WO2001001665A2

WO2001001665A2 - Host-based speaker phone

Info

Publication number: WO2001001665A2
Application number: PCT/US2000/017148
Authority: WO
Inventors: Dana Porrat; Yair Kerner
Original assignee: Conexant Systems, Inc.
Priority date: 1999-06-25
Filing date: 2000-06-22
Publication date: 2001-01-04
Also published as: WO2001001665A3

Abstract

The present invention includes a communication system comprising a first transducer (106) that detects and converts external audio signals into internal electronic signals formatted to be compatible with internal operations of the communication system. The communication system also includes a second transducer (110) that converts internal communication signals into external audio signals. In addition, at least one echo cancellor (200) is included in the communication system and cancels undesirable internal communication signals. Assisting the at least one echo cancellor is a delay module (210) that enables the at least one echo cancellor to carry out specific cancellation procedures during a time period when specific undesirable communication signals are estimated to be passing through the echo cancellor.

Description

IN THE UNITED STATES PATENT AND TRADEMARK OFFICE

TITLE: Host-Based Speaker Phone

SPECIFICATION

BACKGROUND

1. Field of the Invention

The present invention relates to speaker phones, in particular to a speaker phone wherein a conversation can occur on the speaker phone without undesirable feedback noises existing in the background during the conversation.

2. Description of the Related Art

Speaker phones are commonly found in areas such as office telephone systems and the like. The speaker phone allows a user to carry on a conversation over a telephone line while retaining free mobility of their hands. In some cases, the speaker phone provides one-way, or half-duplex, communication for parties engaging in conversation. In other words, when a first party is speaking into a speaker phone, the speaker phone enters a state in which communication signals from the second party, or listening party, are cut off from reaching the first party. This state remains until the communication signals from the first party cease. Once communications from the first part cease, the telephone line becomes open to transmit communication signals from either direction, thus, the second party may now speak and the first party will hear the voice of the second party. Speaker phones operating under the above principles cause conversations to occur in which the listening party must remain silent until the speaking party stops talking. This manner of conversation is unnatural because parties to a conversation commonly speak at the same time and expect to hear overlapping conversation. This problem has lead to speaker phones in which parties on each end of the telephone line may speak at the same time to communicate from both sides simultaneously, i.e., full-duplex communications. This speaker phone technology allows speaker phone conversations to occur with overlapping conversation from the parties involved in the conversation.

Unfortunately, overlapping conversation on a speaker phone introduces additional problems, such as feed-back. For example, a person may speak into a microphone of a telephone such that their voice is transmitted across a telephone line to a speaker on a speaker phone. When the speaker on the speaker phone broadcasts the voice message received from the person speaking at the other end, a microphone on the speaker phone may detect this broadcast voice message and transmit the broadcast voice message back to the person speaking. Thus, along with any other messages transmitted to them, the person speaking hears an echo of their original spoken message in the background.

In addition, typical speaker phones include a "hybrid" (four-wire to two-wire converter). Thus, when a person speaks into a microphone of a speaker phone such that their voice is transmitted across a telephone line, the voice message may be broadcast back through the speaker on the speaker phone as the voice message passes through the speaker phone. In other words, the "hybrid" of a speaker phone is another source of undesirable echoes.

Many other problems and disadvantages of the prior art will become apparent to one skilled in the art after comparing such prior art with the present invention as described herein. SUMMARY OF THE INVENTION

Various aspects of the present inventor may be realized through a communication system comprising a first transducer that detects and converts external audio signals into internal electronic signals formatted to be compatible with internal operations of the communication system. The communication system also includes a second transducer that converts internal communication signals into external audio signals. In addition, at least one echo cancellor is included in the communication system and cancels undesirable internal communication signals. Assisting the at least one echo cancellor is a delay module that enables the at least one echo cancellor to carry out specific cancellation procedures during a time period when specific undesirable communication signals are estimated to be passing through the echo cancellor.

