TIL: The "beeps" in #NASA's #Apollo missions are called #Quindar tones, named after the company that produced the equipment.
There is an "intro" and an "outro" tone. They were generated when CapCom (the person in the control center tasked with talking to the astronauts) pushed the transmit button. Since there were several transmitters on earth, connected to Houston via telephone, this was an in-band signal causing them to activate, transmit, then deactivate again.
Add comment