I'm working with a MATLAB Software-defined Radio, and I need to compute the travel time of the satellite signal, in order to get the pseudo range of the receiver (the direct distance between the satellite and the receiver position) before compute the receiver position.
I've already done sucesfully the acquisition and tracking of the signal, but I'm having problems about computing the travel time of the signal (since it multiplied by the light speed is the range). I can easily obtain the transmitted time from the navigation data, but I don't know how I can get the received time.
According to "A Software-Defined GPS And Galileo Receiver" by Kai Borre. On Pg 121
"For software receivers the situation is a little different. The time tcommon common to all pseudorange observations is defined as the time of transmission at the satellites. Hence the computation of position of satellite k is done at:
t_k=tcommon-dt_k
The only “receiver time” used is the relative time of reception from each of the satellites and which makes the individual pseudorange. A consequence of this time definition is that the computed satellite coordinates immediately refer to the ECEF system, and therefore satellite coordinates are not to be rotated about the Z-axis by an angle equal to the travel time times the Earth’s rotation rate. "