Global Navigation Satellite System (GNSS) has continued research to multiplex signals to provide various services in a limited service band. Multiple signals transmitted on a single carrier must satisfy the condition that the constant envelope (CE) of the power at the input of the transmitter's power amplifier is constant. Among various signal multiplexing techniques, recently, TDMTOC, which implements Time-Division Multiplexing (TDM) based on Tertiary Offset Carrier (TOC) having three levels (‘-1’, ‘0’, ‘1’), has been proposed. Unlike the general TDM modulation, TDMTOC has excellent correlation characteristics and the effect of reducing interference between systems. In addition, compared to Constellation Tailoring (CT), there is no inter-modulation, so power efficiency is good. In this paper, we compare and analyze the performance of signals generated by adjusting various TDMTOC parameters (two different subcarrier frequencies, pseudorandom code frequencies) within the limited bandwidth. In addition, performance is compared with conventional GNSS modulations. Performance evaluation aspects we consider include correlation characteristics, spectral characteristics, and ranging error in multipath channel environments. We prove that TDMTOC is a superior modulation than the conventional GNSS modulations at the same subcarrier frequency and chip rate in general by comparing the simulation performance evaluation results in this paper. |
