A Guide to Bluetooth Technology in Your Car

Bluetooth wireless technology has recently become popular in cars. Most of us know that by "pairing" (connecting wirelessly), our Bluetooth-enabled phones can function as a hands-free system. But Bluetooth also offers other functions, such as wireless music streaming from smartphones and other Bluetooth devices.

A Bluetooth connection opens up two-way communication between a smartphone and, for example, a car stereo, allowing you to hold a conversation. You just need to make sure both devices support the same Bluetooth protocols. The easiest way to ensure your phone and car stereo can connect via Bluetooth is to check if each is compatible with the same Bluetooth protocols.

Whenever you buy a car stereo with Bluetooth technology, the radio's specifications list compatible Bluetooth protocols. Keep in mind that both your phone and car stereo must have compatible Bluetooth protocols for them to work.

MOST BLUETOOTH PROTOCOLS

Protocol Abbreviation Feature

Advanced Audio Distribution Protocol A2DP Audio streaming (wireless music streaming)
Audio/Video Remote Control Protocol AVRCP Control music playback directly from the radio
Hands-Free HFP Hands-free calling via the car radio
Object Push Profile OPP Transferring contact information to the car radio
Phone Book Access Profile PBAP Access to the contact list from the car radio

Protocol: Hands-Free (HFP)

Most people use Bluetooth in their cars as a hands-free headset (HFP), which allows them to make and receive calls without having to touch their phone. HFP is the protocol used by Bluetooth headsets for hands-free calling.

The advantage of having a car radio that works with the hands-free profile is that incoming numbers are shown on the car radio display and the caller can be heard through the car speakers.

When HFP is in use, the phone acts as a "gateway" and the car stereo acts as a "hands-free device." The caller's voice passes through the phone and is sent to the radio, while your voice passes from the external microphone to the radio, then to the phone, and then to the caller. Some car stereos have built-in Bluetooth microphones, while others have external microphones that you can mount somewhere close to you, such as on the sun visor or steering column, and then connect to the back of the car stereo.

Access your phone's contact list

Having access to contacts from the Access Protocol phone book in the car radio makes it easier for us to make calls in the car.

Protocol: Advanced Audio Distribution Profile, phone book access (OPP,PBAP)

The hands-free profile wouldn't be as convenient if you couldn't transfer your contacts. Fortunately, Bluetooth technology allows you to use this in two ways.

The first and most basic is the Object Push Profile (OPP). This protocol allows for the transfer of contacts from the phone to the radio. How this process works depends on the radio itself and the phone, but in principle, it can be assumed to work on a send/receive basis between the phone and the radio. The car radio communicates with the phone to "pull" contacts from the phone, and the phone sends the contacts to the radio. This profile limits the number of contacts that can be sent.

A more advanced profile, the Phone Book Access Profile (PBAP), allows you to continuously transfer contacts from your car stereo to your phone, instead of having to store them. The process is automatic and usually goes like this: you only need to pair your car stereo and phone once.

Once the two devices are paired, the radio will ask your phone, "Hey, can I take a look at my contacts list?" The phone will reply, "I'm not sure, let me check." You'll then receive a message from your phone informing the car radio that it wants to download your contacts list. All you have to do is confirm, and your contacts will appear on your receiver's screen. This makes making calls much easier.

With this profile, many receivers will be able to use voice dialing for contacts, but usually only if the phone supports voice dialing. There are several receivers that will allow voice dialing; in our experience, the best receiver currently with voice dialing in Polish is the Parrot Asteroid.

Enjoy wireless audio streaming

The Advanced Audio Distribution profile allows you to stream music with surprisingly good stereo sound.

Protocol: Advanced Audio Distribution Profile, music streaming (A2DP)

Bluetooth lets you enjoy music without the hassle of wires. As long as the radio and phone are paired and connected via the Advanced Audio Distribution Profile (A2DP), you'll enjoy beautiful music. The radio will play all the music on your phone without the need to connect it. You'll also be able to hear sounds from most smartphone music apps.

So why is this profile called "Advanced"? It has to do with sound quality: A2DP plays higher-quality mono or stereo audio in audio formats like MP3 and AAC, narrower than standard Bluetooth audio.

Take control of your music playback

With AVRCP, you have some control over wireless music playback. With AVRCP version 1.3, you can see the name, artist, album, and track.

Protocol: Audio/Video Remote Control Profile (AVRCP)

The Audio/Video Remote Control Profile (AVRCP) allows you to control the music you're playing on your phone or device from your car radio, and you can also control songs from apps like Spotify. Simply put, AVRCP turns your car stereo into a controller for all your music on your phone. Much like a TV remote, when you press a button on your car stereo, AVRCP translates this action into a signal and sends it to your phone.

Thanks to this, we can use the control buttons on the car radio, we can use functions such as play, pause, and switching between songs.

One of the most important things is that when you connect your iPod® or iPhone® to your car stereo, it will transfer the “metadata” from your Apple device – the song name, artist, title and album information – all of which will be displayed on the car stereo display.

Since 2007, with AVRCP version 1.3, this feature has been automatic. This not only gives you control over your music, but also lets you see what's currently playing, even when playing music from multiple popular apps. Newer versions of AVRCP even allow you to browse and manipulate multiple audio players.

When you want to play audio, AVRCP establishes a dual Bluetooth connection. Your phone or other device sends audio and information to the car stereo, and the car receiver sends commands to your phone.

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