Variant 1. General overhaul of ZSU “Shilka” with overhaul of V-6R1 engine and update 

Update of RPK-2 from the composition of ZSU-23-4 consists in replacing it with radar system RPK-RT in the composition of:
- radar 1RL33-RT;
- two range optic electronic system;
- enhanced concealment radar RL-RT-3, operating in 3 millimeter range, for tracking air objects from a distance up to 10 km;
- digital computing system instead of standard computing device and gun coordinates converter.
Update of workstations by replacing standard equipment with automated workstations.

On the screen of the commander’s AWS there can be displayed:
а) air situation data (logbooks of targets and air objects):
from ZSU radar;
from ZSU optic electronic system;
from control post;
from other ZSU.
b) combat data:
assigned fire area;
prohibited fire areas;
take-off angles;
c) tactical data:
ZSU self position, ZSU coordinates and orientation; 
digital (vector) topographical terrain map;
positions of covered troops, neighbor ZSU and interacting air defense systems.
d) data about condition and operation modes of the gun, hardware and equipment of ZSU:
operation modes of antiaircraft guided missile, quantity and condition of missile;
operations modes, type, quantity and condition of ammunition;
operation modes of radio electronic systems, propelling system, power supply system (from combat information and control system).

Hardware of gunner’s AWS is mounted instead of T-35M box. The hardware allows operating in radio and optic electronic channel for independent searching and tracking of target and firing.
Hardware of distance-operator’s AWS is mounted instead of standard hardware. 
Built-in simulator allows training of standard ZSU crews for firing exercises in maximum realistic conditions. 
Replacement of stabilizer directional gyroscope 1А-Sb.02 with hardware using platformless inertial navigation system technology.
Existing stabilizer directional gyroscope 1А-Sb.02 in ZSU-23-4 is offered to be replaced with platformless inertial navigation system, built with the use of high accuracy accelerometers and fiber optic gyroscopes with a closed loop. In order to improve characteristics in the item it is carried out interconnecting with odometer and satellite navigation GPS/GLONAS signals receiver.
During the update P-123M standard radio station is replaced with modern digital ones (type of radio stations used is determined by the Customer).

During the update of GM-575 track vehicle the following is carried out:
- works for improving driving performance and controllability;
- update of autonomous power supply system;
- installment of protection system from high accuracy weapon guided by laser system.

Driving performance and controllability are improved by means of:
- traction engine with a power not less than 280 h.p.;
- BCN fuel pump in fuel system and AK-150SV compressor with pneumatic equipment set in air starting system;
- hydro mechanical transmission with hydraulic boosters for gas friction and brakes, with dry type disk brakes, with remote control and lever parking brake.

The update of autonomous power supply system is carried out for the purpose of replacement of power system aggregates, taken out of production and decrease of fuel consumption for the need of energy supply (current consumption comprises about 90 l/h, and the achievable one is 12-14 l/h).

The protection from high accuracy weapons is achieved by means of on-board protection screens, and also specialized system covering protection screens from weapons guided by laser. The protection system includes laser and smoke grenades launcher detection system. 

Also during the update of track vehicle the on-board information and control system and air conditioning system are mounted in it.
During the update the observation devices of commander and driver are mounted.
the commander device TKN-N is performed on the base of low-level high-sensitvity television camera and 3rd generation IIT. The device has VIDEO-IN/VIDEO-OUT function. 

Main technical characteristics:

TAIRA – day-night television goggles provide observation in twilight and at night.
For operation in complete darkness goggles have integrated IR-illuminator of 940 nm.
For defogging of eyepieces goggles have two air exhauster fans.

Main technical characteristics:

Comparison characteristics:

Variant 2. Update up to ZSU-23-4M4 

Basic update:
replacement of traction engine;
replacement of power supply system;
installment of hydrostatic rotation mechanism;
installment of compressor into pneumatic supply system;
installment of hydraulic boosters in control drives;
signature decrease in optic and thermal ranges;
radar update;
installment of digital computing system;
installment of air conditioner;
installment of telecode communication.

Additional update elements:
replacement of gas turbine engine of power supply system drive with diesel engine;
installment of self-protection system and laser warning system;
installment of driver’s television system;
replacement of driver’s seat;
installment of air conditioner at driver’s place;
replacement of night vision devices of commander and driver with passive ones.

Comparison characteristics:

Chassis comparison characteristics:

Variant 3. Update

The offered update project is performed on technically operable items 2A6 and includes equipping with passive optic electronic stations, which provide:
around-the-clock air and ground (overwater) target detection in the automated mode;
passive automatic target tracking by angle coordinates (azimuth, elevation) and range;
calculation and output of  full elevation values into 2E2 powered drive for guidance of AZP-23 to the future target.
Optic electronic stations provide 2A6 crew with the possibility to conduct combat operations in the passive mode up until and including fire opening, increasing by that the vitality at the battle field.  

Comparison characteristics: