Bluetooth: this is how every connection works

Bluetooth is particularly suitable for connecting devices over short distances without cables. It doesn’t always work smoothly – but with these tips and background info, you’ll become a blue tooth expert.

Geräte über Bluetooth verbinden - so geht´s!

When it comes to a wireless connection over a short distance, Bluetooth is the standard of choice – not without reason the Corona warning app also uses this technology. You’ll find Bluetooth wireless modules in PCs, notebooks and tablets as well as in speakers, headphones, smartphones, fitness trackers, smart thermometers, mice and keyboards. The technology is so popular because connecting works so easily. Actually. Because often enough problems occur. We provide solutions.

1. What is behind a Bluetooth connection?

Via Bluetooth, data can be transmitted over short distance by radio. This basically includes video, audio and voice. In the simplest case, two devices are connected to each other – such as a Bluetooth speaker and a smartphone. They represent a Piconet (Personal Area Network), where there is a point-to-point connection. The devices identify themselves to each other via AMA (Active Member Address). As a rule, up to eight devices can be actively connected to each other. Then one speaks of a point-to-multipoint connection. Here, one device acts as “master”, any other as “slave”. In addition, the devices in the piconet can also remain in passive mode. Here they are registered but marked as “Standby” or “Parked” in the Bluetooth network. Therefore they get the address PMA (Passive Member Address). As this is an 8-bit address, theoretically up to 256 devices (2 to the power of 8) can remain in standby mode. If several piconetworks are combined, this is called a scatter network. At least one Bluetooth device must be included here together.

To connect two devices via Bluetooth, you have to enable the function on all devices. The pairing process always starts from a device: On the smartphone, select the device from the list available under “Settings -> Bluetooth” appears. Before actually connecting, the devices exchange a security code that you either just confirm or enter on a device. Only then the pairing process starts.

2. How does the transmission method work?

Technically speaking Bluetooth multi-room speaker systems are a piconet with point-to- multipoint connectivity

Bluetooth uses the ISM band (Industrial, Scientific and Medical Band) in the ranges between 2.402 and 2.480 GHz. Here are 79 channels available, each 1 MHz wide. The frequency band around 2.4 GHz is also used by other wireless transmission methods, such as WLAN according to IEEE 802.11. This is why Bluetooth operates frequency hopping (FHSS), changing channels up to 1600 times per second. The many hops and the small data packets make the blue tooth data transmission very stable.

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3. What is the difference between Bluetooth and WLAN?

Bluetooth uses two methods for transmission: Synchronous Connection Oriented (SCO) and Asynchronous Connectionless Link (ACL). SCO is used to transmit voice, which is transmitted in fixed timeslots at a maximum data rate of 64 KBit/s. Bluetooth transmits data via ACL and requires the transmitting device to have memory for it. Unlike WLAN, Bluetooth can handle both transmission methods. WLAN can only transmit asynchronously.

4. Where can I find the Bluetooth function of my device?

Regardless of whether smartphones, tablets or PCs – before devices can be connected via Bluetooth, the function must be activated on each device. On smartphones, Bluetooth is usually found in the “Settings”, more rarely in the “Network” submenu, as well as in the status bar, which you show by swiping down from the top of the screen. You activate the function by tapping on the symbol.

Lödelete old pairing entriesäge from the Bluetooth list

5. How to determine the Bluetooth version?

For mobile devices such as smartphones and tablets, the processor determines the Bluetooth version, because single-chip systems (SOC – Systemon- a-Chip) are installed here. If you want to know which Bluetooth version your Android device has, first download a system app such as “Aida64” or “CPU-Z” to your mobile device to find out the exact CPU designation. For example, you will find the information “Qualcomm Snapdragon 808 1.82 GHz” under the “SOC” tab in CPU-Z. If you look for it on the manufacturer’s page, you will also find the Bluetooth version in the technical data for the processor – in this case 4.1.

Bluetooth classes and range

The Bluetooth classes determine which distance and power the wireless connection supports.

