FYI: Air Flow over module

Q&A forumFYI: Air Flow over module
clive1 asked 5 days ago

As I’ve had a couple of people run into this in recent weeks, I’d like to remind people that it is important to cover or shield the module from airflow. This being a specific concern in air vehicles, but will also impact ground stations and other implementations.
The metal cover is not air tight, there are large gaps by the TCXO clock source, and air incident on this will cause instantaneous frequency changes which the correlators in the receiver will see as massive acceleration/deceleration events, certainly beyond the tracking capability. This often manifests in loss of lock on all signals across all constellations, and drop from FIXED to 3D mode. The TCXO can deal with gradual environmental change, but the control loops inside will not respond quickly enough compared to the integration time of the receiver.
Some sponge insulation beyond the outline of the module would help. You might also be able to achieve this with thick conformal coating, or potting epoxy, but these will invalidate warranty from uBlox. In other situations consider placing the devices in an instrument box or case.
-Clive
sourcer32@gmail.com