Interference between VSAT signals and DP system?

Anyone on an OSV here ever faced issues where the DP system lost position / operated with reduced accuracy due to interference from VSATs or other sat-com equipment in the vicinity?

Had a problem with the LRIT, got an alarm on the GPS unit every time the LRIT sendt a status update.

Reduced accuracy of GPS signal due to physical blockage or “space weather”. What makes you think it might be the VSAT system?

Not an OSV but when the VSAT was installed I recall that the sectors that the antenna transmitted, both vertical and horizontal, could be controlled by software. This was so transmitting in certain directions could be controlled.

For example relative bearing 350 to 010 degrees no transmitted signal below 20 degrees horizontal.

It was the tech that did it not the crew but for trouble-shooting it might be useful to block the sectors where the GPS antennas are located.

We mounted the VSAT at a good distance from the other antennas but it was to keep the other signals from interfering with the VSAT. In particular the radar.

Thanks - I’m suggesting some positions for some new dual VSATs we’re installing onboard. VSAT providers don’t care much about DP system - they just place it whereever to ensure best coverage / line of sight for their antennae… its a fight sometimes - and I just wanted to make sure I wasn’t being irksome or irrational in asking for a dome location further away from the DP sensors…

Agree - not restricted to VSAT - it could be any equipment having a line of sight which comes in the way of the DP GPS sensor…

Thanks Kennebec_Captain - OSVs today have so much comm equipment crammed on the monkey island / top of the wheelhouse. Sometimes its a pain to find that spot. I am working with the VSAT providers to ensure we block off zones such that the DP GPS sensors / gyro wouldnt be in the beam path…

From the responses, seems like I am on the right path to keep our DP system safe and free from interferences - just need to make the SAT providers aware of the block zones…

I have experience on ships with two VSAT domes to cover “blind” headings. Unfortunately, I haven’t experienced loss of signal that could be associated with interference of that kind (or other interference). I could always get a better signal after changing position/heading.

common problem when your gps is mounted above your omni-directional sat antenna.
( or you are way up north and a directional one is looking at the horizon, change your heading)
This heavy aluminum based gps antennas help lots by masking signals from below

1 Like