Bluetooth technology offers a connectivity solution between an assortment of devices, including mobile phones, headphones, mice, laptops, and other such devices. It is a common technology used by numerous devices that require short-range connectivity. Over the years, Bluetooth technology has expanded hugely to help in short-range fixed voice streaming in IoT mesh connectivity and M2M communications applications. Bluetooth technology comes built-in with most devices and you can also pair an external Bluetooth module with a non-Bluetooth device. The modern-day Bluetooth capabilities are more flexible and over extremely fast speed.
In this article, we will discuss the overview and history of this technology. We will also talk about the range and other capabilities of Bluetooth modules for a better understanding. But before we discuss anything else, let’s begin the discussion by explaining this technology.
It is a low-powered, high-speed wireless technology that connects smartphones or other portable devices together. It is an IEEE 802.15.1 specification for the utilization of radio communications (low-power) to link network devices, including computers and phones over short ranges without wires. A Bluetooth module covers short ranges by transmitting wireless signals up to 10 meters (30 feet). It is made possible by embedding transceivers (low-cost) into devices.
The Bluetooth technology supports a 2.45GHz frequency band. And, it offers support for up to 721Kb/s with 3 voice channels. However, this frequency is restricted internationally through agreement for its use in scientific, medical, and industrial devices. It has the ability to link up to 8 devices simultaneously. Every single device will offer a 48-bit unique address from an IEEE802 standard with multipoint or point-to-point connections.
Bluetooth modules are hardware components that provide wireless products to operate with computers. In a few cases, it can be a peripheral or accessory, a headphone, or other products, like cellphones.
Bluetooth technology is named after the Danish King and Viking, Harald Blatand. In the English dictionary, the last name of the King means “Bluetooth”. Bluetooth technology was developed in 1994 from a task started by the company Ericsson Mobile. The motive of this task was to discover a substitute for cables for connectivity between other devices and mobile phones. In the year 1998, companies such as Ericsson, Toshiba, Nokia, and IBM formed a Bluetooth SIG that published the very first version of the Bluetooth in 1999.
The very first version of Bluetooth came with a speed of 1Mb/s data rate with a 1.2 standard. The next Bluetooth version had a speed of 3Mb/s data rate and it was a 2.0+ERD standard. After that, the third version improved its speed to 24Mb/s with 3.2+HS standards. The most recent Bluetooth version available on the market today is the 4.0 version that has a 25Mb/s speed.
Bluetooth technology enables developers to design wireless devices that fulfill the requirements of their specific use case. Though many popular Bluetooth applications, such as wearable and audio streaming are designed for short-range connectivity, it doesn’t mean that there are certain limitations to the technology’s range. A normal Bluetooth module comes with up to 8-10 meters connectivity range. However, this technology can also connect devices at a kilometer distance range. Various factors contribute to determining the signal reliability and range at longer distances. Let’s take a quick look at the most important factors that you must know.
The radio spectrum can stretch from 30Hz up to 300GHz. The lowest frequency offers the longest range. But, the lower Bluetooth frequency results in lower support for data rate. Therefore, choosing the radio spectrum means you will have to compromise between the data rate and range.
The Bluetooth technology utilizes a 2400-2483.5MHz ISM band spectrum (2.4GHz). It allows for a reliable balance between the throughput and range. Additionally, the band 2.4GHz is available across the world. Therefore, it becomes a great low-power Wireless connectivity standard.
Assume that the transmit power is like your voice volume. People would be able to hear your voice from long distances if you speak louder. However, speaking louder will take more energy. The same is the case with transmit power. Selecting the level of transmit power is the design compromise between the power consumption and range. Higher transmit power means that the signals will reach longer distances.
But, with an increase in transmit power the device will be consuming more power. The supported transmit powers of Bluetooth technology are between 0.01 mW (-20 dBm) to 100 mW (+20 dBm). Choosing the transmit power depends on your choice of choosing between the Bluetooth range and power consumption.
The Bluetooth technology requires that the device must achieve at least -70dBm to -82dBm receiver sensitivity, according to the PHY. However, the implementations of Bluetooth usually achieve higher levels of receiver sensitivity of at least 95dBm.
Assume receiver sensitivity is the measure of your hearing quality. The receiver sensitivity measures the signal strength that the receiver interprets. To be more precise, it is the lowest level of power at which a receiver detects the radio signal and maintains the connection, while still demodulating the data.
Apart from the above-discussed factors, there are also a few others, such as antenna gain, PHY, and path loss. All these factors play an important part to determine the range of the Bluetooth. We will cover all those factors in detail in one of our upcoming articles on Bluetooth range and its effectiveness.
Bluetooth modules have different uses in many applications. Below are a few examples of Bluetooth module applications.
Take the example of a compact microcontroller that controls one light switch. The serial port of the microcontroller connects to a module, while the digital production line runs the relay that controls the light. A remote host pushes “ON” text so the relay turns on and “Off” text so the relay turns off.
