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256 Agilent N518xA, E8663B, E44x8C, and E82x7D Signal Generators Programming Guide
Creating and Downloading Waveform Files
Programming Examples
phaseInc = 2*pi*cycles/points;
phase = phaseInc * [0:points-1];
Iwave = cos(phase);
Qwave = sin(phase);
% 2.) Save waveform in internal format *********************************
% Convert the I and Q data into the internal arb format
% The internal arb format is a single waveform containing interleaved IQ
% data. The I/Q data is signed short integers (16 bits).
% The data has values scaled between +-32767 where
% DAC Value Description
% 32767 Maximum positive value of the DAC
% 0 Zero out of the DAC
% -32767 Maximum negative value of the DAC
% The internal arb expects the data bytes to be in Big Endian format.
% This is opposite of how short integers are saved on a PC (Little Endian).
% For this reason the data bytes are swapped before being saved.
% Interleave the IQ data
waveform(1:2:2*points) = Iwave;
waveform(2:2:2*points) = Qwave;
%[Iwave;Qwave];
%waveform = waveform(:)’;
% Normalize the data between +-1
waveform = waveform / max(abs(waveform)); % Watch out for divide by zero.
% Scale to use full range of the DAC
waveform = round(waveform * 32767); % Data is now effectively signed short integer values
% waveform = round(waveform * (32767 / max(abs(waveform)))); % More efficient than previous two
steps!
% PRESERVE THE BIT PATTERN but convert the waveform to
% unsigned short integers so the bytes can be swapped.
% Note: Can’t swap the bytes of signed short integers in MatLab.
waveform = uint16(mod(65536 + waveform,65536)); %
% If on a PC swap the bytes to Big Endian
if strcmp( computer, ‘PCWIN’ )
waveform = bitor(bitshift(waveform,-8),bitshift(waveform,8));