AU2000269773B2 - Method for controlling a transmission system, use of this method, transmission system, receiving unit and hearing aid - Google Patents

Description

1 A METHOD FOR CONTROLLING A TRANSMISSION SYSTEM, A TRANSMISSION SYSTEM, AND A RECEIVING DEVICE The present invention relates to a method for controlling a transmission system, a transmission system, and a receiving device particularly but not exclusive for use with a hearing device.

Miniaturized FM (frequency-modulated) transmission systems have been used already for a considerable time with hearing devices. Essentially the transmission system consists of a microphone-fitted transmitter and a receiver connected to the hearing device. It is critically important that the receiver per se be as compact and as lightweight as possible in order that the unit consisting of receiver and hearing device be of a size readily tolerated by its wearer.

A receiver of the cited kind is known from the US patent 5,734,976 and uses FM transmission wherein the carrier frequency is set by a quartz crystal.

As a result this known state of the art incurs the drawback that changing the carrier frequency, and hence the transmission channel, entails exchanging the quartz crystal. Therefore, this system precludes rapidly switching between different transmission channels.

H:\Priyanka\Keep\speci\2000269773.doc 9/02/06 2 Moreover the known system is a drawback for the hearingdevice manufacturer because a large number of quartz crystals must be kept in stock in order to allow switching between transmission channels in a reasonably short time.

According to one aspect of the invention there is provided a method to control a transmission system comprising at least one transmitter and at least one receiving unit, the method comprising the steps of: transmitting a signal through an information channel the signal being modulated in at least one of amplitude, frequency and phase, transmitting configuration parameters through a control channel independent of the signal transmitted through the information channel, and implementing adjustments in the receiving unit according to the configuration parameters to enable demodulation of the signal transmitted through the information channel, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

According to another aspect of the invention there is provided a wireless transmission system comprising: a receiving unit comprising an antenna, at least one transmitter, H:\Priyanka\Keep\speci\2000269773.doc 9/02/06 3 a signal which is modulated in at least one of amplitude, frequency and phase, the signal being transmitted through an information channel from one of the at least one transmitters to the receiving unit, generating and transmitting means for generating and transmitting configuration parameters through a control channel for enabling demodulation of the signal, said configuration parameters being transmitted to the receiving unit independent of the signal, and receiving and processing means for receiving and processing the configuration parameters, said receiving and processing means being provided in the receiving unit, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

According to another aspect of the invention there is provided a receiving device comprising: a receiving unit for receiving signals transmitted through an information channel, which signals are modulated in at least one of frequency and phase, the signals being received at an antenna connected through a filter/amplifier unit and a consecutive mixer to a demodulator to generate demodulated signals based on configuration parameters, the mixer being loaded with an output signal from a synthesizer which is controlled by a control unit, and H: \Priyanka\Keep\speci\2000269773 .doc 9/02/06 4 transceiving means for receiving the configuration parameters independent of the signals received by the receiving unit, the transceiving means being connected to the control unit, the configuration parameters being transmitted through a control channel, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

Examples of embodiments of the invention offers the following advantages: Problem-free and interference-less switching from a signal which is modulated in amplitude, frequency and/or phase to another signal can be implemented by adjusting configuration parameters in the receiving unit. Because of the low transmission rate, the control channel may be of low power compared with the information channel. As a result, the control channel does not require a special authorization procedure and the required components can be put together in exceedingly economical manner.

Furthermore, by using a synthesizer in the receiving unit to generate the frequencies required to demodulate the received signals, extremely rapid and flexible matching to the employed carrier frequencies is made possible and consequently rapid switching from one information channel to another is assured.

H:\Priyanka\Keep\speci\2000269773 .doc 9/02/06 4a Examples of the embodiments of the invention is elucidated in illustrative manner below in relation to the attached drawings. It is shown in Fig. 1, schematically, a transmission system according to an example with a receiving unit according to an example, Fig. 2 a functional block diagram of the receiving unit according to the example of Fig. 1, and Fig. 3 a control unit used in the transmission system of Fig. 1.

