Data communication systems key terms

Transmitter

Transmitter is a precise Principles of communication systems term in AQA A-Level Physics electronics. Device that converts information into a signal for transmission over a channel. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Channel

Channel is a precise Principles of communication systems term in AQA A-Level Physics electronics. Medium or path through which the signal travels from transmitter to receiver. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Receiver

Receiver is a precise Principles of communication systems term in AQA A-Level Physics electronics. Device that receives the transmitted signal and converts it back into usable information. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Bandwidth

The range of frequencies that a communication channel can transmit effectively, usually measured in hertz (Hz). It determines the maximum data rate.

Noise

Unwanted random signals that interfere with the desired signal, reducing clarity and increasing error rates.

Signal‑to‑Noise Ratio (SNR)

The ratio of the power of the desired signal to the power of background noise, expressed in decibels (dB); higher SNR indicates clearer transmission.

Copper wire

A conductive metal cable that transmits electrical signals via electron flow; it has resistance and signal attenuation over distance.

Fiber optic cable

A cable of glass or plastic that transmits data as light pulses, providing high bandwidth and low attenuation over long distances.

Wireless radio

A transmission medium that uses electromagnetic waves to carry signals through the air, enabling mobility but with limited bandwidth and susceptibility to interference.

Bandwidth

Bandwidth is a precise Transmission media term in AQA A-Level Physics electronics. Maximum data rate a transmission medium can carry, measured in bits per second. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Interference

Interference is a precise Transmission media term in AQA A-Level Physics electronics. Unwanted signals that distort or reduce the quality of a transmitted signal. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Signal Attenuation

Reduction in signal strength as it travels through a medium, affecting bandwidth.

Bandwidth

The range of frequencies that a transmission medium can carry, determining its data‑rate capacity.

Signal attenuation

The reduction in signal strength as it travels through a medium, typically expressed in decibels per unit length.

Transmission media selection criteria

Factors such as required bandwidth, distance, cost and environmental conditions used to choose the most appropriate medium for a communication system.

Synchronisation

Synchronisation is required because, without a common timing reference, multiple data streams would overlap and interfere; the mechanism is that a shared clock aligns the start times of each transmission, preventing overlap; the effect is that each signal occupies a distinct time slot; the consequence is that the receiver can correctly separate and decode the data.

Shared Clock

A shared clock is necessary because, in the absence of a common timing source, devices would drift apart and lose alignment; the mechanism is that the clock broadcasts a timing signal to all transmitters and receivers, ensuring they operate on the same time base; the effect is that all parties stay in sync; the consequence is that data can be transmitted without collision and errors.

Time Slot

A time slot is essential because, without defined intervals, signals would collide and become unreadable; the mechanism is that the multiplexing scheme assigns each data stream a specific, non-overlapping interval within the shared channel; the effect is that each stream is transmitted in its allocated slot; the consequence is that the overall bandwidth is efficiently used and data integrity is preserved.

Time-division multiplexing

A method of transmitting multiple signals over a single channel by dividing the channel into time slots, each assigned to a different signal.

Synchronization

The coordination of timing between transmitting and receiving devices to ensure correct allocation of time slots in a multiplexed system.

Timing diagram

A graphical representation showing the sequence of time slots and the signals transmitted in each slot, used to illustrate multiplexing operations.

Bandwidth efficiency

The ability of a multiplexing system to transmit more data over a single channel by sharing bandwidth among multiple signals.

Reduced transmission cost

Lower infrastructure and operational costs achieved by using fewer physical channels for multiple data streams.

Signal integrity preservation

Maintaining the quality of individual signals by allocating distinct time slots and synchronising transmission.

Carrier signal

Carrier signal is a precise Amplitude and frequency modulation term in AQA A-Level Physics electronics. A high‑frequency sinusoidal wave onto which information is imposed for transmission. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Modulating signal

The low‑frequency signal that carries the information to be transmitted and varies the carrier.

Modulation

The process of varying a property of the carrier signal (amplitude, frequency or phase) in accordance with the modulating signal to encode information for communication.

Modulation

Modulation is a precise Amplitude and frequency modulation term in AQA A-Level Physics electronics. The process of varying a carrier signal’s property to encode information. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Carrier wave

Carrier wave is a precise Amplitude and frequency modulation term in AQA A-Level Physics electronics. A high‑frequency sinusoidal signal that carries the modulated information. When using this term, connect it to the input condition, the relevant component or circuit response, and the output signal, measurement, graph feature, or control effect. This makes the definition curriculum-specific and prevents it becoming a generic electronics phrase.

Modulation index

The ratio describing the extent of variation applied to the carrier, such as amplitude or frequency deviation.