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function [pseudoranges] = calculatePseudoranges(trackResults, ...
msOfTheSignal, ...
channelList, settings)
%calculatePseudoranges finds relative pseudoranges for all satellites
%listed in CHANNELLIST at the specified millisecond of the processed
%signal. The pseudoranges contain unknown receiver clock offset. It can be
%found by the least squares position search procedure.
%[pseudoranges] = calculatePseudoranges(trackResults, msOfTheSignal, ...
% channelList, settings)
% Inputs:
% trackResults - output from the tracking function
% msOfTheSignal - pseudorange measurement point (millisecond) in
% the trackResults structure
% channelList - list of channels to be processed
% settings - receiver settings
% Outputs:
% pseudoranges - relative pseudoranges to the satellites.
% SoftGNSS v3.0
% Copyright (C) Darius Plausinaitis
% Written by Darius Plausinaitis
% Based on Peter Rinder and Nicolaj Bertelsen
%This program is free software; you can redistribute it and/or
%modify it under the terms of the GNU General Public License
%as published by the Free Software Foundation; either version 2
%of the License, or (at your option) any later version.
%This program is distributed in the hope that it will be useful,
%but WITHOUT ANY WARRANTY; without even the implied warranty of
%GNU General Public License for more details.
%You should have received a copy of the GNU General Public License
%along with this program; if not, write to the Free Software
%Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
% CVS record:
% $Id: calculatePseudoranges.m,v 2006/08/09 17:20:11 dpl Exp $
%--- Set initial travel time to infinity ----------------------------------
% Later in the code a shortest pseudorange will be selected. Therefore
% pseudoranges from non-tracking channels must be the longest - e.g.
% infinite.
travelTime = inf(1, settings.numberOfChannels);
% Find number of samples per spreading code
samplesPerCode = round(settings.samplingFreq / ...
(settings.codeFreqBasis / settings.codeLength));
%--- For all channels in the list ...
for channelNr = channelList
%--- Compute the travel times -----------------------------------------
travelTime(channelNr) = ...
trackResults(channelNr).absoluteSample(msOfTheSignal(channelNr)) / samplesPerCode;
%--- Truncate the travelTime and compute pseudoranges ---------------------
minimum = floor(min(travelTime));
travelTime = travelTime - minimum + settings.startOffset;
%--- Convert travel time to a distance ------------------------------------
% The speed of light must be converted from meters per second to meters
% per millisecond.
pseudoranges = travelTime * (settings.c / 1000);