Method and apparatus for emulating a telephone with a modem and headset

• US 5,533,105 A
• Filed: 09/15/1993
• Issued: 07/02/1996
• Est. Priority Date: 09/15/1993
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Brown, Paul M., Hedayat, Shahin, Urbani, George V.
• Primary Examiner(s): Chan, Jason
• Application Number:
  US08/121,615
• Time in Patent Office: 1,021 Days
• Field of Search: 379/93, 379/94, 379/96, 379/97, 379/98, 379/99, 379/100, 379/88, 379/89, 379/39, 379/90, 379/442, 379/443, 379/444, 379/441, 379/388, 379/389, 379/390, 379/395, 379/416, 379/265 , 379/266, 379/348, 375/8
• US Class Current: 379/93.05
• CPC Class Codes: H04M 1/00 Substation equipment, e.g. for use by subscribers subscriber services or facilities provided at exchanges H04M3/00; prepayment telephone coin boxes H04M17/00; current supply arrangements H04M19/08
• CPC Class Codes: H04M 1/58 Anti-side-tone circuits
• CPC Class Codes: H04M 1/6033 for providing handsfree use or a loudspeaker mode in telephone sets arrangements for preventing acoustic echo H04M9/08
• CPC Class Codes: H04M 1/6505 storing speech in digital form
• CPC Class Codes: H04M 1/725 Cordless telephones user interfaces specially adapted therefor H04M1/724
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

An emulator circuit is provided for allowing a data/fax/voice modem, a host computer, and a telephone headset to emulate the functions of a telephone. For voice communication, the emulator circuit connects the telephone headset to the telephone line. For automated data/fax/voice communications, the emulator circuit connects the modem to the telephone line. Two specific embodiments of the emulator circuit are described. In one, the emulator circuit is configured from analog circuit components connected to the modem. In the other, the emulator circuit is an integrated circuit component of the modem. In both embodiments, the provision of the emulator circuit obviates the need to provide a separate telephone for handling voice telephone conversations.

Claims

1. An apparatus for connecting to a telephone line, said apparatus comprising:

a modem including a receive line for receiving information from said telephone line and a transmit line for transmitting information to said telephone line, said receive and transmit lines each including separate tip and ring lines;

an acoustic transducer device for receiving and producing sounds; and

a connection circuit including;

a first amplifier for receiving signals from said transmit line, said first amplifier having first and second input nodes connected through a switch to said tip and ring lines, respectively, of said transmit line;

a second amplifier for receiving signals from said receive line, said second amplifier having first and second input nodes connected through a switch to said tip and ring lines, respectively, of said receive line; and

a third amplifier for receiving outputs from said first and second amplifiers said third amplifier having a first input node connected to outputs of said first and second amplifiers and having a second input node connected to a reference voltage, an output of said third amplifier being received by said acoustic transducer device, said first, second and third amplifiers being differential amplifiers.

2. The apparatus of claim 1, wherein said modem is a data/fax/voice modem;

and said acoustic transducer device includes a microphone and an earphone.

3. An apparatus for connecting to a telephone line, said apparatus comprising:

modem means for receiving information from and for transmitting information to said telephone line;

acoustic transducer means for receiving and producing sounds; and

connection means for connecting said modem means to said telephone line for automated communication and connecting said acoustic transducer means to said telephone line for non-automated voice communication,

wherein said connection means connects said modem means to said telephone line if an incoming message is a data message and connects one of said modem means and said acoustic transducer means to said telephone line if said incoming message is a voice message,

wherein said acoustic transducer means includes an earphone and a microphone,

wherein said modem means has receive, transmit and microphone terminals and wherein said connection means includes;

means for connecting said receive and transmit terminals of said modem means to said telephone line;

earphone connection means for connecting said earphone of said acoustic transducer means to said transmit terminal of said modem means and for selectively connecting said earphone to said receive terminal of said modem means; and

microphone connection means for connecting said microphone of said acoustic transducer means to said microphone terminal of said modem means,

wherein said means for connecting said receive and transmit terminals of said modem means includes a receive line connected to said receive terminal and a transmit line connected to said transmit terminal, said receive and transmit lines each include separate tip and ring lines and wherein said earphone connection means comprises;

first differential detection means for detecting a difference between signals of said tip and ring lines of said transmit line;

second differential detection means, connected through a switch to said receive line, for detecting a difference between signals of said tip and ring lines of said receive line; and

summing means for combining outputs of said first and second differential detection means;

with said earphone being connected to an output of said summing means.

