The Search for MH370

Serving the MH370 Global Community

The new technology proposed in this paper is a global passive radar using radio amateur test signals. A total of 48 Boeing 777 aircraft flights were detected in all regions of the globe. The initial project, where this new passive radar system was used, was to locate flight MH370, which went missing in 2014. Radio amateur data from 7th/8th March 2014 was retrieved from the archives at www.wsprnet.org and the flight path following diversion into the southern Indian Ocean was reconstructed. The crash location was determined to highly likely be in an area with a radius of 30 km centred on 29.128°S 99.934°E. This area is around 1,560 km West of Perth, Australia.

The paper can be downloaded here

There are over 3 million radio amateurs. Many of them send test signals to find out how radio waves propagate around the globe. They want to know what is the best time of day and what is the best frequency to use to talk to their radio contacts around the world. Prof. Joe Taylor is a Nobel laureate and a radio amateur who invented the Weak Signal Propagation Reporter (WSPR) protocol. Taylor used his expertise in systems designed to measure weak radio signals over long distances to benefit the radio amateur community. The WSPRnet database currently contains 8.5 Billion global radio links archived back to 2008, but additions are being made at the rate of around 7 Million each day.

The protocol used was designed to test the propagation of high frequency ionospheric radio transmissions, but can also be used as a passive radar system with the applicable post processing. There are currently on average around 7,500 WSPR links between transmitters and receivers every 2 minutes offering both a near real time as well as historic passive radar capability.

The difference between active and passive radar is that the transmitter is controlled by the radar system in the active case, whereas passive radar uses radio transmissions from other sources. You can think of a passive radar like tripwires going around the globe. When an aircraft crosses a trip wire it disturbs the signal level or the signal frequency. These disturbances are recorded in the WSPRnet database. There are currently on average around 7,500 WSPR links or tripwires between transmitters and receivers every 2 minutes, offering both a near real time as well as historic passive radar capability.

The passive radar system described in this paper combines two long established scientific principles of physics. Firstly, long distance radio communication using High Frequency (HF, 3 – 30 MHz) ionospheric (or skywave) propagation has become standard practice. Secondly, radio waves can be reflected from aircraft that happen to fly through the beam, which is how radar works. We combine the reflection of radio waves by aircraft as used in classical radar, with ionospheric propagation and the WSPR protocol to detect and track aircraft over long distances. 

Prof. Simon Maskell is leading a team at Liverpool University conducting a large scale study into using the WSPR signals from radio amateurs to detect aircraft. The team are tracking thousands of aircraft and comparing the results captured in the WSPRnet database from the radio amateurs with the ADS-B position data transmitted by the aircraft. An international team of academics are being asked to peer review the results of the study prior to publication.