NMAE details

[lakelouise]

Help. Would anyone know a cure for a Navman 650 that displays the message that no NMAE details are available. It wont lock on to the satellites. Has it expired is it time to move on? Thanks

[robertn]

No NEMA data means the GPS reciever is not transmitting anything. It is no about the number of satalites in view, quality of fix or anything else.

Basicly your navman is now a brick - the GPS reciever is poked, away with the fairy's, gone to the weeds etc .

One option would be to get it repaired, although technically an easy job to replace the GPS reciever, it's probably not economocal to even have Navman have a look.

You could try a GPS cold start. As you have nothing to loos try this

1) Hold down the Menu Key while you turn on the 650. You should see a black screen with a menu, something about Secondary Bootloader, and a version number or two.

2) There is a GPS menu - tool around till you find it.
In there are some menus for tests and for Cold Start the GPS. Do a cold start, and I think theres a menu option to report the current GPS status.

DO NOT do anything that says things like format, erase, delete. Only play around with the GPS menu option. You have the ability to really turn you 650 inot a brick in here, however as it already is, you have not got much to lose.

Sorry I can't be more specific, I don't have an iCN anymore, and this stuff is certainly not in any manual you will have.

[Tim Buxton]

robertn, it indicates that the GPSR isn't receiving, not that it isn't transmitting, although what it would be transmitting (it isn't a transmitter) is a little puzzling.

lakelouise, have a read of this.

Are you giving yourself a long enough time to acquire a signal? The 610 is quite old now and, IIRC, has no internal battery. The ephemeris data (that allows a really quick lock) is stored with the help of either a button cell or, more likely, a supercapacitor, either of which could be 'past their sell-by date' by now.

If this is the case, the almanac data (I'm not sure how this is stored but it could be the backup that is mentioned in the other thread) will also be well out of date, thereby confusing your device as to what satellites it should be looking for.

Try leaving it outside and in one place for half an hour or so before condemning it to the bin, especially if it is otherwise working for you.
_________________
Tim

[robertn]

Sorry for the confusion, I could have been clearer.

The GPS reciever is the flip up module on the back of of the iCN. "No NMEA data" means that this module is not sending (transmitting) NMEA sentences down the wire to the motherboard inside the case of the iCN. (At the right baud rate etc etc etc)

The GPS Module always sends NMEA data. Even when the GPS module is not able to see any satalites. So if there is no NEMA data being recieved, something is terribly wrong. It have absolutely nothing to do with being inside, outside, on the moon or at the centre of the earth. You should never see this message (for more than few seconds).

Tim: You are possibly right about the battery, if it's a primary battary (non rechargeable), it could be flat and would need replacement.

If it's a supercap it would still be fine after 10 years, It may also be a rechargeable battery - good for only 2-4 years on paper, but they usually do OK for a lot longer, but may also need replacement.

Supercaps and batteries typically need a long time to fully charge - upto 48hours, although 90% charged in 4-8 hours. If you used your iCN rarely, and for short times, it could be flat. I would suggest plugging the iCN in to the mains power adapter that came with it for at least 24 hours.
If possible, have the GPS antenna by a window (or connect an external antenna if you have one). This would fully charge a supercap, and allow the GPS time to aquire all the almanac and ephemeris data it needs.

I remember a while back some iCN's were having problems getting fixes. Navman released a patch for the GPS firmware to fix it. Has your unit had a recent software update? Maybe you should try this as well.

[robertn]

I pulled apart a broken iCN630 (a mate of mine dropped it a few years ago , and I am a bit of a collector:) )

It looks like the backup for the GPS module is a Lithium cell, not a supercap or rechargeable as I predicted. This means that over a period of time they will go flat. How long is anyones guess form a couple years to 10 years.

Once flat, the GPS needs to cold start every time it is used, as it would not remember all the ephemeris almanac data needed for a faster start. The TTFF for a cold start on these was 120 seconds... Every time you use the iCN... Occhh that would hurt.

It does not look too hard to replace the battery - an electronic professional or geek/wizz could manage it at home, otherwise any reputible electronic repair shop should be able to manage it. The part is probably not too hard to get.

Looking at some past Navman, I suspect some devices already have flat batteries. People are commenting about them taking longer to get a fix than when new etc.

However I don't think this will be causing the "No NMEA data" messages

[TerryWalsh]

Hi Robert:

I always get the "no nema data" message for a couple of minutes following a reset on my ICN520 and have done from new. From the way it behaves I guess that this occurs whilst the nav software is aquiring the GPS receiver. I certainly do not believe that it signifies that something is terribly wrong. Obviously if the message persists and the system never gets a satellite lock then there is a problem.

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