Method of envelope detection and image generation

• US 6,552,677 B2
• Filed: 02/26/2002
• Issued: 04/22/2003
• Est. Priority Date: 02/26/2001
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Time Domain Corporation (Humatics Corporation)
• Inventors: Nag, Soumya K., Fluhler, Herbert U., Barnes, Mark A.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US10/083,191
• Publication Number:
  US 20020175850A1
• Time in Patent Office: 420 Days
• Field of Search: 342/22, 342/25, 342/176, 342/177, 342/179
• US Class Current: 342/22
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals

Abstract

A method of detecting objects reflecting impulse waveforms of generating a detection envelope by receiving a reflected waveform, delaying said waveform by a peak-to-zero delay (PZD) interval. The PZD interval is the time between a maximum energy displacement in the impulse waveform and an adjacent zero crossing. The reflected waveform and its delayed version are squared and then summed to create the envelope. If the envelope is to be defined in terms of voltage, the root of the sum of the squares may be found. Also a method for generating an image using the PZD interval in back-projection techniques is described wherein a sampling point is chosen on each of a plurality of reflected waveforms. The values of the samples are summed and the waveforms are delayed by the PZD interval and the values of the sampling points are again summed. The two sums are squared and added together to generate an image envelope.

Claims

1. A method for detecting an object reflecting impulse radar signals, comprising the steps of:

a. receiving a reflected impulse waveform; and

b. defining an envelope by finding a sum, said sum being found by adding a first square, said first square being the square of said reflected impulse waveform and a second square, said second square being the square of said reflected impulse waveform delayed in time by an interval, said interval being a difference in time between occurrence in said impulse waveform of the greatest energy displacement and an adjacent zero energy value.

2. The method according to claim 1, wherein said step of defining an envelope further comprises finding the square root of said sum.

3. The method according to claim 1, further comprising the step of storing said reflected impulse waveform upon reception of said reflected impulse waveform.

4. The method according to claim 3, wherein said step of storing said reflected impulse waveform is performed by obtaining samples of said reflected impulse waveform at a sampling rate, said sampling rate being less than the Nyquist rate.

5. In a radar apparatus, a method of displaying an image of an object, said object reflecting impulse radar signals, comprising the steps of:

a. receiving a plurality of reflected impulse waveforms;

b. obtaining first samples of each of said plurality of reflected impulse waveforms at a first sample point occurring in each of said plurality of reflected impulse waveforms;

c. obtaining second samples by delaying each of said plurality of waveforms by an interval, said interval being a difference in time between occurrence in said impulse waveform of the greatest voltage displacement and the next-occurring zero voltage, and obtaining said second samples at said sample point in each delayed waveform; and

d. defining an image envelope by finding a total sum, said total sum of a P value, said P value being a first square of a first sum of said first samples and a Z value, said Z value being a second square of a second sum of said second samples.

6. The method according to claim 5 wherein said step of defining an image envelope further comprises finding a square root of said first sum.

7. The method according to claim 5, wherein said step of obtaining second samples comprises delaying the values of the first samples, by said interval.

8. A method of detecting an object reflecting impulse radar signals, comprising the steps of:

a. receiving a reflected impulse waveform; and

b. defining an approximate envelope of said reflected impulse waveform by finding a sum, said sum being found by adding a first absolute value magnitude, said first absolute value magnitude being the absolute value magnitude of said reflected impulse waveform and a second absolute value magnitude, said second absolute value magnitude of said reflected impulse waveform delayed in time by an interval, said interval being a difference in time between occurrence in said impulse waveform of the greatest voltage displacement and the next-occurring zero voltage.