Fig. 1 schematically shows a transmission system consisting of a set of components required according to application or mode of operation.

Part of the transmission system are a transmitter S1 Sn and a receiving unit 1 which are connected by a wireless link hereafter called the information channel 120. If, as in the present case, the signal being transmitted is an audio signal, then this signal shall be modulated at a carrier frequency in the transmitter S1 Sn prior to transmission, for instance using known amplitude, frequency and/or phase modulation. Obviously depending on the transmission power being used and the H:\Priyanka\Keep\apeci\2000269773.doc 9/02/06 4b particular carrier frequency, the information channel 120 also is suitable for long-range transmission or transmission through buildings. Known applicable modulation procedures illustratively are described in ELECTRONIC ENGINEERS' HANDBOOK (Donald Christansen, 4 th ed., McGraw-Hill, chapter 18).

The presence of n transmitters S1, Sn indicates that various audio signals to be transmitted are modulated at different carrier frequencies so that different audio signals can be received in one receiving zone provided there be corresponding tuning to the particular carrier frequency in the receiving unit 1. Conceivably however, merely one transmitter is used instead of the n Sl, Sn transmitters, where said single transmitter is fitted with several, preferably n transmission channels. The principle used also covers this H \Priyanka\Keep\speci\2000269773.doc 9/02/06 5 embodiment of transmitter design. Either design shall be implied hereafter where n transmitters SI, Sn are mentioned.

In order to tune the receiver 1 to one of the transmitters SI, Sn and hence to a particular audio signal, the transmission system of the present invention comprises a control channel 110, 111, 112, 113 transmitting configuration parameters corresponding to the particular transmitter SI, Sn to the receiving unit 1. For this purpose the transmitters SI, Sn have access within themselves or in separate components to corresponding means generating and transmitting the configuration parameters. Illustratively, such means may be selectively a control unit 102 and/or a remote control 107. Regarding the link i.e. for the control channel between the receiving unit 1 and the control unit 102 or remote control 107, they also are wireless and are indicated by the reference signs 110 and 112, respectively, in Fig. 1. If the transmitters S1, Sn themselves are fitted with corresponding means generating and transmitting the configuration parameters, then said parameters shall be transmitted through the control channel 113 to the receiving unit 1. It is pointed out that even though according to Fig. 1 various control channels are conceivable (such as reference signs 110 to 113 in Fig. 1) as regards transmission principles they are one and the same transmission channel because the specifications of the latter, such as rate of 2154732C 1065165.doc 6 transmission and carrier frequency, preferably remain unchanged for one and the same transmission system.

In a preferred embodiment of the present invention, frequency-shift keying (FSK) modulation is used in the control channel, the transmission rate being 1,280 bits/s and the channel center frequency being 40,960 kHz.

Switching or tuning to a specific carrier frequency and hence to a given audio signal, is not initiated in the receiving unit 1 per se in the present invention, but instead and in preferred manner by using one of the control channels 110, 112, 113. In the preferred embodiment of the transmission system of the present invention, the information channel 120 used by the audio signal in no way shall transmit any other data. On the one hand, this feature allows switching from one audio signal to another without requiring manual adjustments in the receiving unit 1. On the other hand, the receiving unit 1 can be remote-controlled, allowing wide applicability of the transmission system of the present invention as discussed below.

Furthermore, a configuration unit 105 is provided in the transmission system of the present invention enabling again to configure/program the receiving unit 1 and any further components connected to said receiving unit 1 through a wireless link 111 (control channel). Because, 215473PC 1065165.doc 7 in the configuration phase, the receiving unit 1 can be positioned near the configuration unit 105, comparatively few demands are placed on the link 111, that is, satisfactory data transmission can be carried out at low transmitting power. This feature is especially critical because, as shown in Fig. 1, the link 11 is bidirectional and furthermore and in particular as regards a miniaturized receiving unit 1, only very little energy is available inside the receiving unit 1 in the sending mode.