Class 1: Here, 100 milliwatts (mW) is used for transmission. The maximum range is 100 meters outdoors. It is the strongest Bluetooth class. Transmitters and receivers of this class are often found in notebooks and PCs.

Class 2: The maximum transmission power is 10 milliwatts (mW), which should be sufficient for a maximum distance of up to 50 meters. Corresponding hardware is installed in PCs, laptops or USB Bluetooth adapters.

Class 3: The lowest power class brings it to 1 milliwatt and a range of 10 meters outdoors. The power class is found in portable devices such as MP3 players. The range achieved in practice depends on factors such as the sensitivity of the receiver or the design of the antennas, in addition to the pure transmission power. In addition, there are obstacles that can affect the performance, such as walls or metal parts. You can reduce the radio signal to a few meters even with a powerful class.

6. Why does the smartphone not recognize all Bluetooth devices?

Besides the Bluetooth version and the installed hardware, the operating system of the mobile device has the greatest influence on the range of functions of the wireless technology. Because it determines the Bluetooth capabilities of the module. The more standard-compliant the wireless technology is integrated into the operating system, the fewer difficulties there are when connecting to other Bluetooth devices, for example. Some manufacturers, such as Samsung, often modify the stock Android in essential parts to increase compatibility with their own devices. The modifications can also have a negative impact on Bluetooth functionality. One possible consequence: Certain devices are not recognized as Bluetooth devices at all.

Wähend the process überprenüfen the displayed sequence of numbers

At the same time, the Bluetooth profiles are integrated in the operating system, which determine with which capabilities the wireless module communicates. An outdated operating system can lead to connection problems, as manufacturers integrate additional profiles in operating system updates. If your smartphone or tablet does not recognize a Bluetooth device, an operating system update can therefore already remedy the situation.

7. Why does the pairing not work, although the device is recognized??

Sometimes your smartphone or tablet displays the Bluetooth device you want to connect to, but can’t pair with it. One reason is old Bluetooth connections, which are managed in a list on most mobile devices up to Android 5. They always remain retrievable so that pairing works immediately when the smartphone is in the vicinity of the already known Bluetooth partner. If there are too many entries in the list, the current pairing often fails. This can be remedied by deleting old pairing entries. You can find previously paired devices listed in the settings under “Bluetooth” and delete an entry by touching the settings icon next to the device and clicking “Unpair”. Once you have deleted all old entries, start the pairing process again with the current device.

Overview: The current Bluetooth versions

Version 3.0: In the Bluetooth 3 specification.0+HS, Bluetooth and WLAN come together. The abbreviation HS stands for High Speed. The version uses WLAN (more precisely 802.11b/a/g) in order to transmit larger amounts of data. The choice falls on WLAN, since the technology already exists and uses the same frequency range. When needed, an ad hoc connection is established that only works between two devices.

Version from 4.0: With the versions Bluetooth 4.0, 4.1 and 4.2 Bluetooth gets the additions Low Energy (LE) or Bluetooth Smart. In both cases, the focus is on low power consumption in order to transfer small amounts of data at larger intervals. The limit here is a maximum of 220 KBit/s. The power-saving function does not work for larger data volumes. At the same time, the transfer in low-energy mode only works up to a maximum distance of 10 meters. If one of the two devices is further away, the connection is broken or requires more power. Theoretically 50 and up to about 100 meters are possible. Bluetooth from version 4.0 is used especially in smartphones, wearables and smartwatches. There are different logos: Bluetooth Smart corresponds to the Low Energy module, such as in activity trackers.

Bluetooth Smart Ready means that the device supports Bluetooth 3.0 and additionally Low Energy is mastered – such as in smartphones.

Version 4.1: Any device can serve as a peripheral or hub. For example, a smartwatch will receive data from a heart rate monitor. In addition, the connection control is newly regulated. This allows an interrupted connection to be re-established as soon as the devices are in wireless contact again. Thanks to IPv6 support, Bluetooth 4.1 Prepared for the Internet of Things (IoT).

