What is digital time division multiplexing?
The correct answer is B: Two or more signals are arranged to share discrete time slots of a data transmission. Digital time division multiplexing (TDM) is when two or more signals are arranged to share discrete time slots of a data transmission. Each signal gets a specific time slot in a repeating sequence.
In TDM, time is divided into slots, and each signal is assigned specific slots. The signals take turns using the channel - signal 1 uses slot 1, signal 2 uses slot 2, signal 1 uses slot 3, etc. This allows multiple signals to share the same frequency channel by using different time periods. TDM is widely used in digital communication systems. It's efficient because all signals can use the full bandwidth during their assigned time slots.
Exam Tip
TDM = Time slots for each signal. Remember: Digital time division multiplexing arranges two or more signals to share discrete time slots. Each signal gets specific time periods in a repeating sequence.
Memory Aid
"**T**DM = **T**ime **S**lots (think 'TDM = TS' = Time Slots)"
Real-World Application
You're using a digital system with multiple users. Each user is assigned specific time slots - user 1 transmits in slots 1, 4, 7..., user 2 transmits in slots 2, 5, 8..., etc. This is TDM - the signals share the same frequency channel by using different time periods. All users can use the full bandwidth during their assigned slots.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. Assigning data streams to discrete sub-carriers on an FM transmitter describes frequency division multiplexing, not time division multiplexing.
Option C: Incorrect. Sharing a channel by transmitting time of transmission as the sub-carrier doesn't describe TDM. TDM uses time slots, not time information as a subcarrier.
Option D: Incorrect. Quadrature modulation increases bandwidth efficiency but doesn't describe time division multiplexing. TDM uses time slots, not quadrature modulation.
题目解析
The correct answer is B: Two or more signals are arranged to share discrete time slots of a data transmission. Digital time division multiplexing (TDM) is when two or more signals are arranged to share discrete time slots of a data transmission. Each signal gets a specific time slot in a repeating sequence. In TDM, time is divided into slots, and each signal is assigned specific slots. The signals take turns using the channel - signal 1 uses slot 1, signal 2 uses slot 2, signal 1 uses slot 3, etc. This allows multiple signals to share the same frequency channel by using different time periods. TDM is widely used in digital communication systems. It's efficient because all signals can use the full bandwidth during their assigned time slots.
考试技巧
TDM = Time slots for each signal. Remember: Digital time division multiplexing arranges two or more signals to share discrete time slots. Each signal gets specific time periods in a repeating sequence.
记忆口诀
**T**DM = **T**ime **S**lots (think 'TDM = TS' = Time Slots)
实际应用示例
You're using a digital system with multiple users. Each user is assigned specific time slots - user 1 transmits in slots 1, 4, 7..., user 2 transmits in slots 2, 5, 8..., etc. This is TDM - the signals share the same frequency channel by using different time periods. All users can use the full bandwidth during their assigned slots.
错误选项分析
Option A: Incorrect. Assigning data streams to discrete sub-carriers on an FM transmitter describes frequency division multiplexing, not time division multiplexing. Option C: Incorrect. Sharing a channel by transmitting time of transmission as the sub-carrier doesn't describe TDM. TDM uses time slots, not time information as a subcarrier. Option D: Incorrect. Quadrature modulation increases bandwidth efficiency but doesn't describe time division multiplexing. TDM uses time slots, not quadrature modulation.
知识点
Time division multiplexing, TDM, Time slots, Digital multiplexing
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.