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Old 25-02-2009, 16:38   #1
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Fluxgate Compass

Can i parallel into my autopilot fluxgate compass, and run the parallel leads to my boat instrument package, or do i need a fluxgate for each system?
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Old 25-02-2009, 19:25   #2
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If it has a NMEA out port, you can send that data to one or more devices devices which have a NMEA in port. There is a limit to how many devices you can send a NMEA sentence to. After that you will need an amplifier or a multiplexer that also works as amplifier. You should though be able to send your fluxgate NMEA sentence to at least two devices.

Some fluxgates use a proprietary language and some have both a proprietary language and NMEA.

What is the brand and model number of yours? The manufacturer will probably have a PDF on their website of your models specifications and a wiring diagram.
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Old 25-02-2009, 19:37   #3
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Thanks David, my autopilot is Alpha 3000, and the instruments are Tacktick. Tacktick has there own compass transducer (fluxgate), but if i can save a buck with the Alpha compass, I'd like to.
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Old 25-02-2009, 19:48   #4
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I just looked on Alphas website. I did not see any specifications for their $2200 fluxgate...wow thats expensive for a fluxgate!

I would give Alpha a phone call and ask them what the output of their fluxgate is. If its a proprietary language then obviously the only instruments that will probably work are Alpha instruments.

What are you trying to connect the output to?...a separate digital heading readout?

It may be less expensive to buy a second fluxgate with a NMEA output and attach it to a heading readout. I have done the same on my boat. I have a ComNav fluxgate just for the autopilot and then a second Furuno fluxgate with a NMEA output that ties into my Furuno system. I believe the Furuno fluxgate was around $800. Defender has it for $680. The Furuno fluxgate also provides heading information for my computer which uses Nobeltec and for a few other computers I use for data logging and for a multi-readout on the afterdeck. (its a research boat)

http://www.defender.com/product.jsp?path=-1|344|302026|187252&id=660622
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Old 25-02-2009, 19:59   #5
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I'll give Alpha a call and check on the language...but Tacktick has a compass, just trying to save a buck.
T909 Compass Transducer
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Old 26-02-2009, 08:30   #6
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Chances are the answer is "no". There are, AFAIK, few NMEA fluxgate compasses around (KVH made one for Raytheon but that's an ancient piece of gear). Otherwise, the the sensor is very much brand and device-specific, precluding "sharing" the sensor.
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Old 26-02-2009, 11:26   #7
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There are several NMEA compasses on the market. KVH makes 3 and Airmar has 2, one of them VERY interesting. The issue is how fast your user instruments need the data. Radar overlays need compass data twice as fast as autopilots, and simple heading displays could be happy with much slower rates.
Airmar has a masthead weather instrument that sends compass data fast enough for MARPA, and reports apparent and true wind extremely accurately. It talks N2K and NMEA 0183. It costs somehwere around $1200.
But the most common solution is the trusty old KVH Autocomp 1000 digital fluxgate sensor. It seems to be universally accepted for Radar overlays, autopilot input, and reliable heading info over NMEA 0183.

If you are dealing with a rotating mast, you may need two compasses to interpret apparent vs true wind. Tacktick and B&G have solutions.
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Old 27-02-2009, 08:59   #8
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Eh, two vendors, five models between 'em... few/several - it's mostly semantics. The KVH 1000 works (I have one on a Raytheon R20X radar), but the output is pretty stone-axe simple (magnetic heading only - up to the user to supply correction to true heading).

However, the original question was:
Quote:
Can i parallel into my autopilot fluxgate compass, and run the parallel leads to my boat instrument package, or do i need a fluxgate for each system?
Except in special cases, the answer to that question is still "no".
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Old 27-02-2009, 14:21   #9
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Quote:
Originally Posted by RBEmerson View Post
Eh, two vendors, five models between 'em... few/several - it's mostly semantics. The KVH 1000 works (I have one on a Raytheon R20X radar), but the output is pretty stone-axe simple (magnetic heading only - up to the user to supply correction to true heading).

However, the original question was:
Except in special cases, the answer to that question is still "no".
Well let me add a few more to Sandy's list just off the top of my head - Northstar, NASA, Autonic, Honeywell - am sure if one set ones mind to it with a positive approach one would turn up many more. So lots of them and by no means special cases.

Sadly, in answer to the original poster's question regarding his sensor I believe that the answer is no - neither from the sensor itself nor at the autopilot (unlike many other pilots or associated compass instrument).
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Old 27-02-2009, 17:46   #10
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And on the n2k front, Maretron has a compass with roll and pitch rate.

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Old 27-02-2009, 21:07   #11
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Quote:
Originally Posted by sandy daugherty View Post
There are several NMEA compasses on the market. KVH makes 3 and Airmar has 2, one of them VERY interesting. The issue is how fast your user instruments need the data. Radar overlays need compass data twice as fast as autopilots, and simple heading displays could be happy with much slower rates.
Airmar has a masthead weather instrument that sends compass data fast enough for MARPA, and reports apparent and true wind extremely accurately. It talks N2K and NMEA 0183. It costs somehwere around $1200.
But the most common solution is the trusty old KVH Autocomp 1000 digital fluxgate sensor. It seems to be universally accepted for Radar overlays, autopilot input, and reliable heading info over NMEA 0183.

If you are dealing with a rotating mast, you may need two compasses to interpret apparent vs true wind. Tacktick and B&G have solutions.
Furuno had me set their PG500R fluxgate to a repetition rate of 100ms for their NavNet 3D systems ARPA.
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