Hensoldt unveils TwInvis passive radar

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German sensor solutions provider Hensoldt has unveiled its recently named TwInvis passive radar, demonstrating it to the public for the first time at the International Aerospace Exhibition (ILA) in Berlin.

Hensoldt on 25 April said the radar’s name is made up from “twin” + “invisible”, as neither TwInvis itself nor the targets to be detected emit any signals on their own, which means that they are “invisible”. Hensoldt’s passive radar offering previously had no official name.

The TwInvis system, which can be integrated into an all-terrain vehicle or a van, does not emit its own signals to monitor air traffic, but simply “passively” analyses the echoes of signals from radio or TV stations.
“Our newly developed, highly sensitive digital receivers now make it possible for a single TwInvis system to monitor up to 200 aircraft in 3D within a radius of 250 kilometres. This was unthinkable even just a few years ago,” said Hensoldt CEO Thomas Müller. “This will open up completely new options for application in such fields as air defence, the protection of large events or air traffic control.”

Working as mere receivers, passive radar systems detect aircraft by analysing the signals that they reflect from existing third-party emissions such as radio and TV stations. TwInvis obtains a precise airspace picture by simultaneously analysing a large number of frequency bands. For example, up to 16 FM transmitters (analogue radio) plus 5 frequencies used by several DAB and DAB+ transmitters (digital radio) as well as DVB-T and DVB-T2 (digital, terrestrial television) can be simultaneously analysed for the first time.
“Furthermore, Hensoldt’s new generation of software will provide unprecedented performance in terms of range and precision of detection,” the company said.

In civil applications, passive radar systems make cost-effective air traffic control possible without any additional emissions and without using transmission frequencies, which are in short supply.

In military applications, the system enables wide-area surveillance using networked receivers, while offering the advantage that passive radar systems cannot be located by the enemy and are very hard to jam. Moreover, no agreement is required with any other public authority, as there is no radiation, which allows the system to be quickly ready for deployment in new locations and to also be used in urban areas. This results in another advantage of the new technology: the system can be used in places where coverage was previously inadequate, in particular for example, in mountainous regions.

Hensoldt said that TwInvis has already shown what it can do in several demonstrations to military customers, air traffic control organisations and other interested parties.



Hensoldt has been working on passive radar for a number of years, starting in 2006. It is currently promoting its system to the civil and military air traffic control markets (particularly in the UK and Germany) and already has customers, although it is reluctant to disclose them. It has also supplied two demonstrator systems to the German Federal Office of Bundeswehr Equipment, Information Technology and In-Service Support (BAAINBw).