About my beloved "Volkhov":

I am sure that "Rab ot VM" works even after missile is launched:
Click to reveal..

Shortly, if we do not know the height when using TT I-87B, K3 and K4 depended by switching of the "Rab ot VM" switch.
If we switch it BEFORE launch or before 18-th second after the launch (11-12 km of the missile flight), K4 goes to missile on the 18-th second, and K3 on the 22.6 second of missile flight.
If we switch "Rab ot VM" after 18-th second of the missile flight - no K4, and K3 is transmiting on the 22.6 second, or in the moment of switching!

If K4 was transmited (switching "Rab ot VM" before 18-th second)- it tunes radiofuse for missile-target relativ speed 750 <V rel < 1750 m/s.
If K4 wasn't transmit at all (switching "Rab ot VM" AFTER 18-th second) - the radiofuse antenas are tuned for relative speed above 1550 m/s.
So if we do not know target speed or it's a high speed target, we should switch "Rab ot VM" after more than 18 seconds after launch.

Also for the VOZVRAT option:
From Hpasp:
Quote:
In STAND (normal) radio proxy fuse mode, 300m before the range boresight, K3 command is sent out, to arm the Radio-Proxy fuse.
If the missile avoid the target, and fly further the range boresight, the K3 command is emitted again by the SNR.
When the K3 received second time, the missile will do, what the SL-I/II switch signaled on the launcher.
If you press the VOZVRAT before the missile reached the range boresight, the K3 is signalled twice

If VOZVRAT is presse before 23-d second after launch, but before pass the range boresight the missile selfdestruct right after 23-d second from launch. if VOZVRAT is pressed after 23-d second from the launch, but before cross the range boresight, it destructed almmost imediately.

Click to reveal..