Article,
A Software Perspective on GNSS Receiver Integration and Operation
International Space University, (2003)
Abstract
The GNSS industry is focusing on potential threats to satellite navigation
integrity, such as intentional and unintentional interference, signal-in-space
(satellite) and ground support infrastructure anomalies, shared spectrum
issues, and multipath. The experience of the International Space
Station (ISS) program, the Space Shuttle program, the Crew Return
Vehicle (CRV) program and other users of GNSS indicate that navigation
outages due to receiver software issues may pose as great a risk,
if not more, to the user than threats currently under study. The
improvement in GNSS receiver tracking capability and navigation accuracy
has been accompanied by an increase in software quantity and complexity.
Current and future GNSS receivers will interface with multiple systems
that will further increase software complexity. Rather than viewing
GNSS receivers as 'plug and play' devices, they should be regarded
as complex computers that interface with other complex computers,
sometimes in safety critical applications. The high cost of meeting
strict software quality standards, and the proprietary nature of
GNSS receiver software, makes it more difficult to ensure quality
software for safety-critical applications. Lack of integrator and
user insight into GNSS software complicates the integration and test
process, leading to cost and schedule issues.