Of note, in some embodiments the at least one echo cancellor can be an acoustic echo cancellor, while in other embodiments the at least one echo cancellor can be a line echo cancellor. In addition, the first transducer is typically a microphone coupled to an analog to digital converter while the second transducer is typically a speaker coupled to a digital to analog converter. The communication system controls interoperation of all the above devices with a controller such as a state machine that is designed to control the communication system with respect to the echo cancellor and the delay module. Further assisting operations in the communication system can be at least one speech detector that is often coupled to a communication line passing through the echo cancellor. The speech detectors prevent the echo cancellor from adjusting when no speech signals occur on the line.

Various aspects of the present invention may also be realized through a telephone communication system comprising at least one microphone that detects audio signals and is coupled to an analog to digital converter to convert the audio signals into digital signals for transmitting within the telephone communication system. At least one speaker that is coupled to a digital to analog converter is included for converting certain of the digital signals within the telephone communication system into audio signals. Also included is at least one cancellor having digital circuitry for canceling specific digital signals that match particular communication characteristics and at least one delay module associated with the at least one cancellor. Finally, a controller is disposed in the telephone communication system and coupled to the at least one cancellor and the at least one delay module such that the controller enables the cancellor to adjust the amount of cancellation occurring in the at least one cancellor according to the digital signals being transmitted therein.

Like the controller of the previous embodiment, the controller often comprises a state machine that controls the telephone communication system with respect to the at least one cancellor and the at least one delay module. In addition, the telephone communication system may further comprise a speech detector that enables the controller to adjust the amount of cancellation occurring in the at least one cancellor according to the digital signals passing therethrough.

With a communication system having a microphone, a speaker, a cancellor, at least one delay module, and a controller, a method for canceling undesirable communication signals in the communication system includes passing communication signals through the communication system such that the at least one delay module temporarily stores the communication signals. The cancellor is then adjusted, with the controller, according to the communication signals that are temporarily stored in the at least one delay module and according to communication signals that have been passing through the communication system over time. Audio signals are received in the microphone of the communication system and then converted into digital communication signals. Finally, in this embodiment, the cancellor cancels particular portions of the digital communication signals in order to produce only desired audio signals at the speaker.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when the following detailed description of the preferred embodiment is considered in conjunction with the following drawings.

Figure 1 is a block diagram of exemplary speaker phones according to principles of the present invention, wherein the speaker phones are configured for communicating across a telephone line.

Figure 2 is a block diagram of, one of the speaker phones of Figure 1 wherein components of the speaker phone are illustrated in more detail for purposes of understanding the principles according to the present invention.

Figure 3 A is a block diagram of an exemplary echo canceller having an adaptive filter for filtering out communication signals that correspond to communication signals detected by a microphone on a speaker phone and that originated with a speaker on the speaker phone.

Figure 3B is a block diagram of an exemplary echo canceller having an adaptive filter for filtering out communication signals that correspond to communication signals detected by a microphone on a speaker phone and that originated with a speaker on the speaker phone, the delay modules being implemented as a single delay module.

Figure 4 is an exemplary computer system that enables the speaker phones of Figure 1 to operate in either hardware, software, or combinations thereof. DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of exemplary speaker phones 100, 102 according to principles of the present invention, wherein the speaker phones 100, 102 are configured for communicating across a telephone line 104. As illustrated, each speaker phone 100, 102 has a microphone 106, 108, respectively, and a speaker 110, 112, respectively. The speaker phones 100 and 102 are configured to allow a user to speak into one of the microphones 106, 108 without hearing an echo of what was said. For example, the user may speak into the microphone 106 to begin transmission of communication signals through the speaker phone 100, across the telephone line 104, to the speaker phone 102, and out the speaker 112. When the communication signals reach the speaker 112, the communication signals are broadcast from the speaker 112 as though the user speaking into the microphone 106 were located at the speaker 112. The communication signals that are broadcast from the speaker 112 are at least partially detected by the microphone 108 and would be transmitted back to the speaker phone 100 and through the speaker 110 except that the speaker phone 102 is configured to filter out any communication signals that have been broadcast from the speaker 112.

