In a communication satellite used for telecommunication and broadcasting, the multiple repeater units that receive, amplify, and retransmit signals are known as what?

Introduction / Context:
Communication satellites play a crucial role in modern telecommunication and television broadcasting. Inside these satellites, special electronic units perform the job of receiving weak signals from Earth, processing them, and sending them back. Competitive exams often ask for the technical name of these repeater units to test basic awareness of satellite communication terminology.

Given Data / Assumptions:

• The question is about multiple repeater units in a communication satellite.
• These units receive signals from Earth, amplify or shift them, and transmit them back to another region.
• Standard communication engineering terminology is assumed.
• No numerical calculations are involved; only recognition of the correct term is required.

Concept / Approach:
In satellite communication, the device that receives an uplink signal from an Earth station, changes its frequency, amplifies it, and sends it back as a downlink signal is called a transponder. The word transponder comes from transmitter plus responder. It effectively acts as a repeater in space. Modulators, detectors, generators, and oscillators are individual circuit elements, but the complete repeater package in a satellite is properly known as a transponder.

Step-by-Step Solution:
Step 1: Identify the function described: receiving, processing, and retransmitting signals in a satellite.Step 2: Recall that a transponder is an electronic unit that receives a signal, shifts its frequency, amplifies it, and sends it back to Earth.Step 3: Note that a modulator only changes the modulation of a carrier and is usually a part of ground equipment, not the complete satellite repeater.Step 4: Detectors and generators have narrower roles, such as detecting or generating signals, but do not describe the full repeater chain in satellite payloads.Step 5: Therefore, the correct technical term for multiple repeaters in a communication satellite is transponders.

Verification / Alternative check:
Descriptions of communication satellites in textbooks and technical manuals refer to a satellite payload as containing several transponders, each assigned to particular frequency bands or channels. Television broadcast satellites, for example, are often rated by the number of transponders they carry. This external confirmation supports the choice of transponders as the proper name of the repeater units mentioned in the question.

Why Other Options Are Wrong:
Option A, modulators, describes circuits that impose information on a carrier wave but are not themselves complete satellite repeaters. Option C, detectors, usually recover the information from a modulated signal and are not responsible for retransmission. Option D, generators, might create carrier waves or power but again are not the repeater chain. Option E, oscillators, stabilise frequency but are internal subcomponents rather than the full repeater unit. Only transponders provide the full receive amplify retransmit function.

Common Pitfalls:
Students sometimes assume that any device linked with signal modification, such as a modulator, must be the answer. The key is to remember that a transponder is a higher level functional block made of several smaller circuits, including amplifiers, oscillators, and filters. Knowing this distinction helps to avoid confusion and correctly identify transponder as the name for multiple satellite repeaters.

Final Answer:
The multiple repeater units in a communication satellite are called Transponders that receive, amplify, and retransmit signals.