>hi gon,
>
>i have this script written by matt wilbur (dowloaded) that returns the I
>and Q channels of MSK/GMSK modulated waveforms. hope it helps.
>
>-fahim
>
>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>function [msk_phase,gmsk_phase,xi,xq,t] =gmsk(bits,Rb,ns,BT)
>
>% Title: bbgmsk.m
>% Author: Matt Wilbur
>% Date: October 19, 1998.
>%
>% Description: This function takes a NRZ sequences of bits
>% (one sample per bit) and returns the phase
>% of an MSK and GMSK signal modulated by them.
>%
>% It also returns the baseband in-phase
>% and quadrature components of the GMSK
>% signal ready for upconverting.
>%
>% This function accepts as arguments:
>%
>% bits - NRZ bit stream (one sample/bit)
>% Rb - baseband bit rate
>% ns - number of samples per bit
>% BT - normalized bandwidth of Gaussian filter
>%
>% Modified:
>
>% Set up some timing variables
>
> Tb = 1/Rb;
> fs = ns*Rb;
> Ts = 1/fs;
>
>% Extend the number of bits by one to make the convolution below
>% work out nicely
>
> numbits = max(size(bits));
> bits(numbits+1) = bits(numbits);
>
>% Generate the msk phase first
>
> bup = upfirdn(bits,ones(ns,1),ns,1);
> bscale = bup * pi/2/ns;
> bscale(1) = 0;
> msk = cumsum(bscale);
>
>% Get the Gaussian impulse response
>
> % 3-dB BW of filter
>
> Bb = BT / Tb;
>
> % Time scale for filter --- 6 Bit periods to be safe
>
> t = -3*Tb:Ts:3*Tb;
>
> % Analog impulse from formulae
>
> h_a = sqrt(2*pi/log(2))*Bb*exp(-2*pi^2*Bb^2*t.^2/log(2));
>
> % Digital impulse from impulse-response matching
>
> h_d = Ts*h_a;
>
>% Get the GMSK phase --- a few delay tricks so beware of shifting
>% indices
>
> [temp,delay] = max(h_d);
>
> y = conv(h_d, msk);
> upper_index = ns*numbits-1;
> gmsk_phase = rem(y(delay:upper_index + delay), 2*pi);
> msk_phase = msk(1:upper_index+1);
>
> t = 0:ns*numbits-1;
> t = t/fs;
> xi = cos(gmsk_phase);
> xq = sin(gmsk_phase);
>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>>Hello,
>>
>>I am studying MSK modulation, does anyone know how to genrate a MSK
>signal
>>in matlab, pls help me..Thanks.
>>
>>Gon.
>>
>>
>>
>
>
>
thnks all
Reply by Steve Underwood●December 6, 20062006-12-06
Heid the baw - goal!! wrote:
> "Jerry Avins" <jya@ieee.org> wrote in message
> news:AemdnVBMaPwpd-nYnZ2dnUVZ_oidnZ2d@rcn.net...
>> Heid the baw - goal!! wrote:
>>
>> ...
>>
>>> Not very helpful...
>> Was it you in another guise who asked for help? If not, how do you know?
>>
>> Jerry
>> --
>> Engineering is the art of making what you want from things you can get.
>> �����������������������������������������������������������������������
>
> Wasn't me,but saying' Try Googling...whatever' - we might as well all go
> home. You can imaging even the smallest gnat knows that one.
If that's the case, why did he ask something so basic? He should have
got the basics from a range of places Google will offer him, and be
asking deeper questions.
Steve
Reply by Jerry Avins●December 5, 20062006-12-05
Heid the baw - goal!! wrote:
> "Jerry Avins" <jya@ieee.org> wrote in message
> news:AemdnVBMaPwpd-nYnZ2dnUVZ_oidnZ2d@rcn.net...
>> Heid the baw - goal!! wrote:
>>
>> ...
>>
>>> Not very helpful...
>> Was it you in another guise who asked for help? If not, how do you know?
> Wasn't me,but saying' Try Googling...whatever' - we might as well all go
> home. You can imaging even the smallest gnat knows that one.
http://users.erols.com/jyavins/google.gif
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Heid the baw - goal!!●December 5, 20062006-12-05
"Jerry Avins" <jya@ieee.org> wrote in message
news:AemdnVBMaPwpd-nYnZ2dnUVZ_oidnZ2d@rcn.net...
> Heid the baw - goal!! wrote:
>
> ...
>
> > Not very helpful...
>
> Was it you in another guise who asked for help? If not, how do you know?
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> �����������������������������������������������������������������������
Wasn't me,but saying' Try Googling...whatever' - we might as well all go
home. You can imaging even the smallest gnat knows that one.
Tam
--
Posted via a free Usenet account from http://www.teranews.com
Reply by fahim●December 5, 20062006-12-05
hi gon,
i have this script written by matt wilbur (dowloaded) that returns the I
and Q channels of MSK/GMSK modulated waveforms. hope it helps.
