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What is a Bluetooth® Transmitter?

A Bluetooth® earpiece.
A Bluetooth® dongle that transmits signals wirelessly.
Article Details
  • Written By: J.S. Metzker Erdemir
  • Edited By: C. Wilborn
  • Last Modified Date: 11 July 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
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In the mid-900s, the Danish king Harald Bluetooth united Denmark and part of Norway into one kingdom. In the late 20th century, Swedish engineers at Ericsson developed Bluetooth® transmission, a wireless technology that can unite different electronic devices regardless of their type, manufacturer, or operating system. Using low-power radio waves, a Bluetooth® transmitter can transmit signals from a computer to a stereo system, from a cell phone to a printer, or from an Apple to a PC.

Remote controls use infrared signals to send information from the remote control to a device like the TV or DVD player. For a remote control to work, however, it must be pointed directly at the TV. With Bluetooth® wireless transmitters, devices within 30 feet (10 m) of each other can communicate, even through walls and around corners. This is because a Bluetooth® transmitter uses 2.45 GHz radio waves to transmit signals, the same frequency used for baby monitors and newer cordless phones.

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When one Bluetooth® transmitter senses another one, it automatically establishes a small wireless network, called a piconet, that works as long as the transmitter and receiver are within 30 feet (10 m) of one another. A user might, for example, walk into his house, and his cell phone calls could automatically be forwarded to his cordless land line. As he passes his computer, his emails could be downloaded into his cell phone or PDA, then he can send downloaded music to his stereo and photos from his digital camera to his daughter’s phone. Bluetooth® wireless technology eliminates the need for a different cord to allow networking between different devices.

Because the 2.45 GHz frequency is also used for other devices in the home, engineers had to work out a way to prevent interference. They needed to prevent things like a cell phone accidentally causing a garage door to open. To accomplish this, a Bluetooth® transmitter uses a very weak signal, just about one milliwatt.

Additionally, a single Bluetooth® transmitter can communicate with up to eight other devices at the same time, without interference. This is done with what is called “spread spectrum frequency hopping.” Since the 2.45 GHz frequency actually encompasses the range between 2.402 GHz and 2.480 GHz, Bluetooth® can hop between 79 different randomly chosen frequencies at a rate of 1,600 changes per second. This makes it unlikely that any two devices will be using the exact same frequency at the same time, and if they are, the interference will last no longer than a few milliseconds.

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Discuss this Article

Azuza
Post 4

@indemnifyme - Bluetooth headsets do look a bit silly, I agree. However, I would much prefer people use a headset than get distracted trying to answer their cell phones while driving.

Cell phone use while driving is a major cause of accidents, and using a hands free device can alleviate this problem. So I'm all for the Bluetooth headsets!

Oh yeah, and I liked the fun fact about King Bluetooth. I wonder if that's where the name Bluetooth came from?

indemnifyme
Post 3

Bluetooth is pretty darn amazing. However, I have to take issue with Bluetooth headsets. I wish they were never invented.

First of all, they just look ridiculous. When people walk around every where with a Bluetooth headset in their ear, they just look so full of themselves. I have to wonder, what phone call are they waiting for that's so important they don't have time to just answer it on their phone.

Second of all, the headsets make people look like they are talking to themselves. When they first came out, I seriously though a ton of people had become schizophrenics! Only later did I realize these people were actually talking on their phones.

MrMoody
Post 2

@miriam98 - That’s cool. I have Bluetooth in my cell phone, and I use it the way the article describes.

When I get close to the computer, I can instantly transfer my cell phone photos and videos in a flash. In the old days I would have to connect my phone to the USB port using a cable and open the files on a folder to do the transfer. Bluetooth is so much easier and more convenient.

miriam98
Post 1

Bluetooth is everywhere these days, and wireless receivers have become part of just about every device on the market.

I have a wireless keyboard and it uses Bluetooth technology. I just plug the Bluetooth device into the USB interface on the back of my computer, and I’m done.

Both the keyboard and mouse transmit the wireless signals. I believe that with the keyboard I have a potential range of 30 feet, like the article says.

I don’t need that range really. I just bought it so I wouldn’t have to mess with the cables. But I could see it coming in handy if, for example, I wanted to watch streaming video on the flat panel TV in my family room.

I can wire the monitor cable to the TV, and then take the keyboard and mouse to the family room. The possibilities are endless.

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