Satellite Testing

Slide1: 

Satellite Communication Subsystem Testing

Slide2: 

Payload Testing

4 Payload Testing: 

4 Payload Testing Beyond design integrity, proper material & process selection and well controlled fabrication techniques, the integration & testing (I&T) of payload equipment provides the last opportunity for payload risk mitigation prior to launch I&T typically comprises very detailed & procedural operations at 3 distinctive levels throughout the S/C construction: Unit level I&T Payload subsystem level I&T (i.e. prior to bus mate) S/C level Testing (i.e. post bus mate)

4.1 Unit Level I&T: 

4.1 Unit Level I&T Payload units must be tested extensively in order to mitigate in-orbit insurance risk For brand new unit designs with no flight heritage, typically several models are fabricated and subjected to various levels of environmental & operational tests prior to fabricating the units to be flown including: Engineering Breadboard Models (EBB or EM) Engineering Qualification Models (EQM) Life Test Models (LTM)

4.1 Unit Level I&T: 

4.1 Unit Level I&T Environmental & operational testing performed at these levels typically expose the units to levels beyond the expected exposure levels in-orbit And, with the exception of LTMs that may continue to be tested even after launch of the S/C, these tests are typically required to be successfully completed prior to fabricating the units to be launched

4.1 Unit Level I&T: 

4.1 Unit Level I&T The units to be launched are called Flight Models (FMs) and are typically tested to environmental and operational levels that are less severe than EQMs and LTMs, yet marginally more severe than the predicted in-orbit requirements Sometimes, the first FM in a batch of units is tested to environmental levels that are intermediate to FMs and EQMs and these units are called Protoflight Models (PFMs)

4.1 Unit Level I&T: 

4.1 Unit Level I&T Environmental testing includes: vibration, shock & acoustic (for reflectors) tests thermal & thermal vacuum tests electromagnetic compatibility (EMC) tests Operational testing includes: unit burn-in, RF power overdrive, under/over voltage, average and peak RF power tests performance testing at hot, cold and ambient environments

4.2 Payload Subsystem I&T : 

4.2 Payload Subsystem I&T Payload Subsystem I&T typically comprises: Payload sections I&T Payload Subsystem I&T The Payload can be divided functionally into four subsections during integration: The common input section comprises: receivers, input test coupler, input isolator, input filter assembly, RF switches, output hybrid, interconnecting waveguide & coaxial cables & select-in-test (SIT) attenuators

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T Common Input Section I&T comprises: gain alignment for the primary and redundant receiver paths by choosing the correct SIT attenuator values RF path switching functional check receiver DC current drain measurements once the unit is turned on The Second Section comprises: IMUXes, input redundancy switch networks, interconnecting coaxial cables and SIT attenuators The Second Section I&T comprises: equalizing the channel path losses by choosing the correct SIT attenuator values

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T RF path switching functional check Input Group Delay & Frequency Response measurements The Transponder Amplifier Section comprises: DAs, TWTAs or SSPAs, interconnecting waveguide & coaxial cable, SIT attenuators and for BSS payloads, IBAs, OBAs & phase adjusters The Transponder Amplifier Section I&T comprises: gain alignment for the primary and redundant transponder amplifier paths by choosing the correct SIT attenuator values phase adjuster alignment for TWTA pairing (BSS only) DA & PA DC current drain measurements after the units are turned on

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T Command and telemetry functional checks gain transfer measurements The High Power Output Section comprises: OMUXes, harmonic/lowpass filters, output redundancy switch networks, output test coupler, high power output isolators & receive rejection filters & interconnecting waveguide The High Power Output Section I&T comprises: a functional check of the RF switches

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T Once all 4 sections are integrated & tested, the Payload Subsystem is then subjected to it’s first end-to-end testing Payload Subsystem End-to-End I&T typically comprises: Command & telemetry function RF Leakage & Susceptibility (“Sniff & Spray”) DC power drain Receiver frequency translation Gain Transfer Input power to saturate Saturated output power

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T Overall Inband & Out-of-band Frequency response Overall Group delay response Linearity Gain Control Inband & Out-of-band Spurious TWTA Helix current/SSPA Gate current telemetry TWTA Anode voltage telemetry RF continuity verification for all possible RF paths in the payload

4.2 Payload Subsystem I&T: 

4.2 Payload Subsystem I&T Anik E I&T

4.3 S/C Level Testing: 

4.3 S/C Level Testing After the Payload Subsystem is mated with the Bus Subsystem, the next phase is referred to as S/C Level Testing and it comprises several distinct test phases: Initial S/C Test S/C Vibration Test S/C Thermal Vacuum Test Final S/C Test Antenna Range & EMC Test

