Originally Posted by
terrymorse
Re: GPS is slower in measuring elevation so it varies more when moving
I am not familiar with this "slowness in measurement" error with GPS.
From Sunnto
GPS based altitude measurement reacts slower to changes in altitude than barometer based altitude measurement, but the readings are not disturbed by weather changes as may be the case with barometric altitude readings.
Re: Both have about the same amount of error in measurement.
That's not my understanding. GPS errors are typically considerably larger, because they exist and are roughly the same on every measurement. Barometric errors creep in as the pressure drifts over several hours, which is why it's a good idea to re-calibrate elevation periodically at a known position.
A Google search of accuracy of the two measurements give a raw error of 10m to 20 m for GPS (35 to 70 feet) while barometers are accurate to ±15 meters. The error is almost the same per measurement. GPS may suffer more from a refresh rate that a barometer doesn’t experience. GPS is averaged over several seconds while barometric pressure may be closer to instantaneous as it is an on-board instrument. If you are stationary, this may no make much difference but when mobile, that averaging can lead to larger errors. Most phones have both GPS and a barometer to increase accuracy.