Conversion of a fax modulation to a data modulation

• US 5,513,212 A
• Filed: 11/15/1993
• Issued: 04/30/1996
• Est. Priority Date: 11/15/1993
• Status: Expired due to Term

• Current Assignee: Paradyne Corporation (Dasan Networks Incorporated)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Bremer, Gordon
• Primary Examiner(s): Coles, Sr., Edward L.
• Assistant Examiner(s): LEE, TOMMY D
• Application Number:
  US08/151,689
• Time in Patent Office: 897 Days
• Field of Search: 375/4, 375/5, 375/7, 375/8, 375/222, 375/226, 375/211, 358/434, 358/435, 358/436, 358/438, 358/439, 358/442, 379/93, 379/97, 379/98, 379/100
• US Class Current: 375/222
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors

Abstract

A simultaneous voice and data (SVD) modem is coupled to both a fax machine, which includes a fax modem, and a telephone set. When the fax machine initiates a fax-call, the SVD modem emulates signaling of the local loop. This allows the fax machine to operate without requiring modifications to the fax machine. After establishing a data connection with a far-end SVD modem, the near-end SVD modem demodulates the fax modulation signal from the fax machine to recover the fax data. The fax data is then re-modulated using a data modulation technique for transmission to the far-end SVD modem. The latter, demodulates the data portion of the signal to recover the fax data, which is then re-modulated using a fax modulation technique for transmission to a far-end fax machine.

Claims

1. A method for use in data communications equipment, the method comprising the steps of:

answering a telephone call;

detecting a first identification signal that identifies a far-end modem as providing fax information within a simultaneous voice and data signal;

sending a second identification signal that identifies the data communications equipment as compatible with the far-end modem;

switching to a fax mode of operation;

receiving the simultaneous voice and data signal;

demodulating the data portion of the simultaneous voice and data signal to provide a data signal;

demodulating the voice potion of the simultaneous voice and data signal to provide a voice signal;

modulating the data signal to provide a fax modulation signal; and

transmitting the fax modulation signal.

2. The method of claim 1 wherein the first identification from the far-end modem and the second identification from the data communications equipment also represent a requested symbol rate.

3. The method of claim 1 wherein the step of sending the second identification signal includes the step of sending a standard answer tone after sending the second identification signal.

4. A method for use in a simultaneous voice and data communications system, the method comprising the steps of:

receiving an off-hook signal from a fax machine;

coupling to a communications channel to dial a telephone number that represents a far-end fax machine;

transmitting a calling signal to the communications channel that represents both a mode of operation and a requested symbol rate subsequent to dialing the telephone number;

accepting a fax signal from the fax machine upon receiving an identification signal from a far-end data communications equipment of the far-end fax machine, the identification signal confirming the requested symbol rate, where the identification signal is received before a standard answer signal;

demodulating the fax signal to provide fax data; and

re-modulating the fax data for transmission to the far-end data communications equipment.

5. Apparatus for use in data communications equipment, the apparatus comprising:

means for a) answering a telephone call, b) detecting a first identification signal that identifies a far-end data communications equipment as providing a simultaneous voice and data signal wherein the data signal represents fax information, and c) providing a second identification signal in response to the first identification signal;

means for demodulating both the data portion of the simultaneous voice and data signal to provide a data signal, and the voice portion to provide a voice signal;

means for modulating the data signal to provide a fax modulation signal; and

means for transmitting the fax modulation signal.

6. The apparatus of claim 5 wherein the first identification and the second identification each represent a requested symbol rate from the respective endpoint.

7. The apparatus of claim 5 wherein the means for providing the second identification signal also sends a standard answer tone after sending the second identification signal.

8. A modem comprising:

a processor responsive to a calling signal received from a telephone line for selecting one of a number of operating modes, wherein one of the number of operating modes is a fax mode and another one of the number of operating modes is a simultaneous voice and fax mode;

a fax modem circuit for demodulating a fax signal to provide a data signal;

a simultaneous voice and data modem circuit for re-modulating the data signal along with a voice signal to provide a simultaneous voice and data signal for transmission over a telephone line; and

a selecting circuit responsive to the selected mode for coupling the fax signal to the telephone line during the fax mode and for coupling the simultaneous voice and data signal to the telephone line during the simultaneous voice and fax mode.