Practical Issues in the Synthesis of Ternary Sequences

TL;DR

This paper investigates practical challenges in synthesizing ternary sequences with specific spectral properties, analyzes the impact of DAC non-uniformity, and proposes a flexible new sequence design method validated through simulations and experiments.

Contribution

It introduces a novel, adaptable approach for designing ternary sequences, improving harmonic suppression performance and addressing real-world DAC non-uniformity issues.

Findings

DAC non-uniformity degrades harmonic suppression

Proposed sequences achieve ~100 dB harmonic suppression

Validated through simulations and experimental tests

Abstract

Several issues related to the practical synthesis of ternary sequences with specified spectra are addressed in this paper. Specifically, sequences with harmonic multiples of two and three suppressed are studied, given their relevance when testing and characterizing nonlinear systems. In particular, the effect of non-uniform Digital to Analog Converter (DAC) levels on the spectral properties of the generated signal is analyzed. It is analytically shown that the DAC non-uniform levels result in degraded harmonic suppression performance. Moreover, a new approach is proposed for designing ternary sequences, which is flexible and can be adapted to suit different requirements. The resulting sequences, denoted as randomized constrained sequences, are characterized theoretically by deriving an analytical expression of the power spectral density. Furthermore, they are extensively compared with three synthesis approaches proposed in the literature. The approach is validated by numerical simulations and experimental results, showing the potential to achieve harmonic suppression performance of approximately 100 dB.