Understanding Signal Impact, Power Measurement, and Decibels

In this lecture, we’ll discuss the impact on a signal and explore how we measure its power using units like watts, milliwatts, and decibels. Let’s dive right into it.

Signal Impact: Key Factors

When we transmit a signal, several factors affect its quality and strength. These can be categorized as follows:

1. Signal Strength
  Signal strength refers to the amplitude of the signal. When we talk about amplitude, we’re discussing how powerful or “strong” the signal is when it reaches the receiver. However, as the signal travels through a medium or environment, it can lose power, resulting in reduced amplitude. If the signal has good amplitude, it indicates a strong signal value.

Noise Floor
The noise floor is the ambient noise level generated by other radio frequency waves in the environment, excluding our desired signal. It’s essential to measure this noise floor to understand the “background noise” in a specific area. For instance, if we check the wireless interface on a MikroTik device, we might see a noise floor value of around -101 dBm. This value indicates the level of ambient noise present in the environment, affecting our signal quality.
Interference
Interference is another critical factor impacting signal quality. This happens when other RF energy sources overlap with our signal frequency, such as a neighboring device using the same frequency. This overlap disrupts the signal, reducing its quality and overall effectiveness.

Signal-to-Noise Ratio (SNR)

The Signal-to-Noise Ratio (SNR) compares the strength of our signal against the noise floor. It’s calculated by subtracting the noise floor from the signal strength. A higher SNR is preferable because it allows for complex modulation, achieving higher data rates.

For example, if we examine a connection between a device and an access point, an SNR of 35 dB is considered good. With a high SNR, we can apply more advanced modulation techniques to increase data rates.