In the late 60s early 70s we put the TOW missile system on Army Cobra (AH1G) attack helicopters. The Tube Launched, Optically guided, Wire command link missile had a "secret frequency" IR source in its ass end.
The pilot tried to keep cross hairs of his sight centered on the target from a moving helicopter (generally they hovered for the anti tank shot...but a good front seat guy could do it on the move)
The Telescopic site unit on the nose of the AH1 had a sensor for the "secret frequency" IR source and had three fields of view progressively getting narrower as time of flight increased. On Board the Cobra were sensors relating to the attitude, speed, and direction of the aircraft. In the tail boom we had several antiquated analog computers that took the data about the aircraft, and deviation of the IR source relative to the optical Cross hairs on the target and sent up, down , left, right commands to the missile
The missile, once fired, went forward a few micro seconds and deliberately jinked left or right to get directly in front of the helicopter hoping the system would detect the IR source and start the communications..Sometimes I would see the missile hunt back and forth, and up and down trying to get this link established...if failed, it would just fly to max range , wire cut, and detonate
I was an 68J Aircraft Armament Repair Specialist at the time and they sent me to school for the air craft TOW system (yes Virginia I was an in flight missile repairman)
As in all Army schools, the instructors loved to play films to fill their required "podium time". My memory is these films had many different views of Ground TOW- how it worked, and early experiments on UH1B Hueys, and some other rather one of a kind installations of the TOW Missile system.
One particular film we watched had the EXACT same soundtrack as Tim posted above
Edited in.... The sound track above was a sarcastic spoof from some group of instructors at Anniston Army Depot around 1975.
They were supposed to teach Enlisted men (E-3s and E-4s) how to trouble shoot and repair the three black boxes in the tail boom. The Rocket scientists who wrote the theory of operation for the TOW system did in in only 37 pages with a LOT of Rho Delta Rho computer description, offset geometry, boolean logic, and heavy with high order math, physics, and still more analog computer logic. There was no way a high school grad (most of us had GEDs) could understand that section of the instruction (The E6 SSG and E-7 SFC instructors did not understand it)
I wish I still had the Tech Manual I bet Bret and Howard would look it over and ask....so whats your question soldier?