Decoding qb50 hex payload

qb50_decoder.py

#!/usr/bin/env python3
import json
import sys
import socket
from datetime import datetime, timedelta

EPOCH_DATE = datetime.strptime('20000101T000000Z', '%Y%m%dT%H%M%SZ')
UDP_IP = '127.0.0.1'
UDP_PORT = 16886


def decode_payload(payload):
    dt = payload[:32]
    datasets = payload[32:]

    # calculate initial datetime
    seconds = int(dt[24:] + dt[16:24] + dt[8:16] + dt[:8], 2)

    telemetry = []

    while datasets:
        dataset = datasets[:64]
        if len(dataset) < 64:
            return
        print('d: {0}'.format(dataset))
        datasets = datasets[64:]

        dataset_datetime = EPOCH_DATE + timedelta(seconds=seconds)
        seconds += 60
        satellite_datetime = datetime.strftime(dataset_datetime, '%Y%m%dT%H%M%SZ')

        # mode
        status = dataset[:8]

        # battery voltage

        u = float(int(dataset[8:16], 2))
        bat_v = round((u + 60) / 20, 2)

        # battery current
        u = float(int(dataset[16:24], 2))
        bat_c = round((u - 127) / 127, 2)

        # 3v3 current
        u = float(int(dataset[24:32], 2))
        v3_c = round(u / 40, 2)

        # 5v current
        u = float(int(dataset[32:40], 2))
        v5_c = round(u / 40, 2)

        # temperature comms
        u = float(int(dataset[40:48], 2))
        comms_t = round((u - 60) / 4, 2)

        # temperature eps
        u = float(int(dataset[48:56], 2))
        eps_t = round((u - 60) / 4, 2)

        # temperature battery
        u = float(int(dataset[56:], 2))
        batt_t = round((u - 60) / 4, 2)

        data = {
            'satellite_datetime': satellite_datetime,
            'damod_data': {
                'status': status,
                'bat_v': bat_v,
                'bat_c': bat_c,
                'v3_c': v3_c,
                'v5_c': v5_c,
                'comms_t': comms_t,
                'eps_t': eps_t,
                'batt_t': batt_t
            }
        }

        telemetry.append(data)
    print(json.dumps(telemetry, indent=4, sort_keys=True))


def hex_to_binary(hex_payload):
    payload = ''
    for part, index in enumerate(hex_payload):
        payload += bin(part)[2:].zfill(8)
    return payload


if __name__ == "__main__":
    print('Listening on {0}:{1}'.format(UDP_IP, UDP_PORT))
    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
    sock.bind((UDP_IP, UDP_PORT))
    while True:
        hex_payload, addr = sock.recvfrom(1024)
        print('hex payload: {0}'.format(hex_payload))
        payload = hex_to_binary(hex_payload)
        print('binary payload: {0}'.format(payload))
        decode_payload(payload[48:])