Method and device for detecting the presence of a carrier signal transmitted in the reverse RF path
AssigneeScientific-Atlanta, Inc.
InventorsThai-Bao H. Kien, Jiening Ao, Lamar E. West, Jr.
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Abstract
The present invention provides an improved apparatus and method for detecting a reverse carrier signal. The present invention utilizes a peak detector/envelope filter for determining the peak level of the reverse analog waveform. The peak level is compared to a threshold level during a predetermined time period to determine the presence of a valid reverse carrier signal. Once determined, an enable signal is provided to an electronics device that allows further transmission of the reverse signals.
Claims4
In a communications system for transmitting forward and reverse signals, the reverse signals including carrier signals and noise signals, the communications system including a dynamic switch, the dynamic switch comprising:
- an input port for receiving a first reverse signal from a first portion of the communications system, wherein the first reverse signal is represented as an analog waveform;
- an analog-to-digital converter for converting the first reverse signal to a digital signal, the digital signal including a plurality of digital bits;
- a carrier-detect device coupled to the input port for detecting the presence of at least one carrier signal, the carrier-detect device comprising:
- a peak detector for detecting a peak level of the analog waveform and for providing a peak envelope signal;
- an analog-to-digital converter for digitizing the peak envelope signal;
- and
- a carrier-detect logic circuit for determining whether the digitized peak envelope signal includes the at least one carrier signal by comparing the digitized peak envelope signal to a threshold power level during a detection period and for providing an enable signal when the at least one carrier signal is detected;
- and
- a buffer for temporarily storing the plurality of digital bits and for outputting the plurality of digital bits when the enable signal is received;
- a digital-to-analog converter for receiving the plurality of digital bits from the buffer and for converting the plurality of digital bits into a second reverse signal corresponding to the first reverse signal;
- and
- an output port for providing the second reverse signal to a second portion of the communications system.
In a communications system having forward and reverse paths for transmitting forward and reverse signals, respectively, the reverse signals including carrier signals and noise signals, the communications system including a communications device, the communications device including:
- a first diplex filter having a high pass filter and a low pass filter, the high pass filter for isolating the forward signals, and the low pass filter for isolating the reverse signals;
- forward path elements coupled to the high pass filter of the first diplex filter for processing;
- a second diplex filter having a high pass filter and a low pass filter, the high pass filter coupled to the forward path elements for providing the processed forward signals to the forward path, and the low pass filter for receiving reverse signals;
- a dynamic switch coupled to the low pass filter of the second diplex filter, the dynamic switch comprising:
- digitizing means for converting a reverse signal to a digital signal having a predetermined number of digital bits;
- detecting means for detecting when at least one reverse carrier signal is present in the reverse signal, wherein the reverse signal is represented as an analog waveform, the detecting means comprising:
- a peak detector for detecting a peak level of the analog waveform and for providing a peak envelope signal;
- an analog-to-digital converter for digitizing the peak envelope signal;
- and
- a carrier-detect logic circuit for determining whether the digitized peak envelope signal includes the at least one carrier signal by comparing the digitized peak envelope signal to a threshold power level during a detection period and for providing an enable signal when the at least one carrier signal is detected;
- and
- a buffer for delaying the plurality of digital bits and for releasing the delayed plurality of digital bits in response to the enable signal;
- and
- converting means for converting the delayed plurality of digital bits back to the reverse signal;
- and
- reverse path elements coupled to the dynamic switch for processing and for providing the processed reverse signal to the low pass filter of the first diplex filter,
- whereby upon detection of the at least one reverse carrier signal, the reverse signal is provided to the reverse path elements.
Dependencies are inferred from the claim text.