Total Height Above Ellipsoid displayed incorrectly in Menu Base

[wjc10240]

I believe I’ve found a bug in version 2.2 of the Facet mosaic firmware. I’m using the serial interface to set the receiver’s Base configuration. See the attached screen shot. It looks to me as if the sum of Antenna Height and Antenna Phase Center, both in millimeters, is being divided an extra time by 1,000 before being added to the ellipsoidal height from line 3.

I believe the correct value for Total Height Above Ellipsoid (HAE APC) should be 71196.500 mm.

[wjc10240]

The bug is in menuBase.ino, in the menuBase() function, at line 32. The sum of settings.antennaHeight_mm and settings.antennaPhaseCenter_mm is being divided by 1000 before being added to the product of settings.fixedAltitude and 1000, thus a quantity scaled to meters is being added to a quantity scaled to millimeters.

It looks like the calculation of totalFixedAltitude in GNSS_Mosaic.ino in GNSS_MOSAIC::fixedBaseStart() is being done correctly, with the result in meters.

I recommend that the calculation in menuBase.ino be changed to that in GNSS_Mosaic.ino and thus print the HAE of the APC in meters, which is a more usual unit for expressing HAEs. The HAE of the APC should be printed with a resolution of 0.0001 meter (0.1 mm). Also, the hyphen in the printed description should be changed; it's confusing, looking like a subtraction is being described. The code at lines 30, 31, and 32 should be replaced with:

        systemPrintf("Total Height Above Ellipsoid of Antenna Phase Center (HAE APC): %0.4fm\r\n",
                     settings.fixedAltitude +
                     (settings.antennaHeight_mm + settings.antennaPhaseCenter_mm) / 1000.0);

[PaulZC]

Hi Bill (@wjc10240 ),

Many thanks for reporting!

It looks like the error crept in in this commit: 6fa9a46

We were doing some tidying up, adding the units to some of the variable names, and it looks like we managed to confuse ourselves in that calculation.

Looking at the code, I'm confident this is limited to that one line. settings.fixedAltitude seems to be used correctly everywhere else.

We'll get this fixed in the next release.

Thanks again!
Paul

[PaulZC]

This is in pcUpdates - commit eca8175