Hi there,
I am working on designing a GPS L1 C/A signal simulator in MATLAB but there are a few things that are confusing me
1. After calculating the doppler frequency how to add it to the signal?
2. How to apply the code phases to the signal
3. When it comes to direct spread spectrum sequence is there any quicker and efficient way to spread all 5 subframes data with the spreading code?
Please read the book
Misra, P, and Enge, P., Global Positioning System: Signals, Measurements, and Performance, 2nd ed, Ganga-Jamuna Press 2006
The book will answer your questions.
Hari Hablani
IIT Indore, Indore, India
Let me try to answer your first question. I guess you are doing simulation of the PHY in baseband. If this is true, and if the baseband signal without Doppler is denoted by s(t), then to add Doppler, you may use s(t)*exp[j*(2*pi*fd*t+a)] to replace s(t), where fd is the Doppler frequency, t is time, and a is an optional phase offset. Hope it helps. Good luck.
Shouxing Qu This is exactly what I have been looking for.
I wanted to generate a baseband signal and then add doppler frequency shift and code phases later on.