Exploring characteristics of BDS-3 PPP-B2b augmentation messages by a three-step analysis procedure

This study discovers three critical characteristics of PPP-B2b augmentation messages, potentially improving positioning continuity and accuracy for time-critical applications. Three new message characteristics are obtained by analyzing 863,895 PPP-B2b augmentation messages collected in June 2022 following a three-step analysis procedure. First, augmentation messages are broadcasted in the order of Message Type 1 (satellite mask), Type 4 (clock correction), Type 3 (DCB correction) and Type 2 (orbit correction) within each 48-s cycle. Average latencies of 5.11 s , 7.13 s , 18.15 s and 25.57 s are detected for these four message types, respectively. Second, two IOD mismatching issues have been identified, resulting in failing precise orbit and clock offset recovery. The first mismatching occurs between Message Type 4 and broadcast ephemerides, accounting for 0.01% out of 178,726 orbit corrections. The second mismatch between Message Type 4 and 2 accounts for 0.81% out of 1,421,519 clock corrections. Third, the service availability of PPP-B2b augmentation messages for BDS-3 and GPS satellites are within latitude (45.17° S, 57.33° N) and longitude (16.06° W, 98.64° W).