Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Testing of subscriber loop or terminal
Reexamination Certificate
1999-12-22
2001-09-04
Tieu, Binh K. (Department: 2643)
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Testing of subscriber loop or terminal
C379S001040, C379S021000, C379S030000, C379S032010
Reexamination Certificate
active
06285744
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a telephony test system and, more particularly, a telephony test system having an adjustable output impedance.
2. Background Art
The telephone industry has evolved from providing “plain old telephone service” (POTS) to a communications industry providing a plurality of digital and analog communications mediums and protocols over the embedded telephone network. Telephone operating companies utilize local test systems to verify the operation of the embedded phone lines and/or telephone equipment connected to the telephone lines. These test systems typically include test devices deployed throughout the telephone network to test the telephone line and the equipment connected thereto, e.g., a subscriber's telephone.
Heretofore, the introduction of a new communication medium, telephony protocol and/or telephony equipment resulted in a unique test device being developed and deployed for testing the same. Hence, test devices evolved in a piecemeal manner such that, over time, each local test system potentially contained a significant number of expensive and inflexible test devices. As technology changes, the test requirements may also change and, therefore, many of the embedded test devices or test systems may not be capable of adapting or being adapted to a new test specification.
It is therefore an object of the present invention to provide a flexible and adaptable telephony test system to test all current telephone services and equipment, as well as many future or planned services or equipment. It is an object of the present invention to provide a test system having a programmably adjustable output impedance. It is an object of the present invention to provide a telephony test system adapted to test telephone circuits over a wide range of frequencies. These and other objects of the invention will become apparent to one of ordinary skill in the art upon reading the following description.
SUMMARY OF THE INVENTION
Accordingly, we have invented a testing apparatus for testing a telephone circuit. The testing apparatus includes a controller and a driver circuit having an input, an output and a control input adapted to receive an impedance adjust signal. A programmable gate array (PGA) connected between the controller and the driver circuit is adapted to receive program commands from the controller. A digital-to-analog converter (DAC) is connected between the PGA and the input of the driver circuit. The DAC generates an output voltage corresponding to data received by the DAC from the PGA. An analog-to-digital converter (ADC) is connected between the output of the driver circuit and the PGA. The ADC generates to the PGA data corresponding to a signal received at an input of the ADC. The signal received at the input of the ADC corresponds to a response of the telephone circuit to a voltage impressed thereon. In response to being programmed by the controller, the PGA controls the operation of the DAC and the ADC such that the ADC samples signals received at the input thereof in synchronization with the DAC generating signals to the driver circuit. The driver circuit generates on its output a voltage corresponding to the output voltage of the DAC received at the input of the driver circuit and the impedance adjust signal received at the control input. The output voltage generated by the driver circuit is impressed on the telephone circuit. The driver circuit adapts its output impedance as a function of the impedance adjust signal received at the control input.
The testing apparatus can include a digital signal processor (DSP) connected to the controller and PGA. The PGA provides to the DSP data corresponding to the data received by the PGA from the ADC. The DSP mathematically manipulates the data provided thereto from the PGA and reports the results of the mathematical manipulation to the controller. The PGA can provide a plurality of data to the DSP. The mathematical manipulation of data by the DSP can include performing a Fourier Transform on the plurality of data to obtain therefrom an indication of an amplitude and/or phase response of the telephone circuit to the output voltage generated to the telephone circuit by the driver circuit.
The driver circuit can include a first differential amplifier having an inverting input and a noninverting input. The noninverting input is adapted to receive a signal corresponding to a signal output by the DAC. The first differential amplifier has an output connected to an input of a multiplying DAC. The multiplying DAC has the control input which is adapted to receive the impedance adjust signal. A second differential amplifier has an inverting input and a noninverting input. The inverting input of the second differential amplifier is connected to the output of the multiplying DAC. A voltage amplifier has an input connected to an output of the second differential amplifier. A programmable resistor has an input connected to the output of the voltage amplifier, an output connected to the telephone circuit and a control input adapted to receive a resistance adjust signal. A programmable gain has an input connected to the telephone circuit and a control input adapted to receive a gain adjust signal. The ADC, the inverting input of the first differential amplifier and the noninverting input of the second differential amplifier are adapted to receive a signal corresponding to a signal generated at an output of the programmable gain. The programmable gain can be a resistor divider or an adjustable gain DAC. The programmable resistor can include a plurality of resistors connected in parallel between the voltage amplifier and the telephone circuit. Each resistor has a switch connected in series therewith. The resistance adjust signal received at the control input of the programmable resistor controls each of the plurality of switches to connect at least one of the plurality of switches between the high voltage amplifier and the telephone circuit.
The testing apparatus can include a wideband/TDR circuit having a second DAC that has an input connected to a bus which is connected between the controller and PGA and a second ADC having an output connected to the bus. The wideband/TDR circuit includes a splitter/combiner connectable between the DAC and the telephone circuit and between the ADC and the telephone circuit. A switch can be connected between the splitter/combiner and the telephone circuit and between the driver circuit and the telephone circuit. The switch has a control input adapted to receive a switch configure signal. In response to receiving the switch configure signal, the switch selectively connects the telephone circuit to the splitter/combiner or the driver circuit.
We have also invented a telephony test system for testing, a telephone circuit having a tip and a ring. The telephony test system includes a programmable gate array having a plurality of logic gates and a plurality of input/output pins. The logic gates are programmably configurable in an array configuration that is programmably connectable to the plurality of input/output pins of the PGA in a desired configuration. A controller is connected to the PGA via a bus. A DAC has an input connected to an output of the PGA. An ADC has an output connected to an input of the PGA. A first driver circuit has a first input connectable to an output of the DAC, a first output connectable to an input of the ADC, a second output connected to one of the tip and the ring and a second input connectable to the one of the tip and the ring. The first driver circuit also has a control input adapted to receive an impedance adjust signal. The controller causes the PGA to configure the plurality of logic gates in a desired array configuration, and causes the PGA to connect the desired array configuration and the plurality of input/output pins in a desired manner. As a function of the controller programming thereof, the PGA controls the DAC to generate an output voltage to the first driver circuit and controls the PGA to s
Bair, Jr. Richard A.
Hiener, III Louis W.
Kiko Frederick J.
Manuel, II Leo W.
Mintzer Lester
Tieu Binh K.
Tollgrade Communications, Inc.
Webb Ziesenheim & Logsdon Orkin & Hanson, P.C.
LandOfFree
Telephony test system with adjustable output impedance does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Telephony test system with adjustable output impedance, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Telephony test system with adjustable output impedance will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2476697