Version 4.2: This version of Bluetooth improves battery life because the controller now resolves the address. At the same time, the response time increases thanks to adjusted data packet lengths. The speed gain should particularly benefit connections between smartphones and activity trackers. Bluetooth 4 is used for this purpose.2 when pairing, only algorithms that are classified as secure by the US standardization authority NIST (National Institute of Standards and Technology) are now used.

With Bluetooth 5, the transfer rate or range of Bluetooth connections increases. However, these innovations only refer to the Bluetooth LE (BLE) mode, i.e. the short-range connection to low-power Bluetooth devices like smartwatches and fitness trackers. In contrast, most other Bluetooth devices such as speakers and headphones use Bluetooth Classic – nothing changes for them with Bluetooth 5. This is why, for example, the dual audio mode of current Samsung smartphones also has nothing to do with Bluetooth 5.

The higher data rate of up to 2 Mbps should enable BLE devices to quickly transfer larger amounts of data, such as extensive firmware updates or more fitness data. Other devices, on the other hand, benefit from a greater range: With Bluetooth 5, this can now be around 200 meters, but only at a maximum transfer rate of 125 kbps. With each Bluetooth transmission, the partners can either use only the higher data rate or the improved range.

Bluetooth 5 is backward compatible with existing versions: Even with new Bluetooth 5 smartphones, for example the Samsung Galaxy S20, the One Plus 8 or the iPhone 11, Bluetooth devices with older versions of the standard can therefore be connected.

Especially smartphones and devices for the Internet of Things, such as sensors, benefit from Bluetooth 5.1. Especially when it comes to navigation, the latest Bluetooth version can show its strengths and determine the position in space with an accuracy of ten centimeters.

The current highest version improves the transmission meanwhile several headphones from the same audio source. In addition, the LC3 codec optimizes audio transmission from hearing aids.

8. What to do if the connection keeps dropping out?

You have successfully connected two devices via Bluetooth – such as a smartphone and a fitness tracker. In the course of the day, however, the pairing is lost again and again. The error can be due to too many entries in the smartphone’s Bluetooth list. Delete entries that are no longer used – see question 7. Check the battery of the paired device. If the battery level is too low, connection interruptions will occur. Apps such as Bluetooth Auto Connect often help with Android smartphones. Using the app, devices that have already been paired can be automatically connected and prioritized under the “Devices” menu item. In addition, under “Profiles” suitable profiles can be activated. For this purpose, the app to the Bluetooth device can be started automatically as soon as the Bluetooth connection is established.

9. How does connecting wearables via app work??

Many devices such as fitness trackers and smartwatches require an app to establish the Bluetooth connection. If you want to connect a smartwatch – such as the LG G Watch R – to your phone, download the appropriate application to your phone – in this case “Android Wear” – and install it. In some cases you also need a WLAN connection to be able to pair the devices for the first time. If you have enabled WLAN on the smartphone, turn on the smartwatch. A list of devices detected in the vicinity will appear on your smartphone. Select the name of your watch. Usually, both the watch and the smartphone display a pairing code. The number sequences should be identical. If this is the case, tap “OK” or place a check mark on the smartphone and clock to begin pairing.

10. Can a Bluetooth version be updated via update?

Recognize each other smartphone and car radio not, creates a firmware update the Bluetooth function of the radio remedy

It would be very practical to change the Bluetooth version via software update from about 3.0 to 4.0 to be able to update. However, the changes from one version to the next usually affect not only the supported profiles, but also the hardware module itself. Therefore, an update per se is not possible. With mobile devices, Bluetooth updates are often integrated in new operating system versions. This benefits with the latest Android at the same time Bluetooth compatibility.

