WO1990009706A1 - Vehicle telephone apparatus - Google Patents

Vehicle telephone apparatus Download PDF

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Publication number
WO1990009706A1
WO1990009706A1 PCT/GB1990/000207 GB9000207W WO9009706A1 WO 1990009706 A1 WO1990009706 A1 WO 1990009706A1 GB 9000207 W GB9000207 W GB 9000207W WO 9009706 A1 WO9009706 A1 WO 9009706A1
Authority
WO
WIPO (PCT)
Prior art keywords
call
speaker
progressively
level
sound
Prior art date
Application number
PCT/GB1990/000207
Other languages
French (fr)
Inventor
Baldev Johal
Charles Edward Priest
Original Assignee
In-Car Systems Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB898903263A external-priority patent/GB8903263D0/en
Application filed by In-Car Systems Limited filed Critical In-Car Systems Limited
Publication of WO1990009706A1 publication Critical patent/WO1990009706A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/3822—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving specially adapted for use in vehicles
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles

Definitions

  • the invention relates to apparatus for use with a telephone and in particular to apparatus for use with a so-called cellular telephone installed in a vehicle such as a car.
  • a vehicle having a cellular telephone usually has a radio and a cassette or compact disc player too. If one of these is on when the telephone rings it is usual to switch off the radio so that the telephone conversation may be carried on at a normal voice level. It is known to provide an accessory comprising a relay which turns off the radio automatically upon receipt of a signal indicative of the transmission or receipt of a telephone call, and which turns the radio on again when the call has finished. However, the sound is instantaneously returned to the level prevailing before the call. This can be jarring and otherwise unpleasant or even frightening, in which case an accident could occur.
  • apparatus for use within a cellular telephone and a radio speaker or the like, the apparatus including means to attenuate the sound level from the speaker upon receipt of a signal indicating that the telephone is transmitting or receiving a call, the means being arranged to progressively cause or allow the volume of sound from the speaker to increase to the level prevailing before the call upon receipt of a signal that the call has finished.
  • the time period and rate at which the volume is progressively returned to the prevailing level may vary widely, but is preferably up to between 2 and 10 seconds and most preferably up to between 5 and 10 seconds.
  • the apparatus may be installed within the radio or the telephone or be provided as a separate accessory.
  • the apparatus comprises a parallel network of resistors of differing values each resistor having a switch means, which network is connected between the output from the radio and the speaker, the switch means being arranged upon receipt of a signal indicating the end of the call to allow the signal from the radio to flow through resistors of progressively smaller values, whereby the level of signal applied to the speaker becomes progressively larger.
  • the switch means comprises transistors which are sequentially activated from the output of a ripple counter means.
  • the apparatus includes clock means in circuit with the resistors arranged to control the speed at which the sound is restored to the original level.
  • the means to attenuate the sound level is controlled by the voltage across a capacitor which is arranged to be charged up during the call and is arranged to discharge progressively at the end of the call, and thereby allow the sound level to increase progressively.
  • Figure 1 shows a circuit diagram of one embodiment of the invention.
  • Figure 2 shows a circuit diagram of another embodiment of the invention.
  • one embodiment of apparatus comprises a circuit to be connected between the speaker output of a radio or the like at R and is connected at T to an output from the vehicle telephone.
  • the circuit is arranged to attenuate the sound from- the radio speaker upon receipt or transmission of a call by the telephone and upon the end of that call to cause or allow the volume of sound from the speaker to increase progressively to the level prevailing before the call, so as not to startle the driver.
  • the sound is completely muted on receipt or transmission of a call.
  • the circuit is connected at T to a mute output of a telephone which places a high on that line upon receipt or transmission of a call.
  • the line T is connected via resistor Rl to the base of transistor TR1.
  • the collector of TRl is connected via both inputs of a dual input Nand gate Nl to the reset pin RST of a Ripple counter RCl.
  • a clock for the counter RCl is provided by a nand gate N2 and a resistor capacitor network R3C1 and its output is connected through one input of another nand gate N3 to provide inverted clock pulses at the clock pin ClK of the counter RCl.
  • the counter RCl uses six of its outputs Ql to Q6. Each output Ql to Q6 is connected via a respective exclusive NOR gate El to E6 and Resistor R4 to R9 to the base of a respective transistor TR2 to TR7, whose emitter is connected to ground.
  • the collector of each of the transistors TR2 to TR7 is connected to the junction, between two resistors RIO to R22. Each pair of resistors is connected in parallel between a 24 volt line 24v and a respective gate of six pairs of parallel arranged field effect transistors TR8 to TR19.
