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by disinfoniacs #69 & #1

## decibels

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### tldr

• Decibels are a logarithmic way of measuring ratios between two values, often used to express power and signal strength levels in electronics
• A change of 3 dB corresponds to a doubling (or halving) of the power or signal level, while a change of 10 dB corresponds to a tenfold increase (or decrease) of the level

## in depth

Decibels (dB) are a unit of measurement that represents the ratio between two values on a logarithmic scale. In electronics, decibels are often used to express power, voltage, or current ratios, making it a useful tool for analyzing signals and circuits. Decibels are important because they allow us to compare very large or very small values more easily, especially when dealing with complex circuits or signals.

One of the key features of decibels is that they express values on a logarithmic scale, which means that a change of 1 dB represents a 10-fold increase or decrease in the value being measured. This is because decibels are a ratio of two power levels, expressed as 10 times the base 10 logarithm of the ratio. For example, if we have a power amplifier that increases the output power by a factor of 10, this would correspond to a 10 dB increase in power, whereas a decrease by a factor of 10 would result in a 10 dB decrease in power.

To make it easier to work with decibels, there are several rules that we can follow. One of the most important is that if we have two values, we can find the difference between them by subtracting their dB values. For example, if we have two power values, P1 and P2, we can calculate the dB difference between them as: 10 log (P1/P2). Similarly, if we have two voltage values, V1 and V2, we can calculate the dB difference as: 20 log (V1/V2).

To help make these calculations easier, we can use a chart that shows the decibel values for common power and voltage ratios. One common chart includes the following values: For example, if we want to find the dB difference between two power values where P1 is 4 times P2, we can see from the chart that this corresponds to a 6 dB difference. Similarly, if we have a voltage ratio of 10:1, we can see that this corresponds to a 20 dB difference.

In summary, decibels are a useful tool for working with complex signals and circuits in electronics, as they allow us to compare very large or very small values more easily. By following a few simple rules and using a chart of common values, we can easily calculate the dB difference between two values and make informed decisions about our circuits and signals.

## conclusion

Take study test for T5 on hamstudy.org until you consistently score at least 85%.

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