Cell Phones behind the Wheel

Introduction

Using a cellular phone while driving a car is dangerous. Everybody who had a quarrel once with his or her company knows how the concentration is reduced. If holding and using the phone is added concentration on the traffic is nearly gone. Hands free car kits can reduce the distraction widely. Additionally, the reception is improved by the use of an external antenna and the phone's battery is preserved or recharged. If someone calls while driving the radio automatically mutes and the phone answers the call (if configured that way) after the first ring. If the microphone and the radio speakers are installed correctly the connection is usually good. Bad communication is usually caused by cheap car kits or wrong installation. After the call the connection is automatically terminated and the radio is demuted. The whole time the driver has not taken his hands off the wheel.

This is not only my opinion but also spoken law in several European countries. Using the phone while driving without (and sometimes even with) car kit can get pretty expensive.

Overview

Surveillance

Since 2021, violations of the cell phone ban while driving have been very successfully prosecuted in the Netherlands using a system called Monocam. This involves a camera that records drivers and a notebook that detects cell phone use. Since 2022, the German police have also been using the system.

Car Kits

Compared to wired hands-free kits used in the past, Bluetooth hands-free kits save on installation. These are now available ex works for almost all cars. They are usually optimally integrated into the multimedia system and a good choice. Many aftermarket radios also offer integrated Bluetooth hands-free functionality. All you need to install, is a microphone.

The connection between car kit and mobile phone is done using Bluetooth. To connect Bluetooth devices a predefined protocol is used. For car kits there are multiple protocols which might be used. The simplest one is HSP (Headset Profile). As the name indicates it was originally intended for headsets and only features speech transmission, call accepting and terminating and volume changes. HFP (Hands Free Profile) is nearly identical but aimed at car kits. If the car kit should also access the smartphone's contacts (calling contacts, show name for incoming calls) PBAP (Phone Book Access Profile) is needed. The most sophisticated profile is SAP. In this case the car kit only uses the SIM card of the mobile for authentication and takes over everything afterwards. This saves the mobile phone's energy and the car kit may use an external antenna to achieve the best cellular connection. Not necessarily part of the car kit but nevertheless useful is A2DP which offers the transmission of music between mobile and car stereo in decent quality. Thus the music on the mobile may be enjoyed by the use of the car's speakers and/or the voice from the navigation app. To start/stop playing the tracks and skip forward/backwards AVRCP (Audio Video Remote Control Profile) is needed in addition. For wireless charging of the mobile phone there is Qi.

Comparison

Standard	Phonebook	Music	External antenna	Energysaving	Recharging
Cable based
Bluetooth HSP					Qi
Bluetooth HFP	PBAP	A2DP & AVRCP			Qi
Bluetooth SAP	PBAP	A2DP & AVRCP			Qi

Overview

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