  • the six pairs of field effect transistors TR8 to TR19 are arranged in a parallel network L between the radio at R and the speaker at S. Although as shown a single radio output is connected to a single speaker S, there may be one parallel network for each radio to speaker connection, e.g. four. Alternatively four such connections may be connected through the same network L.
  • the source-drain path of five of the pairs of transistors TR8 to TR17 is connected in series with a resistor R23 to R27, each resistor being lower in value than the one above.
  • the sixth pair of transistors TR18 and TR19 is connected directly between R and S with no resistor being present.
  • the sixth output Q6 is also connected from the ripple counter RCl through a nand gate N4 to one input of nand gate N3, the other input being connected to the clock output.
  • each of the outputs Ql to Q6 is held high and the base of the transistors TR2 to TR7 is held low; the 24 volt line 24v is thus connected to the gates of the six pairs of transistors TR8 to TR19. Conduction therefore occurs between the Radio at R through the unimpeded path at 0 to the speaker at S. The volume of sound is not changed by the circuit.
  • this condition is signalled by a high appearing on line T.
  • the collector emitter circuit of TRl therefore conducts to ground and a low is applied to the input of nand gate Nl, which therefore applies a high to the reset pin RST of the counter RCl.
  • the outputs on Ql to Q6 are reset to low, so that inverted clock pulses appear at the output of Nand gate N3.
  • the ripple counter is prevented from counting by the high on its reset pin RST.
  • transistors TR2 to TR7 therefore go high so that the +24v is connected to ground through transistors TR2 to TR7.
  • Transistors TR8 to TR19 cease conducting and the connection between R and S is broken. The speakers are silenced and remain in that state while T and the reset pin RST are held high.
  • the ripple counter RCl can start counting clock pulses to sequentially apply a high to each output Ql to Q6 in time with the clock.
  • the first clock pulse or high at Ql prevents transistors TR2 from conducting so that +24 volts is reapplied to the gates of transistors TR8 and TR9 which thereby conduct and allow the radio signal to flow through resistor R23 to the speaker.
  • resistor R23 is of a relatively large value, so that most of the signal is lost across the resistor R23 and the sound from the speaker is of low volume.
  • the next clock pulse at Q2 allows the radio signal to flow through R24, of lower value than R23, so that the volume increases.
  • Successive clock pulses step the ripple counter forward to allow the signal from the radio to flow through resistors of progressively smaller values, whereby the level of signal applied to the speaker becomes progressively larger, until transistor pair TR18 and TR19 conduct when the signal flows unimpeded through 0 to the speaker S and the volume is returned to the level prevailing before the call.
  • the rate of the pulses produced by the clock thus controls the speed at which the sound is returned to the level prevailing before the call.
  • the high on the input of N4 causes a low on one of the inputs to N3 which holds the clock input on RCl low, so that the high level on Ql to Q6 remain until the telephone is used again.
  • the time over which the sound level returns to the prevailing level is determined by the speed of the clock and by the relative values of the resistor R3 and capacitor Cl and is preferably about 5 seconds.
  • the apparatus shown in Figure 2 comprises a +5v line T to be connected to a muting output line from the telephone, a line S to be connected to the positive terminal of a speaker and a 12 volt supply line +12v.
  • the line T is connected via a diode D100 and a resistor RlOO to the base of a transistor TRIOO, whose collector is connected to the +12v supply line via a resistor R400.
  • the emitter of transistor TR100 is connected to earth via resistor R300, and to a diode D200.
  • a capacitor C100 is connected between the other side of the diode D200 and earth.
  • the positive plate of capacitor C100 is connected via resistor R200 to the base of another transistor TR200 whose collector emitter path is connected between the speaker line at S, and earth.
  • the line S In use, and in the absence of a call, the line S is not connected to earth. The receipt or transmission of a call causes a +5v to appear on line T which biases transistor TR100 conducting.
  • the base of the transistor TR200 is thus biased via resistors R200 and R400 so that transistor TR20 conducts.
  • Line S is thus taken to earth through the collector emitter path of TR200, thereby silencing the speaker (not shown) on line S.
  • the capacitor C100 is simultaneously charged up.
  • the degree of attenuation of the sound level is controlled by the voltage across the capacitor C100.
  • the charge on the capacitor C100 leaks away through resistor R200 at a rate determined by the relative values of the two components C100, R200 and so the bias on the base of TR200 falls away progressively, so that conduction of the collector emitter path reduces progressively.
  • the signal applied to the speaker at S increases and the volume of sound therefrom increases progressively to the level prevailing before the call.
  • the values of the components CIOO R200 are chosen so that the sound level returns progressively over a period of time of about 8 seconds.

