Apollo Spacecraft S Band Communication System, Part 24—Interface Simulator

Not only was the Apollo space to ground communication system extraordinary complicated and composed of numerous intricately-related parts, the need to simulate everything on the ground before committing it to flight required additional piles of purpose-built test equipment that reproduced the conditions of a deep space mission. More than a year into the Apollo communications project, the intrepid restorers take on a simulator which combines the various signals transmitted to and from the spacecraft into the complex modulated signal transmitted by the antennas.