EP1050189B1

EP1050189B1 - Method and arrangement for voice communications

Info

Publication number: EP1050189B1
Application number: EP99900900A
Authority: EP
Inventors: Lars Silen
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 1998-01-22
Filing date: 1999-01-21
Publication date: 2004-04-14
Anticipated expiration: 2019-01-21
Also published as: AU2056599A; EP1050189A1; CN1319411C; CN1288648A; DE69916423T2; FI105379B; FI980140A0; BR9907155A; DE69916423D1; WO1999038355A1; FI980140A

Description

FIELD OF THE INVENTION

The present invention relates to methods for voice communications between a microphone and an audio device, such as a sound card of a data processing device. The invention relates further to arrangements for realizing voice communications.

BACKGROUND OF THE INVENTION

Various different microphones are well known by the skilled person. In general the microphones are used for receiving sound, such as speech, and for transducing and transmitting the sound further to an audio device using and/or processing the received sound. The audio device can be understood as being any device which uses microphones in receiving the sound. An example of such are various tape or digital recorders, and another example is so called sound cards used in the processing devices for processing sound.

It is also prior known to utilize a data processing device, such as a microcomputer or a Personal Computer (PC) or a workstation, when establishing a call through a communications network to another party or when receiving a call from another party, or when participating so called conference or group call involving more than two parties. This kind of voice communications may be arranged to be accomplished through an Internet connection or similar network arrangement providing an already existing communications protocol (TCP/IP in the Internet), by means of which the speech data may be transmitted in a digital form, ie. such that it is converted from an analog form to a digitized form. In case of using the Internet, this kind of communication arrangement is sometimes referred to as an "Internet Call" or an "Internet Telephone".

Said Internet Telephones have made it eg. possible to establish an international call at the margin costs of a local call. The skilled person is familiar with the Internet itself and the communications networks in general, and thus they are not explained in more detail herein than by mentioning that the Internet is a global open communications network connecting a great number of local area networks, such as networks of various companies, universities and other organizations by using packet switched connectionless transfer mode. These networks, in turn, may be used by great number of independent workstations and/or computer devices. An individual user may have a direct connection to these local area networks or the individual user may be connected to them through a PSTN (Public Switched Telephone Network) or an ISDN (Integrated Digital Services network) connection using modems or similar devices providing the gateway to the area networks. The two most often used communication protocols for the Internet are TCP and IP protocols (Transport Control Protocol and Internet Protocol, respectively). The use of Internet has been growing rapidly and steadily, and thus it is expected that the use of the Internet Telephones will also rise.

At present the Internet Telephone function is based on so called Internet Relay Chat (IRC), which is best described as a multi-user, multi-channel chatting network. At present the used IRC is based on servers which are specifically intented for text communications, but it is expected that IRC servers specifically intented for the Internet Telephone usage are soon a reality. These are quite likely to improve the quality of the Internet calls by providing greater speed and improved access to the services. It is more than likely that the introduction of these or another possible network apparatus enabling transmission of voice over an IP network will make the Internet Telephones even more lucrative.

To enable the communications in a network by means of the data processing device connected therein the sound has to be firstly received by a microphone, from which it has to be transmitted to the data processing device, where it is then appropriately processed and converted into the digitized form by means of so called sound card implemented into the computer.

An example of one implementation is so called LanPhone™. In this a client program running on Windows95™ uses the sound card of the computer to digitize the speech and sends it over a LAN (Local Area Network) to a gateway computer providing the interface to the actual POTS (Plain Old Telephone System) or other suitable public telecommunications network. In principle, there are several sound cards that could be suitable to be used with the LanPhone™, if an interface towards a standard telephone handsets could be provided.

Today's handsets use condenser microphones requiring a bias voltage between 1 to 11 volts to work properly. The use of different types of sound cards has proven to be a problem since the microphone interface implementation differs between different card types.

At present there are two known microphone interface configurations, which are implemented using a 3.5 mm stereo plug. These two connection types can be described eg. in the following manner:

Version A:: Body --> Ground
Center --> 5 V bias voltage
Tip --> Mic. Signal
Version B:: Body --> Ground
Center --> Mic. Signal
Tip --> 5 V bias voltage

Both of the above types can be used, if the connection between the sound card and the handset is able to switch the signal correctly on basis of the used sound card.

The microphone inputs of the computer are, in turn, usually intented and specified for dynamic microphones only which do not require any internal bias voltage or operating voltage of an amplifier. Some of the sound cards are, however, supplying at least some kind of direct voltage for this purpose. However, there is still no standard defining the pin from which (eg. Center of Tip) the bias voltage supply could be accomplished.

According to the conventional solutions the correct pin or connection type has been selected by performing test by means of DIP switches (Dual-In-line Package switches). For example, the present interface electronics used by said LanPhone™ system between the handset and the sound card uses four DIP switches to allow the same handset adapter to be used with different types of sound cards.

In regard to prior art reference is made to United States patent specification US-5459792, which presents an audio input circuit for voice recognition according to prior art.