Abstract

Apparatus to be operatively connected between a cellular telephone installed within a vehicle and a radio or like speaker also installed within the vehicle, includes means to attenuate the sound level form the speaker upon the receipt of a signal that the telephone is receiving or transmitting a call. According to the invention the apparatus is arranged to increase the sound progressively at the end of the call to the level prevailing before the call so that the driver is not startled by a sudden loud noise.

Description

VEHICLE TELEPHONE APPARATUS
The invention relates to apparatus for use with a telephone and in particular to apparatus for use with a so-called cellular telephone installed in a vehicle such as a car.
A vehicle having a cellular telephone usually has a radio and a cassette or compact disc player too. If one of these is on when the telephone rings it is usual to switch off the radio so that the telephone conversation may be carried on at a normal voice level. It is known to provide an accessory comprising a relay which turns off the radio automatically upon receipt of a signal indicative of the transmission or receipt of a telephone call, and which turns the radio on again when the call has finished. However, the sound is instantaneously returned to the level prevailing before the call. This can be jarring and otherwise unpleasant or even frightening, in which case an accident could occur.
It is one object of the invention to reduce or minimise this problem.
According to one aspect of the invention there is provided apparatus for use within a cellular telephone and a radio speaker or the like, the apparatus including means to attenuate the sound level from the speaker upon receipt of a signal indicating that the telephone is transmitting or receiving a call, the means being arranged to progressively cause or allow the volume of sound from the speaker to increase to the level prevailing before the call upon receipt of a signal that the call has finished.
Because the apparatus increases the volume of sound progressively the driver is not startled by a sudden loud noise. The time period and rate at which the volume is progressively returned to the prevailing level may vary widely, but is preferably up to between 2 and 10 seconds and most preferably up to between 5 and 10 seconds.
The apparatus may be installed within the radio or the telephone or be provided as a separate accessory.
In one embodiment, the apparatus comprises a parallel network of resistors of differing values each resistor having a switch means, which network is connected between the output from the radio and the speaker, the switch means being arranged upon receipt of a signal indicating the end of the call to allow the signal from the radio to flow through resistors of progressively smaller values, whereby the level of signal applied to the speaker becomes progressively larger.
Preferably the switch means comprises transistors which are sequentially activated from the output of a ripple counter means.
Preferably the apparatus includes clock means in circuit with the resistors arranged to control the speed at which the sound is restored to the original level.
In another embodiment the means to attenuate the sound level is controlled by the voltage across a capacitor which is arranged to be charged up during the call and is arranged to discharge progressively at the end of the call, and thereby allow the sound level to increase progressively.
In order that the invention may be well understood it will now be described by way of example with reference to the accompanying diagrammatic drawings in which:
Figure 1 shows a circuit diagram of one embodiment of the invention; and
Figure 2 shows a circuit diagram of another embodiment of the invention.
As shown in Figure 1, one embodiment of apparatus according to the invention comprises a circuit to be connected between the speaker output of a radio or the like at R and is connected at T to an output from the vehicle telephone. The circuit is arranged to attenuate the sound from- the radio speaker upon receipt or transmission of a call by the telephone and upon the end of that call to cause or allow the volume of sound from the speaker to increase progressively to the level prevailing before the call, so as not to startle the driver. In the examples illustrated, the sound is completely muted on receipt or transmission of a call.
The circuit is connected at T to a mute output of a telephone which places a high on that line upon receipt or transmission of a call. The line T is connected via resistor Rl to the base of transistor TR1. The collector of TRl is connected via both inputs of a dual input Nand gate Nl to the reset pin RST of a Ripple counter RCl.
A clock for the counter RCl is provided by a nand gate N2 and a resistor capacitor network R3C1 and its output is connected through one input of another nand gate N3 to provide inverted clock pulses at the clock pin ClK of the counter RCl. The counter RCl uses six of its outputs Ql to Q6. Each output Ql to Q6 is connected via a respective exclusive NOR gate El to E6 and Resistor R4 to R9 to the base of a respective transistor TR2 to TR7, whose emitter is connected to ground. The collector of each of the transistors TR2 to TR7 is connected to the junction, between two resistors RIO to R22. Each pair of resistors is connected in parallel between a 24 volt line 24v and a respective gate of six pairs of parallel arranged field effect transistors TR8 to TR19.
