Voltage booster circuit for telephone systems

Claim 2

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; boost voltage supply means for increasing the magnitude of direct current flow in the subscriber line; switching means for establishing a non-boosting path between the office terminals and the corresponding subscriber terminals, for establishing a first boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means to establish a first boosting condition, and for establishing a second boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means to establish a second boosting condition; current gating means for detecting the presence and absence of normal d-c operating current in each conductor of the subscriber line; voltage detecting means for causing the switching means to establish the first boosting path when the current gating Means detects the flow of normal d-c operating current from the subscriber terminal to the corresponding office terminal in one conductor of the subscriber line and normal d-c operating voltage is detected on the same conductor, for causing the switching means to establish the second boosting path when the current from the subscriber terminal to the corresponding office terminal gating means detects normal d-c operating current in another conductor of the subscriber line and normal d-c operating voltage is detected on the same conductor, and for causing the switching means to establish the non-boosting path when the voltage on both conductors of the subscriber line is substantially less than the normal d-c operating voltage thereof or when the current gating means fails to detect normal d-c operating current in either conductor of the subscriber line; and means for connecting the voltage detecting means and the current gating means to each conductor of the subscriber line.

Claim 3

A voltage booster circuit as set forth in claim 1 wherein the voltage detecting means is connected to the conductors of the subscriber line through the current gating means.

Claim 4

A voltage booster circuit as set forth in claim 1 wherein the current gating means includes first and second current gates connected in series with respective conductors of the subscriber line and wherein each current gate establishes a current threshold which is below the normal d-c operating current of the respective conductor and which is above the test current applied to the respective conductor during the high voltage-low current testing of that conductor.

Claim 5

A voltage booster circuit as set forth in claim 3 wherein the first current gate is connected between the first office terminal and the first subscriber terminal to sense the direction of current flow therebetween and the second current gate is connected between the second office terminal and the second subscriber terminal to sense the direction of current flow therebetween.

Claim 6

A voltage booster circuit as set forth in claim 4 including current time-delay means for causing the current gates to respond relatively slowly to changes in the current flow in the conductors of the subscriber line.

Claim 7

A voltage booster circuit as set forth in claim 5 including reversing means for overriding the current time-delay means during d-c polarity reversals at the office terminals.

Claim 8

A voltage booster circuit as set forth in claim 1 wherein the voltage detecting means includes first and second voltage detectors connected between ground and respective office terminals and wherein each voltage detector establishes a voltage threshold which is below the normal d-c operating voltage at the respective office terminal and which is above the voltage at the respective office terminal during the low voltage-high current testing of the conductor associated with that office terminal.

Claim 9

A voltage booster circuit as set forth in claim 7 wherein the first voltage detector is connected between ground and the first office terminal to sense the polarity of the voltage at the first office terminal and the second voltage detector is connected between ground and the second office terminal to sense the polarity of the voltage at the second office terminal.

Claim 10

A voltage booster circuit as set forth in claim 8 including voltage time-delay means for causing the voltage detectors to respond relatively slowly to changes in the magnitude of voltage on the office terminals during ringing.

Claim 11

A voltage booster circuit as set forth in claim 9 including means for overriding the voltage time-delay means during d-c polarity reversals at the office terminals.

Claim 12

A voltage booster circuit as set forth in claim 1 including pulse correcting means for causing the switching means to establish a non-boosting condition during dial pulse interruptions and means for connecting the pulse correcting means to one office terminal and to the voltage detecting means.

Claim 13

A voltage booster circUit as set forth in claim 11 including ringing disabling means for causing the switching means to establish a boosting condition, during ringing, in spite of the presence of the pulse correcting means, and means for connecting the ringing disabling means to one of the office terminals and to the voltage detecting means.

Claim 14

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; boost voltage supply means for increasing the magnitude of direct current flow in the subscriber line; a first current gate connected between the first office terminal and the first subscriber terminal, the first current gate having a first state when the current flowing between the first subscriber terminal and the first office terminal is substantially less than the normal d-c operating current and having a second state when the current flow from the first subscriber terminal to the first office terminal is approximately equal to the normal d-c operating current; a second current gate connected between the second office terminal and the second subscriber terminal, the second current gate having a first state when the current flowing between the second subscriber terminal and the second office terminal is substantially less than the normal d-c operating current and having a second state when the current flow from the second subscriber terminal to the second office terminal is approximately equal to the normal d-c operating current; a first d-c voltage detector connected between ground and the first office terminal, the first voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is approximately equal to the normal d-c operating voltage; a second d-c voltage detector connected between ground and the second office terminal, the second voltage detector having a first state when the voltage appearing on the second office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage appearing on the second office terminal is approximately equal to the normal d-c operating voltage; switching means for establishing a first boosting path between one of the office terminals and the corresponding subscriber terminal, through the boost voltage supply means, when the first current gate and the first voltage detector are in their second states, for establishing a second boosting path between one of the office terminals and the corresponding subscriber terminal, through the boost voltage supply means, when the second current gate and the second voltage detector are in the second states, and for establishing a non-boosting path between the office and subscriber terminals when both voltage detectors are in their first states or when both current gates are in their first states.