4. An apparatus for connecting to a telephone line, said apparatus comprising:

modem means for receiving information from and for transmitting information to said telephone line;

acoustic transducer means for receiving and producing sounds; and

connection means for connecting said modem means to said telephone line for automated communication and connecting said acoustic transducer means to said telephone line for non-automated voice communication,

wherein said connection means connects said modem means to said telephone line if an incoming message is a data message and connects one of said modem means and said acoustic transducer means to said telephone line if said incoming message is a voice message,

wherein said acoustic transducer means includes an earphone and a microphone,

wherein said modem means has receive, transmit and microphone terminals and wherein said connection means includes;

means for connecting said receive and transmit terminals of said modem means to said telephone line;

earphone connection means for connecting said earphone of said acoustic transducer means to said transmit terminal of said modem means and for selectively connecting said earphone to said receive terminal of said modem means; and

microphone connection means for connecting said microphone of said acoustic transducer means to said microphone terminal of said modem means,

wherein said means for connecting said receive and transmit terminals of said modem means includes a receive line connected to said receive terminal and a transmit line connected to said transmit terminal, said receive and transmit lines each include separate tip and ring lines and wherein said earphone connection means comprises;

a first operational amplifier having first and second inputs connected to said tip and ring lines, respectively, of said transmit line;

a second operational amplifier having first and second inputs connected through a switch to said tip and ring lines, respectively, of said receive line; and

a third operational amplifier having a first input connected to outputs of said first and second operational amplifiers and having a second input connected to a reference voltage;

with said earphone being connected to an output of said third operational amplifier.

5. A system for connecting to a telephone line, said system comprising:

a data/fax/voice modem for connecting to said telephone line;

a microphone/earphone set for connecting to said telephone line and to said modem; and

an connection circuit connecting said microphone/earphone set to said telephone line for incoming and outgoing voice telephone calls and connecting said modem to said telephone line for data/fax/voice modem operations,

wherein said modem has receive, transmit and microphone terminals, and wherein said connection circuit comprises;

means for connecting said receive and transmit terminals of said modem to said telephone line;

earphone connection means for connecting an earphone of said microphone/earphone set to said transmit terminal of said modem and for selectively connecting said earphone to said receive terminal of said modem; and

microphone connection means for connecting a microphone of said microphone/earphone set to said microphone terminal of said modem,

wherein said means for connecting said receive and transmit terminals of said modem to said telephone line comprises;

a transformer for connecting to said telephone line;

a hybrid two-to-one telephone line connector, having first, second and third terminals, with said first terminal connected to said transformer;

a receive line interconnecting said receive terminal of said modem and said second terminal of said hybrid connector; and

a transmit line interconnecting said transmit terminal of said modem and said third terminal of said hybrid connector,

wherein said receive and transmit lines each include separate tip and ring lines and wherein said earphone connection means comprises;

a first operational amplifier having first and second inputs connected to said tip and ring lines, respectively, of said transmit line;

a second operational amplifier having first and second inputs connected through a switch to said tip and ring lines, respectively, of said receive line; and

a third operational amplifier having a first input connected to outputs of said first and second operational amplifiers and having a second input connected to a reference voltage;

with said earphone being connected to an output of said third operational amplifier.