A computer unit 106, for instance a commercial PC, is used as an input and processing accessory to program the receiving unit 1. As a result, it is possible to manage the entire transmission system, new program drivers in particular being downloaded into the receiving unit i.

By means of back-transmitting, it is possible for instance to feed version data from the receiving unit 1 through the configuration unit 105 to the computing unit 106 where they shall be processed further.

As regards the application shown in Fig. 1, the receiving unit 1 is detachably connected to a hearing device 100.

All functions relating to the wireless signal transmission are implemented in the receiving unit 1.

Because of different requirements on the rate of signal transmission and range of transmission when transmitting audio signals and when transmitting control signals, the receiving unit 1 is fitted with two antennas, namely an 215473PC 1065165.doc 8 antenna A for audio signals, and a receiving coil of substantially smaller dimensions for the control signals.

As shown by Fig. 1, the control unit 102 is connected, on the one hand, to a loop antenna 101 and, on the other hand, to an input/computing unit 103. Said unit 103 again is used only for data input and preferably is in the form of a commercial personal computer and in this case communication between the control unit 102 and the input/computing unit 103 takes place for instance through a standardized Universal Serial Bus (USB).

Whereas the control unit 102 connected to the loop antenna 101 is used to transmit low-power control signals to the receiving unit 1, the remote control 107 is used to transmit control signals over short distances, again at low transmitting power. The various embodiments are elucidated in the applications described below.

The main application of examples of the present invention concern a transmission system in which the receiving unit 1 is linked to a hearing device 100, and as a result the potential users are not restricted to the hearingimpaired but also cover people with normal hearing.

It is highly significant that the user of the hearing device 100, which is coupled to the receiving unit 1, need not H:\Priyanka\Keep\speci\2000269773.doc 9/02/06 9 tune this device to a given channel, including a particular carrier frequency, or ascertain which signal processing is required in order to receive and hear the desired audio signal, because these steps are implemented by the receiving unit 1 which shall be configured by the configuration parameters picked up by the receiving coil The needed configuration parameters are transmitted from the control unit 102, from the remote control 107 or from one of the transmitters Sl, Sn directly through a universal communications link, that is the control channel 110 or 112 or 113 to the receiving unit i, without interfering with a transmitted audio signal. The control channel 110 or 11 or 113 is operable only over short distances and comprises its own modulation procedure at a carrier frequency in agreement with international standards. In Europe this is the EN 300 330 standard (Radio Equipment and Systems; short range devices technical characteristic and test methods for radio equipment in the range of 9 kHz to 25 MHZ and inductive loop systems in the frequency range of 9 kHz to MHZ) and in the USA it is the Code of Federal Regulations standard 47 (Telecommunication FCC Part subpart C: Intentional Radiators) apply.

In a preferred embodiment of the present invention, the following parameters are transmitted through the control channel 110 or 111, or 113 the carrier frequency of a desired audio signal; P154732C 1065165.doc 10 a switching signal to complete turn OFF the receiving unit 1; a switching signal causing the received audio signal to be superposed on a microphone signal within the hearing device; a mute command to turn OFF the audio signal; a signal controlling the volume of the received audio signal.

The receiving unit 1 is configured on the basis of all or some configuration parameters exclusively transmitted through the control channel 110 through 113.

As shown by Fig. 1, the control channel 110 through 113 is used in the following cases: In the first place, by means of the remote control 107 operated by the user to control the receiving unit 1 in the hearing device 100 of the transmission system.

