Navman NMEA NASA DSC and AIS

[Robin]

Updating my earlier post about trying to connect a NASA DSC VHF to a Navman 5600, I still cannot get a GPS position (or anything else via NMEA) onto the VHF. I have tried every combination of NMEA sentences and the NMEA leads are connected as per handbook and discussions with NASA. NASA talked me through a master reset on the VHF - Didn't work. Then there was a problem with the Navman 'freezing' and erratic GPS fix stability, cured swiftly by Navimo with new software. But guess what, still won't talk to the NASA.

In case you think Navman's NMEA output isn't working or I have the wrong leads connected, it also goes to a Yeoman Plotter and this is all working fine. The Yeoman will work with a variety of NMEA sentence options, any all or just one, NASA stays irritatingly displaying so many 9s (Lat 99.999, Lon 999.999).

Now that is at least the answer to NASA AIS set buy or not! I was thinking of buying one to cover the hole in the panel vacated by the old GPS that was replaced by the Navman, but NO WAY Jose if NASA DSC won't work with Navman I doubt that NASA AIS will either...

And of course NASA blame Navman and Navman blame NASA!

/forums/images/graemlins/confused.gif

Robin

 

[johna]

You should have joined me on the golf course instead of getting all frustrated with your electronics!!

 

[Captain Haddock]

I've got exactly the same problem but with a Garmin 276c I'm not impressed and I'm seriously thinking of launching the NASA and getting something else.

Phone NASA and I get "what? what problem? must be the Garmin".

I know everything is set up properly, I'm beginning to wonder if the NASA's only work with older GPS units and not the newer ones.

Very, very frustrating.

 

[silvertop]

Sorry to hear about your problems. I use a NASA SX 35 DSC linked to a Navman 5500.

all works perfect.

 

[mikejames]

I think the problem lies with the Garmin GPS. From experience with several, they output a low level signal on their NMEA outputs. Not the proper +/- 12 volts or so, but instead +5 and 0 volts. Normally this is adequate but the protection built in to the output means that it is easy to overload this and then it wont drive many things in parallel. It will not get damaged , so there wont be a problem fitting an NMEA buffer. There is no real fault, just marginal performance.
Annoyingly, the electronics to make an NMEA buffer is dead simple, just not enough are sold to make it worthwhile to make them cheaply so they end up costing more than the GPS.

 

[tillergirl]

Purely a guess. Have you got compatible NMEA. I am currently testing a Standard Horizon DSC which requires NMEA-0183 version 2.0 or higher. Jury rigging it at home to an old handheld Garmin, it would not pick up GPS data. I note the manual on the Garmin says that its talking in NMEA Version 1.5. Took the DSC to TG and plugged it into the Furuno which talks in either 1.5 or 2.0 (its set on 2.0) and it worked immediately.

 

[salamicollie]

Checked my garmin/nasa radio set up today, nasa definitely starts all 999's until there is a lock on the garmin when it spits out a position and immediately nasa picks it up. in your thread you said you couldn't get a position lock 'cos you were in a shed....

for both Robin and Capn Haddock only way to prove if you have a duff radio is to plug it up to another gps and try it

 

[Robin]

If the Navman 5500 works with the NASA SX35 then so should the Navman 5600 because they are almost identical other than screen size, we actually have a 5500i as well as a standalone one in the cockpit. However I DID connect it below in place of the 5600 as the plugs are identical, it didn't fire up the SX35 aither!

So please can you tell me how your set up is connected? I have the white Navman NMEA 'out' lead connected to the brown NASA NMEA'in' lead and the red NMEA ground lead connected to the Navman black -ve lead. (why they use red for a ground I don't know but is IS correct). Also can you please tell me the set up configuration you have on the Navman under 'Comms'. We have autopilot output 'on' and have tried pretty well all the combinations of NMEA sentences, according to NASA it MUST have the RMC sentence so we have that set to 'on'. On the NASA we have Lat/Long LL 'on' and unser NMEA have tried it with 'checksum' both 'on' and 'off'.

I am getting to the stage where I'm thinking of a flotation trial for the Nasa SX35!

Robin

 

[Robin]

Hi John

I guess you got a game then but if you are going to make smart remarks like that I hope you got wet! Frustration and golf aren't good bedfellows either. I am currently writing out 100 times 'I will NOT be beaten by a F@@@@@g computer...

