Instrumentation & Measurement Magazine 25-7 - 39

analyzer to characterize satellite transponder parameters as
explained above. Using a dual ATE system based on the above,
a significant reduction in test time is achieved for complex satellites
consisting of 1000 or more test configurations [16]. A test
configuration is a unique number that identifies a unique RF
path on the payload.
The key contributions of the paper are as follows:
◗ Development of test system architecture and optimum
calibration methodology
◗ Identifying optimum instrument settings to achieve
required measurement uncertainty and optimum test
time
◗ Design of ATS Software
◗ Performance evaluation of the developed system on
hardware simulator
State-of-the-Art
Very few pieces of literature exist worldwide that discuss
multibeam or multiband ATS at the integrated satellite level
to minimize test time. Space players like Tesat Spacecom [3]
and Thales Group [4] provide measurement capabilities for
end-to-end satellite test to various customers worldwide.
They utilize synthetic measurement test philosophy that
encompasses controlled calibration procedures through
measurement software. Along similar lines, [5] uses true synthetic
architecture and provides a single box solution which
is low cost, fast, flexible, has a smaller footprint, reduced software
overhead, and shorter delays between data collections.
Wavecore [6] and Atos [7] provide advanced automated instrumentation
and measurement capabilities for payload
repeaters utilizing commercially-of-the-shelf instruments like
VNA, arbitrary waveform generators, digital controllers, and
power meters coupled with built-in-self-test procedures that
ease calibration time and ensure high repeatability and accuracy
as well as minimize time. The proposed technique in [8]
utilized a synthetic measurement-based ATS system consisting
of commercially-of-the-shelf instruments (COTS) to test
electronic warfare payloads that emulate end-to-end testing
functionality and offer advantages like flexibility, modularity,
size, weight and low cost. The authors in [9] implemented
a PXI based automated test tool to test integrated components
of the satellite communication system (SDU and SCM)
using LabVIEW programming software for end-to-end verification
using the RS-232 interface. Along similar lines, the
work in [10] details the development of virtual instrumentation-based
ATS to test and evaluate C-Band Transmitter
packages for geo-communication spacecraft. The ATS carries
out automation of various instruments on the GPIB interface.
Authors in [11] designed the ATS for VSAT satellite communication
on the .NET framework that focuses on specific
aspects like focusing design, process realization and scalability
of the testing. Authors in [12] developed automated
software to characterize parametric sets of active and passive
subsystems such as frequency, power, spectral characteristics,
response, quality analysis, and EMI/EMC performance
for various satellite earth station components with varying
October 2022
frequency ranges using COTS instruments. Authors in [13]
propose an alternate method of introducing the concept of a
measurement plane for system-level specification. The work
defines a selection matrix for devices under different test and
measurement conditions and discusses the advantages of the
proposed idea on overall cost, quality, and schedule. Authors
in [14] detail the algorithms, methods and models classification
for VNA to provide high measurement s-parameter
accuracy for various types of DUTs. Along similar lines, the
author in [15] explores the capability of VNA in modern ATE
measurement systems. The work also addresses the limitations
of the traditional receiver-based system and describes
VNA capabilities like phase measurement, dynamic range,
non-linear device measurement and accuracy.
The literature surveyed so far demonstrates test capabilities
by developing measurement instrumentation at the
subsystem or system level. Still, no study discusses VNA based
ATS architecture that integrates RF measurement, calibration,
real-time amplitude and phase equalization at the measurement
plane and interfaces with telecommand and telemetry
system for closed-loop RF characterization of payload. Motivated
from the discussions mentioned above, the proposed
architecture establishes the state-of-the-art methodology for
multibeam and multiband payload characterization at various
stages of integrated satellite tests. The proposed method is efficient,
minimizes test system complexity, and allows multiple
parallel deployments of the test setup and a significant reduction
of time with a very minimal contribution to the end-to-end
electrical integrity of the payload.
Architecture of ATS
Architecture
Fig. 1 shows the generic architecture of ATS. It consists of three
crucial building-block categories:
◗ Electrical monitoring and control system
◗ Environmental monitoring and control system
◗ Payload test system
The payload test system performs parametric characterization,
power/gain stability test or signal integrity verification.
The electrical system consists of Telecommand (TC), Telemetry
(TM) and power monitoring and control. The environmental
system consists of vacuum, temperature and humidity
monitoring and control. These entities are interfaced with
the payload for its intended operation at various test stages.
The ATS catering to the parametric measurement for the payload
system is described mainly in this paper. Fig. 2 shows
the setup diagram that consists of VNA, Vector Signal Generator
(VSG) and Vector Signal Analyzer (VSA). The Switching
and Interconnect Network (SINE) is realized for path changeover
between stimuli and measurement equipment. Switch
matrices are an integral part of the spot beam test system.
Components like switches and cables are utilized to realize a
common wideband measurement system. The software running
on a controller (computer) controls the ATS via GPIB/
LAN communication bus.
IEEE Instrumentation & Measurement Magazine
39
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