Ultra-broadband (UWB) over fiber technology has attracted much attention in recent years because of the advantages of large bandwidth and high transmission rate of UWB signals and the advantages of long-distance transmission and low loss of optical fiber transmission.This paper proposes a system for generating UWB signals based on microwave photonic technology. This is based on PM-IM conversion to generate monocycle signals, which are then first-order differential, resulting in a doublet signal that meets FCC mask. The doublet UWB signal has a center frequency of 5.4 GHz and a 10dB bandwidth of 4.3 GHz. This paper also proposes a signal processing technique based on DS-BPSK, convolutional coding, and chirped Bragg gratings for dispersion compensation of the signal. Through the simulation, when the FEC threshold is 3.8×10_-3^{, the sensitivity of the receive}r is increased by 5.5dBm, reduces the bit error rate.