The Industrial Wi-Fi Shop Podcast – Ep. 6 Bluetooth!

Video Description

The Basics • The IEEE standardized Bluetooth as 802.15.1 but no longer maintains the standard • Bluetooth is managed by the Bluetooth Special Interest Group of which there are over 35,000 member companies • As of 2021 over 4 BILLION Bluetooth integrated chipsets are shipped annually Geek Stuff • Frequencies used: • 2.400 GHz through 2.4835 GHz • However, there are “guard” or buffer bands at the top and bottom of this range with the bottom being 2 MHz wide and the top being 3.5 MHz wide • Actual used frequency range is 2.402 GHz through 2.480 GHz • Channels: • Versions prior to 4.0, what is referred to as “Bluetooth Classic” • 79 channels at 1 MHz wide • Versions 4.0 and up, better known as Bluetooth Low Energy (BLE) • 40 channels at 2 MHz wide • 3 channels are referred to as primary advertisement channels which are channels 37, 38 & 39 • 37 = 2.402 GHz, 38 = 2.426 GHz, 39 = 2.480 GHz • That leaves 37 channels to use for data • Data rates: • Bluetooth Classic • Original Bluetooth using GSFK (Gaussian frequency-shift keying) modulation, said to be operating in basic rate (BR) up to 1Mbit per second • Later versions (2.0+) using DPSK (Differential phase-shift keying) modulation, described as Enhanced Data Rate or EDR • EDR2 – 2Mbit per second • EDR3 – 3Mbit per second • 2019 Apple published an extension referred to as HDR using DQPSK (Differential quadrature phase-shift keying) • HDR4 – 4Mbit per second • HDR8 – 8Mbit per second • Bluetooth Low Energy (BLE) • Bluetooth 4 – up to 1Mbit per second • Bluetooth 5 – up to 2Mbit per second • Range for the most part is based upon class, and class is based upon power levels. However, there is lots of conflicting data on this due to sales and media hype of various device manufacturers • Class 1 devices • Power ranges from 10 to 100 mW • Range considered up to approximately 100 meters • BD/EDR devices loosely called class 1.5 are technically considered class 1 with power ranging from 2.5 to 10 mW. Max theoretical range being approximately 50 meters • Class 2 devices • Power ranges from 1 to 2.5 mW • Range considered up to approximately 10 meters (or 33 feet) • BLE • BLE 4 – approximate max theoretical range – 100 meters • BLE 5 – approximate max theoretical range – 400 meters • ***It is important to note that in all cases, no matter the class of the device, the environment plays an important role in real world range and data throughput*** • Reliability • Adaptive Frequency Hopping • Adaptive frequency hopping helps ensure data successfully makes its way through the noise. Individual messages are broken into small data packets, which are sent over different channels in a pre-defined sequence, known only to the transmitting and receiving devices. As many as 1600 channel-switches can take place every second. Any data packets that don’t reach their destination correctly are re-sent, and if the problem was caused by the channel, this gets flagged up so it can be avoided in the future. • In noisy environments, or where data is transmitted over longer distances (more on this below), there’s a chance of bit errors slipping into messages. Bluetooth can detect these, and take action to avoid unreliable channels, if they’re the cause. • It can also use what’s called ‘forward error correction’ (FEC) to rectify errors once data arrives at the receiver. • What is FEC? – FEC is a digital signal processing method that reduces the bit error rate of communication by adding parity bits to the data at the transmitter side so that the receiver side then uses those parity bits to...