Signaling method for invoking a test mode in a network interface unit

• US 6,278,769 B1
• Filed: 11/03/1999
• Issued: 08/21/2001
• Est. Priority Date: 11/25/1998
• Status: Expired due to Term

• Current Assignee: Netgear Holdings Ltd. (NETGEAR, Inc.), NETGEAR, Inc.
• Original Assignee: Westell Technologies Incorporated
• Inventors: Bella, Gregory L.
• Primary Examiner(s): Tieu, Binh
• Application Number:
  US09/433,011
• Time in Patent Office: 657 Days
• Field of Search: 379/1, 379/2, 379/5, 379/6, 379/9, 379/10, 379/12, 379/15, 379/27, 379/29
• US Class Current: 379/29.11
• CPC Class Codes: H04M 1/24 Arrangements for testing
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data
• CPC Class Codes: H04M 3/2209 for lines also used for data transmission
• CPC Class Codes: H04M 3/301 Circuit arrangements at the subscriber's side of the line

Abstract

A network interface device intended to be placed approximate to the customers equipment and remote from a central office of a telephone company (“TELCO”). The purpose of the network interface device is to allow the twisted pair transmission line between the central office and the customer'"'"'s port to be selectively switched from a normal monitoring mode into a test mode. The test mode has two phases. In the first phase, the NIU transmits a signal back to the central office. This allows the central office to determine whether there are any problems with the transmission line, the potential bandwidth for the transmission line and related parameters concerning the efficacy and suitability of the transmission line for a variety of communication services. In the second phase, which is entered into upon completion of the first phase, the customer-end ADSL low pass filter is bypassed so that the central office can test the customer'"'"'s POTS equipment.

Claims

1. A method of invoking a test mode in telephone equipment connected to a central office via a twisted pair transmission line across which said central office normally maintains a predetermined voltage, the method comprising:

deliberately removing said predetermined voltage across said twisted pair transmission line for a first predetermined period of time; and

re-applying said predetermined voltage upon conclusion of said first predetermined period of time, to thereby invoke a test mode without requiring a separate trigger signal from the central office.

2. The method of claim 1, wherein the step of removing said predetermined voltage comprises shorting said twisted pair at the central office.

3. The method of claim 1, wherein the step of removing said predetermined voltage comprises forming an open circuit across said twisted pair at the central office.

4. A method for testing telephone equipment connected to a central office via a twisted pair transmission line along which said central office normally maintains a predetermined voltage, the method comprising:

removing said predetermined voltage along a twisted pair transmission line for a first predetermined period of time;

re-applying said predetermined voltage upon conclusion of said first predetermined period of time, to thereby invoke a test mode without requiring a separate trigger signal from the central office;

sending a first test signal via the twisted pair transmission line back to the central office for a predetermined second period of time; and

automatically bypassing a first electronic component connected in series with a second electronic component, for a predetermined third period of time to thereby test said second electronic component while isolated from said first electronic component.

5. The method of claim 4, wherein the step of removing said predetermined voltage comprises shorting said twisted pair at the central office.

6. The method of claim 4, wherein the step of removing said predetermined voltage comprises forming an open circuit across said twisted pair at the central office.

7. A network interface device operable in one of a normal monitor mode and a test mode having a first test phase and a second test phase, said network interface device configured to interface a twisted pair transmission line to customer equipment in a communication system, said network interface device comprising:

a first port comprising first and second terminals establishing respective first and second voltage nodes;

first and second switches electrically connected to said first and second terminals, respectively;

a detector circuit connected in electrical parallel across said first and second voltage nodes and configured to detect a request signal, said request signal comprising a removal of an applied voltage for a predetermined period of time followed by a resumption of said voltage, said detector circuit being further configured to output a first control signal to said first and second switches upon detection of said request signal, to thereby place the device in the test mode;

a power supply circuit connected to said first port via said first and second switches, and arranged to output a DC supply voltage when the device is in the test mode, said power supply circuit being powered by a voltage applied across the first and second voltage nodes; and

a signal generator circuit coupled to said first port via said first and second switches, and configured to output a predetermined test signal to said first port for a predetermined first period of time, when the device is in a first phase of the test mode, said signal generator circuit being powered by said DC supply voltage from said power supply circuit; and

a bypass circuit configured to electrically isolate at least one electronic component connected which in series with a second electronic component during a second phase of the test mode, to thereby permit testing of said second component.