AIS distance graphing

[Skylark]

On a boat? Never
........Started off with playing around with calcing distance between 2 lat/longs. The equation was cut and paste straight from the web, haversine is it?

No interest in the AIS references I’m afraid but this part has my attention.

Depending upon the distance between the two lat/longs, try getting to grips with the Transfer Tables within Norries. Based upon pretty basic trigonometry, also known as Plane Sailing. Can also do it from dLat and dLong using sin and cosine Tables. Gives distance and CTS.

 

[LadyInBed]

No interest in the AIS references I’m afraid but this part has my attention.

Depending upon the distance between the two lat/longs, try getting to grips with the Transfer Tables within Norries. Based upon pretty basic trigonometry, also known as Plane Sailing. Can also do it from dLat and dLong using sin and cosine Tables. Gives distance and CTS.

http://montymariner.co.uk/wp-content/uploads/2017/03/Flat-Earth.pdf

 

[greeny]

The question should be not so much about the distant vessels your AIS sees, but the closer ones it is blind to?
One could gather stats about the distance at which various species of vessel first appear and subsequently disappear.

Or you could go sailing.

I tried today. No bloody wind again. So came back in the anchorage and messed with ais antenna again instead.

 

[Baggywrinkle]

No interest in the AIS references I’m afraid but this part has my attention.

Depending upon the distance between the two lat/longs, try getting to grips with the Transfer Tables within Norries. Based upon pretty basic trigonometry, also known as Plane Sailing. Can also do it from dLat and dLong using sin and cosine Tables. Gives distance and CTS.

The formula used delivers a true distance over the surface of a sphere (it's the Haversine Function) ... works for all distances and will deliver the great-circle distance between 2 points.

 

[RobbieW]

Last year at SIBS a stand suggested using a small dumpy aerial fitted on the crosstrees if you didn't or couldn't use your main aerial. I'm not to sure whether the mast will affect transmissions in one direction though.

I'd suggest it would, though the further away you can mount the antenna the better. I used to have a receive antenna on a support off the wind generator tower on the pushpit, about 6" from a 2" dia stainless tube and about 3m off the water. Putting a splitter on the masthead VHF antenna made an enormous difference to the number of close targets found.

 

[[70521]]

Totally agree, it is data but of no value.

I know I posted a very quick reply when I first saw this, but has the OP factored in the height of the sending and receiving antenna?