European Space Agency

Generic Test Interface System - GTIS


The primary objective of the GTIS was to provide a means to test next generation complex multi-spot beam payloads. The ever increasing numbers of uplink and downlinks necessitated a corresponding number of interfaces. The Generic Test Interface System looked to provide a re-usable non-flight interface to efficiently test these complex architectures in reduced time frames.

The GTIS was first used on a successful commercial flight program. The GTIS project subsequently explored a number of alternative usage methods and concepts to improve performance, taking into account the lessons learnt from the first practical deployment.

The main objective for the GTIS was to develop an interface and method capable of successfully testing complex multi-spot beam payloads. The challenge was to provide a high volume interface which reduced preparation times and improved the efficiency of testing at all stages of production, in particular at TVAC where managing large numbers of uplinks and downlinks is particularly difficult.

In addition to developing the hardware interface for the GTIS, a forward looking “Future Development” work package was carried out, taking benefit from the experience gained from utilising the interface on a Ka Band payload.

This formed the basis for investigation and study of alternative testing methodologies and test techniques, with parallel test systems interfacing with the GTIS.

GTIS Integrated on a Payload

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The key issues that the generic test interface addressed are:

  • Improvement of current test methods utilised within the AIT phases,
  • Construction of a test interface to aid the build sequence at payload level,
  • Development of current electrical testing capabilities to improve schedule and cost at both communications module and spacecraft levels,
  • Investigation of alternative methods which could be used to effectively test payloads.


The Generic Test Interface System was designed to fit a standard Astrium E3000 spacecraft and to be utilised on payloads for the duration of the testing phase. The main benefits of the inclusion of the GTIS are as follows:

  • Increased effectiveness of testing, providing cost reductions,
  • Improved schedule resulting from faster test methods and improved efficiency,
  • Increased system performance due to improvements in the accuracy and validity of test results,
  • The GTIS is compatible with a TVAC environment and greatly reduces cables through the penetration plate,
  • Reduction in the number of flight test couplers required on payloads,
  • Reduction in the number of calibrations needed during test campaigns.


The GTIS is a fully constructed RF interface which enables the user to switch RF stimulus/response between the spacecraft uplinks and downlinks.

This particular version of the GTIS has been developed with the capability to support up to 128 spot beam interfaces. However, the design of GTIS is modular and can be scaled up or down for future applications.

The GTIS construction is modular with heritage and generic units accounting for use across the frequency bands. The major components are as follows:

  • Two way switch units,
  • Remote calibration unit,
  • Uplink splitter/combiner unit,
  • Downlink combiner unit.


The GTIS project was split into two logical phases. Phase One encompassed the overall system design, build, integration and validation of the GTIS. This was closely followed by the inaugural use of GTIS as the test interface to a large Ka-band multi spot beam payload.

The second phase of the GTIS project was a “Future Developments” work package. This included a review of the use of GTIS, taking into account the lessons learnt from the first deployment. Armed with this valuable operational experience, alternative testing methods and test equipment architectures were studied with the aim of improving test flexibility and performance.

Both phases of the program have now been successfully completed.

Current status

Following the successful implementation of GTIS on a flight program, a further module of Future Development was undertaken to investigate new techniques and methods to improve the efficiency when testing multi-spot beam payloads.

The initial future development activity performed an in-depth review of the GTIS solution summarising improvements on the product and how it could be implemented on future payloads, including those of varying size and architectures.

The study identified ways that the payload architecture could be revised to simplify and improve the GTIS test interface. These architectural changes would facilitate a more efficient parallel testing approach.

Various work package activities investigated how parallel testing with multiple test systems could be employed to affect more efficient test campaigns. In addition other techniques employing multi tone and multi channel stimulus were studied for future incorporation.

Test software enhancements were identified to improve efficiency via test sequence optimisation, to improve the investigation/debugging capabilities, to import test matrices and to further develop results analysis software.

The conclusions from these activities were factored into the specification of a future payload test system. These requirements have in turn produced promising test equipment supplier solutions that are under review.

The success of the GTIS in payload test operation and the subsequent GTIS Future Development program has left Astrium especially well prepared for future contracts of payloads with multiple interface port requirements, the benefits of which have flowed into all areas of payload testing.

Status date

Thursday, February 27, 2014 - 08:48