4.3 S/C Level Testing: 

4.3 S/C Level Testing Anik F Just Prior to S/C Level Testing

4.3.1 Initial S/C Test: 

4.3.1 Initial S/C Test The purpose of the Initial S/C Test, also called the Initial Performance Test (IPT), is to establish a performance reference prior to S/C environmental tests (vibration & thermal vacuum) Typically, the test requirement resemble the Payload Subsystem End-to-End testing & IPT is performed by: terminating the payload output ports with either high power loads or by high power RF absorber boxes calibrating the uplink and downlink test interface before performance testing

4.3.2 S/C Vibration Test: 

4.3.2 S/C Vibration Test The purpose of S/C Vibration Testing is to verify the integrity of the S/C mechanical structure after integration by subjecting it to a simulated launch environment Typically: The antenna assemblies and solar panels are installed prior to the test The command and telemetry functional test is conducted before and after the vibration Payload performance testing is not done during this phase

4.3.3 S/C Thermal Vacuum Test: 

4.3.3 S/C Thermal Vacuum Test The purpose of S/C thermal vacuum test (SCTV) is to gather performance test data in a simulated space environment, to thermally exercise the recently integrated payload and to perform tests that mitigate the risk associated with the quality workmanship The SCTV phase typically consists of: Performance Tests: ambient environment testing (also called open door testing) similar to IPT vacuum hot and cold plateau performance testing similar to IPT

4.3.3 S/C Thermal Vacuum Test: 

4.3.3 S/C Thermal Vacuum Test Workmanship Tests: Thermal vacuum cycling Transponder small-signal gain monitoring through temperature transitions (i.e. hot to cold & cold to hot) Hot, high power soak monitoring in which several transponders are operated at the designed operating point simultaneously until thermal stability is achieved (the chart on the following slide demonstrates one of these tests during which a latent workmanship problem was detected) Thermal balance to ensure that the payload units operate at their predicted temperatures

4.3.3 S/C Thermal Vacuum Test: 

4.3.3 S/C Thermal Vacuum Test Hot, High Power Soak Test Data

4.3.4 Final S/C Test: 

4.3.4 Final S/C Test The purpose of the Final S/C test is to demonstrate that payload performance did not degraded after exposure to environmental tests and to establish a reference for Antenna Range and Launch-site S/C tests Test requirements are typically identical to IPT Testing is typically conducted through the input & output test coupler ports because the Antenna assembly is typically integrated prior to testing

4.3.4 Final S/C Test: 

4.3.4 Final S/C Test NIMIQ Just Prior to Final S/C Test

4.3.5 Antenna Range Test: 

4.3.5 Antenna Range Test Antenna Range test is typically performed in a near-field range or a compact antenna test range (CATR) facility with the S/C in full flight configuration (i.e. all thermal blankets and sun shields installed) Tests typically comprise: Receive airlink antenna pattern measurements Transmit airlink antenna pattern measurements EMC & Passive intermodulation measurements

4.3.5 Antenna Range Test: 

4.3.5 Antenna Range Test MSAT Just Prior to Antenna Range Test

4.4 Launch-site S/C Test: 

4.4 Launch-site S/C Test The purpose of Launch-site S/C testing is to verify the integrity of the payload after spacecraft delivery to the launch-site Typical tests include: Command & telemetry functional check Sometimes, a transponder noise mound test is conducted for each channel Results are then compared with data that was measured at Final S/C testing

4.5 Performance Trending: 

4.5 Performance Trending The purpose of performance trending is: to track the performance of key payload parameters across all S/C test phases in order to identify any anomalies prior to launch to provide a baseline for predictions of performance during in-orbit testing

4.5 Performance Trending: 

4.5 Performance Trending Unit failure identified, unit was replaced Transponder realigned for in-family gain

4.5 Performance Trending: 

4.5 Performance Trending Pronounced sensitivity at cold identified

4.5 Performance Trending: 

4.5 Performance Trending Receiver vacuum sensitivity highlighted, unit was retuned

4.5 Performance Trending: 

4.5 Performance Trending Unit failure identified, unit was replaced

4.6 In-Orbit Testing: 

4.6 In-Orbit Testing The purpose of In-orbit testing (IOT) is to demonstrate that the S/C performance has not degraded after launch and drift orbit environmental exposure The payload IOT typically commences after the fully deployed S/C has arrived at its IOT orbital slot The major payload tests typically include: antenna patterns gain transfer, EIRP and SFD

4.6 In-Orbit Testing: 

4.6 In-Orbit Testing gain-to-noise temperature ratio, G/T in-band frequency response transponder gain control frequency conversion Test results are then compared to the trend of test results taken during ground testing and to the in-orbit predicted performance

4.7 In-Orbit Monitoring: 

4.7 In-Orbit Monitoring The purpose of in-orbit monitoring is to continue the performance trending of the key payload parameters that indicate the “health” of the payload Typically, this is done by monitoring the following telemetry parameters: TWTA helix and DC current or SSPA gate current TWTA anode voltage