Alternative positioning, using time-series geomagnetic data for positioning relative to the Earth’s permanent crustal magnetic anomalies, relies on geomagnetic sensing of high sensitivity, low drift and compact portable form factor. Optically pumped quantum magnetometers (OPMs) meet these three criteria, exploiting resonant interaction between coherent laser light and alkali atomic vapour samples. These sensors achieve femto-tesla sensitivity (parts per billion of the Earth’s magnetic field), alongside self-calibrated measurement, and can be realised in compact pocket-sized packages. However, to use the high accuracy and sensitivity of these devices on magnetically noisy real-world platforms, such as airborne platforms, surface ships and unmanned drones requires a high degree of noise rejection and filtering. Common-mode spectral noise sources in these environments can be several hundreds of nano-tesla, requiring noise rejection ratios in the tens of thousands. Magnetic gradiometry, utilising alkali spin maser techniques in a unique microfabricated caesium cell, is under development at the University of Strathclyde. The technique under development targets very high common-mode noise rejection (CMNR) by cancellation of common-mode systematics, such as alkali density and optical noise, at source, ensuring the bandwidth, uniformity and linearity required for high CMNR.

By developing this device for alternative PNT, employing total field measurement to permit map matching in addition to partial gradiometric tensor output, the requirements of MBDA’s application will be embedded from the outset, maximising impact in this important set of end uses. The PhD project will include meaningful trials with MBDA on UAV platforms and in high-noise magnetic environments, as available. To realise a navigation capability, the availability of suitable resolution maps are a key concern. To this end, a review of support that can be drawn from parallel research at Strathclyde may prove beneficial. It is also important to note the dual-use value of high CMNR, high-sensitivity magnetometry in a range of healthcare and biomedical applications.