In the second place, by means of the control unit 102 connected to the loop antenna 101, whereby each user, i.e. this user's receiving unit 1 is provided with the particular configuration parameters if within the detection range of the loop antenna 101. One or more H:\Priyanka\Keep\speci\2000269773 .doc 9/02/06 11 codes are assigned to each user so that the users may be addressed singly or in groups. Such a transmission system is used in particular in schools where all the advantages of automatic adjustment will apply, in particular the fact that knowledge of the transmission channel (carrier frequency etc.) is not required.

Further applications are conceivable to assembly spaces, for instance conference rooms, churches or railway stations: As soon as such a space is being entered, the hearing-device receiver is automatically tuned to transmission channel of said assembly place.

Be it mentioned in this respect that in a further embodiment, the hearing device is replaced with merely an electro-acoustic transducer coupled to the receiver. In this instance, the various functions offered by a hearing device are not available.

In the third place, the control channel is used to transmit data which shall be stored in a memory of the receiver, that is, the receiver, i.e. its memory, can be programmed through the control channel.

In a preferred embodiment of the invention, individual or several transmitters S1 through Sn are fitted with a transmitter generating a control signal or they transmit the configuration parameters. The transmitted configuration parameters are code-enhanced and this code P15473PC 1065165.doc 12 causes a specifically addressed receiving unit 1 to configure according to the configuration parameters.

Fig. 2 is a functional block diagram of a receiving unit 1 detachably connected in the manner shown in Fig. 1 to a hearing device 100.

A frequency or phase modulated signal SIN is received by an antenna A, and first is fed to a filter/amplifier unit 2 fitted with an externally connected adjusting unit 19 to tune to the desired frequency band. The output of the filter/amplifier unit 2 is connected to the input of a mixer 3. A second input of the mixer 3 is connected to the output signal from a synthesizer 6 that shall be discussed further below. A demodulator 4 is connected to and follows the mixer 3 together with which it generates a demodulated signal S which is fed to an amplifier adjusted by an adjustment unit 7. The output signals S,,utl and Sout2 were matched in the amplifier 5 and are fed either directly to a loudspeaker or to a hearing device (omitted from Fig. 2).

In one embodiment variation of the receiving unit 1, an I2S unit 13 is connected to the amplifier 5. The I 2 S unit 13 is an interface to control a digital 3-conductor bus.

Reference is made in this respect to applicant's international patent application PCT/CH99/00009 with publication no. WO 99/13699. Said H: \Priyanka\Keep\speci\2000269773 .doc 9/02/06 13 application is an integral part of the present one. The

I

2 S unit 13 comprises a digital output from which a digital audio signal SDIGITAL is fed back for instance directly to the hearing device 100 (Fig. 1).

Also an audio-frequency generator 14 is provided and connected to the amplifier 5 generating a signal to be superposed on the signal S. In this manner, a given state of the receiving unit 1, for instance low battery-voltage or setting at the standard carrier frequency, can be acoustically communicated to the user. To receive corresponding control signals, the audio-frequency generator 14 is connected to the adjustment unit 7 which shall be elucidated below.

The transceiver coil already discussed in relation to Fig. 1 is denoted by 15 and receives the configuration parameters through the so-called separate control channel. To tune this transceiving coil 15 operating as an antenna, a series capacitor 16 follows said coil and preferably shall be variable. The transceiver coil 15 and the capacitor 16 are connected to a transceiver 8 which in turn is connected to the adjustment unit 7.

The adjustment unit 7 constitutes the real control center of the receiving unit 1 and besides the already mentioned components, namely the amplifier 5, the audio-frequency generator 14 and transceiver 8, additionally controls the 215473PC 1065165.doc 14 synthesizer 6 wherein the mixed frequencies used in the mixer 3 are generated, and a monitoring unit monitoring and optimizing the energy budget in the receiving unit 1, as a result of which the longest possible and most problem-free operation is assured.