The six pairs of field effect transistors TR8 to TR19 are arranged in a parallel network L between the radio at R and the speaker at S. Although as shown a single radio output is connected to a single speaker S, there may be one parallel network for each radio to speaker connection, e.g. four. Alternatively four such connections may be connected through the same network L. The source-drain path of five of the pairs of transistors TR8 to TR17 is connected in series with a resistor R23 to R27, each resistor being lower in value than the one above. The sixth pair of transistors TR18 and TR19 is connected directly between R and S with no resistor being present.
The sixth output Q6 is also connected from the ripple counter RCl through a nand gate N4 to one input of nand gate N3, the other input being connected to the clock output.
In use, and in the absence of any transmission by the telephone, each of the outputs Ql to Q6 is held high and the base of the transistors TR2 to TR7 is held low; the 24 volt line 24v is thus connected to the gates of the six pairs of transistors TR8 to TR19. Conduction therefore occurs between the Radio at R through the unimpeded path at 0 to the speaker at S. The volume of sound is not changed by the circuit. When the telephone receives or makes a call, this condition is signalled by a high appearing on line T. The collector emitter circuit of TRl therefore conducts to ground and a low is applied to the input of nand gate Nl, which therefore applies a high to the reset pin RST of the counter RCl. The outputs on Ql to Q6 are reset to low, so that inverted clock pulses appear at the output of Nand gate N3. However, the ripple counter is prevented from counting by the high on its reset pin RST.
The bases of transistors TR2 to TR7 therefore go high so that the +24v is connected to ground through transistors TR2 to TR7. Transistors TR8 to TR19 cease conducting and the connection between R and S is broken. The speakers are silenced and remain in that state while T and the reset pin RST are held high.
At the end of transmission the line at T returns to low, signalling that the call has finished, so that the ripple counter RCl can start counting clock pulses to sequentially apply a high to each output Ql to Q6 in time with the clock. The first clock pulse or high at Ql prevents transistors TR2 from conducting so that +24 volts is reapplied to the gates of transistors TR8 and TR9 which thereby conduct and allow the radio signal to flow through resistor R23 to the speaker. However, resistor R23 is of a relatively large value, so that most of the signal is lost across the resistor R23 and the sound from the speaker is of low volume. The next clock pulse at Q2 allows the radio signal to flow through R24, of lower value than R23, so that the volume increases. Successive clock pulses step the ripple counter forward to allow the signal from the radio to flow through resistors of progressively smaller values, whereby the level of signal applied to the speaker becomes progressively larger, until transistor pair TR18 and TR19 conduct when the signal flows unimpeded through 0 to the speaker S and the volume is returned to the level prevailing before the call. The rate of the pulses produced by the clock thus controls the speed at which the sound is returned to the level prevailing before the call. Simultaneously the high on the input of N4 causes a low on one of the inputs to N3 which holds the clock input on RCl low, so that the high level on Ql to Q6 remain until the telephone is used again.
The time over which the sound level returns to the prevailing level is determined by the speed of the clock and by the relative values of the resistor R3 and capacitor Cl and is preferably about 5 seconds.
The apparatus shown in Figure 2 comprises a +5v line T to be connected to a muting output line from the telephone, a line S to be connected to the positive terminal of a speaker and a 12 volt supply line +12v. The line T is connected via a diode D100 and a resistor RlOO to the base of a transistor TRIOO, whose collector is connected to the +12v supply line via a resistor R400. The emitter of transistor TR100 is connected to earth via resistor R300, and to a diode D200. A capacitor C100 is connected between the other side of the diode D200 and earth. The positive plate of capacitor C100 is connected via resistor R200 to the base of another transistor TR200 whose collector emitter path is connected between the speaker line at S, and earth.
In use, and in the absence of a call, the line S is not connected to earth. The receipt or transmission of a call causes a +5v to appear on line T which biases transistor TR100 conducting.
The base of the transistor TR200 is thus biased via resistors R200 and R400 so that transistor TR20 conducts. Line S is thus taken to earth through the collector emitter path of TR200, thereby silencing the speaker (not shown) on line S. The capacitor C100 is simultaneously charged up.
At the end of the call line T returns to ground and transistor TR100 is biased non conducting. However, the degree of attenuation of the sound level is controlled by the voltage across the capacitor C100. The charge on the capacitor C100 leaks away through resistor R200 at a rate determined by the relative values of the two components C100, R200 and so the bias on the base of TR200 falls away progressively, so that conduction of the collector emitter path reduces progressively. In this way, the signal applied to the speaker at S increases and the volume of sound therefrom increases progressively to the level prevailing before the call. In the embodiment shown the values of the components CIOO R200 are chosen so that the sound level returns progressively over a period of time of about 8 seconds.

