So lets try to clarify the V-880 5V28 missiles GSN mode settings.

(from right to left)

DO STARTA (acquire target with the GSN before launch)
POISK V VKL (track target in speed and direction angles)
This is the normal (optimal) mode of the GSN.
The RPC should receive 25dB target signal BEFORE launch.

POISK V VIKL (track target only in direction angles)
This mode is used against noise jamming targets, where the reflected Doppler signal cannot be velocity tracked by the GSN.
The RPC should receive 25dB target signal BEFORE launch.

B POLETE (acquire target with the GSN during flight)
This mode has a special usage. Several sites are surrounded by tall forests.

While the RPC on the elevated platform can track a low altitude incoming target, the missile on the ground cannot lock on it, due the surrounding forest.
So this mode is used against low altitude, incoming targets with 25dB RPC received signal strenght, when the GSN cannot achieve lock due surrounding obstacles.

B POLETE Vcr=<0
This mode is used against incoming targets with lower than 100m/s speed, or receding targets.
You need to have 34dB received signal strength this case.



Non of these modes are designed to extend the missile range.