So what is Bluetooth and all those confusing acronyms, what do they mean and how important are they?When we try to look for gadgets or accessories for our smartphones, computers or entertainment systems components, just to name a few, we start seeing Bluetooth this, Bluetooth that, in any possible combination with words like wireless, hands free, class 2, class 1 etc. To make things worse this "industry jargon salad" is sprinkled with a colorful mixture of acronyms like v2.1, v3.0, v4.0, +EDR, +HS, A2DP ad nauseam. So how can you make any sense of it and figure out if the particular device is going to work for you. Don't despair, we will try to decipher the technology mumbo jumbo, explain what is Bluetooth and help you to understand basic concepts and Bluetooth flavors. In particular we will look at:
- Bluetooth History And Technology Basics
- Communication And Connection
- Device Classes And Range
- Bluetooth Versions
- Bluetooth Device Profiles
Bluetooth History and Technology BasicsBack in 1994 a Swedish telecom company invented a network technology designed to connect devices over the radio waves into a small network over short distances. It later became Bluetooth. It is a wireless technology that uses UHF radio wave in a range around 2.4GHz to establish a communication network between enabled devices.
WARNING: Interesting yet useless facts section:
The Bluetooth name is credited to Jim Kardach that in 1997 proposed the Bluetooth name after the Danish king Harald Bluetooth that in the tenth century, united Danish tribes into a kingdom. The Bluetooth logo had been created by merging two runes (letters in runic alphabet) Hagall and Bjarkan.
Communication And ConnectionBluetooth specifications provide for connecting up to seven devices into an ad-hoc network where on of the devices acts as a master with the remaining devices as acting as slaves, a server/terminals relationship if you will. The devices can switch roles but at any given moment there could only be one master device. The communication between devices is carried over radio waves in a range from 2400 MHz to 2483.5 MHz with 79 or 40 channels depending on the Bluetooth version. The transfer rates vary between versions and will list them in latter sections.
Device Class And Signal RangeBecause the Bluetooth technology had been designed as low power short wave communication protocol, there are certain limitations as far as distance between devices for successful data transfer. Firstly, Bluetooth devices need a line of site or a near line of site to maintain the connection. Secondly, the communication range is limited by the power of the signal. The standard defines three classes that specifies the maximum power used by device transceiver. This in power limiting in turn limits the maximum radio wave range. Bluetooth standard specifies three classes:
- Class 3 - Maximum permitted power 1 mW (milliwat) and estimated range of ~1 m (3 ft)
- Class 2 - Maximum permitted power 2.5 mW (milliwat) and estimated range of ~10 m (30 ft)
- Class 1 - Maximum permitted power 100 mW (milliwat) and estimated range of ~100 m (300 ft)
Bluetooth versionsThe first version that I would like to mention is Bluetooth version 1.2. Even though it would be hard to find any device that runs on version 1.2, since the 2004 release of v. 2.0, the v 1.2 was the frist version that fixed many problems that made matching and connecting devices from different manufacturers very difficult or impossible. Bluetooth version 1.2 was able to transmit data at a rate of 1 Mbit/s and finally organized some of the core standards to make it easier to match devices from different manufacturers. With each consecutive version specification release, the technology was getting more refined and faster and the increased data transfer rate created new possibilities for data intensive applications like HD audio and video streaming. To achieve the higher speeds new technologies had been introduced and they are reflected in the version names, they are: Bluetooth Enhanced Data Rate (+EDR) introduced with version 2.0 and Wi-Fi networking transport technology named High Speed (+HS) introduced with version 3.0 that enabled Bluetooth 3.0 and up to transfer data at 24 Mbit/s data rate. Data transfer speeds for each version listed below:
- Bluetooth 1.2 - 1 Mbit/s
- Bluetooth 2.0 + EDR - 3 Mbit/s
- Bluetooth 3.0 + HS - 24 Mbit/s
- Bluetooth 4.0 - 24 Mbit/s