6. An apparatus for connecting to a telephone line, said apparatus comprising:

modem means including a receive line for receiving information from said telephone line and a transmit line for transmitting information to said telephone line, said receive and transmit lines each including separate tip and ring lines;

acoustic transducer means for receiving and producing sounds; and

connection means including;

a detection circuit for detecting first signals on said transmit line and second signals on said receive line and for producing outputs, said detection circuit including;

first differential means for detecting a difference between said first signals and for producing a first one of said outputs, said first differential means detecting and amplifying a difference between said first signals of said tip and ring lines of said transmit line; and

second differential means for detecting a difference between said second signals and for producing a second one of said outputs, said second differential means detecting and amplifying a difference between said second signals of said tip and ring lines of said receive line;

wherein said first differential means is coupled to said tip and ring lines of said transmit line through a switch; and

wherein said second differential means is coupled to said tip and ring lines of said receive line through a switch; and

a summation circuit for combining said outputs, an output of said summation circuit being received by said acoustic transducer means.

7. The apparatus of claim 6, wherein said modem means includes

means for receiving a data message;

means for receiving a facsimile message; and

means for receiving a voice message.

8. The apparatus of claim 6, wherein said modem means is a data/fax/voice modem.

9. The apparatus of claim 6, wherein said modem means includes means for automatically receiving and processing voice messages received along said telephone line.

10. The apparatus of claim 9, wherein said means for automatically receiving and processing a voice message includes answering machine means for transmitting a prerecorded greeting along said telephone line and for recording a responsive message received along said telephone line.

11. The apparatus of claim 6, wherein said acoustic transducer means is a telephone headset.

12. The apparatus of claim 6, wherein said connection means connects said modem means to said telephone line if an incoming message is a data message and connects one of said modem means and said acoustic transducer means to said telephone line if said incoming message is a voice message.

13. The apparatus of claim 12, wherein said acoustic transducer means includes an earphone and a microphone, wherein said modem means has receive, transmit and microphone terminals and wherein said connection means includes

means for connecting said receive and transmit terminals of said modem means to said telephone line;

earphone connection means for connecting said earphone of said acoustic transducer means to said transmit terminal of said modem means and for selectively connecting said earphone to said receive terminal of said modem means; and

microphone connection means for connecting said microphone of said acoustic transducer means to said microphone terminal of said modem means.

14. The apparatus of claim 13, wherein said means for connecting said receive and transmit terminals of said modem means comprises

a transformer connected to said telephone line;

a hybrid two-to-one telephone line connector, having first, second and third terminals, with said first terminal connected to said transformer;

said receive line interconnecting said receive terminal of said modem means and said second terminal of said hybrid connector; and

said transmit line interconnecting said transmit terminal of said modem means and said third terminal of said hybrid connector.

15. The apparatus of claim 13, further including a means for buffering a common mode voltage of said modem means.

16. A method for processing telephonic communications using a modem, an acoustic transducer device, and a connection circuit, said connection circuit including a detection circuit and a summation circuit, said summation circuit coupled to said detection circuit and said acoustic transducer device, said modem including a transmit line for transmitting information to a telephone line and a receive line for receiving information from said telephone line, said transmit and receive lines each including separate tip and ring lines, said detection circuit including a first differential amplifier and a second differential amplifier, and said summation circuit including a third differential amplifier, said method comprising the steps of:

detecting an incoming telephone call;

determining whether said incoming telephone call contains a voice message or a data message;

selectively connecting said acoustic transducer device to said telephone line using said connection circuit, if said incoming telephone call is a voice message, said step of selectively connecting said acoustic transducer device including the steps of;

detecting first signals from said transmit and receive lines, said step of detecting said first signals including the step of routing said first signals to said detection circuit which detects said first signals, wherein said step of routing said first signals includes the steps of;

routing signals from said tip and ring lines of said transmit line to said first differential amplifier; and

routing signals from said tip and ring lines of said receive line to said second differential amplifier;

producing first output signals from said first signals;

summing said first output signals, including the step of routing said first output signals to said summation circuit which combines said first output signals, wherein said step of routing said first output signals includes the step of;

routing said first output signals to said third differential amplifier;

producing a second output signal from said first output signals; and

routing said second output signal to said acoustic transducer device; and

selectively connecting said modem to said telephone line, if said incoming telephone call is a data message.

