NMEA error correction?
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Posts: 46,084
Hello everyone,
I know this isn't strictly stamp related (although it will be hooked
up to a stamp) but does anyone know if native NMEA contains *any* error
correction at all? I can't seem to find a clear answer on this. . . It
doesn't seem sensible to me that the strings are supposed to go out (to any
number of myriad devices) with out any form of error correction. Are there
checksums on the individual strings, or something?
Duncan
I know this isn't strictly stamp related (although it will be hooked
up to a stamp) but does anyone know if native NMEA contains *any* error
correction at all? I can't seem to find a clear answer on this. . . It
doesn't seem sensible to me that the strings are supposed to go out (to any
number of myriad devices) with out any form of error correction. Are there
checksums on the individual strings, or something?
Duncan
Comments
>
> Hello everyone,
>
> I know this isn't strictly stamp related (although it will be hooked
>up to a stamp) but does anyone know if native NMEA contains *any* error
>correction at all? I can't seem to find a clear answer on this. . . It
>doesn't seem sensible to me that the strings are supposed to go out (to any
>number of myriad devices) with out any form of error correction. Are there
>checksums on the individual strings, or something?
>
>Duncan
To my knowledge no......the GPS just spews the strings out,
all I do is look for the string identifier, say $GPRMC and
do a byte count after the identifier....if the byte count
is a success, then I parse the data to to my device.
In this case I use a BS2SX as a GPS "data filter" for my
Ham Radio TNC. This was used before I got a proper APRS
TNC!
Jack Chomley
Australia
>
>
Jack Chomley
Rockhampton, Q,Land Australia
> At 11:27 PM 1/12/2001 -0500, you wrote:
> > I know this isn't strictly stamp related (although it will be hooked
> >up to a stamp) but does anyone know if native NMEA contains *any* error
> >correction at all? I can't seem to find a clear answer on this. . . It
> >doesn't seem sensible to me that the strings are supposed to go out (to any
> >number of myriad devices) with out any form of error correction. Are there
> >checksums on the individual strings, or something?
Yes, there are checksums:
RMC,225446,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E*68
The 68 on the end is the checksum. That will at least tell you if you have
valid data. How you correct it is another story.
Cheers,
Dave