esg_arb.m

安捷仑的数字调制信号发生器E4438用于很多通信系统的开发过程中。本代码可以用于通过网络接口或GPIB接口向E4438下载被调制数据

%    function esg_arb(filename, waveform_data, scale)
%    where:
%                              waveform_data = complex input data
%                              scale = optional parameter which
%                                      scales the from .0001 to 1 
%                                      of the dac fullscale 
%
%    This function loads a Matlab vector, waveform_data, into the memory
%       of the Dual Arbitrary Waveform Generator of a 
%       Hewlett Packard ESG-D Signal Generator (with option
%       UND).  There are two parts which must be in the 
%       Matlab path:     esg_arb.m
%                        esg_darb.dll
%
%    This was developed in Matlab 5.0.
%
%    The function only works under Microsoft Windows NT or
%       Windows 95 or later.
%
%    It is necessary to have the signal generator connected to
%       the PC via GPIB.  The computer must have a GPIB 
%       interface card from either Hewlett Packard (82341 but
%       NOT 82335 )or National Instruments installed.  If the 
%       card is from HP, the associated SICL library must be 
%       installed.
%
%    This function takes a vector, waveform_data, which is made up of 
%       complex data.  The real part will be loaded into the
%       I part of the Dual Arbitrary Waveform Memory, and the 
%       imaginary part of waveform_data is loaded into the Q part of the
%       ARB memory.  Before downloading, the data in waveform_data is 
%       scaled to the appropriate range and then converted to
%       14 bit integers (for the 14 bit dacs).  
%
%    There is a special case if both the real and imaginary
%       parts of the data are constant and less than or equal
%       to one.  In this case, the values will scale to +1
%       being dac full scale, and -1 being dac 0.  This is
%       useful for entering dc values.
%
%    This program will automatically find the GPIB card, 
%       interface, and the ESG's address.
%
%    No checking is done for ARB memory available.
%    No checking is done to see if the requested filename
%       is being 'played' in the ESG-D.
%    No checking is done to see if the UND option is installed
%       in the ESG-D signal generator.
%
function esg_arb(esg_gpib_addr, filename, waveform_data, scale);

system_dependent(7)        % Causes messages to flush to screen immediately

[numrows, numcols] = size(waveform_data);
if (numrows > 1) 
   waveform_data = waveform_data.';                    % Make a row vector.
end
[numrows, numcols] = size(waveform_data);
if (numrows > 1)      
   disp(' ')
   error('Input data must be a single dimension vector.')
end
if (numcols < 16)
   disp(' ')
   error('Input data vector must have at least 16 points.')
end

if exist('scale') < .5                  % If scale wasn't passed in
   scale = 1;
end
scale = max(scale, .0001);                 % Limit the scale factor to
scale = min(scale, 1);                  %   .0001 to 1.0


if length(filename)==0         % Ensure filename is not blank
   filename = 'user';
end
if length(filename)>16         % Limit length of filename
   filename = filename(1:16);
end

disp(' ');
disp(['Converting Data to ESG Arbitrary Waveform format.']);
center = 8192;                 % Center of dac  ( 0 volts out)

mx = max([max(abs(real(waveform_data))) max(abs(imag(waveform_data)))]);

% Add a special case:  If the data in real and imaginary parts
%  are constant and less than or equal to 1, use the data to
%  give a dc voltage out based on full scale being 1 and 
%  0 scale being -1.

if (max(real(waveform_data)) == min(real(waveform_data)))      
   if (max(imag(waveform_data)) == min(imag(waveform_data)))
      if ((max(abs(real(waveform_data))) <= 1) & (max(abs(imag(waveform_data))) <= 1))
         mx = 1;
      end
   end
end
if mx~=0								 % Range is 8192-8192 to 8192+8191
   waveform_data = waveform_data/mx*(center-1);        % Scale to +/- 8191
end
waveform_data = waveform_data*scale;                   % Apply any user-entered scale
waveform_data = waveform_data + center + j*center;     % Add in the dac offset
waveform_data = round(waveform_data);                  % Round to integers

clear numrows numcols;
clear center;
clear mx;

% At the moment, don't know how to force this DLL to use a specific ESG
% (at esg_gpib_addr).  May figure this out later.

% esg_darb(esg_gpib_addr, waveform_data, filename);   ???

esg_darb(waveform_data, filename);

end