Claim 15

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; boost voltage supply means for increasing the magnitude of direct current flow in the subscriber line; a first current gate connected between the first office terminal and the first subscriber terminal, the first current gate having a first state when the current flowing between the first subscriber terminal and the first office terminal is substantially less than the normal d-c operating current and having a second state when the current flow from the first subscriber terminal to the first office terminal is approximately equal to the normal d-c operating current; a second current gate connected between the second office terminal and the second subscriber terminal, the second current gate having a first state when the current flowing between the second subscriber terminal and the second office terminal is substantially less than the normal d-c operating current and having a second state when the current flow from the second subscriber terminal to the second office terminal is approximately equal to the normal d-c operating current; a first d-c voltage detector connected between ground and the first office terminal, the first voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is approximately equal to the normal d-c operating voltage; a second d-c voltage detector connected between ground and the second office terminal, the second voltage detector having a first state when the voltage appearing on the second office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage appearing on the second office terminal is approximately equal to the normal d-c operating voltage; switching means for establishing a first boosting path between one of the office terminals and the corresponding subscriber terminal, through the boost voltage supply means, when the first current gate and the first voltage detector are in their second states, for establishing a second boosting path between one of the office terminals and the corresponding subscriber terminal, through the boost voltage supply means, when the second current gate and the second voltage detector are in the second states, and for establishing a non-boosting path between the office and subscriber terminals when both voltage detectors are in their first states or when both current gates are in their first states.

Claim 16

A voltage booster circuit as set forth in claim 13 wherein the first voltage detector is connected to the first office terminal through the first current gate and wherein the second voltage detector is connected to the second office terminal through the second current gate.

Claim 17

A voltage booster circuit as set forth in claim 13 including pulse correcting means for causing the switching means to establish a non-boosting condition during dial pulse interruptions.

Claim 18

A voltage booster circuit as set forth in claim 15 including ringing disabling means for causing the switching means to establish one of the boosting paths, during ringing, in spite of the presence of the pulse correcting means.

Claim 19

A voltage booster circuit as set forth in claim 13 wherein: the first voltage detector includes voltage time-delay means for causing the first voltage detector to respond relatively slowly to changes in the voltage on thE first office terminal during ringing; the second voltage detector includes voltage time-delay means for causing the second voltage detector to respond relatively slowly to changes in the voltage on the second office terminal; the first current gate includes current time-delay means for causing the first current gate to respond relatively slowly to changes in the current between the first office terminal and the first subscriber terminal; and the second current gate includes current time-delay means for causing the second current gate to respond relatively slowly to changes in the current between the second office terminal and the second subscriber terminal.

Claim 20

A voltage booster circuit as set forth in claim 17 including reversing means for overriding the time-delay means of one of the voltage detectors and the associated current gate during d-c polarity reversals at the office terminals.

Claim 21

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; boost voltage supply means for increasing the magnitude of d-c current flow in the subscriber line; a first current gate having a first state when current flows between the first subscriber terminal and the first office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the first subscriber terminal to the first office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the first current gate between the first office terminal and the first subscriber terminal; a second current gate having a first state when current flows between the second subscriber terminal and the second office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the second subscriber terminal to the second office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the second current gate between the second office terminal and the second subscriber terminal; a first d-c voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is negative and has a value approximately equal to the normal d-c operating voltage; means for connecting the first voltage detector between ground and the first office terminal; a second d-c voltage detector having a first state when the voltage appearing on the second office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage appearing on the second office terminal is negative and has a value approximately equal to the normal d-c operating voltage; means for connecting the second voltage detector between ground and the second office terminal; first switching means for establishing a first boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means when the first current gate and the first voltage detector are in their second states and for establishing a non-boosting path between those terminals when the first voltage detector is in its first state or when the first current gate is in its first state; and second switching means for establishing a second boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means when the second current gate and the second voltage detector are in their second states and for establishing a non-boosting path between those terminals when the second voltage detector is in its first state or when the second current gate in in its first state.

Claim 22

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; boost voltage supply means for increasing the magnitude of d-c current flow in the subscriber line; a first current gate having a first state when current flows between the first subscriber terminal and the first office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the first subscriber terminal to the first office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the first current gate between the first office terminal and the first subscriber terminal; a second current gate having a first state when current flows between the second subscriber terminal and the second office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the second subscriber terminal to the second office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the second current gate between the second office terminal and the second subscriber terminal; a first d-c voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is negative and has a value approximately equal to the normal d-c operating voltage; means for connecting the first voltage detector between ground and the first office terminal; a second d-c voltage detector having a first state when the voltage appearing on the second office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage appearing on the second office terminal is negative and has a value approximately equal to the normal d-c operating voltage; means for connecting the second voltage detector between ground and the second office terminal; first switching means for establishing a first boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means when the first current gate and the first voltage detector are in their second states and for establishing a non-boosting path between those terminals when the first voltage detector is in its first state or when the first current gate is in its first state; and second switching means for establishing a second boosting path between one of the office terminals and the corresponding subscriber terminal through the boost voltage supply means when the second current gate and the second voltage detector are in their second states and for establishing a non-boosting path between those terminals when the second voltage detector is in its first state or when the second current gate in in its first state.

