This information is edited from a repost of an acig.org forum post by mrdetonator:
http://www.secretprojects.co.uk/forum/index.php/topic,25.msg59.html#msg59
The Sapfir-23E (Izdelie 323E) radar is a coherent pulse Doppler system with the following capabilities:
-search and track of enemy targets from all-aspect angles under any weather conditions, day/night, natural interference (earth /clouds) and active/passive jamming.
-target recognition in co-operation with the SRZO-2 (friend-foe) interrogator.
-single target track, measuring target range, azimuth and angular positions.
-search and track of targets emitting heat, the radar antenna controlled by IRST sensor.
-form control signals for the SAU-23A autopilot in co-operation with LASUR-M (Vozdukh-1M) and RSBN-6S (ROMB-1K) systems, e.g. giving the "break-away" signal.
-form control signals for launching guided A-A missiles.
-provide continuous illumination of the target for the RGS-23 seeker.
-form control signals during gun aiming.
-ensure launching of unguided missiles in the synchronous/asynchronous mode.
-indicate RADAR/IRST information on the SEI indicator and one-way command symbols on the symbol indicator mounted on the gun sight ASP-23DE.
Tracking Technique
The Sapfir-23E uses the mono-pulse technique to track a single target.
Such a radar system consists of two parabolic antennas (moving, fixed) and the four-cone T/R element.
In this system, each returning radar pulse provides target pointing information by being focused at the antenna onto a group of four-cone T/R elements.
Tracking Process:
After pushing the „Zachvat“ button, the radar proceeds an additional search in the antenna position where the target has been found.
During this additional search the scan zone shrinks to ±8º in azimuth and ±52` in elevation.
If the target signal is present, the antenna performs angular tracking of the target and the radar range-finder is switched on.
The range-finder searches the target in the 9km range zone.
If the target is within the 9km zone, the antenna performs range tracking of the target.
The SEI indicator changes its appearance.
It is now showing the crosshair and the circle guidance indicator instead of selection lines (range zone).
The radar is tracking the target.
The tracking principle is based on summing the elevation, azimuth and the reference signal taken from the 4-cone receiver.