PtP Link Between Oil Rig and FSO Tanker

Greetings All,
I have a PtP link between Oil Rig (fixed) and FSO tanker (float and anchorage ship) made by 2 C5c radio, 20.5dBi assymetrical horn antenna(at oil rig side) and 10dBi omni antenna(on top of FSO pole). The distance of this link is 2.5km. the height of the antenna is 45mtr(oil rig) and 41mtr(FSO)-fluctuate. For certain time the signal for this link become unstable and lost. Does anyone have an advice for this problem?

Thank you

Is the outage time regular? Any correspondence with weather or time of day?

I am guessing that by “mtr” you mean “meter”, so I wouldn’t guess that the radios have issues with something getting in their way, not a lot of ships that big that would be regularly passing through… Or not, I am not certain.

With land based equipment we have difficulties shooting over water or wet terrain because of thermal inversion. Basically mirages that distort the path of your signal and make it so that the alignment gets goofy.

Why are you using an omni antenna for the FSO Tanker? Does it move around a lot? If so, how do you keep the alignment on the Oil Rig side of things?

Hi William,
Thanks for your reply.
the outage time is regular and happen in short time. And its correspondence with weather as well, especially on bad weather.
You’re correct, I means mtr is meter. Actually no ship is passing through that tanker.
I’m using omni antenna due to the tanker will move around its anchorage, about 50-70meter radius. So that I’m allign the antenna at oil rig to be in middle of that radius. At oil rig side the radio was set as AP and at fso tanker as station.
Furthermore, using 5800MHz frequency will keep it better signal rather than other range of frequency.
Is that the height of antenna at oil rig not enough sufficient to cover fso tanker movement?
Beside this, what would you recommend for PtP link between fix oil rig and fso tanker?

Well, if it is bad weather that makes sense.

Best bet would be to increase your dB on each end without getting too narrow of a beam. The Assymetrical horn is probably a good idea, I’m going to guess you are using an RF Elements HG3-TP-A20-30. I personally would do the math and see how many degrees of change you should be seeing and maybe look at an RF Elements Ultrahorn which has a 10 degree wide antenna pattern.

Personally, I would do the math and see if an Ultrahorn on each end would work, if so swap out the Omni for an Ultrahorn and see if that improves things. Then if it does and you still want a better signal go to an Ultrahorn on the Oil Rig as well. If the beam width of the Ultra Horn wouldn’t be big enough or you can’t go with that big of an antenna then I would go with an RF Elements HG3-TP-A20-30 or maybe swap to a C5x running a 16 or 20dB antenna which will increase your gain and still give you a pretty wide antenna pattern.

Hi William,
Thank you for your advise.
You’re right, I use HG3-TP-A20-30 Assymetrical horn antenna for oil rig side.
Replace ultra horn with Omni will affect the signal once the ship turn 180degree, i guess.
So, from your idea, improve gain at both side could be a way to have better signal, right.
How about the antenna height? Does it affected the signal especially on high tide, the different height between oil rig and fso is about 4mtr (at normal condition).

Ugh, not only do you have movement in an area, but the ship spins…

4 meters probably isn’t enough to really effect the signal, at least I wouldn’t suspect it too much. Probably would be prudent to do the math, but I’d guess you would have +40 ft of vertical pattern at that distance. That said, you might want to actually do the math and double check. I would also try looking at the angle you have set for the HG3-TP-A20 if it’s set too low then it could be that the ship gets lifted above the signal and would be pretty bad.