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US 5,319,634 AGranted
Multiple access telephone extension systems and methods
AssigneePhoenix Aktiengesellschaft
InventorsDavid B. Bartholomew, A. Ray Ivie, Alma K. Schurig
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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.
Claims19
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.
19 more elements
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.
15 more elements
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.
14 more elements
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.
8 more elements
Dependencies are inferred from the claim text.