Can you explain how Bluetooth technology works, its practical applications, and where the name comes from?

-Karthik Gurumurthy

Bluetooth is a technology that allows various devices like cell phones, TVs, computers, stereos, and entertainment systems to communicate with each other wirelessly. These devices can talk to each other without the hassle of messy wires and cords, all through radio signals.

Bluetooth operates as a small area network on a frequency of about 2.45 gigahertz. The U.S. government has set aside this frequency band for industrial, scientific, and medical (ISM) use. It’s the same band used for baby monitors, garage door openers, and cordless phones.

One of Bluetooth’s key features is its very weak radio signal, only about one milliwatt, with a coverage distance of approximately thirty feet. This extremely low power ensures that Bluetooth devices won’t interfere with other electronics and are very battery-efficient.

Bluetooth uses a technique called spread-spectrum frequency hopping. It utilizes seventy-nine randomly chosen frequencies, switching from one to another regularly. The transmitters change frequencies sixteen hundred times every second, making it unlikely for two transmitters to be on the same frequency simultaneously. This technique prevents Bluetooth from interfering with other household devices like baby monitors or garage door openers.

With Bluetooth, I can set up a personal area network (PAN) at home and in my car. This “piconet” can connect my cell phone, stereo, computer, DVD player, satellite TV, and more.

The ease of setup is one of Bluetooth’s major advantages. There’s no need to wade through lengthy instruction manuals. When I turn on a Bluetooth-ready device, it automatically sends out radio signals to other devices and “listens” for responses. Once a signal is identified, it locks in and remains active with other devices within that thirty-foot range.

Bluetooth enables hands-free cell phone use, which is particularly valuable for driving now that many states have laws prohibiting handheld phone use and texting while driving. I can also use it while jogging, fishing, or relaxing on my veranda while listening to music. The jawbone-shaped headset has become a common sight.

Interestingly, the name comes from Harald “Bluetooth” Gormsson, king of Denmark from 958 to 986 AD. He united Denmark and parts of Sweden and Norway into a single kingdom and introduced Christianity. He built a large Rune Stone in memory of his parents in Jelling, Denmark.

Bluetooth technology was developed by Ericsson, a major telecommunications company in Sweden. The name choice honors the importance of wireless communications for Nordic countries including Denmark, Norway, Sweden, and Finland.