photo: hanno boblenz
your handsfree device suddenly sorts contacts by first name? And with the music streaming also does not work properly? If the smartphone and car radio don’t understand each other, it’s because the bluetooth profile is wrong. We tell you what to look out for.
recently in a 2013 mitsubishi: pairing the iphone with the dvd navigation radio? No problem, after all, the bluetooth logo is emblazoned on it. Phone calls? Missing. the voice control requires "entries in the vehicle phone book", which we had not created cumbersome. And a keyboard for dialing numbers is not available. So with the mitsubishi system you can only receive calls.
Many drivers of company cars complain that their cars and smartphones don’t get along properly. Sometimes the phone book is not transferred, sometimes it does not work with the access to the music files.
Bluetooth should be ordered at the time of purchase
The problem is not limited to a single vehicle. Because car manufacturers now offer hands-free systems ex works. These have the advantage that they are conveniently integrated into the vehicle’s operating concept and, for example, support control via steering wheel remote control or display and center console controller.
Two main transmission paths are used for hands-free systems today: the handsfree profile (HFP) and the SIM access profile (see box). With HFP, the cell phone transmits the data; with SIM access profile, the radio technology is built into the vehicle. the latter is particularly useful if the car is already equipped with a mobile radio module that receives internet-based traffic reports, for example, or handles emergency call functions and the like.
HFP-based systems are considerably cheaper (100 to 250 euros for a hands-free system compared with 600 to 900 euros for a permanently installed telephone electronics system) because no mobile radio technology has to be installed in the vehicle. Many car manufacturers refer to this variant simply as the bluetooth interface.
However, anyone opting for such a system for cost reasons should choose a solution that nevertheless ensures a connection to an external mobile radio antenna. Because a cell phone transmitting in the vehicle leads to a high electromagnetic exposure of the passengers. Moreover, the connection quality suffers. With the consequence that you can’t hear the other person very well, because most of the radio signals are shielded by the sheet metal of the car.
Antenna? No way
However, you won’t find the classic antenna socket for connecting an external antenna that was common in the past on current smartphones. However, it is not absolutely necessary: many manufacturers’ current cell phone cradles use what is known as an inductive antenna connection: in this case, the smartphone’s antenna transmits its signals to a counterpart in the cell phone cradle using the lowest possible radio energy. The signals picked up there are amplified and forwarded to the external antenna.
Radio waves received from the network take the reverse route to the smartphone. Most smartphone-specific holders or snap-in adapters, which are offered at prices of around 100 euros as accessories by car manufacturers for their factory-equipped hands-free connections, work according to this principle. For the connection of the audio signals to the microphone and speakers in the cockpit, bluetooth radio (according to HFP) or, in some cases, a cable connection is used.
Clever solution charging cradle
in addition, suitable cradles are only available for the most popular phone models, often many months after their market launch. That’s why almost all manufacturers now rely on the universal charging cradle. Advantage: every driver can simply place his phone in it and it is inductively coupled with the antenna and charged. At the same time, the phone is safely stowed away during the journey.
If the phone is connected via a cradle, it is charged via the vehicle’s electrical system. Otherwise, the connection is made by cable via the car’s USB port, which should no longer be missing in any company car. If necessary, the phone can be charged via the cigarette lighter using a special cable.
Before ordering new company cars, fleet managers should find out which bluetooth standard the radio or the interfaces of the vehicles use and what exactly they can do. Manufacturers often offer different solutions. In practice, this question can only be answered with a shrug of the shoulders by the dealer. In case of doubt, it is recommended to ask the manufacturer directly.
Handsfree profile (HFP)
VHFP connects the phone to the car’s microphone and speaker system. The calls run over the transmitting unit in the cell phone. The phone can also be connected to an external antenna (via antenna plug or inductive), but this is rarely realized in such a way. Most of the time, the phone is on the radio. This leads to high radiation exposure with poorer radio quality. The ringtone can be switched off in handsfree mode, HFP also supports voice commands such as "redial".
Remote SIM access profile (rsap)
This requires a full-fledged car phone, even if it has no controls such as keypad or handset. Rsap accesses the SIM card of the cell phone. Unlike HFP, the connection always runs via the car’s electronics or antenna, the phone’s radio is switched off. Nevertheless, the driver can be reached under his normal phone number. Disadvantage: With bluetooth coupling, the smartphone is not available for SMS, e-mails or web accesses. This will only work again when the bluetooth connection to the car is disconnected.
Unlike HFP, however, not all cell phones support the remote SIM access profile. the galaxy models from samsung as well as many blackberrys and newer android phones from sony and HTC know rsap, but apples iphone and many older android smartphones do not.
Phonebook access profile (PBAP)
Own profile for accessing the phone book stored in the cell phone. whether and to what extent the manufacturer of the vehicle, car radio or hands-free system supports it is independent of the pure hands-free function. in addition, PBAP only controls the actual access to the data stored in the phone. The phone book is completely copied into the memory of the on-board system. How the data is prepared and displayed (e.g. whether entries are sorted by first or last name and whether this setting can be changed and whether all the phone numbers and addresses stored for an entry are actually transferred) depends solely on the software in the vehicle system.
Advanced audio distribution profile (A2DP)
The very widespread A2DP is used to transmit music, which practically always works, there are differences in the additional functions defined in the standard: whether interpretations and titles are displayed or on you can navigate through the folder structure of the music files via the on-board display, depends on the software of the vehicle system. The A2DP standard provides for these options, but not all vehicle manufacturers have fully implemented them. this has not only optical consequences: only if the vehicle system is able to store the list of music on ipod and co. For example, it is possible to jump comfortably from track to track.