NavEKF3_core::setup_core: is beacon buffer length setted wrong?

[luweiagi]

Here we set beacon buffer length as imu_buffer_length+1:

ardupilot/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp

Line 140 in d0a7e70

if(dal.beacon() && !rngBcn.storedRange.init(imu_buffer_length+1)) {

But, at

ardupilot/libraries/AP_NavEKF3/AP_NavEKF3_core.cpp

Line 96 in d0a7e70

// limit to be no longer than the IMU buffer (we can't process data faster than the EKF prediction rate)

We said that obs_buffer_length should not longer than the IMU buffer because we can't process data faster than the EKF prediction rate even if obs sensor reading-data speed is faster than the IMU update speed.

So, why we set beacon buffer length as imu_buffer_length+1, which >imu_buffer_length?
Can it be changed as:

?

[rmackay9]

Hi @luweiagi,

Thanks for your ongoing bug search, it's very much appreciated.

I think we support multiple beacons that could theoretically each provide an update at a high rate, but I'm also pretty sure that we don't allow the total number of updates from all beacons to be more than 50hz (total, e.g. if 5 beacons then each can only update at 10hz maximum) so I agree that it is probably fine to reduce the size of the rngBcn.storedRange array to be smaller. On the other hand, do we really want to risk making it smaller just to save a few bytes of RAM?

[luweiagi]

@rmackay9
Thanks for reply!
No, it's not necessary. I only made a logical judgment.