SUMMARY OF THE INVENTION

The problem of the present solution relates to the difficult combining and assembly of unstandardized audio devices, such as sound cards, and the different kinds of microphones. This causes great difficulties when installing the microphone, and even makes it impossible for those who are not especially familiar and "handy" with the computer technology or electronics in general. In case the connections are made incorrectly, the microphone will not work, or works improperly/poorly, as the bias voltage becomes connected improperly. The version used at present eg. in LanPhone™ is not optimal as it requires that the user or the one who installs the application knows the exact type and mark of the sound card and then also knows how to configure the DIP switches accordingly. It is clear that this kind of requirement of knowledge efficiently prevents and even scares potential users of such speech transmission which utilizes the data processing device arrangements and open data communications networks.

Thus it is an object of the present invention to overcome the disadvantages of the prior art solutions and to provide a new type of solution for connecting a microphone to an audio device, such as to a sound card of a data processing device.

A further object of the present invention is to provide a method and an arrangement by means of which the user is relieved from making any configurations of the interface between a microphone and used audio device.

A further object of the present invention is to provide a method and an arrangement in which same microphone can be used in connection with various audio devices or sound cards.

Other objects and advantages of the present invention will be brought out in the following part of the specification taken in conjunction with the accompanying drawings.

The objects are obtained by a method of connecting a microphone requiring a bias voltage to a audio device for establishing voice signal communications therebetween, wherein the interface comprises several inputs for the microphone. The method comprises steps of supplying a biasing voltage to the microphone through at least one input of said several inputs for the microphone such that the biasing voltage is conducted through a diode disposed on the respective conduit from said at least one input, and transmitting the voice signal from the microphone to the audio device through another input of said several inputs.

According to an alternative embodiment the invention provides a method of connecting a microphone to a sound card of a data processing device connected to a communications network for establishing a voice signal communication between the mocrophone and the sound card and thereby a subsequent communications transmitting the voice between a user of the microphone and another party connected to said communications network, wherein the connection between the sound card and the microphone comprises several inputs for the microphone. The method comprises steps of supplying a biasing voltage to the microphone from the sound card through at least one of said several inputs for the microphone such that the biasing voltage is conducted through a diode disposed on a respective conduit from said at least one input, and of transmitting the voice signal from the microphone to the sound card through another input of said several inputs.

The invention provides further an arrangement for interfacing a microphone requiring a bias voltage to an audio device in order to establish a voice signal communications therebetween. The interface comprises several inputs for the microphone, a biasing voltage to the microphone being conducted through at least one of said several inputs for the microphone. At least one diode is disposed on each of the conduits from said inputs such that the biasing voltage becomes conducted through said at least one diode, the arrangement being such that the voice signal is transmitted from the microphone to the audio device through another input of said several inputs than the one conducting the biasing voltage.

According to an alternative the invention provides an arrangement for interfacing a microphone to a sound card of a data processing device connected to a communications network for establishing voice signal communications therebetween and thereby a subsequent communications transmitting the voice between the user of the microphone and another party connected to said communications network. The interface comprises several inputs for the microphone, biasing voltage to the microphone being conducted through at least one of said several inputs for the microphone. At least one diode is disposed on each of the conduits from said inputs such that the biasing voltage becomes conducted through said diode, and the voice signal is transmitted from the microphone to the sound card through another input of said several inputs than the one conducting the biasing voltage.

Several advantages are obtained by means of the present invention, since the solution provides a simple, reliable and controllable manner for installing a microphone to a data processing device. The solution relieves the user from making any complicated configurations other than just "plug" the connection cord in the data processing device or some other audio device. Thus it will greatly improve the lucrativeness of starting to use network telephones such as the Internet Telephones or any other audio devices requiring an external microphone. The inventive arrangement provides a simple design for the interface, which is more reliable than the conventional mechanical switches.

In the following the present invention and the other objects and advantages thereof will be described by way of an example with reference to the annexed drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 discloses a prior art solution; and

Figure 2 discloses an arrangement according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematical presentation of one prior art microphone interface arrangement using conventional DIP switches 10 and including a resistor R and a capacitor C between the microphone 1 and the input (and output) pins. The user has to configure ie. switch the DIP switch in a correct manner so as to provide a correct connection to correspond either version A or version B described above at the time of the installation of the microphone. The configuration is depending on the type of the used sound card. The sound card defines which one of the input pins (inp#1 or inp#2) or the output pins (out#2 or out#1) is to be used and for which purpose.

Figure 2 discloses a circuit that solves the problem relating to the required separate configuring of a handset adapter, such as the prior art DIP switch of figure 1, each time when installing it to a new device. The adapter circuit 2 is such that it automatically adapts the two alternative connections, ie. versions A and B described above, by means of directing the supply voltage to the microphone through diodes such that it can be supplied through either one of the two microphone input pins.

According to this embodiment the circuit 2 comprises a resistor R connected on the conduit from the microphone 1 to the input pins. The circuit comprises further two parallel connected capacitors C1 and C2 so as to provide in either case a circuit with at least one resistor and capacitor. In addition, two diodes D1 and D2 are connected in parallel between the resistor R on the conduit and the respective input (output) pins. The arrangement is such that said parallel capacitors C1 and C2 are connected on the conduit between the microphone 1 and resistor R and between the diodes D1 and D2 and the input (output) pins, respectively. The grounding of the microphone and the actual device is arranged in a per se known manner.

