CA1161542A - Method and device for processing wide-band signals having a large dynamic range - Google Patents
Method and device for processing wide-band signals having a large dynamic rangeInfo
- Publication number
- CA1161542A CA1161542A CA000361172A CA361172A CA1161542A CA 1161542 A CA1161542 A CA 1161542A CA 000361172 A CA000361172 A CA 000361172A CA 361172 A CA361172 A CA 361172A CA 1161542 A CA1161542 A CA 1161542A
- Authority
- CA
- Canada
- Prior art keywords
- signals
- analog
- digital
- dynamic range
- large dynamic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H3/00—Measuring characteristics of vibrations by using a detector in a fluid
- G01H3/10—Amplitude; Power
- G01H3/12—Amplitude; Power by electric means
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/36—Detecting the response signal, e.g. electronic circuits specially adapted therefor
- G01N29/40—Detecting the response signal, e.g. electronic circuits specially adapted therefor by amplitude filtering, e.g. by applying a threshold or by gain control
-
- G—PHYSICS
- G04—HOROLOGY
- G04G—ELECTRONIC TIME-PIECES
- G04G7/00—Synchronisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/62—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
- H04B1/64—Volume compression or expansion arrangements
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Analytical Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Analogue/Digital Conversion (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
- Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the processing of a wide-band, analog ultrasonic echo signals of a large dynamic range, and especially echo sig-nals generated in the ultrasonic testing of material, signal distortions must be avoided in order to enable an exact analy-sis of fault signals and a good reproducibility. To accomplish this object, the signals generated by an ultrasonic detector are supplied to a linear preamplifier generating analog output signals. The analog output signals are fed to an analog-to-digital converter, which converts them directly and in parallel way into logarithmically encoded digital signals. In these digital signals one bit is assigned to the polarity of the in-put signals while the other bits correspond to the respective level of the ultrasonic echo signal. The analog-to-digital con-verter is composed of a plurality of parallel-connected units, which together define a logarithmic characteristic curve for positive and negative output signals of the preamplifier. The digital signals are supplied to an evaluation unit connected to the analog-to-digital converter. In this manner, notwithstand-ing the wide-band ultrasonic echo signals of large dynamic range, substantially distortionless processing is achieved.
In the processing of a wide-band, analog ultrasonic echo signals of a large dynamic range, and especially echo sig-nals generated in the ultrasonic testing of material, signal distortions must be avoided in order to enable an exact analy-sis of fault signals and a good reproducibility. To accomplish this object, the signals generated by an ultrasonic detector are supplied to a linear preamplifier generating analog output signals. The analog output signals are fed to an analog-to-digital converter, which converts them directly and in parallel way into logarithmically encoded digital signals. In these digital signals one bit is assigned to the polarity of the in-put signals while the other bits correspond to the respective level of the ultrasonic echo signal. The analog-to-digital con-verter is composed of a plurality of parallel-connected units, which together define a logarithmic characteristic curve for positive and negative output signals of the preamplifier. The digital signals are supplied to an evaluation unit connected to the analog-to-digital converter. In this manner, notwithstand-ing the wide-band ultrasonic echo signals of large dynamic range, substantially distortionless processing is achieved.
Description
5~;~
The invention relates to a method and a device for processing wide-band signals having a large dynamic range, particularly for processing the echo signals in the ultrasonic detection of crack defects, the analog test signals transmitted by a detector being first amplified in a linear preamplifier.
In the a~i~ computer evaluation of ultrasonic test signals in the destruction-free testing of material it is usual to use logarmithmic amplifiers with which the entire dynamic range of the received test signals larger than 60 dB can be processed, whereas when using linear amplification an amplitude range of merely 20 dB can be processed.
According to known methods, after preamplification, the ultrasonic signals are logarithmically amplified in analog form, rectified, digitized and then digitally evaluated.
However, these methods have various disadvantages, particularly with regard to band width and linearity.
Ultrasonic heads having characteristic frequencies >10 MHZ are used to an increasing extent. Therefore, the subse-quent processing system must have a distinctly larger band width so that the test signal transmitted by the detector can be processed without distortion. The band width of the processing system is determined by the band width of the logarithmic amplifier. However, with the logarithmic amplifiers available at present a band width of >10 MHz is very difficult to attain. This results in an insufficient error expansion and error reproducibility.
The linearity of the processing system is determined primarily by -the linearity of the rectifier, whose quality thus is determ;ned substantially by the error quantification. However, because of the large dynamic range required by the rectifier after the logarithmic amplification it is not possible to keep the entire characteristic curve of the rectifier absolutely linear.
