Ultrasonic fault detection system using a high dynamic range analog to digital conversion system

• US 7,963,166 B2
• Filed: 03/25/2009
• Issued: 06/21/2011
• Est. Priority Date: 10/14/2005
• Status: Active Grant

• Current Assignee: Olympus Ndt
• Original Assignee: Olympus Ndt
• Inventors: Thomas, Andrew Robert
• Primary Examiner(s): Williams; Hezron
• Assistant Examiner(s): FAYYAZ, NASHMIYA SAQIB
• Application Number:
  US12/410,922
• Publication Number:
  US 20090223294A1
• Time in Patent Office: 818 Days
• Field of Search: 736/02, 736/29, 736/31
• US Class Current: 73/631
• CPC Class Codes: G01N 2291/044 Internal reflections (echoes), e.g. on walls or defects
• CPC Class Codes: G01N 2291/102 one emitter, one receiver
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/262 by electronic orientation or focusing, e.g. with phased arrays phased arrays per se G10K11/34
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/44 Processing the detected response signal , e.g. electronic circuits specially adapted therefor digital signal processing per se G06F17/00
• CPC Class Codes: G01N 29/4463 Signal correction, e.g. distance amplitude correction [DAC], distance gain size [DGS], noise filtering
• CPC Class Codes: H03M 1/188 Multi-path, i.e. having a separate analogue/digital converter for each possible range

Abstract

A method and apparatus for effecting ultrasonic flaw detection of an object processes an echo signal received from the object being tested in at least three signal channels, wherein the echo signal is scaled to different degrees along each channel to increase and extend the dynamic range of an associated A/D converter system, in a manner which dispenses with the need for using numerous analog high pass and low pass filters and a variable gain amplifier. This reduces complexity and avoids performance limitations. The digital to analog converters sample the differently scaled input signal and a selection circuit selects the output of the digital output obtained from that analog to digital converter which has the highest gain, but which has not overflowed. The digital outputs are seamlessly merged to produce an output that can be displayed as a scan display which shows the location of faults.

Claims

1. An object inspection system, comprising:

a transmit and receive section to generate a test signal and to receive a responsive echo signal,

a transducer that converts the test signal to an ultrasonic signal, applies the ultrasonic signal to a target object to be tested, receives an ultrasonic echo signal and produces the echo signal for the transmit and receive section;

a signal processing circuit coupled with the transmit and receive section for receiving and processing the echo signal, the signal processing circuit including at least two signal processing channels, each channel including a respective preamplifier that scales the echo signal to a different degree;

an analog to digital converter coupled to the preamplifiers via amplification circuits, in a manner that passes to the analog to digital converter only a non-saturated output of at least one of the preamplifiers; and

an automatic gain control circuit which is coupled to outputs of the preamplifiers and is configured to provide signals to an acquisition logic circuit that calculates a system gain based on an output of the analog to digital converter and said automatic gain control circuit provides gain settings to the amplification circuits to assure that non-saturated amplification circuit outputs are provided to the analog to digital converter.

2. The system of claim 1, wherein said acquisition logic circuit is coupled to and receives the output from the analog to digital converter and an additional output which is derived from the automatic gain control circuit.

3. The system of claim 2, wherein the additional output is produced by at least one analog to digital converter provided between the acquisition logic circuit and the automatic gain control circuit.

4. The system of claim 1, wherein the amplification circuits comprise at least one multiplier circuit.