Quantum Enabled Radar

The urban environment is particularly challenging for radar surveillance of small targets in the low to medium airspace. This involves detecting, locating, tracking and identifying all airborne targets operating in this setting, with highly variable applications from counter-drone surveillance to drone traffic management to aeroecology.

However, weak targets can be masked by the strong clutter due to phase noise introduced by the radar local oscillator and thus fundamentally limit the radar sensitivity.

Advances in Quantum technologies offer a step improvement in phase noise performance compared to conventional oscillators. University of Birmingham (UoB) is developing a new class of ultra low phase noise optical lattice clock Quantum oscillator that can provide several orders of magnitude improvement in radar sensitivity against clutter.

To facilitate this enabling research, the Advanced Radar Network (ADRAN) facility funded by the EPSRC Quantum Technologies Hub is being set-up to enable comparative performance assessment of a radar systems with quantum oscillators as compared to conventional alternatives.

This is a measurement facility comprising two staring array radars, that will be referenced to the quantum oscillators, and overlooking Birmingham city centre as an example of a complex scattering environment. The much higher sensitivity systems will reveal new features in scattering that can be used not just for improved detection but also for extracting information pertaining to object type.

Team

Lead investigators

(School of Physics)
 


 

Research staff

PhD students

Gwyn DonlanGwynfor Donlan
(Jointly with Physics)

Darren GriffithsDarren Griffiths
(Jointly with Physics)

Xiaofei RenXiaofei Ren

Daniel WhiteDaniel White
(Graduated, for current work see Distributed and Multi-Static Radar)
 

Quantum oscillator

At the core of the Quantum oscillator sits the Quantum clock that captures precisely Strontium atom transitions that are used to lock an ultra-stable 698 nm laser. This in turn references a Transfer Laser operating at 1397 nm which pushes the optical signal via a phase noise stabilised fibre link up to the radar cabin where it interfaces with a Menlo Microwave Generator Unit (MGU) to produce an output compatible with the staring radar whilst preserving the phase noise characteristics of the optical signal. Microwaves synthesised from the high-quality output generated by Quantum oscillator will also demonstrate the added benefit of unrivalled accuracy of optical clocks compared to that of conventional oscillator devices used in radar systems.

Schematic of quantum-enabled staring radar
Figure 2. Schematic of quantum-enabled staring radar.

Currently the individual sub-systems in the Quantum oscillator network are being bench marked for phase noise characteristics and compared to data for the conventional oscillator currently installed in the staring radar. Furthermore, longer term stability of the frequency in the time domain is being compared using Alan Deviation measurements. In parallel, both staring radar have been installed at UoB Edgbaston Campus and are fully operational. The radar have been baselined through generating clutter maps and recording data from drone flights to quantify phase noise and detection sensitivity with the existing conventional oscillator.

Current work

Work is in progress to complete stabilising the network that connects the Quantum oscillator to the radar and evaluate the staring radar performance improvement as a function of oscillator characteristics in real-life, complex radar environments. This will enable to get a deep understanding of the fundamental limits of radar hardware on performance for monostatic configurations.

Furthermore, in dense urban environments, radar clutter’s spatio-temporal characteristics along with multipath are closely dependent on the transmitter-target-receiver geometry. These effects can be mitigated by spatially distributing the sensors to create a multistatic architecture but its then reliant on good synchronisation between each node in the network. The ultra-stable quantum oscillator can be used as master clock to synchronise the two systems and produce a fully coherent networked testbed. The aim is to measure the performance of the networked radar and explore applications for next generation RF surveillance systems. The investigations will result in understanding of different target scattering mechanisms that takes place over multiple observation angles, further enriching the information pertaining to targets. Using the results from the radar testbed, we aim to create RF scattering models for both targets and background which will be crucial to the development and take-up of networked radar sensing.

In summary the Quantum-enabled networked radar testbed will allow us to not only conduct the generic research on factors limiting radar performance, but also demonstrate its advantages for specific industrial applications, like counter-drone surveillance and aeroecology at a high technology readiness level and in real conditions. Such demonstrations will increase confidence on the readiness of the technology and expedite industrial adoption where the opportunity arises.