Research On Low-Frequency Noise Test System For The Critical Module Of Infrared Earth Sensor

Infrared earth sensor is a kind of component for measuring attitude in the satellitecontrolling system, which is used for measuring attitude deviation between the satellitebody and earth. It provides a benchmark for the antenna in the communication satellite,equivalent to satellite’s eyes. Infrared earth sensor consists of earth probe, bias andamplifying circuit and signal processing circuit and earth infrared characteristic iscaptured through infrared detector mainly contained in earth probe. The weak signalgiven by infrared detector will be amplified about ten thousand times throughamplifying circuit, then the processing circuit firstly do integral amplifier to thepreamplifier output earth trapezoidal wave signal and secondly do differential amplifierand thirdly do plastic processing. Finally, the optical axis of the earth sensor sweep outand in earth and the front and back edge signal is given. The field test results both athome and abroad show Infrared detector, bias circuit and amplifier circuit is the criticalmodule which decide the infrared earth sensor sensitivity and long-term reliability.Based on the working principle of Infrared earth sensor, the paper describes itsfailure mode and critical model in detail. First of all, on the basis of the analysis of thebasic structure of Infrared earth sensor, the quantitative model of key modules is derivedwith its typical feature of noise failure and extract the sensitive parameter oflow-frequency noise corresponding to thermal noise,1/f noise and g-r noise. Secondly,based on the virtual instrument technology, the paper establish the software andhardware system for low-frequency noise test of the critical modules of Infrared earthsensor according to the noise test principle of Infrared earth sensor, and the function andprecision of the test system is well validated. Last but not least, low-frequency noise ofthe infrared detector module, amplifying module and bias circuit module is tested andthe test result is analyzed. Moreover, whether the test system can be more accuratelytest and analysis of low-frequency noise have been validated. The test system alsoprovide a platform for noise detection and analysis of Infrared earth sensor.The bandwidth of the low-frequency noise test system is0.05Hz-1KHz and theamplifier noise voltage is1.2022E-7V. The experimental results show the noise voltageof infrared detector is more8to10times than that of amplifier, so the test system canensure the test accuracy.