In summary, the speaker phones 100 and 102 include modules that cancel undesirable communication signals that originate at the speakers 110 and 112 and that would otherwise be transmitted through the microphones 106 and 108, respectively, back to the original source of the communication signals. Although two speaker phones 100, 102 are illustrated, it should be noted that the principles of the present invention are applicable if one of the speaker phones is replaced with a standard telephone system and only one speaker phone is present in the system. As described in relation to Figure 2, a single speaker phone is configured to minimize echoes that would otherwise be received at a speaker in the standard telephone system. Figure 2 is a block diagram of the speaker phone 100 wherein components of the speaker phone 100 are illustrated in more detail for purposes of understanding the principles according to the present invention. As described above, the speaker phone 100 includes the microphone 106 and the speaker 110 that enable a person located in the vicinity of the speaker phone 100 to carry out a conversation, via the speaker phone 100, with another person. The speaker phone 100 includes an acoustic echo canceller (AEC) 200 that includes circuitry for canceling communication signals that are undesirably transmitted to the microphone 106 from the speaker 110 and for adjusting the canceling circuitry depending upon the traffic on the line. These undesirable signals are those signals that are acoustically reproduced at the speaker 110 and are then detected by the microphone 106 and would be transmitted back to the source of the original communication signal unless canceled at the

AEC 200. In addition, the speaker phone 100 includes a line echo canceller (LEC) 202 that includes circuitry for canceling communication signals that are undesirably transmitted to a

"line-in" 204 from a "line-out" 205. In this manner, the speaker phone 100 cancels undesirable communication signals in two ways:

(i) as the communication signals are sent onto a telephone network through a microphone such as microphone 106; and (ii) as the communication signals are received from the line-in 204 and transmitted to the speaker 110 of the speaker phone 100.

Thus, the AEC 200 and the LEC 202 provide a dual approach to echo canceling and they enable canceling of both undesirable line echoes and acoustic echoes.

The speaker phone 100 also includes speech detectors 206 and 208 that allow the AEC 200 to be adjusted according to the amount of communication signals traveling through the speaker phone 100. In other words, the speech detector 208 allows the circuitry of the AEC 200 to adjust when communication signals are traveling through the speaker 110 and prevents the AEC 200 from adjusting when no communication signals are traveling through the speaker 110. The speech detector 206 allows the circuitry of the AEC 200 to withhold its adjustment when communication signals are generated by the person who speaks into the microphone 106, and enables the AEC 200 to adjust otherwise. In this manner, the AEC 200 may operate continuously while a person uses the speaker phone 100 to carry out a conversation. Of note, the combination of the two speech detectors 206 and 208 allows the AEC 200 to be adjusted only when the remote side is active and the local side is silent.

Also illustrated in Figure 2 is a first delay module 210 that is associated with the AEC 200 and a second delay module 212 that is associated with the LEC 202. The delays 210 and 212 are designed to enhance signal predictability in preparation for signal canceling in the AEC 200 and the LEC 202. For example, the first delay module 210 enables the AEC 200 to adjust its circuitry to cancel almost the exact acoustic signal that is being undesirably detected and transmitted back into the speaker phone 100. A transmit/receive state machine 214 interacts with the first delay module 210, the speech detectors 206 and 208, and the AEC 200 to adjust the circuitry in the AEC 200 in order to more accurately cancel the undesirable acoustic echoes created in the speaker phone 100. Likewise, the second delay module 212 interacts with the transmit/receive state machine 214, the speech detectors 206 and 208, and the LEC 202 to adjust the circuitry in the LEC 202 for greatest cancellation of undesirable echo signals. In this manner, the delays 210 and 212 enhance the echo canceling that is performed by the AEC 200 and the LEC 202.

Of note, the speaker phone 100 may be configured to transmit streaming audio without introducing additional echo problems. For example, the speaker phone 100 could be part of a computer system (e.g., computer system 400, see Figure 4) in which sound library files are available on CD Rom or embedded in a processor/chipset on a sound card. If streaming audio is sent to the speaker phone 100 over the Internet, a MIDI ("musical instrument digital interface") is commonly loaded from the Internet to provide the speaker phone 100 with the ability to recognize and convert the streaming audio signals into audible sound. The speaker phone 100 prevents these audible sounds from being detected by the microphone 106 and being undesirably transmitted into the computer system or, on the other hand, from being undesirably transmitted to the line-in 204 from the line-out 205, or vice- versa.