Data loggers collect important data on remote sites. Then, this data is sent to central sites using Bluetooth-supported phones. Imagine that you access a remote site with a telephone 02084459099 and the computer connected with a modem records the information to a sheet.
So, all a data logger need is to open the connection and send textual information which corresponds to the collected data. Imagine that the logger recognizes the phone’s Bluetooth address exposes a profile of serial port via which it is possible to access the AT modem. Therefore, data loggers are another example where these modules play an integral part.
Bluetooth also plays a key role in establishing a secure connection via link keys. These keys are uniquely created 128-bit entities for every Bluetooth device through the Bluetooth address of the device. Since all addresses of Bluetooth are unique, it helps in creating unique keys. Link keys are private entities and they never expose through an AT interface. They remain inside the Bluetooth module all the time.
Therefore, a module permits the management of the link key by utilizing the addresses of Bluetooth as handles. There are link keys databases in the device and every single record in a database holds two fields. The first field holds the address of Bluetooth, while the other field holds a 128-bit link key. We can only see the field address.
You want to Bluetooth enable your extra serial model and provide Dune Profile (dial-up network) for PCs or PDAs within the range. Moreover, you also wish to make sure that other users can only use the services after pairing.
You have to plug the modem into the socket of the telephone and connect the module to the modem’s serial port. Doing this will provide internet access within a home from anywhere, where someone can access the profile as it is defined in the specification of the Bluetooth.
You will have to prepare the module according to the specific AT Commands and connect the module to your modem via the adapter cable. Therefore, it is another instance where Bluetooth modules are used.
Apart from the above-mentioned applications, there are many other use cases of Bluetooth adapters of modules. Some other examples include remote host modems for modules, vehicle cable replacement through pairing, and Bluetooth headsets.
Bluetooth modules come in a variety of types and sizes. Most smart device makers get confused while choosing a Bluetooth module according to their products.
The selection of the right module depends on what situations and what products a manufacturer is producing. Below, we have the top considerations for purchasing the right module that you must keep in mind while looking for the right module.
The first consideration is the chipset. It determines the module’s computing power. We cannot guarantee the module performance of the Bluetooth without a solid core. The chipset should be the best with Ti, Nordic, CRS, etc. if you have chosen a low-power module. Many reputable manufacturers offer high-quality modules with CRS, Nordic, and Ti chipsets.
In the market, there are two Bluetooth types available, as Low-Energy Bluetooth and Traditional Bluetooth. The traditional module smart devices experience frequent disconnection.
There will be a need for frequent pairing, so the battery of the device will exhaust quickly. On the other side, the low-energy module devices only require a single connection. These devices are powered by dry batteries that run for a longer time. Therefore, it is ideal to use 4.0/4.2/5.0 low-energy modules to make sure that the product lasts in the long run.
Bluetooth modules can transmit data wirelessly. According to such modules, there comes a data module or a voice module. Data modules are suitable for the transmission of data and information in large traffic public areas, like hospitals, plazas, stations, and exhibitions, etc. On the other side, voice modules are suitable for the transmission of voice information between the Bluetooth headset and mobile phone.
While choosing a Bluetooth module, it becomes essential to understand the module application and utilize the rate of data transmission needed by the operating state as a selection standard. There is a difference between the data needed for heartbeat monitoring and transmitting quality music to an earphone.
All manufacturers must understand in what scenario their products will work. It is essential to know whether they will need the short-range or long-range.
Wireless products, like remote controls, wireless earphones, and wireless mouse comes with different working range modules. For example, manufacturers have the luxury of choosing between 10 meters to 50 meters range, depending on their product’s types.
There are three types of Bluetooth modules; surface mount, serial port, and in-line type. The in-line module has pre-welding pins and is perfect for smaller batch productions.
A surface-mount module utilizes semi-circular pads for larger volume soldering reflow for comparatively smaller carriers. The third type, serial port adapters, operates in a situation where it is a hassle to insert a module into a device. You can directly plug it into the 9-pin serial port of the device.
The module interface comprises a serial interface, IO analog port, IO digital port, programming SPI port, voice interface, and USB interface.
It is important to know that different interfaces may perform different functions. It is perfectly alright to utilize a TTL-level serial interface if it is only for the data transfer.
It can look for the Bluetooth module automatically with the lower or same level of Bluetooth version. It waits passively for the search of the Master and makes the connection after that. The common smart devices are all chosen slave modules. On the other hand, Master modules can be perfect for devices like phones that also work as a control center.
There are also some other important factors, such as the antenna and the price. Different products come with different antenna needs. PCB antennas and ceramic antennas are currently the most popular choices available on the market.
It is important to do thorough research about the available modules according to your products. You will be able to choose the best module only if you consider all the important factors that we just discussed.
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