ROV not getting GPS lock

vehicle not getting GPS lock while it connected through tether. but working fine if the Pixhawk is directly connected to QGC via USB cable. i am using u blox gps module any solution?

Hello, we don’t support the use of gps antennas because of their utility is marginal in our applications. It is difficult to get a gps lock on the surface of the water, and it will be lost immediately once the vehicle submerges.

The only gps system we support at the moment is the waterlinked underwater gps system in our store.