Apparatus and methods for generating an AC power signal for cable TV distribution systems
First Claim
1. In a cable TV distribution system comprising a distribution cable for carrying a cable TV signal, a plurality of line-extending amplifiers connected at intervals along the distribution cable for amplifying the cable TV signal, and at least one tap means connected to the distribution cable for coupling a drop cable to the distribution cable, a method of supplying power to the line-extending amplifiers comprising the steps of:
- a. generating an AC power signal having at least a positive half-cycle, where the positive half-cycle comprises a rising portion, a falling portion, and a central portion whose amplitude is maintained within a range centered about a predetermined value; and
b. so limiting the AC power signal within the rising portion that the AC power signal remains within a range inclusively defined by;
i. a first line segment extending between a first point at the beginning of the rising portion and a second point at the end of the rising portion, andii. a first curve segment of a first sinusoidal curve having the same period as the AC power signal, the first curve segment extending between the first and second points;
whereinc. the AC power signal is so generated that it further has a negative half-cycle, the negative half-cycle being related to the positive half-cycle in an inverted, mirror image manner.
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Accused Products
Abstract
A cable TV distribution system in which an AC power signal is generated according to the following steps: (a) generating an AC power signal having at least a positive half-cycle, where the positive half-cycle comprises a rising portion, a falling portion, and a central portion; and (b) limiting the slew rate of the AC power signal within the rising portion to a range of 30 V/ms and 50 V/ms inclusive. Preferably, the slew rate of the AC power signal within the falling portion is limited to the range of -30 V/ms and -50 V/ms inclusive. The AC power signal is preferably generated by a power supply comprising: (a) circuit that generates a first drive signal having a first portion comprising a series of pulses, a second portion comprising a series of pulses, and a third portion comprising a single pulse; (b) a drive circuit that generates a pulsed power signal the timing of which corresponds to the timing of the first drive signal; (c) a transformer; and (d) an output capacitor for integrating the output of the drive circuit.
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Citations
16 Claims
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1. In a cable TV distribution system comprising a distribution cable for carrying a cable TV signal, a plurality of line-extending amplifiers connected at intervals along the distribution cable for amplifying the cable TV signal, and at least one tap means connected to the distribution cable for coupling a drop cable to the distribution cable, a method of supplying power to the line-extending amplifiers comprising the steps of:
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a. generating an AC power signal having at least a positive half-cycle, where the positive half-cycle comprises a rising portion, a falling portion, and a central portion whose amplitude is maintained within a range centered about a predetermined value; and b. so limiting the AC power signal within the rising portion that the AC power signal remains within a range inclusively defined by; i. a first line segment extending between a first point at the beginning of the rising portion and a second point at the end of the rising portion, and ii. a first curve segment of a first sinusoidal curve having the same period as the AC power signal, the first curve segment extending between the first and second points;
whereinc. the AC power signal is so generated that it further has a negative half-cycle, the negative half-cycle being related to the positive half-cycle in an inverted, mirror image manner. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A power supply for generating an AC power signal that is supplied to line extending amplifiers in a cable TV distribution system, comprising:
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a. means for generating first and second drive signals each having a first portion comprising a series of pulses, a second portion comprising a series of pulses, and a third portion comprising a single pulse; b. a transformer having first and second windings, where a center tap is formed in the first transformer winding; c. a DC power source connected between the center tap and ground; d. a first switching transistor connected between one end of the first transformer winding and ground, where the first drive signal is applied to the first switching transistor to allow or prevent current flow from the DC power source through the transformer; e. a second switching transistor connected between another end of the first transformer winding and ground, where the second drive signal is applied to the second switching transistor to allow or prevent current flow from the DC power source through the transformer; and f. means for integrating the voltage across the transformer to obtain the AC power signal, where a first half-cycle of the AC power signal is generated by the first switching transistor and a second half-cycle of the AC power signal is generated by the second switching transistor. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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Specification