Specifications

NMEA Sentence Output

The NMEA-0183 is output in text format with each item separated by a comma (,) and sentences

separated by a new line code (CRLF). The checksum is added up at the line end. The checksum

calculates the XOR’ed value of character data enclosed by $ , ' and * in hexadecimal string values.

Table 2.71

$ Sentence-identifying character , value (, value)… *Checksum CRLF

Multiple sentence types are defined.

Some data containing broken sentences may be read depending on when the GPS is opened and

read. NMEA sentence data can be properly interpreted use programming procedures such as those

listed below.

• Detect head of sentence using $ character.

• Detect end of sentence using line break (CRLF) code.

• Discard broken sentences verified with checksum.