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Old 31-08-2008, 10:08   #1
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NASA Radar Unit Problem

I have installed a NASA Radar unit and can not receive any ship info over two miles away ( at this distance I can read the name on the bow )I have attached a Shakespeare loaded whip anttenna on the radar post arm, the anttenna is on a two foot extension which puts it above the yacht radar and over 14' above the waterline. Any ideas as to what the poblem is? I have sent emails to NASA but nothing back as of yet.

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Old 31-08-2008, 13:29   #2
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if you are receiving some data at 2m, that minimises problems with the unit.

Your aerial height is sufficient for 20nm range on larger merchaant ships

That means that the most likely culprit is the aerial and its connection. I would check your connections and make sure that you have not cross connected the earth wire into the aerial

Please dont call this a radar, it is an AIS receiver. NASA should be shot for using this name.

I had no problems with connection using a 1.1m stainless whip.

However, I set my system up so that I could swap over the VHF aerial to the NASA aerial, and the AIS to the masthead aerial. - redundancy, and another way to check it.
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Old 31-08-2008, 13:36   #3
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first things first
not all vessels have ais so it's possible you didn't get info because there's nothing on that vessel to send it to you

you are describing that after 2Nm of radius you don't get info. probably outer ring radius is too low. play with buttons a bit
it's just a problem of settings on the receiver
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Old 31-08-2008, 14:05   #4
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Thanks, I plan to check the conections with a meter. the problem was it worked fine in harbour as it was a confined area but I could not tell they were dropping off after two miles until I was out in the ocean and picking the ships up on my "Real Radar".
Ps: The only reason I used the NASA Radar term as it is marked was to make it clear this unit was not the AIS engine sold by NASA.
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Old 31-08-2008, 14:08   #5
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Thanks, However I have played with the settings ie: threshold and A & B to no evail.
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Old 31-08-2008, 16:29   #6
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Another possible cause of your problem is RF noise generated by something on-board. You might want to try turning off electrical circuits when there is a ship over 2 nm away.

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Old 01-09-2008, 05:06   #7
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Thanks to all of you for your help, It is the antenna or its connection. I switched the antenna lead from the masthead antenna and picked up ships at more than 8 miles which is pretty good as I am moored in the center of town.
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