Dead Hand

Hi all this is my first thread here although I have been a lurker here on this forum for a long time and apprectate its excellent info it provides on defence related matters

As we all know that both USSR (now Russia) and USA have developed an eloborate system for delivering nucelear wepons , with both first and second strike capability , Both countries have suitcase like system to warn of impeding N-strike and press the button if required , There is one system that was developed by Russia besides the suitcase one which is known as DEAD HAND . What I have read about it is that incase the Russians are not able to retaliate to it incase of preemptive , deadly strikes by USA and if nothing surivives the strike ( again i say assuming) then within few days of the strikes a System called DEAD HAND goes active and if it dosent receives specified signals within certain days , It automatically activates & Launches all the missiles from secret location and Also signals the Subs in the seas (in case it didnt receive the launch codes /signals due to preemptive strikes) to launch it and this System is meant to be so secure and redundant that there is no way one could immobilise or destroy it and it will work for sure .

Can any one confirm if such a system does exist and if so can any any body provide more information on it