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Is longley-rice the reason it is taking ages to generate a coverage map?

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Greetings,
I am working to generate a coverage map for a LoRaWan gateway installed on a water tower. As such, I have created what I believe to accurate params for two devices acting on the 915mHz fequency for this simulation.
g1 = txsite('Name', 'GW1',...
'Antenna', monopole,...
'AntennaAngle', 0,...
'AntennaHeight', (48),...
'TransmitterFrequency', 9.28e+09,...
'TransmitterPower', 2,...
'Latitude', 37.71705,...
'Longitude', -97.29048)
n1 = rxsite('Antenna', monopole,...
'AntennaAngle', 0,...
'AntennaHeight', (1.8288),...
'ReceiverSensitivity', -27,...
'SystemLoss', 0,...
'Name', 'Node1',...
'Latitude', 37.72107,...
'Longitude', -97.26081)
I defined a propagation model using longley-rice. And the only reason I can think such a thing is beneficial; according to my limited knowlege of this fantastic software. It should be able to account for terrain data to build a coverage map for the region which has fairly flat terrain (Wichita, KS).
pm = propagationModel('longley-rice','AntennaPolarization','vertical')
I get a warning on the right letting me know this will generate 78K+ triangles. When I run this section it takes ages. As a matter of fact it has been running for the last 45 minutes, still no results. I can hear the fans spooling up and slowing down. But nothing. The remainder of my code is as follows:
ss = sigstrength(n1,g1)
margin = abs(n1.ReceiverSensitivity - ss)
link(n1,g1)
coverage(g1, pm)
sinr(n1)

Accepted Answer

Jacob Halbrooks
Jacob Halbrooks on 3 Sep 2019
The trouble with the code is a mismatch between the antenna dimensions and the transmitter frequency. The default design frequency for a monopole antenna is 75 MHz, and the software falls over when attempting to solve the antenna radiation pattern for a much higher frequency like 9.28 GHz. When I run the code as-is, I eventually get an "out of memory" error.
You can solve the issue by using the "design" function to set the dimensions of your antennas. For example, design both the tx and rx antennas for the transmitter frequency like this:
>> g1.Antenna = design(g1.Antenna,g1.TransmitterFrequency);
>> n1.Antenna = design(n1.Antenna,g1.TransmitterFrequency);
Now it should be a matter of seconds to generate a coverage map:
>> coverage(g1, pm)
  5 Comments
Clayton Allen
Clayton Allen on 6 Sep 2019
The specs on the transmitter is actually stated to be 27db. So how can I make a command to automatically calculate this?
Cheers and thanks for the assistance. You have been amazing!

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