Non-linear junction detector

• US 20040095243A1
• Filed: 12/15/2003
• Published: 05/20/2004
• Est. Priority Date: 02/13/2001
• Status: Active Grant

• Current Assignee: Audiotel International Ltd. (SRG Realisations (2017) Plc)
• Original Assignee: Audiotel International Ltd. (SRG Realisations (2017) Plc)
• Inventors: Holmes, Steven John, Stephen, Andrew Barry
• Granted Patent: US 6,897,777 B2
• Time in Patent Office: Days
• US Class Current: 340/572.2
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

A non-linear junction detector (“NLJD”) detects junctions between two materials exhibiting dissimilar electronic or electrical properties, such as semiconductor junctions or junctions between dissimilar metals. A target junction is illuminated with energy at a fundamental RF frequency and reflections from the non-linear junction are analysed to determine the type of junction detected. The NLJD automatically controls the power output level of a transmitter emitting the illuminating signal so as to drive the signal strength of said received signals towards a predetermined value, e.g. a minimum threshold value. Advantages of the invention are improved system efficiency and the elimination of target saturation effects and unwanted device triggering/indications.

Claims

1. A non-linear junction detector comprising:

a transmitter for emitting an illuminating signal at a power output level;

a receiver for receiving reflected signals;

means for determining a signal strength of said received signals;

control means for automatically varying the power output level of the transmitter so as to drive the signal strength of said received signals towards a predetermined value.

2. The non-linear junction detector of claim 1 in which the predetermined value is set to approximately a minimum detection threshold of the receiver.

3. The non-linear junction detector of claim 1 in which the means for determining a signal strength of said received signals comprises means for determining the signal strength of the received signal at a frequency that corresponds to a second harmonic of the illuminating signal frequency.

4. The non-linear junction detector of claim 1 in which the means for determining a signal strength of said received signals comprises means for determining the signal strength of the received signal at a frequency that corresponds to a third harmonic of the illuminating signal frequency.

5. The non-linear junction detector of claim 1 in which the means for determining a signal strength of said received signals includes means for determining the differential signal strength between two harmonic components of the received signal.

6. The non-linear junction detector of claim 1 in which the control means is adapted to automatically drive the signal strength of said received signals towards said predetermined value by stepwise adjustments in the transmitter power output level.

7. The non-linear junction detector of claim 1 in which said control means further includes means for limiting variation of said power output level between a predetermined maximum threshold value and a predetermined minimum threshold value.

8. The non-linear junction detector of claim 1 further including display means for displaying to an operator the current received signal strength.

9. The non-linear junction detector of claim 8 in which said display is adapted to display the current received signal strength adjusted by a factor so as to compensate for any adaptation in the actual transmitted power output level made by said control means.

10. The non-linear junction detector of claim 1 in which the control means is adapted to varying the power output level of the transmitter so as to maintain the signal strength of said received signals between a pair of predetermined control levels.

11. A method of detecting non-linear junctions, comprising the steps of:

transmitting an illuminating signal at a first power output level;

receiving reflected signals from a non-linear junction;

determining a signal strength of a selected component of said received signals;

automatically varying the first power output level to a second power output level so as to drive the signal strength of said selected component towards a predetermined value.

12. A non-linear junction detector comprising:

a transmitter for emitting an illuminating signal at a power output level;

a receiver for receiving reflected signals;

means for determining a signal strength of said received signals;

control means for varying the power output level of the transmitter;

feedback means, coupled to said control means and said signal strength determining means, adapted to use the determined signal strength of said received signals as a control parameter for said transmitter control means.