JRC dGPS

[Guest]

Anyone got a colour code/pinout for a JRC dGPS200? I'm trying to connect it to a JRC Radar 1800...

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[David2452]

There are 2 cables apart from the obvious black and red,

White: to radar cable screening braid
Green to Radar NMEA input

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[Guest]

and what about the other two? It seems that the radar can talk to the GPS as well as vice versa... Do you know what the other two are?

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[David2452]

Can't imagine what a radar would need to say to a dgps even if it could, There is no output from the JRC 1800 other than daisy chaining of the NMEA inputs from a fluxgate or GPS

David

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[Guest]

Well apparently it can say things like: switch from auto to manual, and listen on this frequency for the diff signal...

That's the damn problem with it - the Radar 1800 only sees the dGPS200 as a bog standard GPS, and can't get the diff message through. Actually, when first connected to the 'dGPS' port, the radar thinks it gets a dGPS fix, but after 10 seconds it loses it and falls back to GPS.



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[David2452]

Ahh!!! I see, it may be a lost cause unless you can talk direct to the JRC teches then. Mind you I find even the standard GPS is plenty accurate enough for all but the most precision uses (returning to a wreck without even using a fish finder ect.)
still get the nice waypoints displayed on the radar to steer to, confirmation of buoys and stuff. I suppose though if you've paid for dGPS you want dGPS. Can't help further.

Good luck and safe boating

David

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[tome]

Graham

You may be a bit off the mark here. Most GPS receivers will accept DGPS corrections. These are applied to the pseudo-ranges before the receiver computes the position solution, and subsequently outputs them as NMEA messages. If you have a dGPS receiver and it is receiving corrections then the messages going to the radar will by definition be DGPS.

There are quite a few alternative NMEA messages which contain the GPS position so not possible to be definitive. However, the most common is the RMC sentence (recommended mimimum GPS data) which doesn't have any indication of the mode, therefore your radar has no way of knowing if it's differential or not.

If your GPS outputs GGA messages then this includes an indicator as to GPS quality (0= invalid, 1=Non diff, 2=Diff).

Regards
Tom

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[Oldhand]

I found the JRC dGPS so horrible to use (having inherited it with the boat) that it has been consigned to the depths of a locker as a spare and replaced with something useable. I can't imagine why any one would be enthusiatic enough to connect it to anything.

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[Guest]

must be a different unit - mine's just a little mushroom on the radar arch with six wires coming from it. With the old plotter, it just worked...

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[BarryH]

Theres a chap at MES ltd that is a bit of a whizz with things like that. They're JRC dealers as well. Worth a phone call if nothing else.

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