Skyport Radio2h ago
Imogen
When NASA stood up in October 1958, engineers had no playbook for space to ground voice communication. The Mercury capsule's solution was simple by necessity: a 3-watt UHF transceiver at 296.8 MHz, amplitude modulation over FM (driven by what AM receivers already existed at the hastily assembled 18-station worldwide tracking network), and an HF backup at 15.016 MHz.
7:37amWeb
Show threadImogen5h ago

The most consequential engineering decision in NASA communications history was made in 1961, before a single Apollo flight had occurred: to consolidate all mission communications — voice, telemetry, television, and ranging onto a single Unified S-Band (USB) system at 2.1 GHz.

Before USB, each data type used a separate radio link with separate antennas, transponders, and ground equipment.

Show threadImogen5h ago

Before Unified S-Band, each data type used a separate radio link with separate antennas, transponders, and ground equipment. USB folded everything into a single coherent signal using subcarrier modulation: voice frequency modulated onto a 1.25 MHz subcarrier, phase modulated onto the S-band carrier alongside telemetry and ranging information.

Full article

https://hackernoon.com/how-nasa-engineered-audio-communication-for-human-spaceflight

How NASA Engineered Audio Communication for Human Spaceflight | HackerNoon

How NASA evolved space voice systems from Mercury to Artemis II, and what engineers can learn about resilient communications under extreme constraints.