One channel carrier intercom system

Claim 2

A telephone communication device including a pair of communication units connected together during use by a line including a pair of wires comprising: a. means in only one unit for generating a frequency carrier, and means for inserting said carrier frequency in series with the line at said one unit, b. double balanced means for modulating and demodulating the carrier frequency in each of said units, c. means in only the other of said units for amplifying and limiting the carrier frequency, and means for applying the output of said amplifying and limiting means to the modulating and demodulating means in said other unit.

Claim 3

A telephone communication device as defined in claim 1 including means connected between the output of the modulating and demodulating means and the line in each of said units for blocking frequencies in the audible range.

Claim 4

a high pass filter connected to said terminals,

Claim 5

a high pass filter connected to said terminals,

Claim 6

a lattice modulator/demondulator connected to said filter,

Claim 7

a lattice modulator/demondulator connected to said filter,

Claim 8

A telephone communication device as defined in claim 1 wherein said modulating/demodulating means is operable in two directions.

Claim 9

A telephone communication device as defined in claim 1 including means for transferring voice frequencies to said modulating and demodulating means for securing transmission in two directions whereby a two-wire channel is converted to four-wire receiving means.

Claim 10

an impedance matching pad connected to said modulator/demondulator,

Claim 11

an impedance matching pad connected to said modulator/demondulator,

Claim 12

a 4/2 wire hybrid conversion circuit connected to said pad,

Claim 13

a 4/2 wire hybrid conversion circuit connected to said pad,

Claim 14

A telephone communication device as defined in claim 1 wherein said amplifying and limiting means provides a signal in the other of said units of the same magnitude and frequency as the signal generated in said one unit.

Claim 15

A telephone communication device as defined in claim 1 wherein said modulating/demodulating means in the other of said units demodulates a single carrier frequency simplex generated by said one unit.

Claim 16

an amplifying means connected to said conversion circuit,

Claim 17

an amplifying means connected to said conversion circuit,

Claim 18

an audible receiver means connected to said amplifying means, b. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, c. said master unit including a carrier frequency oscillator connected to said modulator/demodulator, and d. said slave unit including means for amplifying and limiting the carrier frequency received from said master unit over the pair of wires and applying the limited carrier frequency to the lattice modulator/demodulator in said slave unit.

Claim 19

an audible receiver means connected to said amplifying means, b. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, c. said master unit including a carrier frequency oscillator connected to said modulator/demodulator, and d. said slave unit including means for amplifying and limiting the carrier frequency received from said master unit over the pair of wires and applying the limited carrier frequency to the lattice modulator/demodulator in said slave unit.

Claim 20

A telephone communication device as defined in claim 4 includiNg means connected to the input of said voice transferring means for tracing and verifying the continuity of the pair of wires.

Claim 21

A telephone communication device as defined in claim 7 wherein said tracing and verifying means comprises a tone circuit having a first oscillator interrupted by a second oscillator.

Claim 22

A telephone communication device as defined in claim 1 wherein said carrier frequency is in the order of 100 KHz.

Claim 23

A telephone communication device including a pair of communication units connected together during use by a line including a pair of wires comprising: a. a master unit and a slave unit including in serial connection:

Claim 24

A telephone communication device including a pair of communication units connected together during use by a line including a pair of wires comprising: a. a master unit and a slave unit including in serial connection:

Claim 25

A master unit for use in a telephone communication system comprising: a. a pair of input/output terminals, b. a high pass filter means connected to said terminals for blocking frequencies in the audible range, c. means only in said unit for generating a frequency carrier, and means for inserting said carrier frequency in series with the input/output terminals, d. a double balanced means for modulating and demodulating the carrier frequency connected to said filter, e. an impedance matching pad connected to said modulator and demodulator means, f. a 4/2 wire hybrid conversion circuit means connected to said pad, g. an amplifying means connected to said conversion circuit, h. an audible receiver means connected to said amplifying means, and i. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, the first of said oscillators being interrupted by the second of said oscillators.

Claim 26

A master unit for use in a telephone communication system comprising: a. a pair of input/output terminals, b. a high pass filter means connected to said terminals for blocking frequencies in the audible range, c. means only in said unit for generating a frequency carrier, and means for inserting said carrier frequency in series with the input/output terminals, d. a double balanced means for modulating and demodulating the carrier frequency connected to said filter, e. an impedance matching pad connected to said modulator and demodulator means, f. a 4/2 wire hybrid conversion circuit means connected to said pad, g. an amplifying means connected to said conversion circuit, h. an audible receiver means connected to said amplifying means, and i. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, the first of said oscillators being interrupted by the second of said oscillators.

Claim 27

A slave unit for use in a telephone communication system comprising: a. a pair of input/output terminals, b. a high pass filter means connected to said terminals for blocking frequencies in the audible range, c. means only in said unit for amplifying and limiting a carrier frequency received through said input/output terminals and applying the limited carrier frequency to a double balanced means for modulating and demodulating the carrier frequency, d. said modulating and demodulating means being connected to said filter, e. an impedance matching pad connected to said modulator and demodulator means, f. a 4/2 wire hybrid conversion circuit means connected to said pad, g. an amplifying means connected to said conversion circuit, h. an audible receiver means connected to said amplifying means, and i. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, the first of said oscillators being interrupted by the second of said oscillators.

Claim 28

A slave unit for use in a telephone communication system comprising: a. a pair of input/output terminals, b. a high pass filter means connected to said terminals for blocking frequencies in the audible range, c. means only in said unit for amplifying and limiting a carrier frequency received through said input/output terminals and applying the limited carrier frequency to a double balanced means for modulating and demodulating the carrier frequency, d. said modulating and demodulating means being connected to said filter, e. an impedance matching pad connected to said modulator and demodulator means, f. a 4/2 wire hybrid conversion circuit means connected to said pad, g. an amplifying means connected to said conversion circuit, h. an audible receiver means connected to said amplifying means, and i. a tone generator means including a pair of oscillators connected to an input of said conversion circuit, the first of said oscillators being interrupted by the second of said oscillators.