The L-band E-801M Oko (Eye) AEW and surface surveillance radar is described as being a pulse-Doppler equipment that makes use of a rectangular passive phased array antenna that is scanned mechanically in azimuth and electronically in elevation. As such, the assembly incorporates an array of 96 individual antenna elements (arranged in four rows with 24 units in each row) and has a rotation rate of 6 rpm.
E-801M is further noted as being optimised for the detection of low-flying air targets in heavy land or sea clutter and as offering air-to-air, air-to-surface and combined operating modes. Here, the combined mode sees the system observing sea surface targets for five azimuth scans, with the sixth switching to air-to-air surveillance.
Functionally, the system acquires, locates and tracks targets and only requires human intervention in terms of switching the radar on, deploying its antenna and selecting the required operating mode. In the Ka-31 application, the E-801M radar is understood to be fully integrated with the platform's onboard avionics and is described as simultaneously displaying a synthetic radar image, target markers/information and 'historic traces' to the helicopter's navigator/system observer (via the CABRIS-31 display sub-system on Indian aircraft - see Status) and handing-off information (via data link) to an associated ground or shipboard control centre.
Designated as E-801ME in its export version, the E-801M is further noted as being supported by a built-in test routine and dedicated test equipment. Janeʼs sources also report NIIRT as having developed ground-mobile (featuring a deployable 12 to 16 m high antenna mast) and airborne ground surveillance (with a 5.5 m long by 0.8 m deep antenna array) variants of the baseline Oko architecture.
