Circuitry for interfacing telecommunications equipment to a communication channel
First Claim
1. A circuit for measuring the resistance of a resistor indicative of the length of local loop in a local loop, said circuit comprising:
- a transformer with a primary winding for connection to said resistor,a voltage divider circuit in which the secondary winding of said transformer is one impedance,an AC signal generator for applying an AC potential across said voltage divider,a measuring circuit for measuring a potential in said voltage divider circuit representative of the resistance of said resistor.
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Accused Products
Abstract
Measuring the programming resistor in a data jack by placing the resistor in an AC voltage divider circuit via a transformer. An AC voltage (preferably generated by the modem'"'"'s own transmitter circuitry) is applied to the voltage divider circuit, and an AC voltage measurement (preferably made by the modem'"'"'s A/D converter) provides the resistance of the programming resistor. Matching the low-pass filter impedance characteristic of a local loop with a network having a matching low-pass filter characteristic, while also compensating the received signal with a compensation network having a high-pass filter characteristic, to reduce the frequency dependent gain effects caused by the matching network and/or the local loop.
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Citations
16 Claims
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1. A circuit for measuring the resistance of a resistor indicative of the length of local loop in a local loop, said circuit comprising:
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a transformer with a primary winding for connection to said resistor, a voltage divider circuit in which the secondary winding of said transformer is one impedance, an AC signal generator for applying an AC potential across said voltage divider, a measuring circuit for measuring a potential in said voltage divider circuit representative of the resistance of said resistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A circuit for detecting the status of a switch indicative of the status of an exclusion key telephone, said circuit comprising:
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a transformer with a primary winding for connection to said switch, a voltage divider circuit in which the secondary winding of said transformer is one impedance, an AC signal generator for applying an AC potential across said voltage divider, a measuring circuit for measuring a potential in said voltage divider circuit representative of the status of said switch. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification