Gate array pulse capture device

• US 5,243,553 A
• Filed: 07/02/1991
• Issued: 09/07/1993
• Est. Priority Date: 07/02/1991
• Status: Expired due to Term

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Loral Vought Systems Corporation
• Inventors: Flockencier, Stuart W.
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US07/724,748
• Time in Patent Office: 798 Days
• Field of Search: 356/5, 382/42
• US Class Current: 356/5.03
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4802 using analysis of echo signal for target characterisation; Target signature; Target cross-section
• CPC Class Codes: G01S 7/4812 transmitted and received beams following a coaxial path
• CPC Class Codes: G01S 7/4817 relating to scanning
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection

Abstract

A gate-array pulse capture device senses, receives, and processes signals derived in response to received laser energy, i.e., signals reflected from a target. The reflected signals are initially in the form of light pulses and are converted into analog electrical signals in the detection module and passed on to the pulse capture device. The pulse capture device determines the time delay between the transmitted and received signals and the intensity of the reflected pulse, and then compares its shape to a predetermined pattern to locate the position and intensity of the peak. This information is then used by an image processor to locate and identify targets.

Claims

1. A high-speed laser ranging system comprising:

a. a laser transmitter that transmits a laser pulse for reflection from a target;

b. a detector that receives the reflection and develops analog voltages indicative of the intensity of the received reflection;

c. a comparator coupled to the detector that develops digital values indicative of the analog voltages, wherein the comparator comprises multiple comparator circuits, each comparator circuit having a different reference voltage, and wherein the reference voltages are spaced in logarithmic intervals over a range of expected voltages;

d. an encoder and de-multiplexer coupled to the comparator to develop time de-multiplexed digital values;

e. a memory coupled to the encoder and de-multiplexer to store the de-multiplexed digital values;

f. a convolver coupled to the memory to compare the de-multiplexed digital values with expected values; and

g. a peak detector coupled to the convolver to determine the maximum value of the comparison from the convolver.

2. The system of claim 1 wherein the encoder and de-multiplexer is an ECL gate array.

3. A method of laser ranging, comprising the steps of:

a. transmitting a laser pulse to a target creating a reflection;

b. receiving the reflection;

c. converting the reflection into sequential digital values indicative of the intensity of the reflection over time;

d. encoding and de-multiplexing the digital values to develop a de-multiplexed waveform;

e. storing the de-multiplexed waveform to develop a stored waveform;

f. convolving the stored waveform to determine the degree of coincidence with a predetermined waveform; and

g. determining the maximum degree of coincidence between the predetermined waveform and a series of stored waveforms to determine the range to the target.

4. The method of claim 3, wherein the step of encoding comprises the steps of sequentially delivering the converted digital values to an array of comparator circuits having reference voltages spaced in logarithmic intervals, to produce a sequence of outputs.

5. The method of claim 4, wherein the step of de-multiplexing comprises the steps of converting the sequence of outputs into a sequence of digital words and time de-multiplexing the digital words to a selected frequency.

6. The method of claim 3, wherein step (g) is performed with a peak detector.