Multiple access telephone extension systems and methods

• US 5,319,634 A
• Filed: 10/07/1991
• Issued: 06/07/1994
• Est. Priority Date: 10/07/1991
• Status: Expired due to Term

• Current Assignee: Low Environ AG LLC (Intellectual Ventures LLC)
• Original Assignee: Phoenix Corporation (Manitex International, Inc.)
• Inventors: Bartholomew, David B., Ivie, A. Ray, Schurig, Alma K.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HSU, ALPUS
• Application Number:
  US07/773,009
• Time in Patent Office: 974 Days
• Field of Search: 370/11, 370/18, 370/24, 370/29, 370/30, 370/69.1, 370/95.3, 370/50, 370/70, 370/95.1, 375/1, 375/38, 375/40, 379/58, 379/59, 379/60, 379/61, 380/34, 455/33.1, 455/33.2, 455/34.1, 455/54.1, 455/49.1, 455/53.1, 455/56.1
• US Class Current: 370/441
• CPC Class Codes: H04B 2203/5408 using protocols
• CPC Class Codes: H04B 2203/5425 improving S/N by matching impedance, noise reduction, gain control
• CPC Class Codes: H04B 2203/5437 Wired telephone
• CPC Class Codes: H04B 2203/5441 Wireless systems or telephone
• CPC Class Codes: H04B 2203/5445 Local network
• CPC Class Codes: H04B 2203/545 Audio/video application, e.g. interphone
• CPC Class Codes: H04B 2203/5483 using coupling circuits
• CPC Class Codes: H04B 2203/5491 using filtering and bypassing
• CPC Class Codes: H04B 3/542 the information being in digital form
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04M 1/71 Substation extension arrangements
• CPC Class Codes: H04M 1/733 with a plurality of base stations connected to a plurality of lines for selection in cordless PBX H04W84/16

Abstract

A method and system for conducting multiple access simultaneous telephone communications in full duplex either over the power lines of a building or using RF transmission. It employs a combination of multiple access techniques selected from among the following: time division, code division, and frequency division. The following features result: a) security coding to prevent unauthorized access and eavesdropping, b) multiple simultaneous conversations through identical and closely coupled transmission media, c) non-interference to other communications systems and users, and d) processing gain for operating in noisy environments.

Claims

1. A telephone communications system, the system comprising:

(a) a base unit comprising;

(i) a first transmitter subsystem,

(ii) a first receiver subsystem, and

(iii) means for connecting said first transmitter subsystem and said first receiver subsystem to a telephone line;

(b) an extension unit comprising;

(i) a second transmitter subsystem, and

(ii) a second receiver subsystem;

each of said first and second transmitter subsystems comprising;

(a) means or converting analog telephone communications signals to digital data signals;

(b) means for generating a transmission carrier controlled by at least one multiple access means, said at least one multiple access means being selected form the group consisting of;

(i) time division multiple access multiplexing means for controlling the times at which the digital data signals are transmitted; and

(ii) frequency division multiple access means for changing said transmission carrier'"'"'s frequency;

(c) means for generating a pseudonoise code;

(d) means for modulating said transmission carrier by said digital data signals and said pseudonoise code to produce a direct spread code division multiple access signal; and

(e) means for coupling said direct spread code division multiple access signal to a communications medium;

and each of said first and second receiver subsystems comprising;

(a) means for receiving said direct spread code division multiple access signal from said communications medium;

(b) means for recovering said modulated transmission carrier from said received direct spread code division multiple access signal; and

(c) means for demodulating said recovered modulated transmission carrier to produce digital data corresponding to said analog telephone communications signals.

2. A telephone communications system as in claim 1 further comprising off hook circuitry for detecting off hook status in said extension unit and placing said telephone line connecting means of said base unit into an off hook condition.

3. A telephone communications system as in claim 1, said base unit further comprising ring detect circuitry for detecting ring signals on said telephone line and transmitting a ring command to said extension unit;

and said extension unit further comprising ring generator circuitry for generating a ring signal in said extension unit upon receipt of said ring command.

4. A telephone communications system as in claim 1, wherein said means for coupling said direct spread code division multiple access signal to a communications medium comprises an RF antenna.

5. A telephone communications system as in claim 1, wherein said means for coupling said direct spread code division multiple access signal to a communications medium comprises a connection to power lines of a building.

6. A telephone communications system as in claim 1, further comprising one or more additional extension units.

7. A telephone communications system as in claim 1, wherein said telephone line connecting means of said base unit connects a plurality of telephone lines to said transmitter subsystem and said receiver subsystem.