Robin

 

[Captain Haddock]

As a further update I noticed my firmware on my Garmin 276c was way out (2.50) the latest is (3.20).

The update file mentions support for DSC and updated NMEA output i.e. faster.

The boat should be out of the shed next week so I'll report how it goes with the updated firmware and a locked on signal.

I also want to thank everyone for their input, it's much appreciated.

 

[Robin]

The Navman puts out NMEA 0183 v2.0 and the NASA should be able to read this and the earlier NMEA 0183 v1.5 as well (I think the 'Checksum' setup option toggles between the 2).

We previously had the NASA running from an ancient Shipmate 5800 (now passed away) and we currently have the Navman running our Yeoman OK just as the Shipmate used to (it too ran both together). With the Shipmate the red NMEA ground lead from the NASA wasn't even connected, just the NMEA 'in' brown lead, presumably the ground was via the set grounds in the power leads.

 

[johna]

[ QUOTE ]
Hi John

I guess you got a game then but if you are going to make smart remarks like that I hope you got wet!
Robin

[/ QUOTE ]

Only got wet on the inside but can agree with the golf/frustration link.

BTW any chance of an hour of your time this evenung to wind me up the mast?

John

 

[milltech]

I can understand your frustration but the Nasa set is actually a high quality Japanese radio branded "Nasa" and Nasa are ending their run with it and it now appears via SMG as the M-Tech SX35. Of course it's possible there is a fault, but it's not a case of poor design, the arrangement does work.

After a slow (for me) start the AIS receiver is also selling well, and the "engine" is proving to be a bit of a hit too. I wouldn't be put off Nasa kit because of your current frustration, it will pass when the penny finally drops. Bloody computer problems are always like that!

 

[Robin]

[ QUOTE ]
for both Robin and Capn Haddock only way to prove if you have a duff radio is to plug it up to another gps and try it

[/ QUOTE ]

Not quite so I'm afraid because it can still be the wiring connections or the configuration of either the GPS or the radio that are at fault. In our case we know the NASA worked with our old GPS, but doesn't work with our (2) Navman ones. We know the Navmans (Navmen?) transmit NMEA OK to the Yeoman, just don't work on the NASA. So the error has to be either in the connections between them or in the configuration of either or both sets. This all should be simple enough, just 2 leads out from the Navman and 2 leads in on the NASA, the NMEA 'out' and NMEA 'in' are a 100% certainty to need connecting together but the reference ground connections are from past experience less certain since some sets use the power feed -ve as the ground and can even obtain the connection via the battery and no need for the 2nd NASA lead to be connected (this was the case with the old GPS). NASA say connect their red NMEA ground to the Navman one (which is the -ve power feed, nope don't work, nor does it work when not connected as it used to on the old set.

 

[Robin]

[ QUOTE ]
BTW any chance of an hour of your time this evenung to wind me up the mast?

[/ QUOTE ]

Since you asked so nicely yes, call me because you will need to give me a lift about 3.30/4.00 would be best for me though whilst 'shes' still out golfing!

Robin

 

[salamicollie]

By attaching to another GPS (one preferably that someone else has got a NASA DSC working on...) you will eliminate the possibility that when your old shipmate popped its clogs it didn't blow the NMEA output of the NASA radio. Then if it works OK you know its a config/ compatability issue!

FWIW my NASA is connected with NMEA -ve attched to 0V with a Garmin and that works OK

 

[Robin]

Yes I take your point, but the old Shipmate GPS didn't blow up as such but was taking ages to find a fix and then would lose it regularly but right up to the very end it was still giving a position to the NASA and the Yeoman, all I then did was disconnect it. The 0v bit is a question of where to find it! Some sets have separate 0v NMEA leads and some just seem to use the power in negative lead as the 0v connection, the Navman does this. I'm 99.9% (all the 9s just like on the NASA screen!) convinced it is a connection and/or config problem, especially as another poster is getting it to work with a Navman 5500/NASA combination.

 

[malcp]

Hi Robin,

Silly question. I suppose you have checked the ground connection between the Navman and the NASA? Measure the voltage between ground connections of the 2 and it should be very close to 0v. If there was a dc offset it could upset a ground referenced NMEA link from working.

Just a thought.

 

[Robin]

I haven't actually measured it but I did try a wander lead between the 2 negative power leads which would have made them both the same, but I might try it again next visit with other combinations of configuration. Thanks

Robin

 

[ribbett]

Try turning off the GLL sentence and using just RMC