Why is pulse position modulation used in mode C transponder transmissions?

Pulse Position Modulation (PPM) is utilized in mode C transponder transmissions primarily to enhance detection by radar systems. This modulation technique effectively encodes information in the time intervals between pulses, allowing for a more distinct and easily recognizable signal pattern. In the context of radar systems, which rely on reflecting signals to determine the distance and speed of an object, having clearly defined pulse positions ensures that the transponder can be accurately detected against any background noise or interference.

Radar systems benefit from the precise timing inherent in PPM, as it allows them to distinguish between different signals based on the timing of their arrivals. This precise timing is crucial in aviation and air traffic control scenarios, where accurate positioning and identification of aircraft is essential for maintaining safety and efficiency in airspace management.