High-Precision Measurement of Sine and Pulse Reference Signals using Software-Defined Radio

TL;DR

This paper presents a cost-effective, high-precision measurement system for sine and pulse reference signals using software-defined radio hardware, outperforming traditional methods and enabling long-term data acquisition.

Contribution

It introduces a novel USRP-based measurement approach with high accuracy and long-term stability, comparing favorably to existing state-of-the-art techniques.

Findings

Achieved measurement precision of 0.36 ps for sine signals and 16.6 ps for pulse signals.

Demonstrated long-term data acquisition over several weeks using standard PC hardware.

Outperformed high-grade digital oscilloscopes in measurement accuracy.

Abstract

This paper addresses simultaneous, high-precision measurement and analysis of generic reference signals by using inexpensive commercial off-the-shelf Software Defined Radio hardware. Sine reference signals are digitally down-converted to baseband for the analysis of phase deviations. Hereby, we compare the precision of the fixed-point hardware Digital Signal Processing chain with a custom Single Instruction Multiple Data (SIMD) x86 floating-point implementation. Pulse reference signals are analyzed by a software trigger that precisely locates the time where the slope passes a certain threshold. The measurement system is implemented and verified using the Universal Software Radio Peripheral (USRP) N210 by Ettus Research LLC. Applying standard 10 MHz and 1 PPS reference signals for testing, a measurement precision (standard deviation) of 0.36 ps and 16.6 ps is obtained, respectively. In connection with standard PC hardware, the system allows long-term acquisition and storage of measurement data over several weeks. A comparison is given to the Dual Mixer Time Difference (DMTD) and Time Interval Counter (TIC), which are state-of-the-art measurement methods for sine and pulse signal analysis, respectively. Furthermore, we show that our proposed USRP-based approach outperforms measurements with a high-grade Digital Sampling Oscilloscope.