FAST real time sine wave Locking And trackiNg devicEs (FASTSINE)

Lead Research Organisation: University of Sheffield
Department Name: Physics and Astronomy


Waves are a fundamental part of the physical world. In nature, they are emitted by oscillators such as a pendulum, and people deliberately generate and transmit waves to carry information. In both of these cases, the waves are not entirely static, but may have an amplitude, frequency, and phase that exhibit slow or rapid changes. Some of these characteristics are relatively easy to monitor, such as the wave amplitude. Others, particularly frequency and phase shifts, are more difficult to measure. In fact, methods for accurately locating frequency and phase shifts in a wave are a central enabling technology for many communications systems. An ordinary FM radio circuit is an early example of such a decoding algorithm. Nowadays, we are interested in transmitting digital data using waves, and we need fast, simple algorithms for determining the frequency and phase content of a digitised wave train embedded in a noisy background. In some cases, the wave trains may be natural - when we are studying a mechanical oscillator such as the suspended mirror of a gravitational wave detector, and the shifts in phase or frequency may be due to temperature fluctuations or strain releases in the suspension wire.

Methods I have developed for the purpose of studying such oscillations have proved also particularly effective for monitoring the phase and frequency of wave trains having other purposes, including those generated and transmitted in the communications industry, and those entering oscilloscopes and other high-end pieces of test and measurement equipment. Furthermore, nature is a source of other waves that we may find useful and interesting, like brain waves measured by electroencephelographs or the confusing mixture of wave trains used for communications during conflicts. In these cases too, methods for rapidly interpreting the information encoded in the fluctuating phase and frequency of the waves may be useful and important.

The proposed project takes the algorithms I have developed and applies them to real-world situations of practical importance both to commercial companies and to society. The algorithms I have developed, though mathematically quite sophisticated, are realised in iteration equations that utilise only simple mathematical operations like multiplies and divides, making them fast to implement digitally. The commercial potential of these algorithms is quite exciting, and we are certainly looking forward to continuing our exploration of these possibilities in the coming months.


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Description An algorithm set called IWAVE used for dynamic tracking of sine waves in noisy data was developed to maturity in work covered by this grant. The tracking of oscillations is a key requirement of many physics and experimental research areas, notably (in physics) gravitational wave searches and (in engineering) electric motor control, dynamic characterisation on power grids, and software defined radio. These methods may impact all of these areas in time. Impact in engineering fields is time consuming because of the tendency of the current methodologies to be preferred even when new methods start to out-perform them.
Exploitation Route These methods should be published in an engineering journal. The group is moving towards this publication.

The work has drawn interest from the medical physics community, in particular Creavo Medical Technologies, where it is being used to de-noise measurements of the magnetic field of the human heart. It shows potential to exceed the performance of earlier processing methods for removing noise from instrument data.

In addition, the method may be useful to remove background from data in a Met office array of low frequency radio antennas used for detecting and localising lightning strikes.

Finally, the work is feeding back into gravitational wave searches for continuous wave signals in the aftermath of binary object mergers. A group has formed in the LIGO scientific collaboration that is implementing these methods.
Sectors Aerospace, Defence and Marine,Digital/Communication/Information Technologies (including Software),Electronics,Energy,Environment,Financial Services, and Management Consultancy,Healthcare,Transport

Description The results of this research have been submitted in UK and international patent applications, and are being promoted for possible commercial impact in several areas including motor control, software defined radio and mobile communications, and power generation. In particular, new applications of the results of this research to (1) magnetocardiography - mapping the magnetic field of the human heart, and (2) analysis of meteorological data relating to lightning strikes are being pursued.
Sector Electronics,Energy,Healthcare
Impact Types Economic

Title APL 
Description APL is a class of phase locked loop developed in other research which in this grant was applied in particular to the problem of tracking parametric instabilities in gravitational wave detectors. As a result of applying APL to this problem, enhanced methods of using APL in the case where multiple oscillations at almost degenerate frequencies were developed. These methods in turn may be applied to other problems where multiple frequencies are present simultaneously in the future. In particular, these enhancements may be applicable to the problem of control of induction motors, where the currents in drive coils contain many frequency components. 
Type Of Material Improvements to research infrastructure 
Year Produced 2016 
Provided To Others? Yes  
Impact APL is being used by the Glasgow group to characterise violin modes of suspension wires for Gravitational Wave interferometers. It is also being used for various dynamic line tracking applications by researchers at the LIGO laboratories. It is one of several methods in place for the suppression of parametric instabilities at LIGO.