Radio frequency (RF) detector with a light emitting diode (LED) indicator

• US 20020128006A1
• Filed: 03/08/2001
• Published: 09/12/2002
• Est. Priority Date: 03/08/2001
• Status: Abandoned Application

• Current Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta LLC (Cisco Systems, Inc.)
• Inventors: Wallis, David W., Martine, Joseph W.
• Application Number:
  US09/802,212
• Publication Number:
  US 20020128006A1
• Time in Patent Office: Days
• US Class Current: 455/423
• CPC Class Codes: G01R 19/145 Indicating the presence of current or voltage
• CPC Class Codes: H04B 1/3833 Hand-held transceivers

Abstract

A broadband communications system for providing radio frequency (RF) signals to subscriber equipment that includes an amplifier for amplifying the RF signals and for providing an indication of the presence of the RF signals. The amplifier includes an input for receiving the RF signals, a first gain circuit for amplifying the RF signals and providing amplified RF signals, and an output for providing the amplified RF signals to the subscriber equipment. An RF detector included within the amplifier where there is a tap circuit for diverting a portion of the amplified RF signals, the tap circuit connected between the first gain circuit and the output, a gain circuit for amplifying the diverted RF signals, a rectification circuit for converting the amplified diverted RF signal to a DC voltage, a comparator for comparing the DC voltage to a reference voltage, and an indicator connected to the comparator for indicating when the DC voltage exceeds the reference voltage, whereby the DC voltage exceeding the reference voltage indicates the presence of an RF signal.

Claims

1. An RF detector for detecting RF signals, comprising:

a gain circuit for amplifying the RF signals;

a rectification circuit for changing the RF signals to a DC voltage;

a comparator for comparing the DC voltage to a reference voltage; and

an LED coupled to the comparator for indicating that RF signals are present within the RF detector and for indicating that RF signals are not present within the RF detector, wherein RF signals are present when the comparator detects a difference between the DC voltage and the reference voltage

2. The RF detector of claim 1, wherein the rectification circuit is a full wave rectifier, comprising:

a biasing diode acting as a temperature compensator for compensating for drifts over temperature.

3. The RF detector of claim 1, wherein the reference voltage is equal to an averaged noise floor that may be present.

4. The RF detector of claim 1, wherein the reference voltage is equal to ground.

5. The RF detector of claim 1, wherein the bandwidth of the RF detector ranges from 5 MHz to approximately 100 MHz.

6. The RF detector of claim 5, wherein the RF signals are detected within channels that are included within the RF detector bandwidth.

7. The RF detector of claim 6, wherein the RF detector detects RF signal levels as low as 2 dBmV for channel 2 and 14 dBmV for channel 6, where each channel has a bandwidth of 6 MHz.

8. The RF detector of claim 1, wherein the RF detector is used within a drop amplifier.

9. The RF detector of claim 8, wherein the drop amplifier is used within a communications system.

10. A drop amplifier including an RF detector for providing a visual indication that RF signals are present within the drop amplifier, the drop amplifier comprising:

an input port for receiving RF signals from upstream;

an amplifier for amplifying the received RF signals;

a tap circuit for diverting a portion of the received RF signals;

an RF detector coupled to the tap circuit, the RF detector comprising;

a gain circuit for amplfying the RF signals;

a rectification circuit for changing the RF signals to a DC voltage;

a comparator for comparing the DC voltage to a reference voltage; and

an LED for indicating that RF signals are present within the drop amplifier,

wherein RF signals are present when the comparator detects a difference between the DC voltage and the reference voltage, and

an output port for providing the amplified RF signals to a subscriber,

whereby the LED of the RF detector provides a visual indication notifying the subscriber to the presence of RF signals through the drop amplifier.

11. The drop amplifier of claim 10, wherein the reference voltage is equal to an averaged noise floor that may be present.

12. The drop amplifier of claim 10, wherein the reference voltage is equal to ground.

13. The drop amplifier of claim 10, wherein the bandwidth of the RF detector ranges from 5 MHz to approximately 100 MHz.

14. The drop amplifier of claim 10, wherein the drop amplifier is used with a communications system.

15. The drop amplifier of claim 14, wherein the communications system transmit the RF signals through a hybrid fiber coaxial (HFC) cable network.

17. The broadband communications system of claim 16, wherein said tap circuit comprises a high impedance resistor, whereby the tap circuit induces little loss signal loss at the output of the amplifier.

16. In a broadband communications system for providing radio frequency (RF) signals to subscriber equipment, an amplifier for amplifying said RF signals and for providing an indication of the presence of said RF signals, said amplifier comprising:

an input for receiving said RF signals,

a first gain circuit for amplifying said RF signals and providing amplified RF signals;

an output for providing said amplified RF signals to said subscriber equipment; and

an RF detector including

a tap circuit for diverting a portion of said amplified RF signals, said tap circuit connected between said first gain circuit and said output;

a gain circuit for amplifying said diverted RF signals;

a rectification circuit for converting said amplified diverted RF signal to a DC voltage;

a comparator for comparing said DC voltage to a reference voltage; and

an indicator connected to said comparator for indicating when said DC voltage exceeds said reference voltage,

whereby the DC voltage exceeding said reference voltage indicates the presence of an RF signal.