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:
#40$WIFI,123532.00,A,-62,D8325A0ABADD,-64,EC172F8965BC,-64,7405A5D457D4,260321*07##
so the XOR for
WIFI,123532.00,A,-62,D8325A0ABADD,-64,EC172F8965BC,-64,7405A5D457D4,260321
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 info@mictrack.com