It is to be noted that the number of the capacitors and resistors may be greater than what is shown in figure 2. If several capacitors or resistors are used, they may be connected in parallel or in series in an appropriate manner.

In operation the new type passive circuit connection of figure 2 functions in the following manner when used in the described two different connection types A and B.

The required connection in connection with a sound card requiring A type connection will be described firstly. It is assumed that Inp#1 carries the bias voltage and thus Inp#2 is used for the microphone return signal, ie. for carrying the speech signal. In this case the diode D1 will be in a conductive state and thus it will provide the necessary biasing voltage for the microphone 1, e.g. a voltage of 5V. Sound arriving into the microphone will cause the impedance of the microphone to vary and thus a small varying AC current can be seen in the resistor R causing a small AC voltage drop over the resistor R. The AC signal is connected to Inp#2 through C2 and is then sensed by the used sound card. The sound card will then process the sound so as to convert it to be suitable for the transmission over the used network.

In case B it is assumed that it is Inp#2 which carries the bias voltage and thus Inp#1 is used for the microphone return signal, ie. for carrying the speech signal. In this case the diode D2 will be the one which is in a conductive state and thus provides the necessary biasing voltage for the microphone 1. As in case A, the sound arriving at the microphone will cause the impedance of the microphone to vary and thus a small varying AC current can be seen in the resistor R causing a small AC voltage drop over the resistor R. The AC signal is now connected to Inp#1 through C1 and is then sensed by the used sound card.

The adapter arrangement 2 of figure 2 has been tested with the following sound cards: SoundBlaster™ and GravisUltrasound™. During the tests the adapter was found to work properly, and to provide the benefits described above.

Thus the invention provides an apparatus and a method by means of which a significant improvement can be achieved e.g. in the area of telecommunications, and more precisely, when connecting a microphone to a data processing device or to some other audio device. The arrangement according to the present invention is easy and economical to realize by per se known components and reliable in use. It should, however, be noted that the foregoing example of the invention is not intended to restrict the scope of the invention defined in the appended claims. All additional embodiments, modifications and applications obvious to those skilled in the art are thus included within the scope of the invention as set forth by the claims appended hereto.

Claims

Method of connecting a microphone (1) requiring a bias voltage to a audio device for establishing voice signal communications therebetween, wherein the connecting interface comprises several inputs for the microphone (1), characterized in that the method comprises the steps of:

supplying a biasing voltage to the microphone (1) through at least one input of said several inputs for the microphone (1) such that the biasing voltage is conducted through a diode on a respective conduit from said at least one input; and

transmitting the voice signal from the microphone (1) to the audio device through another input of said several inputs.
A method according to claim 1, characterized in that the interface comprises two input pins, and that the method comprises supplying the biasing voltage through first one of the input pins and transferring the return voice signal through the other one of the two input pins.
A method according to claim 1 or 2, characterized in that it further comprises a step for providing a capacitor connected in parallel to each of the diodes on each conduit.
A method according to any of the preceding claims for connecting a microphone (1), characterized in that the correct inputs are automatically selected by the adapter circuitry during the installation of the interface such that there are no requirements for the user to have any knowledge about the various parameters of the interface.
A method according to any of the preceding claims for connecting a microphone (1), characterized in that the audio device is a sound card.
A method according to claim 5, characterized in that the microphone (1) is connected to a sound card of a data processing device connected to a communications network for establishing a voice signal communication between the microphone (1) and the sound card and thereby a subsequent communications for transmitting the voice between the user of the microphone (1) and another party connected to said communications network.
An arrangement for interfacing a microphone (1) requiring a bias voltage to an audio device in order to establish a voice signal communications therebetween, wherein
the connecting interface comprises several inputs for the microphone (1),
characterized in that
a biasing voltage to the microphone is conducted through at least one of said several inputs for the microphone (1),
at least one diode is disposed on each of the conduits from said inputs such that the biasing voltage becomes conducted through at least one diode, and
the voice signal is transmitted from the microphone (1) to the audio device through another input of said several inputs than the one conducting the biasing voltage.
An arrangement according to claim 7, characterized in that the audio device is a sound card.
An arrangement according to claim 8, characterized in that the microphone (1) is connected to a sound card of a data processing device connected to a communications network for establishing voice signal communications therebetween and thereby a subsequent communications transmitting the voice between the user of the microphone and another party connected to said communications network.
An arrangement according to claim 7 or 8 or 9, characterized in that the interface comprises two input pins, the arrangement being such that the biasing voltage is supplied through the first one of the input pins and the return voice signal is transferred through the other one of the two input pins.
An arrangement according to any of claims 7 to 10 characterized in that a capacitor is connected in parallel to each of the diodes.
An arrangement according to any of claims 7 to 11, characterized in that the adapter circuitry is arranged to automatically select the correct inputs during the installation of the interface such that there are no requirements for the user to have any knowledge about the various parameters of the interface.