Satellites at a low elevation angle have an increased risk of both multipath, and ionospheric delay / distortion. The default elevation mask for u-blox SPG products is 5°, including M8 / M9 / M10 chipsets.
Specifying an elevation mask of 10° to 15° is relatively common in marine environments. Eliminating these low elevation signals before the internal selection engine even evaluates them leaves it to focus on the more reliable signals.
CFG-NAVSPG-INFIL_MINELEV - default is 5°Specifying 10° or 15° is likely to be beneficial when speed sailing, especially in environments with cliffs, buildings, or ships.
References:
The online GNSS View can be used to see the effects of different mask angles.
Suggest the ESP GPS adds support for an elevation mask (i.e. minimum elevation), so that it can be be set to 10°.
My expectation is that it will give the M10 a helping hand, quickly discarding the lowest quality signals.