11. Your car radio does not recognize the phone. What brings remedy?

Some car radios or navigation systems do not recognize current smartphone models. A firmware update of the car radio usually solves the problem. At the same time, an update can bring further advantages, such as a higher stability of the connection to the smartphone or better audio streaming. You can update the firmware with a Bluetooth-enabled notebook – provided the Bluetooth module supports FTP.

Every firmware update of the car radio deletes the user data, Bluetooth settings, the connected phones and the phonebook data. Check on the manufacturer’s page whether the update also fits your radio model. Download the update file to the notebook. To upload the new firmware, there must be a Bluetooth connection with the radio. In addition, the radio must be switched on. Before the update process, delete all devices from the radio’s Bluetooth pairing list and verify that Bluetooth and audio streaming features are enabled. No phone should be connected to the radio during the update process.

Now establish a Bluetooth connection between the notebook and the radio. To do this, go to the computer to “Control Panel -> Hardware and sound -> Devices and Printers” and click on “Add device”. Select the radio and confirm the pairing with “Yes” on the radio. Now the radio shows that it is connected to the computer. Windows also confirms that the device is added. Under “Devices and Printers” select the radio and terminate the connection first of all. The firmware update should not start until you initiate it on the radio and restore the Bluetooth connection on the computer at the same time.

For data transfer, use a free tool such as Bluetooth File Transfer . Select “Connect -> Refresh” to display the radio. Double-click on the device name and then on the “Update” folder. Move the downloaded firmware file to the “Update” folder. This copies the file to the radio. Do not press any buttons on the radio during the update process. Once the firmware is updated, disconnect the computer and turn the radio off and on again.

12. Simultaneous audio output to two devices does not work

Per Bluetooth lässt sst music actually not on two Audiogeräten simultaneously play

You want to output music from your smartphone via Bluetooth to a speaker and headphones at the same time. Although you can pair both peripherals with the phone, music playback only works on one device at a time.

Provided that the smartphone supports at least Bluetooth 4.0 is supported, a simultaneous connection to two devices is possible. Because then the Bluetooth module in the cell phone masters the so-called dual mode. However, one of the connected devices must support Bluetooth Classic, which is the normal Bluetooth mode. The other has to be connected via Bluetooth LE – and this standard is mainly mastered by small devices like fitness trackers, but only a few headphones. Simultaneous audio output to two devices currently only works on Samsung smartphones: since the Galaxy S8 and S8+, there is the Dual Audio feature that allows this to happen. Conversely, dual audio connection has been possible for some time: Bluetooth headphones with multipoint function can be connected to two smartphones at the same time: you can then switch between the two audio sources on the headphones.

Common Bluetooth profiles

Profiles are responsible for how and if it works between devices with Bluetooth communication. There are a variety of profiles, here are the most common ones:

A2DP: The “Advanced Audio Distribution Profile” transmits stereo audio signals.

AVCTP: “Audio/Video Control Transport” transmits audio and video data. It initiates and controls this.

AVRCP: The “Audio Video Remote Control Profile” controls the remote control of audio and video devices.

BPP: The “Basic Printing” profile handles printing from the phone. Usually these are simple documents like emails.

BIP: The “Basic Image” profile can be used to transfer, display and print images in JPEG format.

GAVDP: The Generic AV Distribution profile controls the transfer of audio and video data via streaming.

HFP: Hands Free Profile” allows you to make hands-free phone calls.

HSP: The “Headset Profile” controls spoken input and output via headphones.

PBAP: Via the “Phonebook Access Profile” the connected device accesses the phonebook.

SYNC: The “Synchronization” profile controls the synchronization of organizer data. Bluetooth devices can thus trigger the synchronization process by coming within radio range of the PC.

Windows and Bluetooth: tips and solutions for everyday use

In the current Microsoft Windows 10 operating system, you can find the Bluetooth settings under “Settings -‘ Devices -‘ Bluetooth and other devices”. There you can activate the Bluetooth radio via a slide switch. Then turn on the device you want to connect to the PC and make sure it can be seen by the computer.

