Band-limiting and Dispersive Effects on High Order BOC Signals

Binary Offset Carrier signals are split-spectrum signals, with multiple "lobes" in the frequency domain spread over a large bandwidth. This is in contrast to BPSK signals traditionally used in GNSS systems. When a signal is passed through a linear filter, every frequency component experiences a different attenuation, phase shift and delay. In this work we address the impact of a linear filter on high order BOC signals, i.e. BOC signals where the subcarrier rate is high with respect to the code rate. In this case, the BOC lobes are widely spaced and, potentially, subject to significantly different delays. In this paper it is shown that this leads to a divergence between the code and the subcarrier. In addition, a simple approximation to the correlation function is derived under the condition that only the first pair of main lobes is passed through the receiver front end. Finally, the impact of bandlimiting on the code signal is addressed, where it is shown that the effective code bandwidth is potentially much less than the RF filter bandwidth, which has implications for tracking in thermal noise and multipath.