NMEA Data query

[chasroberts]

I have a programme that requires NMEA 0183 V2.0 data to operate. Both my GPS mouse and handheld gps (Garmin 76) both seem to only be putting out V2.2 data. I seem to be able to get time and date data but position data doesn't seem to be getting through. Is there that much difference in the two versions?
If this is the problem does anyone have any idea how i can get hold of V2.0 data?
As always I defer to the wisdom of the forum.
Many thanks
Chas

 

[captainslarty]

Chas, what specific sentences are they looking for, and, what program is it. if there is an option, for example with the gps mouse, try selecting RMC sentence in the prog if available.

 

[chasroberts]

Thanks for the reply.
I think that the CD i got with the mouse (which was bought off the forum) is corrupted. The only things on the CD are the manual and a logo for Windows XP. When i try to download anything from this then I don't seem to get anything unzipped. Could this be the problem you think?

 

[captainslarty]

Hi Chas, if you are getting the date and time then the usb to serial converter part of the mouse is ok and working. What program are you using for the navigation though, also, do you know how to see which com port the mouse gps or indeed the garmin is on ?, if so, are you selecting the correct comm ports in the nav program. Please explain which nav program you are feeding the gps data into.
Joe

 

[chasroberts]

Hi Joe

Checked all the com port settings etc and am fairly sure that they are correct. On tracing the data stream big chunks of data are showing up in blue which according to the help thingy indicates that the data is incorrect. (Programme is Tsunamis 99) and according to the T99 manual requires NMEA0183 V2.0. Both my GPS' give out NMEA0183 V2.2 as stated above which is where I think the problem has got to lie.
I've googled this up and found a virtual driver which claims to convert V2.2 to V2.0 for use on older programmes but it's all a bit complicated for me to understand I'm afraid. You any good with pooters? If so I'll send you the link and you can tell me ifit's beyond the scope of us mere mortals......
From an increasingly ratty and frustrated and ready to dump the whole lot in the oggin Chas.

 

[Piddy]

Hi Chas,

I use Tsunamis Navigator (and before that T99) with a number of GPS including Garmin, MLR & Leica and haven't had any problems with different versions of 0183. Some older versions of NMEA such as 0180 had less information but the format hasn't changed that much.
I would try using hyperterminal in Windows to look at what is coming in to the serial port. Set the baud rate at 4800 and leave everything else as standard and you should see a constantly updated stream of data looking something like: (but not limited to (These are the only ones I can remember))
$GPGLL,N5001123,W00110012,0,0
$GPRMC,
It should repeat itself regularly (about twice or three times a minute)
Also check the input/output interface is set to NMEA output rather than the GARMIN proprietary format.

Cheers

Andy

 

[chasroberts]

Cheers Piddy and everyone else for their thoughts.

In the end bit the bullet and hooked the whole thing up to the fixed GPS which gives out NMEA0183 V2.0 according to the book and Hey Presto success!!!

Now got to start looking for a GPS mouse that puts out NMEA V2.0. I didn't think that it would have had that much effect but obviously does.

Once again, thanks to all.

Chas

 

[whiteoaks7]

I haven't looked - but I will be absolutely astounded if there is a significant difference between V2.0 and V2.2 in the major sentences (position being one of them). If you google NMEA you should find copies of the standards and you can check. So maybe your problem is elsewhere - update your software perhaps?

Since you seem to have V2.0 and V2.2 sources, use Hyperterminal (programs / accessories / communications / hyperterminal) to compare the signals you're getting. Please let me know if you find a difference . . .

 

[Danny]

I would also be interested if you find the significant difference.

I suspect it's more likely to be a software deficiency in the parsing of the sentences rather than a specific difference between 2.0 and 2.2. If you follow David's suggestion, check the number of decimal places in the position data fields. Different GPS receivers use 2, 3 or 4 decimal places. Amazingly some products can't cope with this.

Version 2.3 added a field to certain sentences but I don't think there's any changes to the number of fields between 2.0 and 2.2.