1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-11a71 Center Point of Contact: JPLa71 Submitted by: Wil HarkinsSubject: Radiated Susceptibility System Verification Practice: Verify that a flight vehicle or system is hardened to the launch, boost, and flight electromagne
2、tic radiation environment by radiating simultaneously, during system checkout, on all major emission frequencies that are known to exist during vehicle operations. Monitor all critical systems for erroneous performance while the spacecraft or system is stepped through all operating modes.Abstract: P
3、referred Practice for Design seven antennas are directed toward the Energetic Particle Detector (EPD). The antenna assembly was moved to appropriate locations to illuminate each sensitive area as the test progressed.Provided by IHSNot for ResaleNo reproduction or networking permitted without license
4、 from IHS-,-,-refer to D descriptionD Figure 1: Galileo System Test with Seven Antennas Directed Toward the EPD When a spurious response is observed, each transmitter is turned off and on sequentially until the cause of the response is isolated to one or a combination of radiators. The probability o
5、f the particular signal or combination of emitted signals occurring simultaneously with the particular spacecraft mode must be evaluated before any remedial action is initiated.In a complex system which emits and is exposed to a number of radiated signals, there is a large number of spurious frequen
6、cies which may produce unexpected results during ground checkout, launch, and flight. Sources of electromagnetic radiation are listed in Table 1.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Table 1: Sources of Radiated Emissions EXTERNAL a71 Test
7、Range Tracking Radarsa71 Space Shuttle Transmittersa71 Booster Transmittersa71 AM, FM, & TV Broadcast TransmittersINTERNAL a71 On-board Transmittersa71 Receiver Local Oscillatorsa71 Data Bus Clock FrequenciesThese signals or their harmonics may combine to produce intermodulation products at a sensit
8、ive frequency which could cause an unwanted response. Susceptible frequencies that may respond to the emissions are receiver main tuning frequencies, image frequencies, and the 1st and 2nd receiver intermediate frequencies.By simulating the radiation environment that the vehicle will be exposed to d
9、uring system checkout and free flight, potential sources of interference can be identified, evaluated, and corrected, if necessary. Synergistic combinations of sources may be detected with this approach. The probability of a successful flight will be increased by performing this verification test.Re
10、ferences:1. “INTERMOD“, A computer program to calculate intermodulation products of multiple transmitters that fall within the bandwidths of multiple receivers, Paul Rusales, Lockheed California Co., January 1987.Impact of Non-Practice: Erratic or uncontrolled performance may occur which could compr
11、omise or abort the mission.Related Practices: N/AAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2000-04-11a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
