大气湍流中直升机助降紫外光引导调制研究

摘要

为了研究大气湍流中不同调制方式对无线紫外光通信系统的性能影响,基于紫外光非直视通信模型,理论推导了弱湍流条件下开关键控、脉冲位置调制的误比特率.采用紫外光引导直升机助降模型,在不同调制方式下仿真分析了发射功率、通信距离、发散角、接收视场角、收发仰角对误比特率的影响.结果表明,不同调制方式的误比特率随着发射功率、发散角、接收视场角的增大而不断减小,随着通信距离、收发仰角的增大而增大;在相同条件下,脉冲位置调制比开关键控的误比特率更低,而且随着调制阶数的增加,误比特率会越来越小.这一结果对提高紫外光通信系统在大气湍流中的抗干扰能力具有一定的应用价值.%In order to study effect of different modulations on performance of wireless ultraviolet(UV)communication systems in atmospheric turbulence,the expressions of bit error rate(BER)using on-off keying(OOK)and pulse position modulation(PPM)based on UV non-line-of-sight(NLOS)communication model in weak turbulence were derived.Helicopter landing model using UV guiding technology was introduced and effect of transmission power,range,transmitter(Tx)beam divergence,receiver(Rx)field of view(FOV),Tx and Rx elevation angle on BER under different modulations were simulated.The results show that BER under different modulations decreases with the increase of transmitted power,Tx beam angle and Rx FOV,while increases with the increase of range,Tx and Rx elevation angle.Under the same condition,PPM has a better BER performance than OOK.BER decreases with the increasing of modulation order.The results have applicable values for improving the jamming-rejection capability of ultraviolet communication systems in atmospheric turbulence.