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US 8,005,452 B2Granted
Digital comb limiter combiner
AssigneeSentel Corporation
InventorMichael A. Maiuzzo
Life of this patent
Estimating the term…
Abstract
A wideband receiver comprises a comb limiter combiner wherein the limiting is conducted by digitization and frequency excision in the frequency domain. The received signal is divided up into sub-bands by a bank of bandpass filters having contiguous pass bands spanning the entire receiver range. In each sub-band the band limited signal is digitized and subjected to digital signal processing. A threshold is set such that any frequency with a magnitude that exceeds the threshold is excised in the frequency domain. When converted back to the time domain, the high-power interference frequencies will no longer be present, thereby leaving only the low-power noise and the desired signal.
Claims36
A digital comb limiter combiner comprising:
- an antenna, wherein the antenna receives an analog signal;
- an input coupler connected to the antenna, wherein the input coupler receives the analog signal from the antenna;
- a plurality of sub-band signal processing paths connected to the input coupler, wherein each sub-band signal processing path receives the analog signal and wherein each sub-band processing path comprises:
- an input bandpass filter connected to the input coupler, wherein the input bandpass filter selects a sub-band of the analog signal;
- an analog to digital converter (A/D) connected to the input bandpass filter, wherein the A/D comprises instructions to convert the analog sub-band signal to a digital sub-band signal;
- a digital signal processor (DSP) connected to the A/D, wherein the DSP comprises:
- an excision threshold;
- instructions to convert the digital sub-band signal from a time domain to a frequency domain;
- instructions to excise signal components of the digital sub-band signal at frequencies at which a digital sub-band signal amplitude exceeds the excision threshold thereby producing a processed digital sub-band signal;
- and
- instructions to convert the processed digital sub-band signal from the frequency domain to the time domain;
- a digital to analog converter (D/A) connected to the DSP, wherein the D/A comprises instructions to convert the processed digital sub-band signal to a processed analog sub-band signal;
- an amplifier connected to the D/A;
- and
- an output bandpass filter connected to the amplifier to filter intermodulation products from the processed analog sub-band signal;
- and
- an output coupler connected to the output bandpass filter of each of the plurality of sub-band signal processing paths so as to receive the processed analog sub-band signal from each of the plurality of sub-band signal processing paths and to combine the processed analog sub-band signal from each of the plurality of sub-band signal processing paths into a composite signal.
14 more elements
A method for reducing electromagnetic interference in an analog signal received via an antenna with a digital comb limiter combiner comprising:
- coupling the analog signal from the antenna into a plurality of sub-band processing paths;
- in each sub-band processing path:
- selecting a sub-band of the analog signal;
- converting the analog sub-band signal to a digital sub-band signal;
- transforming the digital sub-band signal from a time domain to a frequency domain;
- excising signal components of the digital sub-band signal at frequencies that exceed the excision threshold to produce a processed digital sub-band signal;
- converting the processed digital sub-band signal from the frequency domain to the time domain;
- converting the processed digital sub-band signal to a processed analog sub-band signal;
- and
- filtering the processed analog sub-band signal to remove intermodulation products;
- and
- combining the processed analog sub-band signal from each of the plurality of sub-band signal processing paths into a composite signal.
9 more elements
A digital comb limiter combiner comprising:
- an antenna, wherein the antenna receives an analog signal;
- an input coupler connected to the antenna, wherein the input coupler receives the analog signal from the antenna;
- a plurality of sub-band signal processing paths connected to the input coupler, wherein each sub-band signal processing path receives the analog signal and wherein each sub-band processing path comprises:
- an input bandpass filter connected to the input coupler, wherein the input bandpass filter selects a sub-band of the analog signal and wherein the input bandpass filters of the plurality of sub-band signal process paths have pass bands that are contiguous with one another across the entirety of a nominal bandwidth for the digital comb limiter combiner;
- an analog to digital converter (A/D) connected to the input bandpass filter, wherein the A/D comprises instructions to convert the analog sub-band signal to a digital sub-band signal;
- a digital signal processor (DSP) connected to the A/D, wherein the DSP comprises:
- an excision threshold;
- instructions to convert the digital sub-band signal from a time domain to a frequency domain;
- instructions to excise signal components of the digital sub-band signal at frequencies at which a digital sub-band signal amplitude exceeds the excision threshold thereby producing a processed digital sub-band signal;
- and
- instructions to convert the processed digital sub-band signal from the frequency domain to the time domain;
- a digital to analog converter (D/A) connected to the DSP, wherein the D/A comprises instructions to convert the processed digital sub-band signal to a processed analog sub-band signal;
- and
- an output coupler connected to the D/A of each of the plurality of sub-band signal processing paths so as to receive the processed analog sub-band signal from each of the plurality of sub-band signal processing paths and to combine the processed analog sub-band signal from each of the plurality of sub-band signal processing paths into a composite signal.
11 more elements
A digital comb limiter combiner comprising:
- an antenna, wherein the antenna receives an analog signal;
- an input coupler connected to the antenna, wherein the input coupler receives the analog signal from the antenna;
- a plurality of sub-band signal processing paths connected to the input coupler, wherein each sub-band signal processing path receives the analog signal and wherein each sub-band processing path comprises:
- an input bandpass filter connected to the input coupler, wherein the input bandpass filter selects a sub-band of the analog signal;
- a notch filter connected to the input bandpass filter;
- an analog to digital converter (A/D) connected to the notch filter, wherein the A/D comprises instructions to convert the analog sub-band signal to a digital sub-band signal;
- a digital signal processor (DSP) connected to the A/D, wherein the DSP comprises:
- an excision threshold;
- instructions to convert the digital sub-band signal from a time domain to a frequency domain;
- instructions to excise signal components of the digital sub-band signal at frequencies at which a digital sub-band signal amplitude exceeds the excision threshold thereby producing a processed digital sub-band signal;
- and
- instructions to convert the processed digital sub-band signal from the frequency domain to the time domain;
- a digital to analog converter (D/A) connected to the DSP, wherein the D/A comprises instructions to convert the processed digital sub-band signal to a processed analog sub-band signal;
- an amplifier connected to the D/A;
- and
- an output bandpass filter connected to the amplifier to filter intermodulation products from the processed analog sub-band signal;
- and
- an output coupler connected to the output bandpass filter of each of the plurality of sub-band signal processing paths so as to receive the processed analog sub-band signal from each of the plurality of sub-band signal processing paths and to combine the processed analog sub-band signal from each of the plurality of sub-band signal processing paths into a composite signal.
15 more elements
Dependencies are inferred from the claim text.