process_adsb.py

import pyModeS as pms

def convert_timestamp(msg):
    msg = bytes(msg, "utf-8")

    nanosec = (msg[2] & 0x3f) << 24 | msg[3] << 16 | msg[4] << 8 | msg[5]

    daysec =  msg[0] << 10 | msg[1] << 2 | msg[2] >> 6

    hh         = int((daysec/3600) % 24)
    mm         = int((daysec/60) % 60)
    ss         = int(daysec % 60)

    return f"{hh}:{mm}:{ss}.{nanosec}"

file = open("20190702_station_leipzig.dat", "r")

adsb_frames = []

with file as f:
    while f:
        line = f.readline()
        if line != "":
            if line[0] == "@":
                if line[-2] == ";":
                    adsb_frames.append({"timestamp":line[1:13], "adsb_frame":line[13:-2]})
                    # print(line[1:-2])
        else:
            break
print(len(adsb_frames))
print(convert_timestamp(adsb_frames[10]["timestamp"]))