Figure 3A is a block diagram of an exemplary echo canceller 300 having an adaptive filter 302 for filtering out undesirable communication signals such as those signals that correspond to communication signals detected by a microphone on a speaker phone and that originated with a speaker on the speaker phone. The adaptive filter 302 is a dynamic filter that is adjusted according to signals that it receives from a state machine such as the transmit/receive state machine 214. Of course, the adjustments made to the adaptive filter 302 by the state machine depend on signals that the state machine receives from other related components such as delay modules 304, speech detectors 306 and 308, etc. Of note, the echo canceller 300 is an exemplary echo canceller that can be used as either the acoustic echo canceller 200 or the line echo canceller 202.

Figure 3B is a block diagram of the exemplary echo canceller 300 having an adaptive filter 302 for filtering out undesirable communication signals such as those signals that correspond to communication signals detected by a microphone on a speaker phone and that originated with a speaker on the speaker phone. Like Figure 3A, the adaptive filter 302 is a dynamic filter that is adjusted according to signals that it receives from a state machine such as the transmit/receive state machine 214. The signals that the state machine receives from the delay modules 304 is replaced by a single delay module 310 that is positioned so as to delay the signals from a single location. Of course, either embodiment allows the speaker phone to operate in a communication system such as a host processor with certain components implemented in software on the host processor. Figure 4 is an exemplary computer system that enables the speaker phones 100 and 102 to operate in either hardware, software, or combinations thereof. The computer system 400 is preferably an IBM-compatible, personal computer (PC) system or the like, and includes a motherboard and bus system 402 coupled to at least one central processing unit (CPU) 404 and a memory system 406. The motherboard and bus system 402 include any kind of bus system configuration, such as any combination of a host bus, one or more peripheral component interconnect (PCI) buses, an industry standard architecture (ISA) bus, an extended ISA (EISA) bus, microchannel architecture (MCA) bus, etc., along with corresponding bus driver circuitry and bridge interfaces, etc., as known to those skilled in the art. The CPU 404 preferably incorporates any one of several microprocessors, such as the 80486, Pentium™, Pentium II™, etc. microprocessors from Intel Corp., or other similar type microprocessors such as the K6 microprocessor by Advanced Micro Devices, and supporting external circuitry typically used in PCs. The external circuitry preferably includes an external or level two (L2) cache or the like (not shown). The memory system 406 may include a memory controller or the like and be implemented with one or more memory boards (not shown) plugged into compatible memory slots on the motherboard, although any memory configuration is contemplated.

The computer system 400 includes one or more output devices, such as speakers 409 coupled to the motherboard and bus system 402 via an appropriate sound card 408 and a monitor or display 412 coupled to the motherboard and bus system 402 via an appropriate video card 410. One or more input devices may also be provided such as a mouse 414, a keyboard 416, and a microphone 418, the mouse 414 and keyboard 416 coupled to the motherboard and bus system 402 via appropriate controllers (not shown) as known to those skilled in the art, and the microphone 418 coupled to the sound card 408. A storage system 420 is coupled to the motherboard and bus system 402 and may include any one or more data storage devices, such as one or more disk drives including floppy and hard disk drives, one or more CD-ROMs, one or more tape drives, etc. Other input and output devices may also be included, as well as other types of input devices including a joystick, pointing device, voice recognition, etc. The input and output devices enable a user to interact with the computer system 400 for purposes of a speaker phone, as further described below.

The motherboard and bus system 402 may be implemented with at least one expansion slot 422, which is configured to receive compatible adapter or controller cards configured for the particular slot and bus type. Typical devices configured as adapter cards include network interface cards (NICs), disk controllers such as a SCSI (Small Computer System Interface) disk controller, video controllers, sound cards, etc. The computer system 400 may include one or more of several different types of buses and slots, such as PCI, ISA, EISA, MCA, etc. Each slot 422 is configured to receive an expansion card 424, such as a sound card, a modem card, a network interface controller (NIC) or adapter, etc.

