[Loadstone] No GPS time with wintec wbt300

Shawn Kirkpatrick shawn at odyssey.cm.nu
Sun Jun 10 01:41:37 BST 2007


This is a strange problem. Loadstone uses the following nmea fields: GGA, 
GSA, GSV, RMC. It can also use the gll and vtg fields but they're completely 
untested and aren't really needed if you have gga and rmc. All of these 
should be set to be sent once per second except for gsv, that should be set 
to send every 5 seconds since multiple messages come in with that one. As 
far as time goes, gga and rmc both contain time information. The gga message 
contains the time of day and the rmc messages contains this same time of day 
as well as a current date field. In order for loadstone to do anything 
useful you need at least the gga and rmc fields. If you're getting those you 
should be getting the correct time as well. The only time the time should be 
wrong is right when the receiver is started up and hasn't locked on to a 
satellite. If you have a valid gps signal then you should also have a valid 
time. Even when the time is wrong it'll still change, not get stuck on a 
single value. If this problem is consistant then turn on loadstone's logging 
and send me a copy of the log off list. Maybe this receiver is outputting 
something different from what's expected. As far as the other fields go they 
can probably be turned off but if you're going to send me a log of what this 
receiver is doing then maybe leave them on so I can get an idea of what 
those messages can contain.

On Sat, 9 Jun 2007, Hasan Karahasan wrote:

> Hello folks,
> a fiew months ago I wrote about this here, but because I had very less
> information, we couldn't solve this issue together in this list.
>
> Once again to remember: Loadstone does not get the correct GPS time using a
> wbt 300 with the antaris 4 chipset. Pressing the star key always results in
> constantly being 02 O.Clock. No change at all.
>
> Now I have played around with its configuration tool. It is well accessible
> with Jaws. You can set the receiver's update rate from 1 to 4 hz and you can
> enable or disable each NMEA record. You can also set the interval in seconds
> how often a record is to be transmitted.
>
> The receiver offers the following NMEA records:
> GGA, GLL, GSA, GSV, RMC, VTG, GRS, GST, ZDA, GBS, DTM.
>
> I have set them all to be repeated once per second. So maybe someone of you
> can recognize what is going wrong here. For example, I read about a NMEA
> record named GDT that is used for time and date information. This record
> definitely does not exist in my receiver's output. But it uses the ZDA
> record instead. As I can see this is also a kind of date and time info.
>
> Well, what comes up to my mind is:
> Wich of the above records are needed by loadstone?
> And does it make any sence to disable the records not used by loadstone?
> Is this missing GDT record causing my time problem?
>
> Thanks for any idea.
> Hasan
>
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