Passive drone detection systems to overcome existing gaps in air defence network

Enhancing its capability against the increasing proliferation of drones and to fill up certain operational voids in the existing defence, the Indian Army has sought 30 Passive Surveillance Suite and Detection Systems (PSSDS).

Passive systems, unlike radars and jammers, do not emit signals such as radio waves and are hence less susceptible to enemy observation and counter-measures. Passive systems rely on gathering information silently.

“The rapid proliferation of Unmanned Aerial System (UAS) poses a credible air threat across military and critical infrastructure domains. These threats range from unauthorised surveillance and intelligence gathering to payload delivery and Kamikaze attacks,” a request for proposal (RFP) issued by the Ministry of Defence states.

Presently only active sensors exist with the Army Air Defence (AAD) to carry out detection and tracking of such UAS, which has limited ranges of detection and tracking. Furthermore, use of such sensors put them at risk of detection by enemy’s electronic intelligence resources, making them vulnerable to enemy counter operations.

“For optimum performance, it is ideal that both active and passive sensors be employed together in an integrated manner. The present void of passive detection of such UAS is impacting the operational capability for undertaking an effective engagement,” the RFP adds.

Drones of various types were extensively used in Operation Sindoor, the brief but intense military exchange between India and Pakistan in May this year, which marked a drastic change in the nature of military operations as compared to past confrontations.

The proposed PSSDS is required to have a passive radio frequency detection system to detect, identify and display the direction of the hostile UAS through radio signal interception, and have an electro-optical tracking system consisting of a thermal imager, TV camera and laser range finder.

The system should be capable of detecting drones as small as 30 cm across at a distance of at least 3.5 km and a UAS having a size of 1.6 meters at ranges above 6 km, lock on to the target and track it automatically.

PSSDS would also be integrated with the Army’s Akashteer air defence command and reporting network for two-way date exchange to be an integral part of the air defence environment. It would be deployed across all terrains from high altitude to plains, deserts and coastal areas.