All About Signal Distortion in Transmission Impairment

Key Takeaways

• Signal quality is compromised due to imperfections in the transmission medium. This is called transmission impairment.

• There are three main types of transmission impairment: signal distortion, attenuation, and noises.

• The three main reasons for signal distortion in transmission impairment are environmental parameters, properties of the transmission medium, and distance between the transmission end and receiving end.

The three major causes of transmission impairment are attenuation, noise, and distortion

The non-idealities of a transmission medium can be harmful to data communication. The transmission medium introduces imperfections, called transmission impairments, in analog as well as digital signal propagation. The three major causes of transmission impairments are attenuation, noise, and distortion. The signal distortion in transmission impairment alters the shape of the signals, especially composite signals. In this article, we will explore transmission impairment and signal distortion in detail.  

Transmission Impairment in Data Communication

When analog and digital signals travel through transmission mediums, some sort of signal quality deterioration occurs. Signal quality is compromised due to imperfections in the transmission medium, which is called transmission impairment.

Transmission impairment causes differences in transmitted and received signals. The quality, shape, and strength of the transmitted signals do not match with the received signals, and this reveals the existence of transmission impairment in the communication. Transmission impairment is present in analog as well as digital signal transmission, which we will look at next.

Impairments in Analog Signal Communication

In analog signal communication, the effect of transmission impairment presents itself as signal quality degradation, which is a serious concern when it comes to signal integrity in mission-critical data communication systems. 

Impairments in Digital Signal Transmission

Digitally transmitted signals experience bit error at the receiving end due to transmission impairment. This type of transmission impairment can lead to glitches, loss of data, or communication errors in digital data communication systems. 

There are three main types of transmission impairments: signal distortion, attenuation, and noises. We will focus our discussion on signal distortion in the next section.

Signal Distortion in Transmission Impairment 

In data communication, signals are primarily composed of different frequency components and are called composite signals. Composite signals are victims of signal distortion resulting from transmission impairment. No signal transmission medium is ideal, and the non-idealities are responsible for attenuating the frequency components of the signal unequally. Imperfections in the transmission medium also delay the frequency components disproportionately. The change of waveshape is the aftereffect of signal distortion in transmission impairment.

The three main reasons for signal distortion in transmission impairment are:

1. Environmental parameters
2. Properties of the transmission medium
3. Distance between the transmission end and receiving end 

The signal distortion in transmission impairment can be of two types: frequency distortion and phase or delay distortion.

Frequency Distortion

In frequency distortion, frequency components of the signal undergo unequal levels of attenuation. The frequency distortion changes the waveshape of the signal, and the receiving end signal becomes unidentical with the transmitting end signals. 

Phase or Delay Distortion

Frequency components of the composite signal propagate through the transmission medium at different velocities. The velocity of the signal propagation is higher towards the center of the frequency and falls down around the two sidebands. The difference in the signal velocities of frequency components introduces a delay in the signal reaching the receiving end. Signal distortion of this kind causes a phase difference between the signal at the receiving end and the transmitting end, known as phase or delay distortion. The delay constraint changes the shape of the receiving end signal compared to the transmitting end signal. 

A Common Consequence of Signal Distortion

One of the major consequences of signal distortion is the timing jitter problem. The timing jitter problem is caused by the deviation of the receiving end clock signal from the transmission end signal in a random fashion. The delay distortion experienced in timing jitter problems can result in miscommunication, glitches, or loss of data. 

Using the Equalization Technique to Mitigate Signal Distortion

Equalization techniques are beneficial for smoothing out signal distortions in transmission impairment. The equalization technique adjusts the frequency and phase characteristics of the signal transmitted over the transmission medium and equalizes the transmission impairment in all frequency components present in the signal. 

Distinguishing Signal Distortion From Attenuation in Transmission Impairment

There can sometimes be a misunderstanding regarding the classification of transmission impairments. Below are some differentiating points that might help differentiate signal distortion from attenuation in transmission impairment.

1. Signal distortion changes the shape of the signals, whereas attenuation keeps the shape intact.

2. The attenuation transmission impairment is easy to remove, but mitigating signal distortion is difficult.

3. The amplification method of removing attenuation aggravates the signal distortion at the receiving end.

The signal distortion in transmission impairment is critical to audio and video signal transmission. Non-ideal communication channels are responsible for transmission impairment. Introducing equalizers into communication systems can improve the performance of non-ideal transmission mediums by compensating the signal distortion as well as signal attenuation. 

With the help of Cadence’s suite of design and analysis tools, you can develop an equalizer network that ensures the communication channel is free from transmission impairment. Leading electronics providers rely on Cadence products to optimize power, space, and energy needs for a wide variety of market applications. If you’re looking to learn more about our innovative solutions, talk to our team of experts or subscribe to our YouTube channel.