The adjustment unit 7 assumes sequence control and further data from a memory 11 connected through a bus system to the adjustment unit 7. The memory 11 is nonvolatile and programmable, for instance an EEPROM (electrically erasable programmable read-only memory). It is well known that higher voltages are required to program such memories than are typically needed by the other components. For that reason a voltage multiplier 9 with capacitors 18 is employed. Such a design attains voltages as high as several times that of the basic source.

Most of the components shown in Fig. 2 are contained within a box shown in dashed lines. Those are the components which preferably are integrated onto a chip in applicable CMOS technology. All other components such as the capacitors 18, the antenna A, the transceiving coil the adjusting unit 21 etc. are outside the integrated circuit to which they are connected by appropriate terminals. The memory 11 is included in latter components and in practice has been exposed to severe overloads and therefore its life is shorter than that of the other components.

P15473PC 1065165.doc 15 Lastly a single switch 17 driven by the user is present at the receiving unit 1 to initiate for instance the following functions: By "briefly" closing the switch 17, the following operational modes will be switched between each other: "transmit the audio signal", "audio signal with superposed microphone signal", and "no audio signal" (toggle mode); By closing the switch for a "long time", and after receiving the audio signals, the frequency band is scanned (scan mode); By closing the switch of a "very long time", the receiving unit 1 is disconnected; by closing the switch 17 again, the receiver 1 is re-connected.

The above functions or their transitions can be initiated by means of the remote control 107, the transmitter Sl through Sn or as called for also by means of the control unit 102 (Fig. 2).

In order to minimize energy consumption in the receiving unit 1, steps are taken in the demodulator 4. in addition to those carried out by the monitoring unit Illustratively, the amplifier 5 is automatically squelched as soon as the demodulator 4 ascertains that an P15473PC 1065165.doc 16 audio signal no longer is being received. This state is transmitted by the adjustment unit 7 and the amplifier through the connection SQ and as a result the components demodulating the transmitted audio signal SIN can be deactivated. As a result, the energy consumption drops as desired in the receiving unit 1. At the same time, any noise shall be eliminated because being not at all transmitted to the subsequent hearing device 100 (Fig.

1) Fig. 3 is a functional block diagram of a control unit 102 connected to a loop antenna 101 of Fig. 1.

Substantially,. the control unit 102 consists of a microcomputer 200 which is radially connected to a memory 204, an input/output unit 203, a display 202, a modulator 201 and an interface 205. Preferably the interface 205 is designed to drive an USB (universal serial bus) type bus system.

In a further embodiment of the present invention, data correcting the transfer function of the information channel are fed to the receiving unit 1. Such correction information is ascertained by calculating a desired total transfer function of the information channel based on the uncorrected total transfer function. In this manner, any undesired characteristics of the original total transfer function can be corrected.

215473C 1065165.doc 17 It is hereby emphasized again that even though the receiving unit of the present invention and the transmission system of the present invention were discussed with respect to an illustrative hearing device, application in no way is restricted to such a field.

Instead the present invention is applicable to arbitrary fields wherein information channels must be controlled.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

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Claims (19)

1. A method to control a transmission system comprising at least one transmitter and at least one receiving unit, the method comprising the steps of: transmitting a signal through an information channel the signal being modulated in at least one of amplitude, frequency and phase, transmitting configuration parameters through a control channel independent of the signal transmitted through the information channel, and implementing adjustments in the receiving unit according to the configuration parameters to enable demodulation of the signal transmitted through the information channel, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

2. A method according to claim 1, wherein an identification code is transmitted through the control channel and in the identification code is checked in the receiving unit, and based on the check, the adjustments are carried out in the receiving unit according to the corresponding configuration parameters. H:\Priyanka\Keep\speci\2000269773.doc 9/02/06P15473PC 1065165 .doc 19

3. A method according to any one of the preceding claims, wherein the receiving unit is programmed by a configuration unit and the transmission of the programming data for programming the configuration unit is transmitted through the control channel.

4. A method according to claim 3, wherein information is transmitted from the receiving unit through the control channel to the configuration unit.

