US4384291A
Expired / Lapsed
US
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Efficient low-sidelobe pulse compression
Assignee: United States Department of the Navy
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Filing: 1981-04-15
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Granted: 1983-05-17
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Expires: 2001-04-15
Abstract
Abstract A pulse compression system for use with step approximation to linear FM andrank coded signals to eliminate sampling errors and range time grating lobes while providing large pulse compression ratios comprising: a receiving circuit for receiving echo signals, a converting circuit for converting echo signals from the receiver to I and Q baseband signals without clock sampling, a sliding window discrete Fourier Transform or fast Fourier Transform (FFT) circuit including a taped delay line and a plurality of resistor-type phase weighting networks and adders for generating a plurality of output signals representing the different frequency steps in the signals, a delay circuit for differentially delaying the output frequency steps from the sliding window DFT circuit so the the output steps occur simultaneously, and a summer for adding the differentially delayed outputs to yield a short pulse with a peak amplitude when a coded echo pulse is correctly indexed within the delay line of the DFT circuit.
Inventors
- 👤 Bernard L. Lewis
- 👤 Frank F. Kretschmer, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:01
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/08; G01S13/10; G01S13/26; G01S13/28; G01S13/284; G01S13/286
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
188 words
A pulse compression system for compressing the echo signal returns from the pulse waveforms of electromagnetic energy propagated by a transmitter comprising: means for receiving an echo signal; a sliding window discrete Fourier Transform (DFT) circuit comprising: analog delay means with N signal taps, with a predetermined delay between each pair of adjacent signal taps; phasor means including a series of resistor-type networks for resistively phase weighting the signals on said N taps to yield N 2 phase weighted signals; and N adder circuits, each adder circuit adding a particular set of N signals from said N 2 phase weighted signals so that only one frequency may peak at each adder circuit output; means for applying the echo signal from said receiving means to the delay means of said sliding window DFT circuit without clock sampling; means for differentially delaying the outputs from said N adder circuits; and means for adding the differentially delayed outputs from said differentially delaying means to yield a short pulse which will have a peak amplitude when an echo signal is properly indexed in said delay line means of said sliding window DFT.
Claim 2
Dependent Claim
188 words
A pulse compression system for compressing the echo signal returns from the pulse waveforms of electromagnetic energy propagated by a transmitter comprising: means for receiving an echo signal; a sliding window discrete Fourier Transform (DFT) circuit comprising: analog delay means with N signal taps, with a predetermined delay between each pair of adjacent signal taps; phasor means including a series of resistor-type networks for resistively phase weighting the signals on said N taps to yield N 2 phase weighted signals; and N adder circuits, each adder circuit adding a particular set of N signals from said N 2 phase weighted signals so that only one frequency may peak at each adder circuit output; means for applying the echo signal from said receiving means to the delay means of said sliding window DFT circuit without clock sampling; means for differentially delaying the outputs from said N adder circuits; and means for adding the differentially delayed outputs from said differentially delaying means to yield a short pulse which will have a peak amplitude when an echo signal is properly indexed in said delay line means of said sliding window DFT.
Claim 3
Dependent Claim
49 words
A pulse compression system as defined in claim 1, wherein said applying means comprises means for converting said echo signal to I and Q baseband signal pairs, and wherein said sliding window DFT circuit and said differentially delaying means are designed to operate on I and Q signal pairs.
Claim 4
Dependent Claim
24 words
A pulse compression system as defined in claim 2, further comprising means for amplitude weighting the inputs to said adding means to control sidelobes.
Claim 5
Dependent Claim
116 words
A pulse compression system as defined in claims 2 or 3, further comprising a transmitting circuit including a frequency synthesizer for generating a frequency modulated pulse; means for mixing the frequency modulated pulse from said frequency synthesizer to RF; and means for transmitting said RF pulse; and wherein said I and Q baseband converting means comprises: means for converting said received echo signal to an intermediate frequency (IF) signal; first mixer means for mixing the IF signal with a reference signal from said frequency synthesizer to obtain the I baseband signal; and second mixer means for mixing the IF signal with said synthesizer reference signal shifted in phase by 90° to obtain the Q baseband signal.
Claim 6
Independent Claim
180 words
A method for compressing the echo signals from pulse waveforms of electromagnetic energy propagated by a transmitter comprising the steps of: receiving an echo signal; converting said echo signal to a baseband signal without clock sampling; processing said baseband signal using Fourier Transform steering including the steps of: delaying said baseband signal by a series of N-1 equal delays and taking a signal tap before each delay and after the last delay to yield N signals; resistively phase-weighting each of said N signals to prevent ringing to yield N 2 phase-weighted signals, adding N different sets of N phase-weighted signals from said N 2 phase-weighted signals so that a different frequency will peak for each different set of N phase-weighted signals means for differentially delaying the added output signals from the N different sets of N phase-weighted signals in said adding step to make them occur simultaneously; and adding the differentially delayed output signals from said differentially delaying step to yield a short pulse which will have a peak amplitude when an echo is properly indexed in said delaying step.
Claim 7
Independent Claim
180 words
A method for compressing the echo signals from pulse waveforms of electromagnetic energy propagated by a transmitter comprising the steps of: receiving an echo signal; converting said echo signal to a baseband signal without clock sampling; processing said baseband signal using Fourier Transform steering including the steps of: delaying said baseband signal by a series of N-1 equal delays and taking a signal tap before each delay and after the last delay to yield N signals; resistively phase-weighting each of said N signals to prevent ringing to yield N 2 phase-weighted signals, adding N different sets of N phase-weighted signals from said N 2 phase-weighted signals so that a different frequency will peak for each different set of N phase-weighted signals means for differentially delaying the added output signals from the N different sets of N phase-weighted signals in said adding step to make them occur simultaneously; and adding the differentially delayed output signals from said differentially delaying step to yield a short pulse which will have a peak amplitude when an echo is properly indexed in said delaying step.
Claim 8
Dependent Claim
27 words
A method as defined in claim 5, wherein said converting step comprises the step of converting said echo signal to an I and Q baseband signal pair.
Claim 9
Dependent Claim
24 words
A method as defined in claim 6, further comprising the step of amplitude weighting the differentially delayed output signals prior to said adding step.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-16 | 1986-11-15 | 1987-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-16 | 1990-11-15 | 1991-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-16 | 1994-11-15 | 1995-05-17 | $7700.00 | Window Closed / Lapsed |