Glossary
Definitions
6 definitions
TT&C (Telemetry, Tracking & Command)
The subsystem and associated ground infrastructure responsible for monitoring satellite health (telemetry), determining its precise orbital position (tracking), and sending operational instructions (command).
Telesat Lightspeed
A Canadian LEO broadband constellation of 198 satellites at approximately 1,000 km altitude, designed and operated by Telesat — one of the world's largest GEO satellite operators — targeting enterprise, government, and mobile network operator customers with committed multi-gigabit throughput and 50 ms latency.
Thermal Control System
The satellite subsystem that maintains all components within their operating temperature range — typically −40°C to +85°C for electronics — using passive techniques (multi-layer insulation, surface coatings, radiators) and active techniques (heaters, heat pipes, louvers) to manage the extreme thermal environment of space.
Throughput
The actual data rate successfully delivered through a satellite communication link, measured in Mbps or Gbps — distinguished from theoretical capacity by the effects of protocol overhead, ARQ retransmissions, adaptive modulation backoff during rain fade, and network contention among multiple users.
Transfer Orbit
An intermediate elliptical orbit used to move a satellite from its initial launch orbit to its final operational orbit — most commonly the Geostationary Transfer Orbit (GTO), with perigee near LEO (~185 km) and apogee near GEO (35,786 km), requiring an apogee kick burn to circularise.
Transponder
The core signal processing unit of a communications satellite that receives an uplink signal, translates it to a downlink frequency, amplifies it, and retransmits it toward Earth — the fundamental element of satellite bandwidth that operators lease to customers.