无线电工程

目前部分运载火箭导航接收机采用双天线功率合成的方式接收处理信号，功率合成将两路输入信号在射频端进行合路，但可能会引入一路噪声，带来信噪比（Signal-to-Noise Ratio， SNR）的损失。为了提高天线对接收卫星信号的覆盖性能及对载体姿态变化的适应能力，提出了多天线信号分集接收的方式，分集接收在完成各支路信号的同频同相调整后，进行各路信号的加权合并。对两种导航信号接收处理技术进行了对比研究，介绍了功率合成与分集接收的原理，讨论了2种接收方式对SNR的影响，对提出的分集接收方式给出了加权方法、推导了加权系数并进行了测试，对适用于分集接收的双锁相环（Phase-Locked Loop， PLL）与传统的单锁相环进行了比较。结果表明：功率合成使用简便，但可能存在至多3 dB的SNR降低；分集接收算法相对复杂，但采用的双PLL设计减少了环路抖动，带来至多3 dB的SNR增益，有利于抵抗信号衰落。采用分集接收方式的产品已经过了飞行验证并取得了良好的效果，尤其在箭体发生大的姿态机动变化时。

Currently， some launch vehicle navigation receivers utilize a dual-antenna power combining method for signal reception and processing. Power combining merges two input signals at the radio frequency end， but this may introduce additional noise， leading to a loss in Signal-to-Noise Ratio (SNR). To improve the antenna's coverage performance for receiving satellite signals and its adaptability to carrier attitude changes， a diversity reception method for multi-antenna signals is proposed. Diversity reception performs weighted combining of signals from various paths after completing co-frequency and co-phase adjustments for each branch signal. A comparative study on these two navigation signal reception and processing techniques was conducted. The principles of power combining and diversity reception were introduced， and the impact of both reception methods on SNR was discussed. For the proposed diversity reception method， a weighting method is provided， weighting coefficients are derived and tested， and a comparison between the dual Phase-Locked Loop (PLL) suitable for diversity reception and the traditional single PLL was performed. Results indicate that: power combining is simple to use but may result in a SNR reduction of up to 3 dB; the diversity reception algorithm is relatively complex， but the adopted dual PLL reduces loop jitter， improves SNR with a gain of up to 3 dB， and is beneficial for resisting signal fading. Products adopting the diversity reception method have undergone flight verification and achieved good results， especially during large attitude maneuver changes of the rocket body.