EP2030330A2

EP2030330A2 - Apparatus for emitting short-range radioelectric waves

Info

Publication number: EP2030330A2
Application number: EP07803884A
Authority: EP
Inventors: Michael Attali
Original assignee: BBWorld
Current assignee: BBWorld
Priority date: 2006-06-22
Filing date: 2007-06-18
Publication date: 2009-03-04
Also published as: WO2007148009A2; WO2007148009A3; FR2902948A1

Abstract

The invention relates to an apparatus (12) for emitting short-range radioelectric waves for transmitting audio signals from the loud speaker of a mobile telephony apparatus (10) to a radio receiver (14). The apparatus comprises: - means (16), such as a microphone, for picking up the audio signal from the loud speaker, this signal corresponding to the speech of the person speaking to be transmitted, - means for processing this audio signal in such a way as to obtain a frequency transposition to a predetermined frequency band, - means for emitting the transposed signal in the form of radioelectric waves (18), and - means for monitoring the apparent power radiated by the apparatus.

Description

APPARATUS FOR TRANSMITTING LOW-RANGE RADIO WAVES

The present invention relates to an apparatus for transferring audio signals from a telephone speaker to a receiver, especially in the context of a "hands-free kit" allowing the use of a mobile phone when the user drives a vehicle.

There are currently many solutions for continuing a phone conversation without holding the mobile phone in his hands. For example, mobile phones equipped with a "hands-free" function in which telephone conversations are amplified in reception and transmission, including through a speaker and a microphone amplifier. Often, the audio quality offered by this type of phone is not very good, since it is relatively expensive to include in a device of this size a good quality speaker.

There are also hands-free kits, separate from mobile phones, which consist of a separate speaker and microphone. These systems are connected to the mobile phone wired or using wireless communication technology, such as "Bluetooth" technology. The disadvantage of these kits lies in the fact that they are not usable on all mobile phones. Indeed, the outlets of phones vary from one model to another, and, as for wired kits, it is necessary to use a kit specifically adapted to his phone. In addition, Bluetooth technology is not yet present on all mobile phones, and some phones are not compatible with the hands-free kits using this technology. Some of these handsfree kits also offer a function to automatically turn off the radio when a call is in progress, so as not to interfere with the phone user in his conversation. These kits have the disadvantage of not being very mobile, since they require the use of a separate speaker, and are therefore often installed permanently in a vehicle.

On the market are also car radios with means to communicate with a mobile phone, for example using wireless technology, and thus offer a hands-free feature using the speakers already installed in the vehicle. This solution has the disadvantage of being usable only in a vehicle.

The object of the present invention is to remedy at least some of these disadvantages by providing a hands-free kit usable on any type of mobile phone, and in any situation. More specifically, the invention relates to an apparatus for transferring audio signals from the speaker of a telephone to any type of radio receiver. This device can be used both in a vehicle, where the conversation is transferred to the speakers of the car radio, as in any room with a radio receiver. The object of the invention is therefore mainly intended for use on a mobile phone in a vehicle, but it can also be used for a wireless home phone.

Thus, the invention relates to a device for transmitting short-range radio waves for transmitting audio signals from the loudspeaker of a mobile telephone device to a radio receiver. This apparatus comprises: means, such as a microphone, for picking up the audio signal coming from the loudspeaker, this signal corresponding to the speech of the interlocutor to be transmitted, means for processing this audio signal so as to obtain a frequency translation in a predetermined frequency band, antenna means for transmitting the transposed signal in the form of radio waves, and means for controlling the effective power radiated by the apparatus, for example such that this power only allows a reception in a perimeter of about three meters in free field around the device.

Moreover, the power control means are such that they make it possible to comply with the current limit of regulation set at 50 nW.

The limit of three meters in the free field makes it possible, in particular, to ensure that waves emitted by an apparatus located in a vehicle will be picked up by the antenna located on the vehicle and not by an antenna of a neighboring vehicle. In the case of obstacles between the transmitter and the receiver, the range of the transmitter is lower for an apparent apparent radiated power.

In one embodiment, the apparatus comprises means for performing frequency transposition over a range of 88 MHz to 108 MHz. Preferably this device is fixed on the mobile phone, for example by means of a clip or suction cup. Preferably the device is small, so that it can be easily transported and not be too bulky when installed on the phone.

In some countries, for example France, the conditions of use concerning broadcasting are very strict, since the assignment of broadcasting channels is carried out by a public body, the Higher Audiovisual Council (CSA), which is the the FM band with an exclusive status. An apparatus such as that defined by the invention must, for use in these countries, meet certain regulatory criteria.

