Bandwidth (signal processing) facts for kids

Bandwidth is a term used in many areas, especially when talking about communication. It helps us measure how much "space" a signal takes up, or how much information can travel at once.

Think of bandwidth in two main ways:

• It can mean the range of frequencies a signal uses. This is important for things like radio waves.
• It can also mean how much data can move through a computer network in a certain amount of time. This is often called "data speed" or "data transfer rate."

What is Frequency?

Many systems work by making continuous movements, like a swing going back and forth. Each full "back and forth" movement is called a cycle. The number of cycles that happen every second is called its frequency.

Frequency is measured in units called "Hertz" (Hz). One Hertz means one cycle per second. So, if something cycles 100 times in one second, its frequency is 100 Hz.

Frequency Bands and Bandwidth

Most signals, like sound or radio waves, don't just have one frequency. They use a range of frequencies. This range is called a frequency band.

For example, people can hear sounds with frequencies from about 20 Hz (very low sounds) up to 20,000 Hz (very high sounds). The "band" of frequencies we can hear is from 20 Hz to 20,000 Hz.

Bandwidth is simply the width of this frequency band. You find it by subtracting the lowest frequency from the highest frequency in the band.

So, for human hearing, the bandwidth is 20,000 Hz - 20 Hz = 19,980 Hz. This means our ears can process a wide range of sound frequencies!

How Bandwidth is Used

Bandwidth is very important for understanding electromagnetic spectrum signals. These include radio waves, light waves, and even X-rays. These waves are like tiny electric and magnetic fields that wiggle.

Radio Examples

Let's look at radio stations:

• An AM radio channel in the United States might use frequencies from 535,000 Hz to 545,000 Hz. Its bandwidth is 10,000 Hz (545,000 - 535,000 = 10,000). All AM stations use this same bandwidth, but each station has its own specific frequency band.
• An FM radio channel might use frequencies from 88,000,000 Hz (88 MHz) to 88,200,000 Hz (88.2 MHz). Its bandwidth is 200,000 Hz (or 200 kHz).

Notice that an FM radio channel uses a much wider bandwidth (200,000 Hz) than an AM channel (10,000 Hz). This wider bandwidth often allows FM radio to carry more detailed sound, like music, with better quality.

Bandwidth and Data Speed

Sometimes, people use the word "bandwidth" to mean how fast data can travel on the internet or a computer network. For example, you might hear someone say, "My internet has high bandwidth," meaning it's fast.

While a wider frequency bandwidth can allow more data to be sent, the correct term for how much data a communication channel can carry is "channel capacity." Channel capacity is measured in bits per second (bps).

In general, systems with a wider frequency bandwidth can often achieve a higher channel capacity. However, many other things also affect how much data can be sent. So, channel capacity and frequency bandwidth are related but not exactly the same thing.

See also

In Spanish: Ancho de banda para niños