# Longley Rice propagation model and reciprocity

조회 수: 3(최근 30일)
Joel Johnson 2021년 10월 9일
댓글: Joel Johnson 2021년 10월 14일
Code snippet below seems to show that MATLAB's Longley-Rice propagation model may not always be reciprocal - is this correct? Thanks!
close all; clear all;
% A test to show that the Matlab LR functions don't seem to be reciprocal
pm = propagationModel('longley-rice','AntennaPolarization','vertical');
freq = 469e6; % Tx freq (MHz)
S1 = [39.420200,-82.875300]; % Lat/Lon of Site 1
S2 = [39.413000,-82.896111]; % Lat/Lon of Site 2
s1ht = 1:50; % Antenna height @ site 1
s2ht = 2.08; % Antenna height @ site 2
% Link from S1 to S2
tx = txsite('Latitude',S1(1),'Longitude',S1(2),'AntennaHeight',s1ht,'TransmitterFrequency',freq);
rx = rxsite('Latitude',S2(1),'Longitude',S2(2),'AntennaHeight',s2ht);
PL1 = pathloss(pm,rx,tx);
tx = txsite('Latitude',S2(1),'Longitude',S2(2),'AntennaHeight',s2ht,'TransmitterFrequency',freq);
rx = rxsite('Latitude',S1(1),'Longitude',S1(2),'AntennaHeight',s1ht);
PL2 = pathloss(pm,rx,tx);
plot(PL1,s1ht,'linewidth',2); set(gca,'Xdir','Reverse'); set(gca,'Fontsize',20); xlabel('Path loss (dB)'); ylabel('Tx Antenna height (m)')
hold on
grid on
plot(PL2,s1ht,'x','linewidth',2);
legend('S1 to S2','S2 to S1')
##### 댓글 수: 1표시숨기기 없음
Joel Johnson 2021년 10월 9일
I subsequently noticed that there is no difference in the two in R2021b so probably this got fixed somewhere between R2018 and R2021.

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### 채택된 답변

Tanmay Das 2021년 10월 14일
Hi,
As pointed out by Joel, the bug has been fixed in the future releases. So it is recommended to update the MATLAB version in order to leverage its full functionality.
##### 댓글 수: 1표시숨기기 없음
Joel Johnson 2021년 10월 14일
Thanks!

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R2018b

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