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function [gpsEph,iSv] = ClosestGpsEph(allGpsEph,svIds,fctSeconds) |
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%[gpsEph,iSv] = ClosestGpsEph(allGpsEph,svIds,fctSeconds); |
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%find ephemeris in a GPS ephemeris structure allGpsEph for all svIds listed |
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%return gpsEph = unique ephemeris for svIds, with fctToe closest to fctSeconds, |
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% and |fctToe - fctSeconds| < fitInterval |
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% |
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%output: gpsEph, iSv |
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% gpsEph = valid ephemeris corresponding to svIds(iSv) |
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%Author: Frank van Diggelen |
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%Open Source code for processing Android GNSS Measurements |
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gpsEph = allGpsEph(1);%initialize gpsEph |
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numEph = 0; |
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%find all ephemeris corresponding to svIds(i) |
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for i=1:length(svIds) |
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iThisSv = [allGpsEph.PRN] == svIds(i); |
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if any(iThisSv) |
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ephThisSv = allGpsEph(iThisSv); |
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%find Toe within fit interval |
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%set fit interval |
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fitIntervalHours = [ephThisSv.Fit_interval]; |
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%Rinex says "Zero if not known", so adjust for zeros |
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fitIntervalHours(fitIntervalHours == 0) = 4; |
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%full cycle time of ephemeris Toe |
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fctToe = [ephThisSv.GPS_Week]*GpsConstants.WEEKSEC + [ephThisSv.Toe]; |
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%find freshest Toe |
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[ageSeconds, iMin] = min(abs(fctToe - fctSeconds)); |
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if ageSeconds < (fitIntervalHours/2)*3600; |
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numEph = numEph+1; |
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gpsEph(numEph) = ephThisSv(iMin); |
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iSv(numEph) = i;%save index into svIds |
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else |
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fprintf('No valid ephemeris found for svId %d,', svIds(i)) |
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ageHours = (fctToe(iMin)-fctSeconds)/3600; |
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fprintf(' closest Toe is %.1f hours away.\n',ageHours) |
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end |
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end |
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end |
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if numEph==0 |
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gpsEph=[];iSv=[];%return empty matrices |
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end |
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end %of function ClosestGpsEph |
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |
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% Copyright 2016 Google Inc. |
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% |
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% Licensed under the Apache License, Version 2.0 (the "License"); |
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% you may not use this file except in compliance with the License. |
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% You may obtain a copy of the License at |
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% |
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% http://www.apache.org/licenses/LICENSE-2.0 |
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% |
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% Unless required by applicable law or agreed to in writing, software |
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% distributed under the License is distributed on an "AS IS" BASIS, |
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% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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% See the License for the specific language governing permissions and |
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% limitations under the License. |
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