For example, in Europe, these criteria are set by Articles 3.1a, 3.1b and 3.2 of the European Directive 1999/5 / EC of 9 March 1999 transposed into French law by Article R.20-1 of the Post Code. and electronic communications.

The essential requirements provided for in Article R.20-1 of the Code include the following: health and safety of persons, - electromagnetic compatibility, proper use of the radio frequency spectrum in the case of radio equipment.

This last requirement involves designing the equipment so as to avoid any interference with radio receivers located in the vicinity of the device, and which do not belong to the user. It must be ensured, for example, when in a vehicle, that the transmission of telephone conversation will be directed only in the direction of the radio antenna located on the user's vehicle, and not on those of a nearby vehicle. This non-interference is made possible by the use of the control means of the effective radiated power and the adequate filtering of the signal so as not to transmit on an adjacent channel.

Among the requirements applicable to the equipment, it is necessary to respect precise limits and / or tolerances for the following parameters:

- the error in frequency, since the apparatuses can emit only in a very precise frequency band,

the spectral occupation of the band passing from the transmitting signal,

- the limitation of emissions of spurious emissions, and

- the existence of a function put on standby, so that the device does not emit radio waves unnecessarily in case of prolonged absence of speech, for example for a period longer than one minute.

Concerning this last parameter, the regulatory limit is currently set at 5 minutes by the European Telecommunications Standards Institute, in the harmonized ETSI 301 357 standard).

According to the embodiments, the apparatus comprises one or more ancillary functionalities, making it possible to respond to these regulatory constraints and implemented by various means. These features and the means used for the realized will be described in more detail using the figures.

In one embodiment, the apparatus comprises standby means when no audio signal from the loudspeaker The speaker is not detected for a specified duration, such time being, for example, between one minute and five minutes.

In one embodiment, the apparatus comprises means for limiting the unnecessary and / or non-essential emissions of the antenna radiation.

In one embodiment, the apparatus comprises means for controlling the frequency error of the transposed signal, so that this error remains below a predetermined value, for example plus or minus 10 kHz. In one embodiment, the apparatus comprises frequency traversing means enabling a user to choose the frequency of the transposed signal.

These means are useful to allow correct use of the apparatus. Indeed, the device is, in particular, intended to be installed in a motor vehicle. It is therefore brought to be moved over relatively large distances, and thus to change region regularly. However, the radio landscape, in France as in other countries, is such that the frequencies of radios vary from one region to another, and it is therefore useful to be able to modify the frequency to position itself, at any moment, on a free frequency in the region in which the device is located.

In one embodiment, the apparatus comprises means for transmitting radio signaling signals, in particular of the RDS (Radio Data Signal) type, in order to allow the automatic setting of a radio receiver on the frequency of the transmitter.

FM. In this way, the frequency on which the transmitter transmits the signals is made a priority for the FM receiver, ie it is detected automatically by the receiver.

In one embodiment, the radio signal signaling means comprise means for sending an information signal, this signal being such that a signaling text corresponding to the broadcast is displayed on a screen of a receiver.

In one embodiment, the apparatus comprises means for automatically selecting a channel, in order to allow an automatic choice of the transmission frequency, this choice being made randomly or among available frequencies.

In one embodiment, the apparatus comprises means for pre-emphasizing the audio signal from the telephone so as to have a better quality of sound in reception.

In one embodiment, the apparatus comprises an input for an audio signal distinct from that of a telephone, originating in particular from a walkman-type device or an MP3 player, and intended to be broadcast on the loudspeaker (s). speaker (s) of a radio receiver.

In one embodiment, the apparatus comprises means for recording and coding the signals corresponding to the speaker's speech using known compression algorithms, in particular of the MP3 type.

In one embodiment, the apparatus comprises means for recording, as a dictaphone, the speech other than that of the telephone, in particular by a rotary support providing the possibility of turning the face in which the microphone is located to the outside.

In one embodiment, the apparatus comprises means for keeping in memory the recorded files.

In one embodiment, the apparatus comprises standby means, means for detecting the reception of a call, and means for inhibiting the standby on receiving a call. In one embodiment, the means for detecting the reception of a call comprise means for detecting a vibration of the telephone, such as a piezoelectric sensor.

In one embodiment, the vibration detection means use the means for capturing the audio signal

Other advantages and characteristics of the invention will become apparent with the description of some of these embodiments, made with the aid of the drawings, among which: FIG. 1 represents a communication system using an apparatus according to the invention, FIG. 2 represents a block diagram of an apparatus according to the invention, in which the functions are integrated in digital components, FIG. 3 represents a simplified analog version of the functional diagram of an apparatus according to the invention.