Therefore, it is the aim of the invention to find a method and a device for processing wide-band signals having a large dynamic x~nge~ particularly for processing echo signals in the ultrasonic detection of crack defects, which permit the undistorted processing of the test signals having a large band width, the analog test signal transmitted by a detector being first amplified in a linear preamplifier.
Accoxding to the invention this aim is achieved in that the test signal is logarithmically digitized directly af-ter the preamplification. This has the advantage that the ana-loy logarithmlc amplifier and the rectifier are dispensed with.
Accordingly, therefore, the invention provides a method of processing wide-band,analog signals having a large dynamic range from an ultrasonic detector, comprising passing said signa]s through a linear preamplifier, logarithmically encoding the amplified signals in a symmetric manner in an analog-to-digital converter producing parallel output signals with one bit representing polarity and the remaining bits re~
presenting signal level, and feeding the logarithmically en-coded signal to a digital evaluating unit.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which -Fig~ 1 is a block diagram of a processing apparatus in accordance with the invention; and Fig. 2 is a block diagram of a functional unit as shown in Figure l.
The sequence of the method according to the invention is shown in detail in Figure 1 in diagrammatic representation.
The wide-band signal (1) transmitted by a detector is fed, after preamplification t2~, to a functional unit (3), which advanta~eousl~ combines the functions of input amplifica-tion, logarithmic conversion, digitization and rectification.
For this purpose the progxess-ion of the individual quantization
The invention relates to a method and a device for processing wide-band signals having a large dynamic range, particularly for processing the echo signals in the ultrasonic detection of crack defects, the analog test signals transmitted by a detector being first amplified in a linear preamplifier.
In the a~i~ computer evaluation of ultrasonic test signals in the destruction-free testing of material it is usual to use logarmithmic amplifiers with which the entire dynamic range of the received test signals larger than 60 dB can be processed, whereas when using linear amplification an amplitude range of merely 20 dB can be processed.
According to known methods, after preamplification, the ultrasonic signals are logarithmically amplified in analog form, rectified, digitized and then digitally evaluated.
However, these methods have various disadvantages, particularly with regard to band width and linearity.
Ultrasonic heads having characteristic frequencies >10 MHZ are used to an increasing extent. Therefore, the subse-quent processing system must have a distinctly larger band width so that the test signal transmitted by the detector can be processed without distortion. The band width of the processing system is determined by the band width of the logarithmic amplifier. However, with the logarithmic amplifiers available at present a band width of >10 MHz is very difficult to attain. This results in an insufficient error expansion and error reproducibility.
The linearity of the processing system is determined primarily by -the linearity of the rectifier, whose quality thus is determ;ned substantially by the error quantification. However, because of the large dynamic range required by the rectifier after the logarithmic amplification it is not possible to keep the entire characteristic curve of the rectifier absolutely linear.
Therefore, it is the aim of the invention to find a method and a device for processing wide-band signals having a large dynamic x~nge~ particularly for processing echo signals in the ultrasonic detection of crack defects, which permit the undistorted processing of the test signals having a large band width, the analog test signal transmitted by a detector being first amplified in a linear preamplifier.
Accoxding to the invention this aim is achieved in that the test signal is logarithmically digitized directly af-ter the preamplification. This has the advantage that the ana-loy logarithmlc amplifier and the rectifier are dispensed with.
Accordingly, therefore, the invention provides a method of processing wide-band,analog signals having a large dynamic range from an ultrasonic detector, comprising passing said signa]s through a linear preamplifier, logarithmically encoding the amplified signals in a symmetric manner in an analog-to-digital converter producing parallel output signals with one bit representing polarity and the remaining bits re~
presenting signal level, and feeding the logarithmically en-coded signal to a digital evaluating unit.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which -Fig~ 1 is a block diagram of a processing apparatus in accordance with the invention; and Fig. 2 is a block diagram of a functional unit as shown in Figure l.
The sequence of the method according to the invention is shown in detail in Figure 1 in diagrammatic representation.
The wide-band signal (1) transmitted by a detector is fed, after preamplification t2~, to a functional unit (3), which advanta~eousl~ combines the functions of input amplifica-tion, logarithmic conversion, digitization and rectification.
