Digitally modulated CATV power measurement using undersampling
First Claim
1. An apparatus for measuring power of a first signal, the first signal comprising a carrier signal modulated by an information signal, the first signal having a signal strength spectrum that approximates a signal strength spectrum of white noise, the apparatus comprising:
- a) an RF receiver for receiving the first signal and generating an intermediate signal therefrom, the intermediate signal comprising at least a portion of the first signal and having a bandwidth and a cutoff frequency;
b) an A/D stage operably connected to the RF receiver to receive the intermediate signal therefrom, said A/D stage operable to generate a digital intermediate signal from the intermediate signal, the digital intermediate signal having a sample rate of less than twice the cut-off frequency;
c) a digital signal processing circuit operable to generate a power measurement on the digital intermediate signal using a sufficient number of samples of the digital intermediate signal to reduce an error due to undersampling to below a predetermined amount, the power measurement representative of the power of at least a portion of the first signal.
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Accused Products
Abstract
A signal power measurement apparatus for measuring the power of a first signal, with the first signal comprising a carrier signal modulated by an information signal. One embodiment of the present invention includes a signal power measurement apparatus comprising a RF receiver, an A/D converter, and a digital signal processing circuit. The RF receiver is operable to receive a first signal and generate an intermediate signal, with the intermediate signal comprising at least a portion of the first signal and having a bandwidth and a cutoff frequency. The A/D converter is operably connected to the RF receiver to receive the intermediate signal. The A/D converter generates a digital intermediate signal based on the intermediate signal, the digital intermediate signal having a sample rate less than twice the cutoff frequency. The digital signal processing circuit is operable to perform a power measurement on the digital intermediate signal, with the power measurement being representative of the power of at least a portion of the first signal.
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Citations
20 Claims
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1. An apparatus for measuring power of a first signal, the first signal comprising a carrier signal modulated by an information signal, the first signal having a signal strength spectrum that approximates a signal strength spectrum of white noise, the apparatus comprising:
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a) an RF receiver for receiving the first signal and generating an intermediate signal therefrom, the intermediate signal comprising at least a portion of the first signal and having a bandwidth and a cutoff frequency; b) an A/D stage operably connected to the RF receiver to receive the intermediate signal therefrom, said A/D stage operable to generate a digital intermediate signal from the intermediate signal, the digital intermediate signal having a sample rate of less than twice the cut-off frequency; c) a digital signal processing circuit operable to generate a power measurement on the digital intermediate signal using a sufficient number of samples of the digital intermediate signal to reduce an error due to undersampling to below a predetermined amount, the power measurement representative of the power of at least a portion of the first signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of measuring power of a first signal, the first signal comprising a carrier signal modulated by an information signal, the first signal having a signal strength spectrum that approximates a signal strength spectrum of white noise, the method comprising:
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a) receiving the first signal and generating an intermediate signal therefrom, the intermediate signal comprising at least a portion of the first signal and having a bandwidth and a cutoff frequency; b) generating a digital intermediate signal from the intermediate signal, the digital intermediate signal having a sample rate of less than twice the cutoff frequency; c) using digital signal processing to generate a power measurement on the digital intermediate signal using a sufficient number of samples of the digital intermediate signal to reduce an error due to undersampling to below a predetermined amount, the power measurement representative of the power of at least a portion of the first signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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Specification