 zl=2./(1-szp*tan(300*pi/fs))-1;
    0038 al=real(poly(zl(2,:)));
    0039 bl=real(poly(zl(1,:)));
    0040 sw=[1;-1;1;-1];
    0041 bl=bl*(al*sw)/(bl*sw);
    0042 zh=2./(szp/tan(3400*pi/fs)-1)+1;
    0043 ah=real(poly(zh(2,:)));
    0044 bh=real(poly(zh(1,:)));
    0045 bh=bh*sum(ah)/sum(bh);
    0046 b=conv(bh,bl);
    0047 a=conv(ah,al);