Figure 1 shows a device implementation system. This system comprises a mobile phone 10 on which the apparatus 12 is installed.

When a conversation is in progress on the mobile phone 10, the device 12 picks up, via a microphone 16, the audio signal coming out of the loudspeaker of the telephone. The apparatus 12 converts this signal into radio waves 18 which are transmitted to a radio receiver 14. The audio signals are then demodulated in baseband and broadcast by the loudspeakers 15 of the radio receiver.

FIG. 2 shows an exemplary block diagram of an apparatus according to the invention, realized in a digital mode.

In this figure, we see the different means that can be implemented in such a device, such as the power control, the standby function, the signaling function by RDS type radio signals, or the pre-emphasis function.

To manage the various functions of the device, a microcontroller 20 is used. At input 21 of this microcontroller is an accentuated audio signal. This accented audio signal corresponds in fact to a sound coming from the speaker of the mobile phone, which has been picked up by a microphone 22 and pre-accentuated by a pre-emphasis filter 23 so as to increase the signal-to-noise ratio. For example, this pre-emphasis is of the order of 6 dB per octave for frequencies higher than 3.18 kHz in Europe. The input 21 is an input corresponding to an analog / digital conversion ("analogical / digital"), which means that the analog audio signal received at the input of the microcontroller is intended to be converted into a digital signal.

The digital signal obtained after conversion is transmitted to FM wave transmission means 24. This transmitting means modulates the audio signals using FM analog modulation with channels spaced at 20OkHz.

In case the user requests the recording of these conversations by pressing a record button

24 of the user interface, the digital signal is at the same time sent to an encoding means 32 for creating mp3 files corresponding to conversations.

The MP3 files are then sent to the microcontroller 20 so as to be transmitted to a memory 33, for example of the Compact Flash type, in order to be recorded.

In order to allow this recording, the memory 33 also receives from the microcontroller 20 control information, via a control bus 34, and addressing information via the link 35. control, for example, to manage the recording and / or deletion of data. The addressing information makes it possible to indicate to the memory 33 to which address it must write the data transmitted to it. Furthermore, the user can, if he wishes, transfer these files or other data to a personal computer 36 of PC type via a USB port 37.

As required by certain regulatory provisions, the apparatus includes means for controlling the effective power radiated by the apparatus. These means take the form of a power attenuation function 38, and a function 39 for selecting different power levels according to the applicable regulations and the need for the necessary range. For example, for a car radio of very high sensitivity the user decreases the power to reduce the risk of jamming a car radio neighbor.

In the same way, the apparatus also comprises a standby function for cutting the emission of radio waves when no more modulating audio signal is detected on the input 24. Preferably, this standby occurs. after a fixed period, for example 1 minute. For this purpose, the apparatus comprises a quartz-based stable reference clock 40 connected to the clock of the microcontroller to determine the elapsed time since the last presence of an audio or speech signal. In another embodiment, two different quartz are used for the microcontroller and the FM transmitter. Indeed, this solution allows to use quarters adjusted at different frequencies for the two clocks.

According to the information received from the reference clock 40, the microcontroller sends a control signal to the FM transmitter 24 in order to stop the signal. This sending of a control signal corresponds to a function of extinction of signal, called function "shutoff". The sleep mode output is preferably when the device detects a sound input, for example the ringing of the phone. If the phone is in vibration mode, the arrival of a call on the phone is detected by a piezoelectric sensor 41, and the device then leaves the standby mode.

In another example, the microphone 22 is used to detect a vibration of the telephone, since this microphone may also have a piezoelectric sensor function. The apparatus also has a resetting means 42 for resetting all the functions. This resetting means acts on the reset input of the microcontroller.

In addition, to facilitate the use of the device, a user interface is provided.

This interface comprises means allowing the user to choose the transmission frequency by traversing the frequency band in one direction or the other, and stopping on the desired frequency. In the embodiment described here, these means are buttons 25, 26 and 27, respectively corresponding to a stop button, an advance button and a back button. If the user prefers that the choice of channel is done automatically, he can use the function "RDS" of the device, this function being activated by pressing a button 31.

As indicated above, the interface also comprises a means allowing the user to trigger the recording of his conversations, for example a button 38. The stop recording is done by a second touch on this button.

Preferably, the apparatus also comprises means for adjusting the sensitivity of the microphone, in particular buttons 29 and 30. This sensitivity setting corresponds to a adjusting the amplitude of the modulating signal from the microphone.

Furthermore, the apparatus comprises a priority control circuit buttons 43 to manage the support on several buttons and dual function buttons such as buttons 26 and 27 which serve both to select the frequency channel and to choose the audio file to listen. To select one type of function with respect to another, the choice is made by pressing the button 31 for 5 seconds. After these 5 seconds of continuous support it is the audio recorder or dictaphone mode which is activated, depending on the active input. The device has means to automatically detect which input is active, and therefore to enter recorder mode or dictaphone mode.