Claims

Apparatus to be operatively connected to a cellular telephone installed within a vehicle and to a speaker of a radio or the like also installed within the vehicle, the apparatus including means to attenuate the sound level from the speaker upon receipt of a signal indicating that the telephone is transmitting or receiving a call characterised in that the means to attenuate the sound level are arranged to cause or allow the volume of sound from the speaker to increase progressively to the level prevailing before the call upon receipt of a signal that the call has ended.
Apparatus according to Claim 1 characterised in that the means are arranged to progressively increase the volume over a period of at least about 2 seconds.
Apparatus according to Claim 2 characterised in that the means are arranged to progressively increase the volume over a period of between 5 and 10 seconds.
Apparatus according to any preceding Claim characterised in that the means comprises a parallel network of a plurality of resistors of differing values (R23-R27), and switch means (TR2-TR19), the network to be connected between an output from the radio (R) and a speaker (S), the switch means (TR2- TR19) being arranged upon receipt of a signal indicating the end of the call to allow the signal from the radio to flow through resistors of progressively smaller values, whereby the level of signal applied to the speaker becomes progressively larger.
5. Apparatus according to Claim 4 characterised in that the switch means comprises a plurality of transistors (TR2- TR19) each connected to a resistor (R23-R27) and which are sequentially activated from an output (Q1-Q6) of a ripple counter means (RCl).
6. Apparatus according to Claim 4 or, 5 characterised by clock means (Cl, R3, N2, N3) in circuit with the ripple counter (RCl) and arranged to control the speed at which the sound is returned to the level prevailing before the call.
7. Apparatus according to any of Claims 1 to 3 characterised in that the speed at which the sound level returns to the level prevailing before the call is controlled by the voltage across a capacitor (CIOO) which is arranged to be charged up during the call and is arranged to discharge progressively at the end of the call.
8. Apparatus according to Claim 7 characterised in that the apparatus includes a transistor (TR200), whose controlled path is arranged to be connected between a positive speaker terminal (S) and earth, the arrival of a signal indicating the receipt or transmission of a telephone call being arranged to bias the control electrode of the transistor (TR200) and to allow the positive speaker terminal to be taken to ground, the capacitor (C200) being connected between the base of the transistor and ground, whereby at the end of the call the capacitor (C200) discharges and thereby reduces the bias progressively so that the signal applied to the speaker progressively returns to the level prevailing level before the call.
PCT/GB1990/000207 1989-02-14 1990-02-09 Vehicle telephone apparatus WO1990009706A1 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8903263.5 1989-02-14
GB898903263A GB8903263D0 (en) 1989-02-14 1989-02-14 Telephone accessory
GB8919665.3 1989-08-31
GB8919665A GB2231238A (en) 1989-02-14 1989-08-31 Attenuating audio source during car telephone operation

