Parsing GPS receiver output via regex in Python

Question

I have a friend who is finishing up his masters degree in aerospace engineering. For his final project, he is on a small team tasked with writing a program for tracking weat

Answer 1

You should also first check the checksum of the data. It is calculated by XORing the characters between the $ and the * (not including them) and comparing it to the hex value at the end.

Your pastebin looks like it has some corrupt lines in it. Here is a simple check, it assumes that the line starts with $ and has no CR/LF at the end. To build a more robust parser you need to search for the '$' and work through the string until hitting the '*'.

def check_nmea0183(s):
    """
    Check a string to see if it is a valid NMEA 0183 sentence
    """
    if s[0] != '$':
        return False
    if s[-3] != '*':
        return False

    checksum = 0
    for c in s[1:-3]:
        checksum ^= ord(c)

    if int(s[-2:],16) != checksum:
        return False

    return True