统一载波测控系统下行信道噪声功率谱密度标定依据分析与探讨

Analysis and Discussion on Calibration Basis for Noise Power Spectral Density of Downlink Channel of Unified Carrier TT&C System

统一载波测控系统集跟踪、测距、测速、遥测、遥控、通信、数传等功能于一体;噪声功率谱密度是测控设备下行信道的基本参数之一,反映了信道接收弱信号的能力,调节综合基带输入端的噪声功率谱密度至合理范围是完成航天测控任务的前提;介绍了统一载波测控系统下行信道的基本组成及设计要求;分析了噪声功率谱密度在下行信道中的传递特性,提出了在不同信号电平、不同测控体制下噪声功率谱密度标定的基本依据和原则;结合某型号S频段统一测控系统的工程实际,系统分析了噪声功率谱密度的原理和具体标定方法,该方法根据不同应用环境和测控体制,充分考虑各级增益的分配标准,准确计算各级信号噪声的电平,合理进行噪声功率谱密度标定,以确保系统工作的可靠性和稳定性,为设备性能指标测试和航天测控任务参数设置提供参考和依据。

Unified carrier TT＆C system integrates tracking, ranging, speed measurement, telemetry, remote control, communication, data transmission and other functions in one. The noise power spectral density is one of the downlink channel basic parameters of the telemetry and tracking and command （TT＆C） system equipment, which reflects the receiving ability of the channel for weak signal. Regulating the input noise power spectral density of baseband to a reasonable range is the prerequisite for completing aerospace TT＆C task. The basic composition and design requirements of downlink channel of unified carrier TT＆C system were introduced, and the transmission characteristic of noise power spectral density transferring in downlink channel was analyzed, then the fundamental reference and principle for demarcating noise power spectral density in different voltage levels and different command systems were proposed. Combining with a certain type of S- band unified carrier TT＆-C system practical engineering, the principle and specific calibration method of noise power spectral density were analyzed. In the method, according to different application environments and TT＆-C systems, noise power spectral density was calibrated reasonably, based on fully considering the allocation criteria of gain and accurate calculating the level of signal noise at all levels, in order to ensure the reliability and stability of the system. The method could provide the reference and basis for testing the indicators of the device and setting the aerospace TT＆C mission parameters.