A method according to any one of claims 2 through 4, wherein one or more identification codes are addressed to a plurality of receiving units.

6. A method according to any one of the preceding claims wherein the demodulation of the signal based on the configuration parameters is carried out using the generated frequency, to produce at least one demodulated signal and the at least one demodulated signal is fed to another processing unit of at least one of a hearing device and an electro-acoustic transducer.

7. A method according to any one of the preceding claims wherein a total transfer function resulting from the transmitter and the receiving unit is modified in the H:\Priyanka\Keep\speci\2000269773.doc 9/02/06P15473PC 1065165 .doc 20 receiving unit by transmitting transfer-function parameters of the transmitter through the control channel to the receiving unit, said transfer-function parameters comprising amplification and frequency of transmission, and wherein the transfer function of the receiving unit is modified in relation to a desired total transfer function.

8. A method according to any one of the preceding claims, wherein an antenna that receives the modulated signal is tuned to the particular transmission frequency.

9. A method according to any one of the preceding claims, wherein the transmission through the control channel is carried out using FSK (frequency shift keying) modulation.

A method according to any one of claims 1 through 9, wherein audio signals are transmitted from the transmitter, wherein the at least one receiving unit is connected to at least one of a hearing device and an electro-acoustic transducer.

11. A wireless transmission system comprising: a receiving unit comprising an antenna, at least one transmitter, H:\Priyanka\Keep\speci\2000269773.doc 9/02/06P15473PC 1065165. doc 21 a signal which is modulated in at least one of amplitude, frequency and phase, the signal being transmitted through an information channel from one of the at least one transmitters to the receiving unit, generating and transmitting means for generating and transmitting configuration parameters through a control channel for enabling demodulation of the signal, said configuration parameters being transmitted to the receiving unit independent of the signal, and receiving and processing means for receiving and processing the configuration parameters, said receiving and processing means being provided in the receiving unit, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

12. A system according to claim 11, wherein the generating and transmitting means is provided in at least one of a remote control in a transmitter, in a control unit connected to a loop antenna, and a configuration unit.

13. A system according to claim 11 or 12, wherein the receiving unit is connected to at least one of a hearing device and an electro-acoustic transducer. H:\Priyanka\Keep\speci\2000269773.doc 9/02/06P15473PC 1065165.doc 22

14. A receiving device comprising: -a receiving unit for receiving signals transmitted through an information channel, which signals are modulated in at least one of frequency and phase, the signals being received at an antenna connected through a filter/amplifier unit and a consecutive mixer to a demodulator to generate demodulated signals based on configuration parameters, the mixer being loaded with an output signal from a synthesizer which is controlled by a control unit, and -transceiving means for receiving the configuration parameters independent of the signals received by the receiving unit, the transceiving means being connected to the control unit, the configuration parameters being transmitted through a control channel, wherein a transmission range of the information channel is larger than a transmission range of the control channel.

A device according to claim 14, wherein the transceiving means comprises a transceiver, a transceiving coil and a capacitor to adjust the transceiving coil.

16. A device according to claim 14 or 15, further comprising an integrated circuit on a CMOS chip, the H:\Priyanka\Keep\speci\2000269773.doc 9/02/06P15473PC 1065165. doc 23 integrated circuit comprising the filter/amplifier unit, the mixer, the demodulator, the synthesizer and the control unit.

17. A device according to claims 14 to 16, fitted in a hearing aid.

18. A method as claimed in any one of claims 1 to 10, and substantially as herein described with reference to the accompanying drawings.

19. A system as claimed in any one of claims 11 to 13, and substantially as herein described with reference to the accompanying drawings. A device according to any one of claims 14 to 17, and substantially as herein described with reference to the accompanying drawings. Dated this 9 th day of February 2006 PHONAK AG By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia H:\Priyanka\Keep\Bpeci\2000269773.doc 9/02/06P15473PC 1065165. doc