Data Transmission Overview

Flashcards covering key concepts in data transmission techniques, signal characteristics, and challenges.

What are the two categories of media for data transmission?

Guided Media and Unguided Media (Wireless)

What is the primary characteristic of guided media?

Waves are guided along a physical path, such as twisted pair, coaxial cable, optical fiber.

Define Simplex transmission mode.

Signals are transmitted in only one direction, with one station as the transmitter and the other as the receiver.

Define Half Duplex transmission mode.

Both stations transmit, but only one at a time; one acts as a transmitter and the other as a receiver.

Define Full Duplex transmission mode.

Both stations may transmit simultaneously, with the medium carrying signals in both directions.

What distinguishes analog signals from digital signals?

Analog signals vary continuously over time, while digital signals maintain constant levels with abrupt changes.

List three key parameters of a sine wave.

Peak Amplitude, Frequency, Phase.

Explain the concept of wavelength (λ).

The distance occupied by a single signal cycle, or the distance between two points of corresponding phases of two consecutive cycles.

What is the significance of Fourier analysis in data transmission?

It shows that any signal is made up of components at various frequencies, typically sine waves.

What is the effect of bandwidth on a digital signal?

Higher data rates require greater bandwidth for transmission.

Define Attenuation in the context of data transmission.

The reduction in strength of a signal as it travels over a transmission medium.

What causes Delay Distortion?

It occurs when propagation velocity of a signal varies with frequency in guided media, leading to phase shifts between components.

What is Noise in a data transmission system?

Unwanted signals inserted between transmitter and receiver that affect system performance.

Explain Thermal Noise.

Noise caused by thermal agitation of electrons, impacting communications performance especially in satellite systems.

What is Asynchronous Transmission?

Data transmitted one character at a time, with each character ranging from 5 to 8 bits.

What is Synchronous Transmission?

A steady stream of bits transmitted in blocks, requiring synchronization between the transmitter and receiver.

What is Channel Capacity?

The maximum rate at which data can be transmitted over a communication channel under specific conditions.

How does Shannon's Capacity relate to data rate and noise?

It describes how faster data rates can lead to higher error rates due to noise interference.

What can be inferred from Nyquist's Bandwidth principle?

The maximum data rate is determined by the bandwidth of the signal and can be expressed as 2B for a noise-free channel.

What is the Nyquist formula for data rate with multiple signalling levels?

C = 2B log2(M), where M is the number of discrete signal levels.

How is Signal-to-Noise Ratio (SNR) calculated?

SNR_dB = 10 log10(SNR) where SNR = signal power to noise power.

What are the primary impairments to transmission mentioned?

Attenuation, Delay Distortion, and Noise.

What effect does increased attenuation have on higher frequencies?

Attenuation increases and can lead to degradation of signal quality.

What does a DC component in a signal refer to?

The component of zero frequency within a signal.

What happens during intersymbol interference in digital signals?

Parts of one bit spill over into others due to delay distortion, causing errors.

What is the average noise level in a communication channel indicative of?

It reflects how much noise affects the performance of the communication system.

Describe Digital Signaling advantages compared to Analog Signaling.

Digital signaling is generally cheaper and less susceptible to noise interference.

What is the major disadvantage of Digital Signals?

They suffer more from attenuation than analog signals.

What are the types of thermal noise?

Uniformly distributed across bandwidths, referred to as white noise.

What consideration must be made for effective digital transmission?

Data integrity, capacity utilization, and security measures need to be prioritized.

Explain the purpose of amplifiers or repeaters in transmission systems.

They help maintain signal strength and quality over longer distances.

What role does the root mean square (RMS) value play in voltage measurement?

It reflects the average voltage of a signal, crucial for understanding power of AC signals.

Define Multipoint communication.

A scenario where more than two devices share the same transmission medium.

What does the maximum signal capacity indicate?

The highest amount of data that can be transmitted without error under given conditions.

What factors affect the bit error rate in a transmission system?

Signal strength, amount of noise present, and channel bandwidth.

How is signal quality assessed in a communication system?

By measuring how well the signal can be interpreted by the receiver despite noise interference.