Method and system for spread spectrum gating

• US 20050161588A1
• Filed: 01/26/2004
• Published: 07/28/2005
• Est. Priority Date: 01/26/2004
• Status: Active Grant

• Current Assignee: Elbit Systems of America LLC (Elbit Systems Limited)
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Bowen, James Hoge, Long, Jerry Raymond, Kominsky, Richard Allen
• Granted Patent: US 7,109,467 B2
• Time in Patent Office: Days
• US Class Current: 250/214.VT
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

A gating module for gating an image intensifier tube. The gating module includes a frequency generator generating a base signal having a base frequency. A modulator spread-spectrum modulates the base frequency of the base signal to generate a modulated signal. A gating circuit coupled to the modulator generates a gating signal in response to the modulated signal.

Claims

1. A gating module for gating an image intensifier tube, the gating module comprising:

a frequency generator generating a base signal having a base frequency;

a modulator for spread-spectrum modulating said base frequency of said base signal to generate a modulated signal; and

a gating circuit coupled to said modulator, said gating circuit generating a gating signal in response to said modulated signal.

2. The gating module of claim 1 wherein:

said frequency generator and said modulator are implemented by an oscillator.

3. The gating module of claim 2 wherein:

said oscillator includes a first resistor establishing said base frequency.

4. The gating module of claim 3 wherein:

said oscillator includes a second resistor coupled to a modulation pin of said oscillator, said second resistor establishing a percent of modulation of said base frequency.

5. The gating module of claim 4 wherein:

said oscillator includes a switch connecting said modulation input to ground, closure of said switch deactivating said modulating said base frequency.

6. The gating module of claim 2 wherein:

said oscillator is a band-limited random noise generator.

7. The gating module of claim 1 wherein:

said modulator is a pseudorandom sequence generator.

8. The gating module of claim 1 wherein:

said gating circuit is a one-shot.

9. A system for viewing an object under low light conditions, the system comprising:

an image intensifier tube generating an image of said object;

a power supply providing power to said image intensifier tube;

a gating module coupled to said power supply, said gating module generating a spread-spectrum modulated gating signal to said power supply to provide gated power to said image intensifier tube.

10. The system of claim 9 wherein:

said image intensifier tube includes a sensor, a microchannel plate and an anode.

11. The system of claim 9 wherein:

said sensor is a photocathode sensor.

12. The system of claim 9 wherein:

said gating module includes;

a frequency generator generating a base signal having a base frequency;

a modulator for spread-spectrum modulating said base frequency of said base signal to generate a modulated signal; and

a gating circuit coupled to said modulator, said gating circuit generating said gating signal in response to said modulated signal.

13. The system of claim 12 wherein:

said frequency generator and said modulator are implemented by an oscillator.

14. The system of claim 13 wherein:

said oscillator includes a first resistor establishing said base frequency.

15. The system of claim 14 wherein:

said oscillator includes a second resistor coupled to a modulation pin of said oscillator, said second resistor establishing a percent of modulation of said base frequency.

16. The system of claim 15 wherein:

said oscillator includes a switch connecting said modulation input to ground, closure of said switch deactivating said modulating said base frequency.

17. The system of claim 13 wherein:

said oscillator is a band-limited random noise generator.

18. The gating module of claim 12 wherein:

said modulator is a pseudorandom sequence generator.

19. The system of claim 12 wherein:

said gating circuit is a one-shot.

20. A method for gating an image intensifier tube, the method comprising:

generating a base signal having a base frequency;

spread-spectrum modulating said base frequency of said base signal to generate a modulated signal;

generating a gating signal in response to said modulated signal; and

applying said gating signal to said image intensifier tube.