Telephonic communications – Diagnostic testing – malfunction indication – or electrical... – Of trunk or long line
Reexamination Certificate
2000-03-07
2001-08-28
Tieu, Binh (Department: 2643)
Telephonic communications
Diagnostic testing, malfunction indication, or electrical...
Of trunk or long line
C379S001030, C379S012000, C379S016000, C379S021000, C379S022000, C379S022020, C379S022070, C379S027010, C379S029010, C370S248000, C370S251000
Reexamination Certificate
active
06282265
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to telecommunication systems, and is particularly directed to a new and improved two-ended, line-driving and receiving/tone signal analysis system for identifying opposite ends of a telephone line (tip/ring) pair, without interfering with analog signaling or digital data traffic that may be carried on the line under test.
BACKGROUND OF THE INVENTION
In the face of the increasing demand for a variety of high speed digital data communication services (such as, but not limited to HDSL, ADSL and SDSL), telecommunication service providers are continually seeking ways to optimize utilization of their very substantial existing copper plant, which was originally installed for the purpose of carrying nothing more than conventional analog (plain old telephone service or POTS) signals. Associated with this expanded utilization of the telephone line pairs is the need to verify end-to-end connections of a respective wireline pair. It is essential that the technique employed be non-intrusive to the line under test, which could be an unused spare, an idle line connected to subscriber equipment, or a busy line (namely, one carrying analog and/or digital signals). This non-intrusive requirement is especially paramount if the line is carrying digital data traffic.
SUMMARY OF THE INVENTION
In accordance with the present invention, the above-described line connection verification problem is successfully accomplished by a new and improved two-ended, line-driving and receiving/tone signal analysis system that is operative to apply a low-distortion, low-amplitude sine wave test signal to one end of a cable pair under test and to monitor the response of a remote end cable pair. In accordance with a non-limiting but preferred embodiment, the fundamental test signal frequency may be on the order of 110 Hz. This frequency was chosen as the test frequency, since it avoids domestic and foreign AC power signal frequencies and is spectrally equidistant from their harmonics (e.g., 100 Hz and 120 Hz, respectively). It also avoids ringing frequencies for POTS lines, and remains safely below the 350 Hz lower limit of POTS and other telephone line system services.
For this purpose, a pair of embedded processor-controlled test signal interface units, termed two (2)-end-verify driver/receiver units (or 2EV-DRUs), are coupled to tip and ring access locations of local and remote ends of what is hopefully, but is not necessarily, the same wire pair of a cable plant distribution system. Under commands supplied by an associated external system controller, such as a laptop computer or personal digital assistant, a respective 2EV-DRU may operate in either send/drive or receiver mode. In drive mode, the 2EV-DRU is operative to generate the (110 Hz sine wave) signal, while in receiver mode, the 2EV-DRU looks for the test signal and a pair of associated nearby frequencies slightly higher and lower than the 110 Hz sine signal on the pair to which it is connected, and it reports its detection status to its external system controller.
Each 2EV-DRU contains a test signal drive section, a test signal receive section, and a control processor (or micro-controller). The test signal drive section includes circuitry which operates under commands from the control processor to controllably source an amplitude-scaled (110 Hz) test signal to the tip-ring leads of the pair-under-test, when that 2EV-DRU is operating in drive mode. The drive mode 2EV-DRU adjusts the amplitude of the (110 Hz) test signal to a step-up transformer to adjust the current through high value resistors to the value necessary to achieve a prescribed voltage level across the tip and ring ports. Tip-ring signal feedback control is carried out using the test signal receive section to monitor voltage applied to the tip and ring ports.
In the receive section, the tip and ring ports are AC-coupled to a differential summing amplifier, the output of which contains AC components due to voice, modem signals, test signal, etc. The received and buffered signal is filtered in a bandpass filter, which attenuates most voice signals, data signaling, and power line interference signals. To compensate for potential interference, digital signal processing is executed in the control processor to extract the actual (110 Hz) test signal from the filtered signal. The bandpass filtered signal is amplified and digitized for application to the control processor.
When the 2EV-DRU is operating in drive mode, its micro-controller uses the test signal receive section to measure the 110 Hz test signal present between the tip and ring ports for controlling the magnitude of the 110 Hz signal applied by the test signal drive section to the tip and ring leads of the line under test. A complete measurement of the received signal level constitutes a Fourier correlation operation cycle (FCOC). When the 2EV-DRU is placed in drive mode, an FCOC is executed to measure the amount of signal applied to the tip and ring ports. In receiver mode, the control processor effectively prevents the test signal drive section from applying a 110 Hz sine wave test signal to the tip and ring ports. It then executes an FCOC, measures the level of the 110 Hz component, as well as that of two other ‘spectrally nearby’ frequency components (slightly is higher at 112 Hz and slightly lower at 108 Hz), and outputs a measurement report to the associate external system controller.
The values calculated for each of the monitored frequencies are compared. If the magnitude of the Fourier component test signal at the fundamental test frequency (110 Hz) is more than a prescribed differential greater than the magnitudes of the two ‘nearby’ frequencies, it is inferred that the receiver mode 2EV-DRU is connected to the same wire pair as the driver mode 2EV-DRU, indicating that the two ends of the same wire pair under test have been identified. If not, it is inferred that the receiver mode 2EV-DRU is connected to a wire pair other than the selected wire pair under test to which the driver mode 2EV-DRU is currently connected.
The external controller associated with the driver mode 2EV-DRU then instructs the external controller associated with the receiver mode 2EV-DRU to cause an associated tip/ring pair access device, such as a portable test head to which a multi-terminal connector at respective terminating end of the cable plant is connected, to switch the receiver mode 2EV-DRU to a different wire pair, so that the above-described test may be carried out for the new pair. This process may be repeated, as necessary, for additional wire pairs until the remote ends of the tip and ring pair of the selected line under test have been identified.
REFERENCES:
patent: 5355405 (1994-10-01), Bernstein
patent: 5799060 (1998-08-01), Kennedy et al.
patent: 5857011 (1999-01-01), Kennedy et al.
patent: 6002746 (1999-12-01), Mulcahy et al.
patent: 6091713 (2000-07-01), Lechleider et al.
Gold Kenneth S.
Humphrey Glen H.
Kennedy Michael F.
Lowell Alan B.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Harris Corporation
Tieu Binh
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