Inline power device detection

• US 7,061,142 B1
• Filed: 05/28/2003
• Issued: 06/13/2006
• Est. Priority Date: 05/28/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Marshall, Robert A.
• Primary Examiner(s): Feild, Lynn
• Assistant Examiner(s): Rutland-Wallis, Michael
• Application Number:
  US10/447,419
• Time in Patent Office: 1,112 Days
• Field of Search: 307/105, 307/106
• US Class Current: 307/106
• CPC Class Codes: H04B 3/46 Monitoring; Testing

Abstract

According to one embodiment of the invention, a method for providing power to a device coupled to a communications switch through a data line is provided. The method includes determining that the device includes a diode. The method also includes providing power to the device in response to the determination.

Claims

1. A method for providing power to a device coupled to a communications switch through a data line, comprising:

determining that the device includes a diode; and

in response to the determination, providing power to the device; and

wherein the diode is operable to cause a harmonic distortion of a signal, and wherein determining that the device includes a diode comprises;

transmitting a test signal at a particular frequency through the device; and

detecting a harmonic distortion of the test signal at a particular harmonic order of the frequency.

2. The method of claim 1, wherein the test signal is a sinusoidal signal.

3. The method of claim 1, wherein the particular harmonic order is a third harmonic order.

4. The method of claim 1, and further comprising:

reducing voltage of power provided to the device from an initial level to a level below the bias voltage level;

detecting a resulting change in a level of current;

determining that the resulting change in the level of current is non-linearly related to the change in voltage; and

in response, raising voltage of power back to the initial level.

5. The method of claim 1, wherein the power is at 48 volts.

6. The method of claim 1, and further comprising receiving the device at a jack coupled to the communications device, the jack operable to provide inline power.

7. A method for providing power to a device coupled to a communications switch through a data line, comprising:

determining that the device includes a diode;

in response to the determination, providing power to the device; and

further comprising;

reducing voltage of power provided to the device to a level below the bias voltage level;

detecting a resulting change in a level of current;

determining that the resulting change in the level of current is not non-linearly related to the change in voltage; and

in response, turning off the power to the device.

8. A system for providing inline power, comprising:

a circuit operable to detect a diode of the device;

a control switch coupled to the circuit the control switch operable to activate inline power from a communications switch in response to a detection of the diode; and

wherein the diode is operable to cause a harmonic distortion in a signal, and wherein the circuit is operable to detect the diode by transmitting a test signal to the diode and detecting the harmonic distortion in the signal.

9. The system of claim 8, wherein the circuit comprises:

a signal generator operable to transmit a test signal having a frequency through the device;

a current sensor coupled to the signal generator, the current sensor operable to measure a change in current of the test signal;

a bandpass filter coupled to the current sensor and operable to measure a voltage change resulting from the change in current measured by the current sensor;

a level detector coupled to the bandpass filter and operable to determine that the voltage change measured at the bandpass filter has exceed a predetermined threshold; and

wherein the control switch is coupled to the level detector, the control switch operable to activate inline power in response to a determination at the level detector that the measured voltage change has exceed the predetermined threshold.

10. The system of claim 9, wherein the current sensor is a resistor having approximately 45,000 ohms of resistance.

11. The system of claim 8, wherein the test signal is a sinusoidal signal.

12. The system of claim 8, wherein the circuit is further operable to:

reduce voltage of inline power provided to the device from an initial level to a level below a bias voltage level of the diode;

detect a resulting change in a level of current;

determine that the resulting change in the level of current is non-linearly related to the reduction of voltage; and

raise voltage of power back to the initial level.

13. The system of claim 8, wherein the circuit is further operable to:

reduce voltage of inline power provided to the device from an initial level to a level below a bias voltage level of the diode;

detect a resulting change in a level of current;

determine that the resulting change in the level of current is not non-linearly related to the change in voltage; and

deactivate the inline power in response to the determination.

14. The system of claim 8, and further comprising:

a communications switch having a jack, the communications switch operable to provide inline power through the jack, the jack operable to receive a data line of the device; and

wherein the circuit and the control switch are coupled to the communications switch.

15. A method for providing inline power, comprising:

receiving a communications device at a data connector, the communications device comprising a diode;

increasing voltage at the diode to a level sufficient to forward bias the diode;

determining that an increase in current resulting from increasing voltage is non-linearly related to the increase in voltage;

in response to the determination, providing power to the communications device through the data connector; and

further comprising;

decreasing voltage of power to a level sufficient to reverse bias the diode;

determining that a decrease in current resulting from decreasing voltage is not non-linearly related to the decrease in voltage; and

in response, turning off the power to the communications device.

16. A method for providing inline power, comprising:

receiving a communications device at a data connector, the communications device comprising a diode operable to initiate a harmonic distortion;

transmitting a signal having a frequency and an initial harmonic state to the diode through the data connector;

determining that a change of the initial harmonic state at a particular harmonic order of the frequency has exceeded a predetermined threshold; and

in response to the determination, providing power to the communications device through the data connector.

17. The method of claim 16, wherein the change of the initial harmonic state is a first change, and further comprising:

determining that a second change of the initial harmonic state at the particular harmonic order of the frequency has fallen below the predetermined threshold; and

in response, turning off the power to the communications device.

18. The method of claim 16, wherein the data connector is coupled to a communications switch, and wherein the signal is generated from the communications switch using a signal generator.

19. The method of claim 16, wherein the signal is a sinusoidal signal.

20. The method of claim 16, wherein the harmonic order is a third harmonic order.

21. The method of claim 16, wherein determining that a change of the initial harmonic state has exceeded a predetermined threshold comprises detecting a change of voltage associated with the initial harmonic state.

22. A method for providing inline power from a communications switch to a communications device through a data connector, the communications device comprising at least one diode, the method comprising:

increasing voltage at a node positioned in the communications switch and electrically coupled to the at least one diode, the voltage increased at an approximately constant rate to a level sufficient to forward bias the diode;

measuring a first current level at the node after increasing voltage but before reaching the level sufficient to forward bias the diode;

measuring a second current level at the node after reaching the level sufficient to forward bias the diode;

determining that the second current level is higher than the first current level;

in response to the determination that the second current level is higher, providing power to the communications device through the data connector;

decreasing voltage of provided power to a level sufficient to reverse bias the at least one diode;

determining that a decrease in current resulting from decreasing voltage is not non-linearly related to the decrease in voltage; and

in response, turning off the power to the communications device.