How you proceed differs depending on the device: With a speaker, headphones or a mouse, you usually have to press a certain button longer so that Bluetooth is switched on and visibility is activated. Now click on “Add Bluetooth and other devices” in the Windows settings and click on “Bluetooth” for device type. Now the device should appear in the selection list, where you click on it and press “Done” to establish the connection. For some devices you have to authorize the connection setup with a PIN code. It is often 0000, otherwise the appropriate code should be in the manual of the Bluetooth device.

1. Windows does not find Bluetooth hardware

Problem: You cannot enable Bluetooth on the PC because the corresponding power button is missing in the Windows settings.

Solution: First check in the Device Manager if the Bluetooth module is listed there. You should see a product name or a description like “Bluetooth Adapter” or “Bluetooth Radio” in the “Bluetooth” menu. If this is not the case, restart the computer: often Windows cannot activate Bluetooth drivers after waking up from standby or hibernation mode, which is why the Bluetooth hardware disappears from Device Manager.

2. The Bluetooth functionality cannot be activated

Problem: The Bluetooth hardware can be seen in the Device Manager. However, the switch in the Windows settings cannot be set to “On”, but always jumps back to the off state.

Solution: Go to the Device Manager and double click on the entry for the Bluetooth hardware. From the “Drivers” menu, select “Update Driver” and let Windows automatically check for new driver software. If the operating system claims that the latest driver is already installed, go to the website of the PC or notebook manufacturer, and search for Bluetooth drivers for your device there. Also take a look at the WLAN drivers offered, because many current notebooks have both wireless networks on one hardware module.

3. Bluetooth hardware has disappeared after Windows update

To find a current driver, you ll need to know the manufacturer of the Bluetooth hardware

Problem: After updating to Windows 10 or a newer version of the system, for example the Fall Creators Update, Bluetooth no longer works on your PC. No hardware is displayed under “Bluetooth” in the device manager either.

Solution: If the installed driver does not support the update, Windows 10 will no longer use it. The Bluetooth hardware therefore appears as an unknown device in the Device Manager. Therefore, check whether you can find a corresponding entry in the device manager. If yes, you have to search for a current driver at the PC manufacturer or the provider of the Bluetooth hardware. Especially with a USB dongle this can be difficult, because you don’t have a manual for these external devices or you don’t know who the Bluetooth adapter is from at all. In this case the device manager can give you a hint: Double-click on the entry for the unknown device and go to the “Details” menu. Select the entry “Hardware IDs” under “Property” and note the number sequence behind VID. You can search for it on this website, for example, which will then show you the manufacturer name that is hidden behind the VID, the Vendor ID. You can then search for a current driver for the Bluetooth device on the manufacturer’s support page.

4. USB Bluetooth adapter is not recognized under Windows

Problem: The Bluetooth hardware does not show up in Device Manager, but no unknown device is listed there either.

Solution: It is possible that the error is not caused by the Bluetooth hardware itself, but by a device it is connected to – for example, the USB controller. Therefore, change the view in the Device Manager by going to “View -‘ Devices by Connection”. Now fan out all submenus, which are recognizable by the square bracket, until you see the Bluetooth hardware displayed. Now you can see to which internal interface the adapter is connected – usually it is a USB root hub or a PCI Express root port.

If you see a yellow triangle with an exclamation mark on one of these devices, you should update the corresponding driver – usually it is the driver for the processor or chipset, which you can get from the PC manufacturer or from AMD or Intel respectively.

5. Dropouts during audio playback on Bluetooth speakers

problem: You have wireless speakers connected to the notebook via Bluetooth. But every now and then, malfunctions occur during playback.

Solution: As with WLAN, interference signals can have an impact on Bluetooth transmission. Therefore, first bring the notebook and speakers closer together. If playback is still faulty, you should check whether you still have Windows Bluetooth settings open on the laptop. In this case, the notebook continues to search for nearby Bluetooth devices to connect to. But this activity can cause the dropouts in the audio output.

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