Estimation of Satellite-User Ranges Through GNSS Code Phase Measurements - Global Navigation Satellite Systems: Signal,Theory and Applications - page 123

2.3035 x 10 7

P s eudorange evolution f or PRN #3 0

Common transmission time
Common reception time

2.303

2.3025

2.302

2.3015

2.301

3.1174 3.1174 3.1174 3.1175 3.1176 3.1176 3.1176 3.1177

x 10 5

Time-TOW [s]

Fig. 9. Comparison between pseudoranges computed by using common reception time and
common transmission time

If we suppose to start the PVT computation at the beginning of a subframe, updating the
computation every second, using the common transmission time method, the first set of
pseudorange corresponds to a time of transmission equal to TOW and is always an integer
time of seconds for the subsequent sets. On the contrary, using the common reception time
method, the pseudorange is computed at a transmission time that is not the same as TOW,
but changes according to the reception time that has been fixed in the receiver. An example
of real values of transmission time, following the two different approaches is reported in
Table 1 for GPS satellite with PRN 30.

TIME OF TRANSMISSION [s] for GPS SV 30
Common transmission time Common reception time

311736 311736.277662467

311737 311737.277664239

311738 311738.27766595

311739 311739.277667661

311740 311740.277669371

311741 311741.277671082

311742 311742.277672854

311743 311743.277674503

311744 311744.277676275

311745 311745.277677986

Table 1. Different time of transmission according to the “common transmission” and
“common reception” methods