DSC Radio and GPS compatibility?

[Murray Peterson]

It seems different manufacturers can't quite make their products 100% compatible in this area and the sales people always say Yes, Yes, Yes when you ask questions in this area and after you buy the equipment they refer you to their technical staff who tell you the equipment is not compatible.

My case in point is my GME GX600D VHF DSC transciever and my Northstar Explorer 657 Combination GPS/Sonar/Chartploter unit. It is not until I "conected the wires", it didn't work as claimed, and I was informed that the Northstar unit can only accept DSC data in "Navbus" (Northstar/Navman's own propriety format) format so I can't plot any other vessels on the chartplotter. The Northstar Technician's "helpful suggestion" was to buy a Northstar DSC radio!

Instead of doing that, does anyone have suggestions for a "Navbus" to NMEA0183 or NMEA2000 converter?

[pamarine]

From the NavBus Manual:

NMEA cannot be converted to NavBus
and shared using NavBus.

In other words, to use a NMEA device with a Northstar Device, the NMEA interface is made at each device seperately and must transmit compatible sentences. Your Chartplotter doesn't transmit or receive and DSC NMEA sentences.

Hope this Helps.

[Murray Peterson]

My Chartplotter transmits NMEA to my DSC Radio but the Chartplotter dose not receive the NMEA from my radio. The Northstar Explorer 657 Chartplotter only plots data on the chart that it can receive in Navbus format. (Contrary to the claims of some salesmen.)

[pamarine]

Right, your chartplotter transmits your GPS position to your radio for hte DSC function on the Radio. This is done via sentence GPA.

The Explorer 657 has the follow NMEA 0183 Capabilities:

[quote]NMEA 0183 Interface
NMEA Input:
BWR, DPT, GGA, GLL, GSA, GSV, HDG, HDM, HDT, MTW, MWV, RMC, VHW, VTG and DBT
NMEA Output:
APA, APB, BWR, DBT, DPT, GGA, GLL, GSA, GSV, RMB, RMC, MTW, VHW, VLW, VTG, XTE
[quote]


GGA is Fix Info (Accuracy, 2d or 3d, etc)
GLL is Lat/Lon Data (This is what your radio is using for DSC, along with GGA)

Although your radio may actually be using RMC with is a minimum set of GPS information combined into one sentence

The 657 can receive Waypoint Bearing info (but not waypoint) Water depth, speed and Temp, Speed over ground, Pretty much all necessary GPS Info, Heading information (such as would be sent from an electronic compass) from any NMEA 0183 Compliant device that can send it.

It can send The same information along with the necessary minimum information for an Autopilot, and some additional navigation information like Cross track error (Which is incedental to the Autopilot info).

From a NMEA standpoint, it is meant to function as a simple chartplotter and depth sounder, and control and autopilot. It is a very basic setup as far as a all-in-one system would go. Any additional capabilities it may have stem solely from the ability to interface to a NavBus system, but as already pointed out, NavBus cannot convert NMEA information to the proprietary language.

Your Chartplotter would need to be capable of receiving DSC (input) in order for your radio to transmit other vessels positions to your it.

The Garmin 430/440 and 530/540 sereies are the only current chartplotter I know in the same price range that will track position information via DSC on the plotter

[Murray Peterson]

That is correct. The silly thing about it in my opinion is that it does receive NMEA data from the Northstar remote GPS receiver, and the fuel flow sensor (this probably confused the salesmen) but not from a DSC Radio.

[pamarine]

Originally Posted by Murray Peterson

That is correct. The silly thing about it in my opinion is that it does receive NMEA data from the Northstar remote GPS receiver, and the fuel flow sensor (this probably confused the salesmen) but not from a DSC Radio.

again, as it should.

For under 1K US you aren't really going to find a lot of extras when it comes to functionality unless you go with a Garmin.

[Murray Peterson]

Originally Posted by pamarine

again, as it should.

For under 1K US you aren't really going to find a lot of extras when it comes to functionality unless you go with a Garmin.

I have thought that way - the Northstar has the hardware and evidently the software coded elseware in the PIC-Micro it runs on (or equivalent). Why not one more line of software to be able to accept NMEA data form a radio? The cost in production would be negledgeable.

More importantly, they should be required to state that this chartplotter will not accept data from a DSC Radio in NMEA format.

[Murray Peterson]

Thanks for you comments - really appreciated. One more question - Can you provide me with the specifications of Navbus. Northstar/Navman won't supply the specifications. NMEA0183 is well published but I can't find specifications for Navbus. If I have the specifications I may be able to program a PIC-Micro to do the translation.

[pamarine]

Originally Posted by Murray Peterson

I have thought that way - the Northstar has the hardware and evidently the software coded elseware in the PIC-Micro it runs on (or equivalent). Why not one more line of software to be able to accept NMEA data form a radio? The cost in production would be negledgeable.

More importantly, they should be required to state that this chartplotter will not accept data from a DSC Radio in NMEA format.

They do in the specifications for the Unit they list all the NMEA sentences that it can use.

Unfortunately you ran in to the #1 problem in the marine electronics industry, uneducated (or lazy) salespeople.

[pamarine]

Originally Posted by Murray Peterson

Thanks for you comments - really appreciated. One more question - Can you provide me with the specifications of Navbus. Northstar/Navman won't supply the specifications. NMEA0183 is well published but I can't find specifications for Navbus. If I have the specifications I may be able to program a PIC-Micro to do the translation.

Unfortunately NavBus is a proprietary protocol for Northstar. Unlike similar systems from Raymarine, Garmin, Lowrance, and Furuno, it does not seem to be based on or compliant with any industry standard protocols.