write_sequence_to_esg.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

%Parameters:
%   esg_gpib_addr - configured gpib address of the ESG. May not be
%                   applicable to all setups.
%   filename      - name of the file when stored on the ESG
%   input_bits    - array of bits of the waveform to be stored.
%   slot_setup    - configuration of the data with respect to the 2 slots:
%                   0 = NULL data in Slot 1 and Slot 2
%                   1 = Input Data in Slot 1 and NULL data in Slot 2
%                   2 = NULL Data in Slot 1 and Input Data in Slot 2
%                   3 = Input Data in Slot 1 and Slot 2

function write_waveform_to_esg(esg_gpib_addr, filename, input_bits, slot_setup);


% New filter to save trouble
%clear all;
%clc;


N = 121;		% Length of filter in samples
Fs = 48000;	% Sampling rate
%Fs = 384000;	% Sampling rate
Fb = 4800;	% Symbol rate
I = Fs/Fb;  % upsampling factor
modulation_h = 0.25;

% This is the time vector for the filter samples, such that plot(t,h) plots the filter coefficients
% against time.  The offset by 0.5/Fs is to ensure an even length filter.
t = -(N/2)/Fs+0.5/Fs:1/Fs:(N/2)/Fs-0.5/Fs;
M = length(t);
t = t((M-N)/2+1:end-(M-N)/2);

alpha = 0.2 + 1E-8;	        % Filter excess bandwidth
h = rrc(t, alpha, 1/Fb);	% Generate filter
h = h/(10^(20.04/20));

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% START HERE %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


NULL24 = zeros(1,24);   %NULL array to balance input waveform
NULLslot = zeros(1,size(input_bits,2)); %NULL array to replace the input_bits for a given slot

%Based upon the slot_setup input, configure the final waveform for Slots 1 and 2.
switch slot_setup
    case 0,
        input_bits = [NULL24 NULLslot NULL24 NULLslot];
    case 1,
        input_bits = [NULL24 input_bits NULL24 NULLslot];
    case 2,
        input_bits = [NULL24 NULLslot NULL24 input_bits];
    case 3,
        input_bits = [NULL24 input_bits NULL24 input_bits];
    otherwise,
        input_bits = [NULL24 input_bits NULL24 input_bits];
end        


%#######################################
%   MAKE THE ULTIMATE SEQUENCE
%#######################################

input_symbols = bit2ESGsymbolmapping(input_bits)';
input_symbols = input_symbols*50/3;
input_sym1 = repmat(input_symbols,5,1);  % replicate frame 5 times 

baseband_samples1 = conv(h, I*upsample(input_sym1, I));

baseband_samples1 = baseband_samples1(61:end-60);    % remove the filter delays to get a clean-cut signal

% slice off the center of the filtered waveform to get a proper wraparound signal
% take the 4th block
fourth_block = baseband_samples1(3*size(input_symbols,1)*I+1:3*size(input_symbols,1)*I+size(input_symbols,1)*I);

third_block = baseband_samples1(2*size(input_symbols,1)*I+1:2*size(input_symbols,1)*I+size(input_symbols,1)*I);

diff1 = fourth_block - third_block;

%-------------------------------------------------------
% if the difference between 3rd and 4th block is zero
% that means the block is perfectly fine to be 
% wrapped around.
%------------------------------------------------------

wrap_sig = fourth_block;    % grab either the 3rd or the 4th block.

carrier_phase    = pi * modulation_h/I * cumsum(wrap_sig);

THE_SIGNAL       = exp(j * (carrier_phase));

scale = 1;

%-------------------------------------------------------
% Write waveform to ESG
%-------------------------------------------------------

% setup parameters
sample_rate = Fs;
play_flag = 'no_play'; % turn OFF Arb
scale = 'normscale'; % default -- 70%
markers = zeros(2,length(THE_SIGNAL));  % clear all markers

% setup connection to ESG
connection = agt_newconnection('GPIB', 0, esg_gpib_addr);

% write waveform to ESG
%esg_arb(esg_gpib_addr, filename, THE_SIGNAL, scale);
[esg_status, esg_status_descr] = agt_waveformload(connection, THE_SIGNAL, filename, sample_rate, play_flag, scale, markers)

% close sessions
agt_closeAllSessions();

end