NMEA0183 GPS Position and Time From Navman 5600

[Deleted member 36384]

Hello,
I have not been able to get position read out on my ICOM M601, ICS Nav6 and ST60 Multi Display from my Navman Tracker 5600.

The Navman picks up position and quickly without a problem from start up, but the date is 23 Sep 2001.

In the past I had this date problem but with slow start up finding position and a dicky cable. I replaced the GPS antenna and cable and the date was fine. Now it is not as stated above.

My query is, I assume there is an issue with the Northstar antenna, cable again, hence the date problem. Would this date issue stop the Navman sending NMEA position to the above instruments or prevent the instruments from reading the NMEA data correctly i.e. both position and date need to be received to be annunciated on the other instruments?

Trying to troubleshoot, before I buy a new antenna. I have checked on the Navman and both Output sources, Autopilot and Navbus are on, so I am expecting data out. The tide function date is also the 2001 date and there is no offset date values set.

Any hints and tips eg if I put a volt meter across the NMEA out, would I be able to test if something is there?

Thanks,

BlowingOldBoots

 

[andsarkit]

Could it be the internal back-up battery?
Navman 5600 problem
Your fast start up might rule that out but the date error could be significant.

 

[Deleted member 36384]

I don’t think the 5600 has an internal battery.

I placed my multimeter over the two NMEA out wires, 20V DC setting. I get voltages continually changing from about 0.3v to 4.8v, with an occasion -0.3 or 0.45v.

Tested at the NMEA out lead from the plotter at the chart table and at the plug to the VHF, so getting some sort of signal.

 

[TernVI]

I have an old Garmin GPS V which finds a position OK, but the date is wrong.
If it's getting a correct position, (not just remembering an old one), I don't see it being an aerial problem.
Possibly it's an internal battery problem, possibly it's an obsolete receiver now.
I had a TomTom, which stopped displaying anything other than midnight, it wasn't an internal battery problem, there was only the Lithium rechargeable inside.

 

[TernVI]

I don’t think the 5600 has an internal battery.

I placed my multimeter over the two NMEA out wires, 20V DC setting. I get voltages continually changing from about 0.3v to 4.8v, with an occasion quick - sign if 0 shows but no voltage at - that I can read from the multimeter.

So it's trying to put out data.
Is the baud rate correct?

 

[Deleted member 36384]

I can’t find any instructions on setting baud rate, but it all used to work. Measured voltages at the back of the actual Navman at the lead terminals and get the same range as before.

According to VHF instruction book, manual position entry is not possible if a GPS receiver is connected to the VHF. I checked the manual position entry and I can enter a position with the key board. Hence, I can conclude that whatever these voltages are they don’t mean anything to the VHF and as such it thinks there is no NMEA 0183v2 connected.

I’ll order up a new GPS antenna and see if that fixes it.

I do have an ACU400 Autopilot and GPS Antenna, works independently from the old stuff. Probably time for a new plotter and VHF.

 

[laika]

Rollover issue?
https://service.navman.com/m0100/FileReader_114407_UK Ireland NAVMAN_English Navman.html

 

[Deleted member 36384]

Laika,
That does appear to be consistent with what I am seeing. I guess the position and time need to be sent together as an NMEA sentence to be picked up.

I guess I have to put the update file onto CMap Card. Or send it away as the 5600 does not have a SD card slot.

Edit Update: The LM is not the same as the Navman Tracker 5600. I will contact one of the repair companies, see what they say. Thanks for the idea though.

 

[Deleted member 36384]

Would it matter the order that the devices are connected e.g. From Navman, to Multi Display, to VHF, to Navtex?

 

[laika]

Would it matter the order that the devices are connected e.g. From Navman, to Multi Display, to VHF, to Navtex?

If I understand correctly and the Navman is the GPS receiver which is formatting and outputting NMEA sentences to the other devices, and if this *is* a rollover issue which it very very much looks like it is, then "no". The problem is that the GPS receiver is misinterpreting the 10-bit GPS week and putting the wrong date into the NMEA sentences it produces and sends out to other devices. The fix (if this is the problem) would be a firmware update and that would depend on the inclination of the manufacturer to produce one (clearly there from the availability for the other product I mistakenly pointed to) and the ability the manufacturer built into the device for it to be updated (possibly not looking so good if it has no card slot). As you suggested, talking to the manufacturer is probably your best bet.

 

[robmcg]

Definitely sounds like a rollover issue. I had the same with a Furuno GP30 unit that suddenly reverted to the wrong date. I had a very, very full and detailed response from Furuno technical support. The short answer was buy a new GPS ?! If it is any consolation, I compared the Furuno position data with the Raymarine position on the chart plotter and they always matched so it didn't appear to affect its ability to report an accurate position.

