# phase shift for a spreading signal

For a chirp spread spectrum with $$2$$ users, I can use an up-chirp and down-chirp for the spreading signals.

This is my questions:

1) These $$2$$ signals have a phase shift. If my $$2$$ users are at different distances from the receiver will this phase shift be problematic?

2) Should we care about the phase shift of the spreading signals for chirp spread spectrum with users at different distances from the receiver?

• You need to worry more about the symbol timing offset , or how you can arrange for the two transmitters to send signals that start and end at the exactly the same time I instants. The orthogonality might not extend to the case when one chirp arrives a few microseconds after the other: remember that light travels at approximately one foot per nanosecond in free space. – Dilip Sarwate Mar 27 at 14:20