Publications (1)

Publication Number Publication Date
WO1990009706A1 true WO1990009706A1 (en) 1990-08-23

Family

ID=26294949

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/000207 WO1990009706A1 (en) 1989-02-14 1990-02-09 Vehicle telephone apparatus

Country Status (3)

Country Link
AU (1) AU5095190A (en)
PT (1) PT93129A (en)
WO (1) WO1990009706A1 (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0659029A3 (en) * 1993-12-16 1996-02-07 Grundig Emv Loudspeaker selection device.
WO1996007243A1 (en) * 1994-08-30 1996-03-07 Co-Pat Oy Auxiliary equipment for mobile telephones
EP0809413A1 (en) * 1996-05-24 1997-11-26 Philips Patentverwaltung GmbH Audio devide for a vehicle
GB2338621A (en) * 1998-04-15 1999-12-22 E Lead Electronic Co Ltd Integrated mobile-phone hands free kit combining with vehicular stereo loudspeakers and having common power supply

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2950338A1 (en) * 1979-12-14 1981-07-02 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Radio telephone installation in vehicle - has signal monitor which adjusts amplifier gain dependent upon signal type being received
US4425477A (en) * 1982-02-08 1984-01-10 Paul Alan Magil & Associates Telephone line triggered attenuator
US4524461A (en) * 1983-07-18 1985-06-18 American Transceiver Corp. Helmet-supported radio transceiver and broadcast receiver system
WO1986003353A1 (en) * 1984-11-23 1986-06-05 Andrew Warrack Acoustic signal attenuator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2950338A1 (en) * 1979-12-14 1981-07-02 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Radio telephone installation in vehicle - has signal monitor which adjusts amplifier gain dependent upon signal type being received
US4425477A (en) * 1982-02-08 1984-01-10 Paul Alan Magil & Associates Telephone line triggered attenuator
US4524461A (en) * 1983-07-18 1985-06-18 American Transceiver Corp. Helmet-supported radio transceiver and broadcast receiver system
WO1986003353A1 (en) * 1984-11-23 1986-06-05 Andrew Warrack Acoustic signal attenuator

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0659029A3 (en) * 1993-12-16 1996-02-07 Grundig Emv Loudspeaker selection device.
WO1996007243A1 (en) * 1994-08-30 1996-03-07 Co-Pat Oy Auxiliary equipment for mobile telephones
EP0809413A1 (en) * 1996-05-24 1997-11-26 Philips Patentverwaltung GmbH Audio devide for a vehicle
GB2338621A (en) * 1998-04-15 1999-12-22 E Lead Electronic Co Ltd Integrated mobile-phone hands free kit combining with vehicular stereo loudspeakers and having common power supply

Also Published As

Publication number Publication date
PT93129A (en) 1991-10-15
AU5095190A (en) 1990-09-05

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