Mr. Saint

Can a kid get a comment in here on the fail safe problem? I would like to suggest to you radar and electronics people that very often the making of a circuit fail safe involves a twist of the wrist. If you need a checking device to check a check device to check a checking device, etc., and so on, until the failure of the checking device then determines the reliability of the system rather than the basic component, that may sometimes be because you failed to put the twist of the wrist in there. Let me illustrate it by something that is out of the radar line all together. Suppose you want to check all the doors on a pressurized airplane. You could do that by sending a positive energy through a micro-switch at each one of the points you want to check and have the positive energy coming through any one of those switches to light a red light in the cockpit that tells the pilot there is a door open somewhere. Well, one of these switches could fail and that airplane could be operated for three months without anyone knowing that the switch was not operating properly. Whereas, if you put a loop circuit around all those switches they can be made to operate a green light to tell the pilot that the doors are all closed now. You added a twist of the wrist to the thing by the failure of the check circuit; it gives you the wording the same as the failure of the original equipment. I sort of kicked that in there but I couickrt help that. I haven´t got much to add to this except that we are going through this test signal program as rapidly as we can. That applies to a basic signal on the ground with which you can test the unscrambling qualities of the airborne receiver and at least determine whether it is operating correctly.