User's Manual

Smart Systems User’s Manual Version 1.1

End String

The GPS receiver can be set up to send one or more types of data strings. These

strings are called NMEA-0183 strings and each contains positional or other information

in specific formats. Each type of string is specified by a 5-character prefix. There are

numerous NMEA strings but examples of three different NMEA strings (GPGGA,

GPVTG and GPGSA) are shown below.

$GPGGA,134713.00,4338.221086,N,07938.421365,W,2,06,2.1,152.51,M,-35.09,M,5.0,0118*79

$GPVTG,34.0,T,,,001.4,N,002.5,K,D*70

$GPGSA,A,3,30,26,10,13,24,06,,,,,,,4.2,2.1,3.6*36

$GPGGA,134713.00,4338.221086,N,07938.421365,W,2,06,2.1,152.51,M,-35.09,M,5.0,0118*79

$GPVTG,34.0,T,,,001.4,N,002.5,K,D*70

$GPGSA,A,3,30,26,10,13,24,06,,,,,,,4.2,2.1,3.6*36

$GPGGA,134713.00,4338.221086,N,07938.421365,W,2,06,2.1,152.51,M,-35.09,M,5.0,0118*79

$GPVTG,34.0,T,,,001.4,N,002.5,K,D*70

$GPGSA,A,3,30,26,10,13,24,06,,,,,,,4.2,2.1,3.6*36

$GPGGA,134713.00,4338.221086,N,07938.421365,W,2,06,2.1,152.51,M,-35.09,M,5.0,0118*79

$GPVTG,34.0,T,,,001.4,N,002.5,K,D*70

$GPGSA,A,3,30,26,10,13,24,06,,,,,,,4.2,2.1,3.6*36

Before using the GPS with the Noggin, the DVL software needs to know the prefix of the

LAST string being sent in each group. In the example above, three strings are being

sent each time (GPGGA, GPVTG and GPGSA). Since GPGSA is the last one being

sent in each group, the End String needs to be specified as GPGSA.

To see what the End String is for your particular GPS, run System Test #1 and note the

first 5 characters on the last line after each series of strings is written to the screen.

These are the 5 characters that need to be filled in under End String.

The End String option allows the user to fill in the 5 character GPS prefix. Use the Left

and Right buttons to move left or right to different characters in the string. The currently

selected character will have an “^” under it. To change the letter of the current

character, use the Next button to change it to the next letter in the alphabet and the

Previous button to change it to the previous letter in the alphabet. Using these keys all 5

characters can be filled in with the necessary GPS End String.

See the GPS Receiver User’s Guide for details on how to set up the receiver to output

specific NMEA strings or groups of NMEA strings.

System Test #1

After all the settings above have been input and the GPS receiver is attached to the

serial port on the DVL, the user can test that the DVL is receiving the GPS output by

using the Test option.

If the NMEA strings are successfully being read by the DVL they will appear on the DVL

screen. This is a good time to note the prefix of the last NMEA string in the list and input

it in the End String setting above.

If the NMEA strings do not appear, check that the port settings are correct. It is also

possible that a crossover cable is required between the output cable of the GPS receiver

and the serial port on the DVL.