Acoustic comms : Propagation model

[adityapande-1995]

🎉 New feature

Summary

This PR adds a propagation model for acoustic comms, using RFComms implementation as a guide. The difference is in the way signal loss is calculated and modulation is implemented.

Here, we use the sonar equation to calculate signal to noise ratio (SNR). SNR is used to calculate Eb/N0, which gives us the bit error rate using BPSK modulation. FInally we calculate the packet drop probability.

This feaure is turned off by default and oly works if the SDF tags are used when declaring the plugin.

A short comparison of propagation model approaches :

• Acoustic comms propagation model (This PR) :
  SNR using sonar equation -> Eb/N0 -> bit error rate (BPSK) -> packetDropProbability
• RFComms propagation model (Taken as a reference) :
  Log path loss equation -> bit error rate (QPSK) -> packetDropProbability

Test it

Added a test with a world file acoustic_comms_propagation.sdf. It is impossible to get the packets to drop with the default values and the LRAUvs being that close to each other (< 5 m). Moving them apart would make the tests run a lot slower.

I've exaggerated the noise and source power to make the packets drop.

Note

This is still an experimental feature, and I'm no expert in communications. If there is a better model for propagation, I'd be happy to improve this.

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸🔸

[adityapande-1995]

Open to suggestions on how cloning can be avoided here. GetElement cannot be applied to const Element members it seems, and _sdf->GetElement("foo") throws an error that " this argument discards qualifiers."

[arjo129]

Typically, I use GetFirstElement and then iterate. It's not ideal and very counter intuitive that a Get* method is non-const. You don't have to do this. I don't see this clone as very expensive.

[codecov]

Codecov Report

Merging #1793 (5d8e097) into gz-sim7 (8ba08a8) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           gz-sim7    #1793      +/-   ##
===========================================
+ Coverage    64.24%   64.27%   +0.03%     
===========================================
  Files          336      336              
  Lines        26900    26924      +24     
===========================================
+ Hits         17282    17306      +24     
  Misses        9618     9618              

Impacted Files	Coverage Δ
src/systems/acoustic_comms/AcousticComms.cc	96.22% <100.00%> (+1.10%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

[arjo129]

Just did a quick pass. Couple of small knits.

[arjo129]

Typically, I use GetFirstElement and then iterate. It's not ideal and very counter intuitive that a Get* method is non-const. You don't have to do this. I don't see this clone as very expensive.

[arjo129]

One more tiny issue. After that it looks like its good to go.

[arjo129]

Lgtm. Test failures unrelated.