Autohelm ST4000 not recognising NMEA XTE data from GPS

curious1

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My Autohelm ST4000 has suddenly decided not to recognise NMEA XTE data from my GPS. I know there is no fault with the GPS, it is sending the data and I have proved the continuity of the data cable. The ST 4000 does NOT show the 'no data' message unless I switch off the GPS. All other functions of the St 4000 are working.
Has anyone overcome this problem which I understand is quite common. /forums/images/graemlins/confused.gif
 
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[ QUOTE ]
My Autohelm ST4000 has suddenly decided not to recognise NMEA XTE data from my GPS.

[/ QUOTE ]

It isn't clear from your post as to how you have determined this to be the case. Please elaborate.

Steve Cronin
 

curious1

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Hi Steve

NMEA signals are being detected by the ST 4000 but it is NOT recognising or reacting to the XTE portion of the signal. I assume the rest of the signal is being recieved as only when I turn the GPS off does the "not receiving data" message appear on the ST4000.
NMEA position signals are being received by the VHF/DSC radio.
 
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This might have just triggered a spark in my memory. I seem to remember that my Non Raytheon plotter/ST60/AH4000+ set up has a difficulty with XTE. As I remember it is only when a full Seatalk link from a Raytheon GPS is present that you get XTE. Not certain; can you wait until after 070907 following our next trip out to Greece?

Steve Cronin
 

Danny

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The ST4000 NMEA interface should definitely be able to extract XTE from either the RMB or XTE sentences, both of which are transmitted as standard from the Garmin 152 GPS.

Looks like the cabling is OK and the GPS is transmitting at least the current position (because, from your previous thread, you stated your DSC radio gets position data OK).

Most GPS's will send an empty RMB sentence, or none at all, until such time as they are told to go to a waypoint or follow a route. Unless you've actually traced the sentences I don't think you can say which device is at fault.

It may be that the ST4000 can't decode the XTE but it could just as well be that the GPS isn't sending the additional sentences it should when navigating to a waypoint.

You suggested in the other thread that this was a new problem and that it had all worked OK before. Has anything been changed?

Another thought, Jonfred: in your other thread you said-
[ QUOTE ]
The Autohelm only shows 2 of the 3 required fields, ie. bearing, and 000's in the distance to object field.

[/ QUOTE ]Does that mean that the bearing (to waypoint) shown on the A/P agreed with the bearing shown on the GPS?
 

curious1

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1. The only thing that has changed is to rectify a disconnection in the power feed to the GPS.
2. The bearing shown is the autohelm standby compass bearing.
3. The condition is still present after selecting "Navigate to Waypoint x" then "go to x" on the GPS.
Regards

jonfred
 
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