China Suggests Solution to Compass-Galileo Overlay Problem

August 24, 2009

China presented one possible solution to the impasse on frequency overlay between that country’s Compass system and the European Galileo program.

In a July 30 talk before the International Committee on GNSS (ICG) Working Group A – Compatibility and Interoperability (WG-A) in Vienna, Yuanxi Yang, from the China National Administration of GNSS and Applications (CNAGA) showed plans to move Compass signal modulation to binary offset carrier (BOC) , with an altBOC (15,10) open service (OS) signal in the aeronautical radionavigation band at E5b (centered at 1191.8 MHz).

FIGURE 1

FIGURE 2

Figure 1 shows an updated Compass signal plan, while Figure 2 shows the spectrum distribution.

Yang stated that spectral separation between the respective systems’ signals “would be beneficial for all GNSS systems and users,” while maintaining that overlapping of authorized service signals and frequencies between all GNSS “is unavoidable.”

China has not yet published a signal interface control document (ICD) for Compass.

Yang’s 11-slide presentation is downloadable at the ICG Working Group’s web page along with other presentations from that same workshop.