For this purpose the progxess-ion of the individual quantization
- 2 -~ b, L5 ~
stages of the ~nalog-digital converter CADC) is carried out according!.to ~ logarithmic characteristic curve, i,e., symmetri-cally for positi~e and negative signals. The digiti7ed output signal C4~ then contains directly in decibels (dB) the ampli-tude of the input signal tl~ and the latter's polarity. Said output signal can be subsequently evaluated in the computer (5) and after a digital-analog converter, DAC, (6) rendered visible on an oscillograph. ~7) or recorder.
In this manner it is advantageously made possible to attain a band width of the processing system of up to and exceed-ing ~ 2a -~., 20 MHz since it now depends only on the linear preamplification and input amplification of the ADC (3). secause of the rectifier in accordance with the invention the non-linearities of the rectification are now dispensed with. The polarity of the signal is indicated by the highest-value bit of the digital ADC output signal (4) while the amount of the amplitude is b~-ts indicated by the residual-~i~. If this sign digit bit is not further processed, then the function of the rectifier is practically satisfied. According to the invention it is thus ~ 10 possible to evaluate the large dynamic range of the -test signals I without loss in quality.
The process according to the inven~ion can be carried out preferably with the favourable device shown diagrammatically in Figure II as a block diagram.
The ADC t3) is composed of individual modules (8), each module containing, for example, 8 comparators. The progession of the reference inputs of the 8 comparators is logarithmic. 5 modules, i.e., 40 comparators, are combined at a time in order to convert one third of the entire dynamic 20 range at a time. The third, i.e., the third coarse region, is formed by 6 modules.
The region in which the individual module operates is determined by the adjustment of the reference power sources (9) -In order to assure as identical as possible a ~ modulation of the three coarse regions, each coarse region has ; its own input amplifier (10).
The ADC (3) operates in parallel, i.e., a comparator is present for each 0.5 dB of change in the analog input voltage (corresponding to 1 bit).
Example An analog-digital converter is designed for a frequency of 150 MHz and a dynamic range of 60 dB, with a resolution of 0.5 dB. For an analog input signal of 5 volts the number 60 ~hen appears in digital form at the output. For an analog input signal of 2.5 volts the number 54 appears at the output.
This amount/ 60 or 54, is coded in 7 bits corresponding to the resolution. Theeighth bit charac-terizes the polarity, i.e., "minus 5 volt" input li]cewise produces the number 60, merely with another state of the sign bit.
With this device it is assured that a logarithmic charac~eristic curve having an optional dynamic range per se can be realized from the logarithmically graduated individual comparators of the modules (8).
stages of the ~nalog-digital converter CADC) is carried out according!.to ~ logarithmic characteristic curve, i,e., symmetri-cally for positi~e and negative signals. The digiti7ed output signal C4~ then contains directly in decibels (dB) the ampli-tude of the input signal tl~ and the latter's polarity. Said output signal can be subsequently evaluated in the computer (5) and after a digital-analog converter, DAC, (6) rendered visible on an oscillograph. ~7) or recorder.
In this manner it is advantageously made possible to attain a band width of the processing system of up to and exceed-ing ~ 2a -~., 20 MHz since it now depends only on the linear preamplification and input amplification of the ADC (3). secause of the rectifier in accordance with the invention the non-linearities of the rectification are now dispensed with. The polarity of the signal is indicated by the highest-value bit of the digital ADC output signal (4) while the amount of the amplitude is b~-ts indicated by the residual-~i~. If this sign digit bit is not further processed, then the function of the rectifier is practically satisfied. According to the invention it is thus ~ 10 possible to evaluate the large dynamic range of the -test signals I without loss in quality.
The process according to the inven~ion can be carried out preferably with the favourable device shown diagrammatically in Figure II as a block diagram.
The ADC t3) is composed of individual modules (8), each module containing, for example, 8 comparators. The progession of the reference inputs of the 8 comparators is logarithmic. 5 modules, i.e., 40 comparators, are combined at a time in order to convert one third of the entire dynamic 20 range at a time. The third, i.e., the third coarse region, is formed by 6 modules.
The region in which the individual module operates is determined by the adjustment of the reference power sources (9) -In order to assure as identical as possible a ~ modulation of the three coarse regions, each coarse region has ; its own input amplifier (10).
The ADC (3) operates in parallel, i.e., a comparator is present for each 0.5 dB of change in the analog input voltage (corresponding to 1 bit).
Example An analog-digital converter is designed for a frequency of 150 MHz and a dynamic range of 60 dB, with a resolution of 0.5 dB. For an analog input signal of 5 volts the number 60 ~hen appears in digital form at the output. For an analog input signal of 2.5 volts the number 54 appears at the output.
