TD-AltBOC: A new COMPASS B2 modulation

Abstract: AltBOC(15,10) is the baseline of COMPASS B2 signal modulation. It is a BOC-like signal having different PN codes in the lower and the upper main split lobes, which allow one signal service per lobe. The two lobes can be received and processed separately like two BPSK(10) signals, or coherently processed to achieve better performance. Interoperability among COMPASS B2, Galileo E5 and GPS L5 is also achievable using AltBOC modulation. However, Galileo’s 4-code AltBOC has drawbacks such as low efficiency and great receiver complexity. This paper presents a new modulation type named TD-AltBOC (Time Division AltBOC). The signal generation scheme and receiving method are presented, and are compared with AltBOC in the areas of power spectrum, ranging accuracy, anti-multipath performance, anti-interference performance, processing flexibility and complexity. Analysis results show TD-AltBOC has similar spectrum characteristics, interoperability, flexibility and anti-interference performance with AltBOC. When the frontend bandwidth is more than 50 MHz, TD-AltBOC can achieve better ranging accuracy and anti-multipath performance. It also has such advantages as high efficiency and low receiver complexity. TD-AltBOC could be a good solution to COMPASS B2 navigation signal.