Mictrack GPS tracking device reports the GPS data in the NMEA format, so the checksum is an XOR of all the bytes between the $ and the * (not including the delimiters themselves), and written in hexadecimal.
For example, if your server gets the data as follows:
so the XOR for
output is 07
Following is the software engineers share and maybe also can help you understand it again.
Any questions please do not hesitate to contact us at firstname.lastname@example.org