Airbus Defence and Space

EARTH OBSERVATION, NAVIGATION AND SCIENCE

Navigation signal generation unit

The Navigation Signal Generation Unit is a space-qualified rad-hard unit that provides the three Navigation signals for the Galileo Navigation System. This includes the

• Generation of the Navigation message format from buffered data sets,

• Addition of self-generated timestamps to the Navigation message

• Modulation of the data stream onto spread spectrum codes,

• Mapping of multiple spreaded signals into a complete navigation signal,

• Programmable filtering and up-conversion to provide l signals in or near baseband.

As the timing and modulation performance of the signal generation is essential for the performance of the Navigation system, the design was optimized to be robust against environmental effects degrading the stability. Together with this product, test systems were developed to asses the signal performance within open and closed-loop tests. These test tools are also usable for the verification of other Navigation signal generators. The NSGU is the product of cooperation between Saab Space and Austrian Aerospace together with Airbus Defence and Space Germany. Airbus Defence and Space’s responsibilities were the development of the Power Converter, the Application Software, VHDL Code for the spreading codes and the environmental and technical performance test on box level.

Features / technical details

• Independent Generation of three Navigation Signals for Galileo (E5, E6 and L1)

• Autonomous formatting of the Navigation data streams based on pre-stored buffers

• Shift register-based PRN code generators for Primary Codes

• Memory-based generation of the Secondary Codes

• Several configuration options for Code and Data Rates and BOC frequencies and modulation schemes

• Independent complex programmable filtering for each sub-channel to adapt the signal bandwidth and apply a pre-distortion to compensate for linear degradations of following modules in the signal path (e.g. up-converter, power amplifier, antenna)

• Master Clock input frequency 122.76 MHz

Applications

• Navigation Payloads (global or regional)

• Pseudolite Systems