Analog to digital conversion system

• US 5,610,613 A
• Filed: 09/15/1995
• Issued: 03/11/1997
• Est. Priority Date: 09/15/1995
• Status: Expired due to Term

• Current Assignee: OL Security LLC (Intellectual Ventures LLC)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Hazard, Robert W., Bouchard, George A., Carmella, Jeffrey E., DeMilia, Michael P.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/528,571
• Time in Patent Office: 543 Days
• Field of Search: 342/194, 342/195, 342/197, 342/94, 342/95, 342/115, 342/135
• US Class Current: 342/195
• CPC Class Codes: H03M 1/12 Analogue/digital converters H03M1/001 – H03M1/10 take precedence

Abstract

A system for obtaining digitized samples of an analog signal at a selectable rate, R. The system includes: a timing generator for producing a train of sampling pulses at a predetermined sampling rate, f_s ; an analog to digital converter for producing a digitized sample of the analog signal in response to each one of the sampling pulses; a processor; and, a selector, for passing each Nth one of the digitized samples produced by the analog to digital converter, where N=f_s /R to the processor. The selector includes a decimator, responsive to a signal, N=f_s /R, representative of the ratio of the sampling rate, f_s, to the digitized signal obtaining rate, R, for producing pulses at the rate, R=f_s /N; and, a register for storing each Nth one of the digitized samples produced by the analog to digital converter, each one of such digitized samples being stored in response to a corresponding one of the pulses produced by the decimator. A radar system is provided wherein range cells signals of the video signals produced in response to a train of transmitted pulses are obtained at a rate, R, related to the range cell resolution selected by the radar system. An analog to digital conversion system is fed by the video signal. The analog to digital conversion system includes: a timing generator for producing a train of sampling pulses at a predetermined sampling rate, f_s ; an analog to digital converter for producing a digitized samples of the analog signal in response to each one of the sapling pulses; and, a processor section for processing each Nth one of the digitized samples produced by the analog to digital converter.

Claims

1. A radar system comprising:

means for processing digitized samples of an analog signal at a selectable rate, R, for changing range cell resolution of the radar system comprising;

a timing generator for producing a train of sampling pulses at a predetermined sampling rate, f_s ;

an analog to digital converter for producing a plurality of digitized samples of the analog signal in response to each one of the sampling pulses; and

,

a processor to determine a doppler frequency of a received signal in each Nth one of the digitized samples and, a selector for passing to the processor each Nth one of the digitized samples produced by the analog to digital converter, where N=f_s /R.

2. A radar system comprising:

means for changing range cell resolution of a range cell of a radar system comprising;

means for digitizing samples of video signals at a constant rate for providing a plurality of digitized samples; and

means for selecting selected samples of the plurality of digitized samples for processing by a digital processing section for determining a doppler frequency of a received signal in the selected samples comprising;

a selector, for passing each Nth one of the digitized samples produced by the analog to digital converter to the processor at a predetermined rate, R, where N=f_s /R.

3. The system recited in claim 2 wherein the selector comprises:

a decimator, responsive to a signal, N=f_s /R, representative of the ratio of the sampling rate, f_s, to the digitized signal obtaining rate, R, for producing pulses at the rate, R=f_s /N; and

,

a register for storing each Nth one of the digitized samples produced by the analog to digital converter, each one of such digitized samples being stored in response to a corresponding one of the pulses produced by the decimator.

4. A radar system comprising:

means for changing range cell resolution of the radar system, wherein range cells signals of the video signals produced in response to a train of transmitted pulses are obtained at a selectable rate, R, related to the range cell resolution desired by the radar system, such radar system including an analog to digital conversion system fed by the video signal, the analog to digital conversion system, comprising;

a timing generator for producing a train of sampling pulses at a predetermined sampling rate, f_s ;

an analog to digital converter for producing a digitized samples of the analog signal in response to each one of the sampling pulses; and

,

a processor section including;

a processor; and

, a selector for passing to the processor each Nth one of the digitized samples produced by the analog to digital converter following each one of the transmitted pulses, where N=f_s /R, such processor processing each Nth one of the digitized samples produced by the analog to digital converter and passed thereto by the selector, where N=f_s /R, and for determining Doppler frequency of energy in the range cells from the processed digitized samples.

5. A radar system comprising:

means for obtaining digitized samples of video signals produced in response to a series of transmitted pulses, such digitized samples being obtained at a selected rate, R, within a predetermined range of range cell obtaining rates, each transmitted pulse being produced in response to a radar transmit trigger signal, a gating window pulse being produced a predetermined time after each trigger signal, comprising;

a digitizer section for producing digitized samples of the video signal in response to a train of sampling pulses having a sampling frequency, f_s, such sampling rate being related to the range cell resolution desired by the radar system;

a digital processing section for processing each Nth one of the digitized samples produced by the analog to digital converter during the time duration of the gating window following each one of the transmitted pulse, where N=f_s /R, to determine the Doppler frequency of energy in the range cells from the obtained digitized samples during the time duration of the gating window.