8. A telephone communications base unit comprising:

(a) a transmitter subsystem,

(b) a receiver subsystem, and

(c) means for connecting said transmitter subsystem and said receiver subsystem to a telephone line;

said transmitter subsystem comprising;

(a) means for converting first analog telephone communications signals to first digital data signals;

(b) means for generating a first transmission carrier controlled by at least one multiple access means, said at least one multiple access means being selected from the group consisting of;

(i) time division multiple access multiplexing means for controlling the times at which said first digital data signals are transmitted; and

(ii) frequency division multiple access means for changing said transmission carrier'"'"'s frequency;

(c) means for generating a pseudonoise code;

(d) means for modulating said first modulated transmission carrier by said first digital data signals and said pseudonoise code to produce a first direct spread code division multiple access signal; and

(e) means for coupling said first direct spread code division multiple access signal to a communications medium;

and said receiver subsystem comprising;

(a) means for receiving a second direct spread code division multiple access signal from said communications medium;

(b) means for recovering a second modulated transmission carrier from said second direct spread code division multiple access signal; and

(c) means for demodulating said second modulated transmission carrier to produce second digital data corresponding to second analog telephone communications signals.

9. A telephone communications base unit as in claim 8 further comprising off hook circuitry for placing said telephone line connecting means of said base unit into an off hook condition.

10. A telephone communications base unit as in claim 8, said base unit further comprising ring detect circuitry for detecting ring signals on said telephone line and transmitting a ring command to an extension unit.

11. A telephone communications base unit as in claim 8, wherein said means for coupling said direct spread code division multiple access signal to a communications medium comprises an RF antenna.

12. A telephone communications base unit as in claim 8, wherein said means for coupling said direct spread code division multiple access signal to a communications medium comprises a connection to power lines of a building.

13. A telephone communications base unit as in claim 8, wherein said telephone line connecting means of said base unit connects a plurality of telephone lines to said transmitter subsystem and said receiver subsystem.

14. A telephone communications extension unit comprising:

(a) a transmitter subsystem, and

(b) a receiver subsystem;

said transmitter subsystem comprising;

(a) means for converting first analog telephone communications signals to first digital data signals;

(b) means for generating a first transmission carrier controlled by at least one multiple access means, said at least one multiple access means being selected form the group consisting of;

(i) time division multiple access multiplexing means for controlling the times at which said first digital data signals are transmitted; and

(ii) frequency division multiple access means for changing said transmission carrier'"'"'s frequency;

(c) means for generating a pseudonoise code;

(d) means for modulating said first modulated transmission carrier by said first digital data signals and said pseudonoise code to produce a first direct spread code division multiple access signal; and

(e) means for coupling said first direct spread code division multiple access signal to a communications medium;

and said receiver subsystem comprising;

(a) means for receiving a second direct spread code division multiple access signal from said communications medium;

(b) means for recovering a second modulated transmission carrier from said second direct spread code division multiple access signal; and

(c) means for demodulating said second modulated transmission carrier to produce second digital data corresponding to second analog telephone communications signals.

15. A telephone communications extension unit as in claim 14, said extension unit further comprising ring generator circuitry for generating a ring signal in said extension unit upon receipt of a ring command from a base unit.

16. A telephone communications extension unit as in claim 14, wherein said means for coupling said direct spread code division multiple access signal a communications medium comprises an RF antenna.

17. A telephone communications extension unit as in claim 14, wherein said means for coupling said direct spread code division multiple access signal to a communications medium comprises a connection to power lines of a building.

18. A method for telephone communications between a first unit and a second unit, the method comprising the steps of:

(a) said first unit converting analog telephone communications signals to digital data signals;

(b) said first unit generating a transmission carrier controlled by at least one multiple access technique selected form the group consisting of;

(i) time division multiple access for controlling the times at which the transmission carrier is transmitted; and

(ii) frequency division multiple access for changing said transmission carrier'"'"'s frequency;

(c) said first unit generating pseudonoise code;

(d) said first unit modulating said transmission carrier with said digital data signals and said pseudonoise code to produce a direct spread code division multiple access signal;

(e) said first unit transmitting said direct spread code division multiple access signal to said second unit;

(f) said second unit recovering said modulated transmission carrier from said direct spread code division multiple access signal; and

(g) said second unit demodulating said modulated transmission carrier to produce digital data corresponding to said analog telephone communications signals.

19. A method for telephone communications as in claim 18, further comprising:

(h) connecting one or more telephone lines to said first unit with corresponding ring, off hook and duplex audio signals to provide said first unit with a base unit capability.