Claim 23

A voltage Booster circuit as set forth in claim 19 wherein the first voltage detector is connected to the first office terminal through a first current gate and wherein the second voltage detector is connected to the second office terminal through the second current gate.

Claim 24

A voltage booster circuit as set forth in claim 19 including pulse correcting means for causing the switching means to establish a non-boosting condition during dial pulse interruptions and means for connecting the pulse correcting means to the first offic terminal and to the second voltage detector.

Claim 25

A voltage booster circuit as set forth in claim 19 including ringing disabling means for causing the switching means to establish one of the boosting paths, during ringing, and means for connecting the ringing disabling means to the first office terminal and to the second voltage detector.

Claim 26

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; a first and a second boost voltage supply; a first current gate having a first state when current flows between the first subscriber terminal and the first office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the first subscriber terminal to the first office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the first current gate between the first office terminal and the first subscriber terminal; a second current gate having a first state when current flows between the second subscriber terminal and the second office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the second subscriber terminal to the second office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the second current gate between the second office terminal and the second subscriber terminal; a first d-c voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is negative and has a value approximately equal to the normal d-c operating voltage; first switching means for inserting the first boost voltage supply between the first office and first subscriber terminals when the first current gate and the first voltage detector are in their second states and for metallically connecting the first office and first subscriber terminals when either the first current gate or first voltage detector is in its first state; means for connecting the first switching means to the first voltage detector and to the first office and first subscriber terminals; second switching means for inserting the second boost voltage supply between the second office and second subscriber terminals when the second current gate and the second voltage detector are in their second states and for metallically connecting the second office and second subscriber terminals when either the second current gate or the second voltage detector is in its first state; means for connecting the second switching means to the second voltage detector and to the second office and second subscriber terminals.

Claim 27

A voltage booster circuit for telephone systems which comprises: first and second office terminals for connection to a central office; first and second subscriber terminals for connection to a subscriber line; a first and a second boost voltage supply; a first current gate having a first state when current flows between the first subscriber terminal and the first office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the first subscriber terminal to the first office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the first current gate between the first office terminal and the first subscriber terminal; a second current gate having a first state when current flows between the second subscriber terminal and the second office terminal and has a value substantially less than the normal d-c operating current and having a second state when current flows from the second subscriber terminal to the second office terminal and has a value approximately equal to the normal d-c operating current; means for connecting the second current gate between the second office terminal and the second subscriber terminal; a first d-c voltage detector having a first state when the voltage appearing on the first office terminal is substantially less than the normal d-c operating voltage and having a second state when the voltage on the first office terminal is negative and has a value approximately equal to the normal d-c operating voltage; first switching means for inserting the first boost voltage supply between the first office and first subscriber terminals when the first current gate and the first voltage detector are in their second states and for metallically connecting the first office and first subscriber terminals when either the first current gate or first voltage detector is in its first state; means for connecting the first switching means to the first voltage detector and to the first office and first subscriber terminals; second switching means for inserting the second boost voltage supply between the second office and second subscriber terminals when the second current gate and the second voltage detector are in their second states and for metallically connecting the second office and second subscriber terminals when either the second current gate or the second voltage detector is in its first state; means for connecting the second switching means to the second voltage detector and to the second office and second subscriber terminals.

Claim 28

A voltage booster circuit as set forth in claim 23 including pulse correcting means for causing the first and second switching means to insert the first and second boost supplies between the office and subscriber terminals, in cancelling relationship to one another, during dial pulse interruptions.

Claim 29

A voltage booster circuit as set forth in claim 24 including ringing disabling means for overriding the pulse correcting means during ringing to terminate the cancelling relationship and thereby asSure the provision of a continuous d-c boost during ringing.

Claim 30

A voltage booster circuit as set forth in claim 25 including voltage time-delay means for causing the voltage detectors to respond relatively slowly to changes in the voltages at the respective office terminals.

Claim 31

A voltage booster circuit as set forth in claim 26 including a reversing network for overriding the time-delay means of at least one of the voltage detectors during d-c reversals at the office terminals.

Claim 32

A voltage booster circuit as set forth in claim 23 including voltage time-delay means for causing the voltage detectors to respond relatively slowly to changes in the voltages at the respective terminals.

Claim 33

A voltage booster circuit as set forth in claim 28 including a reversing network for overriding the time-delay means of at least one of the voltage detectors during d-c reversals at the office terminals.