NON-LINEAR AMPLIFICATION TECHNIQUE FOR IMPROVING SIGNAL TO NOISE CONTRAST

• US 3,807,226 A
• Filed: 11/29/1972
• Issued: 04/30/1974
• Est. Priority Date: 11/29/1972
• Status: Expired due to Term

• Current Assignee: Nathaniel S. Williams
• Original Assignee: Nathaniel S. Williams
• Inventors: Williams, Nathaniel S.
• Primary Examiner(s): Woodiel, Donald D.
• Application Number:
  US05/310,340
• Time in Patent Office: 517 Days
• Field of Search: 73/146,355R 250/242,360,338,450 340/227R
• US Class Current: 374/4
• CPC Class Codes: G01M 17/027 using light, e.g. infrared, ultraviolet or holographic techniques

Abstract

Disclosed is a dynamic tire testing apparatus with an infrared sensor disposed near a rotating, loaded tire and an alarm apparatus that indicates the presence of a predetermined level of infrared emissions from the tire indicating faults therein. Included in the alarm apparatus is a non-linear amplifier that provides one level of amplification for values of signals below a predetermined minimum amplitude level and a second, higher level of amplification for signals in excess of the predetermined minimum level. Signal to noise contrast is improved by proper selection of the minimum level. The tire load can be provided from a road to a tire mounted on a moving automobile or by a pressure roller to a tire mounted on a test bench. Also included is a keying apparatus to track the angular position of the tire under test and a monitor that is responsive to both the keying apparatus and the alarm to indicate the location of faults in the tire under test. The non-linear amplifier disclosed herein is also useful in conjunction with other radiation detectors that are sensitive to, for example, microwaves, ultrasonics, etc.

Claims

1. Tire testing apparatus comprising:

motive means for rotating a tire under test to simulate road usage of the tire under a load;

radiation sensor means disposed near the tire under test for sensing thermal infrared radiation emanating therefrom and providing an output signal in response thereto; and

signal means for receiving said output signal and providing an alarm signal in response to predetermined characteristics thereof wherein said signal means comprises non-linear amplifier means for providing one level of amplification for values of said output signal below a minimum amplitude and a higher level of amplification for values of said output signal above said minimum amplitude so as to provide improved signal to noise contrast.

2. Apparatus according to claim 1 wherein said non-linear amplifier means comprises a zener coupling diode for passing signals exceeding a critical level.

3. Apparatus according to claim 1 wherein said non-linear amplifier means comprises adjustable bias means for selectively varying said critical level.

4. Apparatus according to claim 1 wherein said radiation sensor is disposed near the tread of the tire under test.

5. Apparatus according to claim 1 wherein said radiation sensor comprises an infrared sensor.

6. Apparatus according to claim 1 including pressure roller means for contacting the tread of the tire under test so as to induce wear thereof.

7. Apparatus according to claim 6 including keying means for providing a keying signal responsive to the angular position of the tire under test and monitoring means for indicating the location of hot-spots in the tire under test in response to said alarm and keying signals.

8. Apparatus according to claim 7 wherein said monitoring means comprises an oscilloscope.

9. Apparatus according to claim 8 wherein said keying means comprises a photoresponsive means for producing a pulse in response to each revolution of the tire under test.