 

[TernVI]

But rollover issue should just result in the GPS blurting out the wrong date in a perfectly valid NMEA data sentence.

 

[TernVI]

Would it matter the order that the devices are connected e.g. From Navman, to Multi Display, to VHF, to Navtex?

You've got all these on one pair of NMEA data wires?
I would try connecting one thing at a time.

 

[TernVI]

Definitely sounds like a rollover issue. I had the same with a Furuno GP30 unit that suddenly reverted to the wrong date. I had a very, very full and detailed response from Furuno technical support. The short answer was buy a new GPS ?! If it is any consolation, I compared the Furuno position data with the Raymarine position on the chart plotter and they always matched so it didn't appear to affect its ability to report an accurate position.

Given that you can buy a GPS receiver module for about a tenner, buying new is not such a daft idea!

Alternatively, I think you can make something with an Arduino to reformat the date.

 

[ctva]

I had a similar issue on the 5500 unit, turned out to be the internal battery that needed replaced. That sorted the date issue and speed of acquiring location but in the end I binned it as it just became too old and I fitted a 2K network. These units are probably 20ish years old now.

 

[Deleted member 36384]

Talked to The Service Centre, in Poole, and they confirmed the battery may be the issue but stated it should pick up the date from the GPS signal. They also said that it sounds like a hardware issue that is likely fixable. Apparently their software is modern enough not to be effected by date rollover.

Thanks for all the comments. I’ll let you know the outcome from The Service Centre.

I’ll send it off as I don’t want to change out at the moment, but that is on the cards for later.

 

[laika]

I had a similar issue on the 5500 unit, turned out to be the internal battery that needed replaced.

How similar? Was yours like BlowingOldBoots whereby it was consistently showing a date 1024 weeks in the past, or was it only displaying the wrong date during startup?

I’ll let you know the outcome from The Service Centre.

Please do: I'd be interested to know. From what I've read, some GPS units have logic such that if the GPS week they receive is less that the last date that was saved (in battery backed memory), they add (saved GPS week rounded up to the next 1024) to the received week to yield (hopefully) the correct time, so a duff battery would break that. However without a mechanism to manually input the correct date, I'm not sure how replacing a dead battery would cure the problem. Perhaps others know more? I'd be dubious about "hardware issue" unless they mean firmware.

 

[Deleted member 36384]

Update
The Service Centre has verified that the unit is working fine but the date issue is rollover and there is no patch to fix it. They tested it on various items and they received the data.

They could not help with the installation query but said that date , time and position was being sent, so should get picked up.

They indicated that the ST60 Multi Display would need a converter from NMEA to Seatalk. However, I have never seen a device fitted before and after the rewire.

At the moment I have a pair of wires at the chart table, black and red, from the plotter that is sending NMEA position and date information. I am flummoxed what to do with them to get the devices in the OP reading position and the date.

I feel my wallet straining to be opened

If I buy a new Raymarine Plotter, will I need a device to allow the VHF, Navtex and ST60 to work accept data? I guess so. Do you think it would be worth buying a new VHF?

Any quick fixes from the pair of cables to the devices? For example the ST60 Multi Display has NMEA In and NMEA out on the back, 2 pins each. These are below the ST60 seaTalk cable ports. I have two of these ST60 cables, with just one connected to the top right port. At the Seatalk top left port, it I have 2 of the 3 pins connected, with what I think is power only. I tried connecting the red and black from plotter NMEA to the ST60 NMEA in but there was no date displayed.

 

[laika]

They indicated that the ST60 Multi Display would need a converter from NMEA to Seatalk. However, I have never seen a device fitted before and after the rewire.

That's weird because I'm pretty sure, and your previous installation confirms, that the ST60 multi itself converts nmea to seatalk
ST60 multi manual here confirms too:
Box
Connections are on page 24

Do I understand correctly that you've done the oh-so-easily done thing of disconnecting to troubleshoot and and forgetting how they were connected (been there, done that in which case I'll skip the "how was it wired before?" question).
Do first satisfy yourself that red and black really are NMEA out and not power. Double check the colours from the navman manual and then potentially ignore when you realise a previous owner has extended the wires with different colours :-/
If you're feeding old style single ended NMEA from the plotter you'd want to connect "NMEA out" to "NMEA IN +" on the st60 multi and ground to "NMEA IN -".

If there's no firmware fix the options might include:
* Living with the wrong date (the position is still correct, yes?)
* One of Tern IV's suggestions from post #14 (of which the simplest, though least interesting, is to buy a new GPS)

This problem must be so common *someone* must have put together a little microcontroller-based project which reads in NMEA-0183, corrects rollover errors, then pumps the corrected sentences out the other side.

 

[Deleted member 36384]

Thanks laika, it is very possible that I have messed up somewhere in the wiring. I'll be at the boat this weekend, hopefully with potter, so will investigate further.