Moku:Pro’s Phasemeter measures phase (relative to a reference clock) of up to four input signals with better than 6 μradian precision from 1 kHz up to 300 MHz. Based on a digitally implemented phase-locked loop architecture, Moku:Pro’s Phasemeter provides exceptional dynamic range, zero deadtime, and measurement precision that exceeds the performance of conventional lock-in amplifiers and frequency counters.
Moku:Pro’s 4-Channel Phasemeter
Figure 1: User interface for Moku:Pro’s Phasemeter
As part of the new Moku:Pro platform, Liquid Instruments offers a unique solution for high-accuracy frequency and phase measurement. Unlike a conventional frequency counter or lock-in amplifier, our Phasemeter implements a digital phase-locked loop that can track frequency and phase continuously with exceptional dynamic range, zero dead-time, and automatic phase unwrapping. This advanced instrument provides an optimized solution for applications such as laser interferometry, fiber sensing, and optical and ultrasound ranging.
For example, this instrument has been used by scientists at NASA who developed a novel optical-based interplanetary communication system that overcomes the plasma-induced interference for a conventional X-band coherent radio link. They used the Moku:Lab Phasemeter to characterize the baseline performance of this system, which was possible because the Phasemeter can continuously measure the phase of a signal to extremely high precision with no dead time.
Simultaneously and Continuously Measure Phase, Frequency, and Amplitude
Moku:Pro’s Phasemeter is based on a phase-locked loop (PLL) architecture that tracks and records the phase, frequency, and amplitude of up to four independent signals. The high-precision measurements are taken relative to an onboard reference clock with greater than 300 ppb accuracy, resulting in better than 6 μradian precision from 1 kHz up to 300 MHz. Alternatively, an external reference clock can be used with the 10 MHz synchronization port. Measurements can be taken with zero dead time, and if a signal fades unexpectedly, free-wheeling mode intelligently holds the loop state and automatically re-engages when the signal returns. The phase-locked loop tracking also allows for ultimate flexibility with adjustable tracking bandwidth from 10 Hz (a great option for signals with a low signal-to-noise ratio) to 10 kHz (ideal for signals with large dynamics). See an example application which implements a PLL for laser frequency offset locking using Moku:Pro’s Phasemeter.
The integrated waveform generator enables users to produce up to four sine waves up to 500 MHz with the option to phase lock the output to their corresponding input signal. This integrated, software-defined instrumentation setup is cost-effective as it removes the need for additional standalone waveform generation equipment.
Integrated Datalogging, Real-Time Visualization, and Analysis
The Phasemeter facilitates rapid data acquisition with its integrated data logger. Users can log data directly to the onboard memory at rates of 30 Hz, 120 Hz, 477 Hz, 1.9 kHz, 15.3 kHz, and 122 kHz and transfer the data via a wireless connection.
The Phasemeter works with a touch-based interface that is intuitive and easy to use yet comprehensive. Out-of-the-box the Phasemeter can be used for real-time visualization and to apply data analysis methods such as power spectral densities, coherence, Rayleigh spectra, or Allan deviations. With these standard features, there is no need for users to perform calculations manually or conduct post-processing. Python and MATLAB application programming interfaces (APIs) are also available to develop automated test sequences or take advantage of a multi-instrument setup.
With exceptional dynamic range, zero dead-time, and measurement precision exceeding the performance of conventional lock-in amplifiers and frequency counters, the Phasemeter can handle your most challenging phase measurement needs. Able to accommodate evolving research, demanding timelines, and high-performance requirements, the Phasemeter is just one of many instruments available on the Moku:Pro, a single platform that brings high-performance software-defined instrumentation to the benchtop.
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