QuitExams

🔹 Introduction

When data travels through a physical medium such as copper cables, fiber optics, or radio waves, the signal may experience degradation. These unwanted effects are called Transmission Impairments.

Impairments cause errors, loss of quality, slower transmission, and reduced reliability. There are **three major types** of impairments:

• Attenuation
• Distortion
• Noise

1️⃣ Attenuation

Attenuation is the loss of signal strength as it travels through a medium. As distance increases, the signal becomes weaker.

✔ Formula

Attenuation (dB) = 10 log10 (Pin / Pout)

✔ Causes

• Long cable distances
• Poor quality media
• Resistance in copper
• Fiber bending losses

✔ Solutions

• Repeaters in copper cables
• Optical amplifiers in fiber (EDFA)
• Using higher quality cables

✔ Diagram

Signal Strength
|\
| \
|  \
|   \________ Distance

2️⃣ Distortion

Distortion occurs when the signal changes its shape during transmission. It happens when different frequency components of a signal travel at different speeds.

✔ Causes

• Different propagation speeds
• Imperfect media characteristics
• High-frequency components weakening faster

✔ Types of Distortion

• Delay Distortion – frequencies arrive at different times
• Amplitude Distortion – amplitude changes unevenly
• Phase Distortion – phase shifts occur across frequencies

✔ Diagram

Before:  ~~~~~~    
After :  ~~~__~_~   (Shape changed)

✔ Solutions

• Equalizers
• High-quality cables
• Using fiber optics

3️⃣ Noise

Noise refers to any unwanted electrical or electromagnetic signal that interferes with the original data signal.

✔ Major Types of Noise

📌 1. Thermal Noise (White Noise)

• Caused by random electron motion
• Present in all electronic devices

📌 2. Intermodulation Noise

• Signals of different frequencies mix together
• Occurs in amplifiers

📌 3. Crosstalk

• Signal from one wire leaks into another
• Common in UTP cables

📌 4. Impulse Noise

• Sudden high-energy spikes
• Caused by lightning, power lines, motors

✔ Diagram

Signal:  ~~~~~~~~------
Noise :     * *  *
Output: ~~~*~~-~~*--~~~

✔ Solutions

• Shielded cables (STP)
• Error detection & correction (CRC, FEC)
• Better grounding
• Avoiding EMI sources

4️⃣ Comparison Between Impairment Types

5️⃣ Real-World Examples

✔ Attenuation Example

Wi-Fi signal becomes weak when moving far from the router.

✔ Distortion Example

Telephone audio sounds unclear over long copper lines.

✔ Noise Example

Static noise heard near power lines due to electromagnetic interference.

📝 Conclusion

Transmission impairments reduce the quality of signals and affect network performance. Understanding attenuation, distortion, and noise helps in designing better networks, selecting proper media, and implementing corrective techniques such as amplification, shielding, and error correction.