The device defined here can also include a function of compressed audio file reader, these files being present in a memory of the device, this memory being able to be of external type, for example a "compact flash" memory, or of internal type , for example an EEPROM memory. For this purpose, the apparatus comprises means for coding and decoding these files of this type 32 as well as means for managing the audio files. These management means include means for stopping the reading or move to the next or previous file (25, 26 and 27).

When the device is not in use, it is interesting to disable it to save energy. Thus, the apparatus comprises an ON / OFF function 43, as well as a two-color light-emitting diode 44 indicating the on / off state and the sleep mode state.

Regarding the power supply of the device, it is performed by means of a rechargeable battery 45 which is preferably connected to the cigarette lighter of the vehicle for recharge. The battery can also be charged via USB 37 when the camera is connected to a computer.

In the embodiment described in this figure, the apparatus also comprises display means 46 for displaying information on an LCD type screen. This information may in particular be the transmission frequency used by the device, and / or data concerning the playback of the current audio files.

Figure 3 shows an analog and simplified version of the block diagram of Figure 1.

As in the diagram described above, the audio signals from the mobile phone are picked up by a microphone 50 and transmitted to a signal pre-emphasis means 51. The accented signals are then transmitted to the means 52 for transmitting radio waves. In this case, the transmission means 52 takes the form of a voltage controlled oscillator (VCO), for example a MAX2606 type oscillator existing on the market. At the output of this transmission means are power control means 53, 54 and 55.

As in the digital version, this block diagram includes a device standby function. This function is implemented by an electronic circuit 56 of VAD (voice activity detection) silence detection which cuts the transmission of the speech when a silence is detected for a time greater than a determined time interval. This electronic circuit 56 has as an input parameter the audio signal picked up by the microphone 50 and a duration determined by time measuring means 57, 58. The circuit 56 operates on a power-up means 57 to stop the transmission. .

This block diagram also shows the power on and off function of the apparatus 58, the apparatus being powered by means of a battery rechargeable 60, for example connected to the cigarette lighter of a vehicle.

Claims

A short-range radio wave transmitting apparatus (18) for transmitting audio signals from the speaker of a mobile telephone apparatus (10) to a radio receiver (14), said apparatus comprising: means (16; 22; 50), such as a microphone, for picking up the audio signal from the loudspeaker, this signal corresponding to the speech of the interlocutor to be transmitted, - antenna means (24; 52) for processing this audio signal so as to obtain frequency transposition over a predetermined frequency band, means for transmitting the transposed signal in the form of radio waves, and - means (38; 39; 53; 54; ) to control the effective power radiated by the apparatus (12) such that this power only allows reception in a perimeter of the order of three meters in a free field.

An apparatus according to claim 1 comprising means for performing frequency transposition over a range of 88 MHz to 108 MHz.

An apparatus according to claim 1 or 2 including means for standby when no audio signal from the speaker is detected for a specified duration.

4. Apparatus according to one of the preceding claims comprising means for limiting the unnecessary emissions and / or non-essential radiation of the antenna.

5. Apparatus according to one of the preceding claims comprising means for controlling the frequency error of the transposed signal, so that this error remains below a predetermined value, for example plus or minus 10 kHz.

6. Apparatus according to one of the preceding claims comprising frequency traversing means allowing a user to choose the frequency of the transposed signal.

7. Apparatus according to one of the preceding claims comprising means for transmitting radio signal signals, including RDS (Radio Data Signal) type to allow an automatic setting of a radio receiver on the frequency of the FM transmitter .

8. Apparatus according to one of the preceding claims comprising, upstream of the transposition means, means (23; 51) for pre-emphasizing the audio signal from the loudspeaker of the telephone so as to increase the transmitted signal-to-noise ratio. the means of transposition.

9. Apparatus according to one of the preceding claims comprising an input for an audio signal separate from that of a telephone intended to be broadcast on the speaker (s) of a radio receiver.

10. Apparatus according to one of the preceding claims comprising means for recording the audio signals from the speaker.

11. Apparatus according to one of the preceding claims comprising means for standby, means for detecting the receipt of a call (41), and means to inhibit sleep on receipt of a call.

12. Apparatus according to claim 11 wherein the means (41) for detecting the reception of a call comprises means for detecting a vibration of the telephone, such as a piezoelectric sensor.

Apparatus according to claim 12 wherein the vibration detecting means utilizes the means

(16; 22; 50) to receive the audio signal.