-fahim
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function [msk_phase,gmsk_phase,xi,xq,t] =gmsk(bits,Rb,ns,BT)
% Title: bbgmsk.m
% Author: Matt Wilbur
% Date: October 19, 1998.
%
% Description: This function takes a NRZ sequences of bits
% (one sample per bit) and returns the phase
% of an MSK and GMSK signal modulated by them.
%
% It also returns the baseband in-phase
% and quadrature components of the GMSK
% signal ready for upconverting.
%
% This function accepts as arguments:
%
% bits - NRZ bit stream (one sample/bit)
% Rb - baseband bit rate
% ns - number of samples per bit
% BT - normalized bandwidth of Gaussian filter
%
% Modified:
% Set up some timing variables
Tb = 1/Rb;
fs = ns*Rb;
Ts = 1/fs;
% Extend the number of bits by one to make the convolution below
% work out nicely
numbits = max(size(bits));
bits(numbits+1) = bits(numbits);
% Generate the msk phase first
bup = upfirdn(bits,ones(ns,1),ns,1);
bscale = bup * pi/2/ns;
bscale(1) = 0;
msk = cumsum(bscale);
% Get the Gaussian impulse response
% 3-dB BW of filter
Bb = BT / Tb;
% Time scale for filter --- 6 Bit periods to be safe
t = -3*Tb:Ts:3*Tb;
% Analog impulse from formulae
h_a = sqrt(2*pi/log(2))*Bb*exp(-2*pi^2*Bb^2*t.^2/log(2));
% Digital impulse from impulse-response matching
h_d = Ts*h_a;
% Get the GMSK phase --- a few delay tricks so beware of shifting
% indices
[temp,delay] = max(h_d);
y = conv(h_d, msk);
upper_index = ns*numbits-1;
gmsk_phase = rem(y(delay:upper_index + delay), 2*pi);
msk_phase = msk(1:upper_index+1);
t = 0:ns*numbits-1;
t = t/fs;
xi = cos(gmsk_phase);
xq = sin(gmsk_phase);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
>Hello,
>
>I am studying MSK modulation, does anyone know how to genrate a MSK
signal
>in matlab, pls help me..Thanks.
>
>Gon.
>
>
>
Reply by Sastry●December 5, 20062006-12-05
MATLAB communications blockset has MSK built in function that you can
use.
I totally agree with Jerry's response. No other better way to learn.
:-)
And hey, these days, Wikipedia is real rocking as far as communications
and Random Process concepts are concerned. :-) My take.
Tim Wescott wrote:
> Jerry Avins wrote:
>
> > ofdm wrote:
> >
> >> Hello,
> >> I am studying MSK modulation, does anyone know how to genrate a MSK
> >> signal
> >> in matlab, pls help me..Thanks.
> >
> >
> > Google "minimum-shift keying". Obce you know what it is, you'll probably
> > know haw to generate it. If not, you'll learn Matlab trying.
> >
> > Jerry
>
> It was Googling (well, AltaVista-ing) "minimum-shift keying" that led to
> me posting my Master's thesis on the web.
>
> Here it is again: http://www.wescottdesign.com/articles/MSK/mskTop.html.
>
> --
>
> Tim Wescott
> Wescott Design Services
> http://www.wescottdesign.com
>
> Posting from Google? See http://cfaj.freeshell.org/google/
>
> "Applied Control Theory for Embedded Systems" came out in April.
> See details at http://www.wescottdesign.com/actfes/actfes.html
Reply by Tim Wescott●December 5, 20062006-12-05
Jerry Avins wrote:
> ofdm wrote:
>
>> Hello,
>> I am studying MSK modulation, does anyone know how to genrate a MSK
>> signal
>> in matlab, pls help me..Thanks.
>
>
> Google "minimum-shift keying". Obce you know what it is, you'll probably
> know haw to generate it. If not, you'll learn Matlab trying.
>
> Jerry
Was it you in another guise who asked for help? If not, how do you know?
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Heid the baw - goal!!●December 4, 20062006-12-04
"Jerry Avins" <jya@ieee.org> wrote in message
news:weSdnXvfSdpQ9unYnZ2dnUVZ_s6dnZ2d@rcn.net...
> ofdm wrote:
> > Hello,
> >
> > I am studying MSK modulation, does anyone know how to genrate a MSK
signal
> > in matlab, pls help me..Thanks.
>
> Google "minimum-shift keying". Obce you know what it is, you'll probably
> know haw to generate it. If not, you'll learn Matlab trying.
>
> Jerry
> --
> Engineering is the art of making what you want from things you can get.
> ����
]
Not very helpful...
�������������������������������������������������������������������
--
Posted via a free Usenet account from http://www.teranews.com
Reply by Jerry Avins●December 4, 20062006-12-04
ofdm wrote:
> Hello,
>
> I am studying MSK modulation, does anyone know how to genrate a MSK signal
> in matlab, pls help me..Thanks.
Google "minimum-shift keying". Obce you know what it is, you'll probably
know haw to generate it. If not, you'll learn Matlab trying.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������