# bandwidth for a chirp

Let $$s(t)$$ an up-chirp with bandwidth $$B$$ and $$y(t)$$ an down-chirp with the same bandwidth. For a multi user chirp spread spectrum (2 users), I use the up-chirp and down-chirp as spreading signal. The system bandwidth is $$B_c$$ with $$B_c=B$$.

But if I look at the spectrums for the 2 users, there is no superposition. Consequently, can we transmit these signals because we must have a system bandwidth $$B_c$$?

• "when I look at two spectra, there is no superposition" <- I don't think I understand what you mean. Can you put this in formulas, or a picture, maybe? – Marcus Müller Feb 21 '19 at 19:10
• without a window on the chirp, the bandwidth is arbitrarily wide. – robert bristow-johnson Feb 21 '19 at 23:36