What does New Horizons say when it calls home? Nothing, without the help of software that transforms zeros and ones from New Horizons’ computers into images, instrument readings, or useful information on the spacecraft’s status. Those datasets are then transmitted to Earth by the telecommunications (radio) system aboard New Horizons.
But if our Pluto-bound spacecraft could talk, it would sound something like the “tune” members of the New Horizons communications team created from actual ranging signals that New Horizons traded with NASA Deep Space Network (DSN) receiving stations earlier this year. (Listen to New Horizons)
The New Horizons team uses these ranging measurements to determine the spacecraft’s orbit, or its precise location in space. The DSN station modulates a ranging code and transmits it to the spacecraft, which demodulates the code (essentially processing the signal to receive the data) and transmits back to Earth. The DSN station then measures the round-trip time delay – in seconds – between transmission and reception of the ranging code. The measurement allows the team to determine the time needed for a signal to travel between the DSN station and the spacecraft.