DSC VHF to GPS

[catketch]

Has anyone any experience of connecting a NASA SX35DSC radio to an Apelco GXL1100 GPS. The radio says it needs the $GPRMC NMEA data sentence. The GPS says it outputs NMEA 0183 data containing the RMC, RMB, GLL, GTD, VTG, APB, and BWC sentences. The two do not seem to be communicating. Is the problem in my wiring or connections, or is it a software problem.

 

[fireball]

I've got our Apelco GPS talking to Offshore Navigator ok ... well its only in the boat park at the moment, but the position is certainly shown ...
I've tee'd off the wire from the GPS (Mega) mushroom as this is a GPS in its own right and the head unit is really just a display and waypoint management system (plus I can't be bothered to learn how to use it). Is this the way you've done it or have you come out the back of the head unit?

 

[Chris_Rayner]

I've had the devil of a job interfacing a Silva S15 DSC with my Raymarine plotter. Not your problem, I know, but the apparent solution may have a bearing. The radio picks up the relevant NMEA stuff from a Garmin 72, but the NMEA out from the chartplotter/radar is not seen by it. What the technical people at Raymarine told me is that the sentences have a prefix on them which gives their source, and that some DSC radios will only accept sentences which come direct from the GPS. Makes sense, if rather infuriating, to me.

 

[dmayes]

The NMEA data is just an asynchronous data sentence (PC talk, sorry). Your operative word to get them both talking is the "RMC" part. You should check that the data rate is the same on both devices, normally 4,800 bits per second (or baud rate), you need to look at the manuals for this info. The GPS will output these sentences on the "NMEA out" and a "signal ground" (usually the battery negative). These should be connected to the Radio "NMEA in" and it's battery negative or signal ground whatever the manual calls it. The radio will ignore all the other GPS sentences and just act on the RMC data sentence. Good luck.

 

[dmayes]

I have a Word document entitled "The NMEA FAQ" if anyone is interested. It came off the web but I cannot remember where I got it. How can I post it to make it available to whoever wants it?

 

[BrendanS]

Depends how big it is. You can go to word, 'select all', copy, then paste here. Otherwise host it on a website, and provde url

 

[Lee_Shaw]

[ QUOTE ]
Is the problem in my wiring or connections, or is it a software problem.

[/ QUOTE ]

Have you connected the negative from the data cable coming out the back of your NASA to the negative bus of your leccy installation?

 

[stephenmartin]

I have a little program that you run and looks downs the GPS serial cable and tells you what sentences are coming down the wire...if any...then just switch off what you don't need if you can....

Its called GPSNMEA worth its weight in gold....let me know if you want it...its very dos based but it works and saved me eons of messing about and bad language

 

[desert_aampal]

any one know how to connect nmea of gps furuno gp 70 to icom vhf