Other components, devices and circuitry are normally included in the computer system 400 but are not particularly relevant to the present invention and are not shown. Such other components, devices and circuitry are coupled to the motherboard and bus system 402, such as, for example, an integrated system peripheral (ISP), an interrupt controller such as an advanced programmable interrupt controller (APIC) or the like, bus arbiter(s), one or more system ROMs (read only memory) comprising one or more ROM modules, a keyboard controller, a real time clock (RTC) and timers, communication ports, non-volatile static random access memory (NVSRAM), a direct memory access (DMA) system, diagnostics ports, command/status registers, battery-backed CMOS memory, etc. Although the present invention is illustrated with an IBM-compatible type PC system, it is understood that the present invention is applicable to other types of computer systems and processors as known to those skilled in the art.

A speaker phone that is implemented primarily in software is particularly suited for the computer system 400 when a user installs an internal expansion card (not shown) such as a modified modem card that provides speaker phone capabilities when appropriate software is operating on the computer system 400. Alternatively, if the expansion card 424 is external to the computer system 400, additional hardware is required to operate the modem as a speaker phone.

The above-listed sections and included information are not exhaustive and are only exemplary for speaker phones and computer systems. The particular sections and included information in a particular embodiment may depend upon the particular implementation and the included devices and resources. Although a system and method according to the present invention has been described in connection with the preferred embodiment, it is not intended to be limited to the specific form set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents, as can be reasonably included within the spirit and scope of the invention as defined by the appended claims.

Claims

CLAIMSWhat is Claimed is:

1. A communication system comprising: a first transducer that detects and converts external audio signals into internal electronic signals formatted to be compatible with internal operations of the communication system;

a second transducer that converts internal communication signals into external audio signals; at least one echo cancellor that cancels undesirable internal communication signals; and a delay module that enables the at least one echo cancellor to carry out specific cancellation procedures during a time period when specific undesirable communication signals are estimated to be passing through the at least one echo cancellor.

2. The communication system of claim 1 wherein the at least one echo cancellor is an acoustic echo cancellor.

3. The communication system of claim 1 wherein the at least one echo cancellor is a line echo cancellor.

4. The communication system of claim 1 wherein the first transducer is a microphone coupled to an analog to digital converter.

5. The communication system of claim 1 wherein the second transducer is a speaker coupled to a digital to analog converter.

6. The communication system of claim 1 further comprising a state machine that controls the communication system with respect to the at least one echo cancellor and the delay module.

7. The communication system of claim 1 further comprising at least one speech detector.

8. The communication system of claim 1 wherein the communication system includes a host processor having software modules that enable the communication system to operate as a speaker phone when executing on the host processor.

9. A telephone communication system comprising: at least one microphone that detects audio signals, the at least one microphone being coupled to an analog to digital converter to convert the audio signals into digital signals for transmitting within the telephone communication system; at least one speaker coupled to a digital to analog converter for converting certain of the digital signals within the telephone communication system into audio signals; at least one cancellor having digital circuitry for canceling specific digital signals that match particular communication characteristics; at least one delay module associated with the at least one cancellor; a controller disposed in the telephone communication system and coupled to the at least one cancellor and the at least one delay module such that the controller enables the cancellor to adjust the amount of cancellation occurring in the at least one cancellor according to the digital signals being transmitted therein.

10. The telephone communication system of claim 9 wherein the controller comprises a state machine that controls the telephone communication system with respect to the at least one cancellor and the at least one delay module.

11. The telephone communication system of claim 9 further comprising at least one speech detector that enables the controller to adjust the amount of cancellation occurring in the at least one cancellor according to the digital signals passing therethrough.

12. The telephone communication system of claim 9 comprising a host processor having software modules that enable the telephone communication system to operate with the at least one cancellor, the at least one delay module, and the controller.

13. A method for canceling undesirable communication signals in a communication system having a microphone, a speaker, a cancellor, at least one delay module, and a controller, the method comprising: passing communication signals through the communication system such that the at least one delay module temporarily stores the communication signals; adjusting the cancellor, with the controller, according to the communication signals that are temporarily stored in the at least one delay module and according to communication signals that have been passing through the communication system over time; receiving audio signals in the microphone of the communication system; converting the audio signals to digital communication signals; and cancelling, with the cancellor, particular portions of the digital communication signals in order to produce only desired audio signals at the speaker.