Research on linear frequency modulation detection technology based on fractional fourier transform

A coal mine roadway is a long and narrow confined space filled with high-power magnetic interference from electrical equipment, which may be accompanied by explosive substances such as gas, dust, etc. Thus, coal mine roadway wireless transmission is confronted with strong noises, severe multipath fading, limited transmission power, and many other challenges. Time-domain matching compression (TDMC) characteristics of linear frequency modulation (LFM) signals allow for signal detection via energy focalization, while the distribution of signal power during transmission is low and meets mine explosion-proof intrinsic safety requirements, making LFM-TDMC-binary orthogonal keying (BOK) one of the ideal schemes for wireless transmission for coal mine roadways. However, it is difficult to eliminate strong electromagnetic interference in the time-domain, which increases the bit error rate (BER) of this transmission scheme. Previous research has shown that an LFM signal through fractional Fourier transform (FrFT) can obtain similar energy focalization characteristics while avoiding noises and interference in the time-domain. Thus, compared to TDMC-based transmission, FrFT-based transmission has superior transmission performance by time-frequency transformation. In this study, based on the comparison and analysis of the energy aggregation properties of TDMC and FrFT, an LFM-FrFT-BOK transmission model is proposed. Analysis and simulation results show that, within acceptable algorithm complexity, the BER performance of LFM-FrFT-BOK is better than LFM-TDMC-BOK.