Multiplexing Performance Assessment of POCET Method for Compass B1/B3 Signals

Abstract

Compared with traditional GPS signals, modern GNSS signals are much more complex and have various new modulations. This introduces a difficulty in combining multiple signal components into a constant-envelope signal that maximises the power efficiency of High Power Amplifiers (HPA) on satellites. This paper first describes the fundamental Phase-Optimised Constant-Envelope Transmission (POCET) technique that searches the optimum combining solution for multiple binary navigation signals. Then the Compass B1/B3 signals are modelled by POCET. For the B1 band, a binary complex sub-carrier is adopted to implement the centre frequency difference between regional and global Compass navigation systems. Regional B1 Open Service (OS) signals and global TMBOC signals are combined with optimum loss of 1·0 dB. For the B3 band, Interplex modulation is proved to be the optimum method to combine QPSK (10) and BOC (15, 2·5) signals. Signal quality in the presence of finite word-length effects of Digital-Analog (DA) converters is analysed. Simulations for signal model validation are conducted. The result indicates that relative amplitude error less than 0·01 and angle error less than 0·1 degree can be achieved with 10 bit DA converters. The POCET method is demonstrated as an efficient solution for Compass signals.

General AltBOC Modulation with Adjustable Power Allocation Ratio for GNSS

“…Figure 2 shows the signal vectors in the first two sub-periods of subcarrier. After one sub-period, the phase angles of s 1 and s 2 would decrease 45° along the clockwise direction, and the angles of s 3 and s 4 would increase 45° along the counter clockwise direction (Zhang et al, 2012).

Figure 2.Signal vectors.

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“…At the B1 frequency, the early BeiDou regional (Phase II) system is transmitting a Quadrature Phase Shift Keying (2) (QPSK(2)) signal at 1561·098 MHz (Liu et al, 2010). However, the centre frequency for the BeiDou global system (Phase III) is 1575·42 MHz (Zhang et al, 2011). For the B2 signal, two service signals need to be transmitted at the B2a (1176·45 MHz) and B2b (1207·14 MHz) frequencies, respectively (Tang et al, 2010).…”

Constant‐envelope dual QPSK‐like modulation and its generalised form for modern GNSS signals

“…The baseline of Compass B1 signals contains a traditional BPSK(2) signal at 1561.098 MHz and MBOC (6,1,1/11) signals and BOC(14, 2) modulated authorised service (AS) signals at 1575.42 MHz [1]. In this Letter, the AS signals are not considered and assumed to be transmitted from a separate aperture in order to make the multiplexing problem easier [1].…”

“…In this Letter, the AS signals are not considered and assumed to be transmitted from a separate aperture in order to make the multiplexing problem easier [1].…”

“…Dual QPSK-like modulation: We first define the QPSK-like modulation as s 0 (t) = s 1 (t) + e jf s 2 (t) (1) where s 1 (t) and s 2 (t) are the two binary spreading code signals and ϕ is the phase shift angle between them. QPSK modulation is the special case for ϕ = π/2.…”