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Old 19-11-2015, 04:01   #16
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Re: KA4WJA - Iridium question...

Originally Posted by ka4wja View Post
And, I'm wondering if this is where his recommendation comes into play??? As this instance / use at very high latitudes, is where handoffs can become more critical...
Could be. He was semi-specialized in comms for boats going to the Antarctic.

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Old 19-11-2015, 10:53   #17
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Re: KA4WJA - Iridium question...

Originally Posted by estarzinger View Post
I primarily heard this from johnathan selby - the guy who wrote weatherfax2000 and skyeye. As I said, I have no idea of its validity, but Johnathan is a damn bright and practical guy.
I can tell you why this is. John correctly points out that the satellites shut down beams near the poles, because you have total saturation with a smaller number of beams, and too many causes handover chaos or interference.

OTOH, at the equator the satellites are at their maximum spread. In theory - in ideal conditions and if the satellites are all correctly placed - you should have continuous coverage. In reality, inside the tropics there is a potential for occasional coverage holes to open up. Those can be caused by weather interference, and also slight drift in the orbits of the satellites creating gaps. The usual failure is a handover failure when going from satellite to satellite. I would guess that the best guaranteed way to make a call would be to know when you get to the leading spot beam of a satellite and try to complete the entire call in the 10 minutes or so the satellite is overhead (handing you off from spot beam to spot beam). That's what the prediction software will give you. As an aside, my friends using the Go for GRIBs in this years Transpac had little/no trouble with connection drops.

That said, most of the connection software does a great job at picking up where it left off. XGate is a great example. I think that's what PredictWind uses. Their latest app is wonderfully simple to use and set up and IMO is a perfect solution for a non-technical sailor wanting GRIBs.

Evans, I think your point about the cable and connectors is also spot on. Back to the OP, he'd get much more gain ensuring good quality and corrosion free connectors and cable to an omni external antenna than I think he would ever gain from a beam antenna.

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