AC/DC-monitoring telephone line ringing voltage detector

Claim 2

Apparatus for detecting at the location of a subscriber''s telephone set the presence of AC ringing voltage in a telephone line connected to the set, where the line includes conductors that will present such voltage with placement of a call to the set, as well as conductors wherein DC voltage of two different levels may exist at different times depending upon the on-hook or off-hook condition of the set, such DC voltage being larger than a certain voltage with the set in an on-hook condition, and less than said certain voltage with the set in an off-hook condition, said apparatus comprising an AC monitor circuit adapted for connection to those conductors in a telephone line which present AC ringing voltage, a DC monitor circuit adapted for connection to those conductors in a telephone line wherein DC voltage indicative of the on-hook/off-hook condition of a connected telephone set exists, a DC voltage level determiner operatively connected to said DC monitor circuit for determining whether the magnitude of DC voltage presented to the DC monitor circuit is above or below said certain voltage, a conjunction indicator operatively connected both to said AC monitor circuit and to said DC level determiner for indicating when, simultaneously, AC voltage appears at said AC, and said level determiner determines that voltage applied to said DC monitor circuit exceeds said certain voltage, and output means operatively connected to said conjunction determiner for producing an output signal reflecting the presence of ringing voltage in a line following indicating by said conjunction indicator of simultaneity of the type mentioned.

Claim 3

Apparatus for detecting at the location of a subscriber''s telephone set the presence of AC ringing voltage in a telephone line connected to the set, where the line includes conductors that will present such voltage with placement of a call to the set, as well as conductors wherein DC voltage of two different levels may exist at different times depending upon the on-hook or off-hook condition of the set, such DC voltage being larger than a certain voltage with the set in an on-hook condition, and less than said certain voltage with the set in an off-hook condition, said apparatus comprising a DC monitor circuit adapted for connection to those conductors in a telephone line wherein DC voltage indicative of the on-hook/off-hook condition of a connected telephone set exists, a level determining circuit operatively connected to said DC monitor circuit for producing an indication of one type with voltage at said monitor circuit above said certain voltAge, and an indication of another type with voltage at the DC monitor below said certain voltage, an AC monitor circuit adapted for connection to those conductors in a telephone line which present AC ringing voltage, a simultaneity circuit operatively connected both to said level determining circuit and to said AC monitor circuit for indicating the simultaneous existence of an indication of said one type by said level determining circuit along with AC voltage applied to said AC monitor circuit, and output means operatively connected to said simultaneity circuit for producing an output signal reflecting the presence of ringing voltage in a line following a simultaneity indication by the simultaneity circuit.

Claim 4

Apparatus for detecting at the location of a subscriber''s telephone set the presence of AC ringing voltage in a telephone line connected to the set, where the line includes conductors that will present such voltage with placement of a call to the set, as well as conductors wherein DC voltage of two different levels may exist at different times depending upon the on-hook or off-hook condition of the set, such DC voltage being larger than a certain voltage with the set in an on-hook condition, and less than said certain voltage with the set in an off-hook condition, said apparatus comprising a DC monitor circuit adapted for connection to those conductors in a telephone line wherein DC voltage indicative of the on-hook/off-hook condition of a connected telephone set exists, a level determining circuit operatively connected to said DC monitor circuit for producing an indication of one type with voltage at said monitor circuit above said certain voltAge, and an indication of another type with voltage at the DC monitor below said certain voltage, an AC monitor circuit adapted for connection to those conductors in a telephone line which present AC ringing voltage, a simultaneity circuit operatively connected both to said level determining circuit and to said AC monitor circuit for indicating the simultaneous existence of an indication of said one type by said level determining circuit along with AC voltage applied to said AC monitor circuit, and output means operatively connected to said simultaneity circuit for producing an output signal reflecting the presence of ringing voltage in a line following a simultaneity indication by the simultaneity circuit.

Claim 5

Apparatus for detecting at the location of a subscriber''s telephone set the presence of AC ringing voltage in a telephone line connected to the set, where the line includes conductors that will present such voltage with placement of a call to the set, as well as conductors wherein DC voltage of two different levels may exist at different times depending upon the on-hook or off-hook condition of the set, such DC voltage being larger than a certain voltage with the set in an on-hook condition, and less than said certain voltage with the set in an off-hook condition, said apparatus comprising input means adapted for connection to the conductors in a telephone line, a DC voltage monitor operatively connected to said input means for producing an indication of a certain type with the level of DC voltage in those telephone line conductors wherein the magnitude of DC voltage is indicative of the on-hook/off-hook condition of a connected telephone set above said certain voltage, an AC voltage monitor operatively connected to said input means for producing an indication when AC exists in the telephone line, and a simultaneity circuit operatively connected to said DC and AC voltage monitors for indicating the simultaneous occurrence of an indication of said certain type from the former, and of an indication by the latter that AC exists in the telephone line.

Claim 6

Apparatus for detecting at the location of a subscriber''s telephone set the presence of AC ringing voltage in a telephone line connected to the set, where the line includes conductors that will present such voltage with placement of a call to the set, as well as conductors wherein DC voltage of two different levels may exist at different times depending upon the on-hook or off-hook condition of the set, such DC voltage being larger than a certain voltage with the set in an on-hook condition, and less than said certain voltage with the set in an off-hook condition, said apparatus comprising input means adapted for connection to the conductors in a telephone line, a DC voltage monitor operatively connected to said input means for producing an indication of a certain type with the level of DC voltage in those telephone line conductors wherein the magnitude of DC voltage is indicative of the on-hook/off-hook condition of a connected telephone set above said certain voltage, an AC voltage monitor operatively connected to said input means for producing an indication when AC exists in the telephone line, and a simultaneity circuit operatively connected to said DC and AC voltage monitors for indicating the simultaneous occurrence of an indication of said certain type from the former, and of an indication by the latter that AC exists in the telephone line.