17. A method for processing telephonic communications using a modem, an acoustic transducer device, and a connection circuit, said connection circuit including a detection circuit and a summation circuit, said summation circuit coupled to said detection circuit and said acoustic transducer device, said modem including a transmit line for transmitting information to a telephone line and a receive line for receiving information from said telephone line, said transmit and receive lines each including separate tip and ring lines, said method comprising the steps of:

detecting an incoming telephone call;

determining whether said incoming telephone call contains a voice message or a data message;

selectively connecting said acoustic transducer device to said telephone line using said connection circuit, if said incoming telephone call is a voice message, said step of selectively connecting said acoustic transducer device including the steps of;

detecting first signals from said transmit and receive lines;

producing first output signals from said first signals wherein said steps of detecting said first signals and producing said first output signals include the steps of;

detecting a difference between third signals of said tip and ring lines of said transmit line to produce a first one of said first output signals; and

detecting a difference between fourth signals of said tip and ring lines of said receive line to produce a second one of said first output signals;

summing said first output signals;

producing a second output signal from said first output signals; and

routing said second output signal to said acoustic transducer device; and

selectively connecting said modem to said telephone line, if said incoming telephone call is a data message.

18. An apparatus for connecting to a telephone line, said apparatus comprising:

a modem for receiving information from and for transmitting information to said telephone line, said telephone line including receive and transmit lines, said modem including a processor for processing signals, said processor having an input and an output;

an acoustic transducer for receiving and producing sounds; and

a connection circuit including;

summing means, having a first input for receiving a first input signal, and a second input for receiving a second input signal from a microphone means, said summing means for summing said first and second input signals and applying said summed signals to said acoustic transducer, said microphone means coupled to said transmit line;

analog-to-digital conversion means, having a first input connected to said microphone means and a second input, for converting signals from analog-to-digital, said analog-to-digital conversion means having an output connected to said input of said processor; and

digital-to-analog conversion means having an input connected to the output of said processor for converting digital signals from said processor to analog signals;

wherein said second input of said summing means is connected to an output of said digital-to-analog conversion means, and

wherein said microphone means is coupled to said transmit line through said analog-to-digital conversion means, said processor, and said digital-to-analog conversion means.

19. The apparatus of claim 18, wherein said connection circuit further includes gain adjustment means, connected to said receive line, for controlling the gain of signals received along the receive line, wherein said first input of said summing means is connected to an output of said gain adjustment means and wherein said second input of said analog-to-digital conversion means is connected to an output of said gain adjustment means.

20. The apparatus of claim 18, wherein said connection circuit further includes amplification means for amplifying a signal output from said digital-to-analog conversion means and applying said signal to said transmit line.

21. A method for processing telephonic communications using a modem, a microphone/earphone set, and a telephone line, said telephone line including separate receive and transmit lines, and said modem including a processor, said method comprising the steps of:

detecting an incoming telephone call;

determining whether said incoming telephone call contains a voice message or a data message;

selectively connecting said microphone/earphone set to said telephone line, if said incoming message is a voice message; and

selectively connecting said modem to said telephone line, if said incoming message is a data message;

wherein said step of selectively connecting said microphone/earphone set to said telephone line includes the steps of;

routing signals output from a microphone of said microphone/earphone set to said transmit line;

routing signals carried on said receive line through a gain adjustment circuit;

routing signals output from said gain adjustment circuit and said signals output from said microphone through a summing amplifier which outputs a signal in representative of a combination of said signals output from said gain adjustment circuit and said microphone,

wherein said step of routing signals output from said microphone of said microphone/earphone set to said transmit line includes the steps of;

routing said signals output from said microphone through an analog-to-digital converter;

routing signals output from said analog-to-digital converter through said processor;

routing signals output from said processor through a digital-to-analog converter; and

routing signals output from said digital-to-analog converter onto said transmit line through an amplifier; and

routing the output of said summing amplifier into an earphone of said microphone/earphone set.