This amount/ 60 or 54, is coded in 7 bits corresponding to the resolution. Theeighth bit charac-terizes the polarity, i.e., "minus 5 volt" input li]cewise produces the number 60, merely with another state of the sign bit.
With this device it is assured that a logarithmic charac~eristic curve having an optional dynamic range per se can be realized from the logarithmically graduated individual comparators of the modules (8).
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of processing wide-band-analog signals having a large dynamic range from an ultrasonic detector, com-prising passing said signals through a linear preamplifier, logarithmically encoding the amplified signals in a symmetric manner in an analog-to-digital converter producing parallel output signals with one bit representing polarity and the remain-ing bits representing signal level, and feeding the logarith-mically encoded signal to a digital evaluating unit.
2. A method as claimed in claim 1, wherein the sig-nals after evaluation are passed through a digital-to-analog converter and displayed in a display unit.
3. A method as claimed in claim 1, wherein the ana-log signals have a frequency of approximately 150 MHz and a dynamic range of approximately 60 dB.
4. An apparatus for processing wide-band, analog signals having a large dynamic range from an ultrasonic detector, comprising a linear preamplifier having an input for receiving the analog signals, an analog-to-digital converter connected to the output of the preamplifier and adapted to encode logarith-mically in a symmetric manner the amplified signals and generate a parallel output signal with one bit representing polarity and the remaining bits representing signal level, said output sig-nal being suitable for feeding to a digital evaluating unit.
5. An apparatus as claimed in claim 4, wherein the analog-to-digital converter comprises a plurality of comparators which together define a logarithmic characteristic conversion curve for the analog signals.
6. An apparatus as claimed in claim 5, wherein each comparator has an adjustable reference input for varying the dy-namic range of the apparatus.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2939617A DE2939617C2 (en) | 1979-09-29 | 1979-09-29 | Device for fast and distortion-free conversion of the analog ultrasonic test signals generated by a detector into digital signals |
| DEP2939617.6 | 1979-09-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161542A true CA1161542A (en) | 1984-01-31 |
Family
ID=6082288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000361172A Expired CA1161542A (en) | 1979-09-29 | 1980-09-29 | Method and device for processing wide-band signals having a large dynamic range |
Country Status (7)
| Country | Link |
|---|---|
| JP (1) | JPS5651660A (en) |
| BR (1) | BR8006147A (en) |
| CA (1) | CA1161542A (en) |
| DE (1) | DE2939617C2 (en) |
| FR (1) | FR2466912A1 (en) |
| IT (1) | IT1129268B (en) |
| SE (1) | SE449930B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4829824A (en) * | 1985-11-02 | 1989-05-16 | Deutsche Forschungs- Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. | Method for digital peak value measurement for ultrasonic test pulses |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57201806A (en) * | 1981-06-08 | 1982-12-10 | Aloka Co Ltd | Ultrasonic diagnostic device |
| JPS6123967A (en) * | 1984-07-11 | 1986-02-01 | Kubota Ltd | Ultrasonic flaw detecting device |
| DE3538948C1 (en) * | 1985-11-02 | 1987-04-23 | Deutsche Forsch Luft Raumfahrt | Method for digitally measuring the peak value of ultrasonic test pulses |
| DE3728173A1 (en) * | 1987-08-24 | 1989-03-09 | Wellhausen Heinz | Logarithmic signal converter |
| JPH0580034A (en) * | 1991-09-19 | 1993-03-30 | Tokimec Inc | Ultrasonic flaw detector |
| DE19926684C2 (en) * | 1999-06-11 | 2003-02-13 | Intelligendt Sys & Serv Gmbh | Method and device for logarithmic conversion of an input signal |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3685046A (en) * | 1970-06-02 | 1972-08-15 | Texaco Inc | Seismic playback/monitor system |
| DE2226172C3 (en) * | 1972-05-30 | 1975-12-04 | Thyssen Niederrhein Ag Huetten- Und Walzwerke, 4200 Oberhausen | Process for measuring and evaluating ultrasonic test pulses with a selected pulse repetition frequency for the ultrasonic testing of metal sheets and similar test objects using the pulse-echo method |
| GB1545505A (en) * | 1975-09-16 | 1979-05-10 | Ca Minister Nat Defence | Excitation and spectral calibration of acoustic emission systems |
| GB1517533A (en) * | 1976-04-01 | 1978-07-12 | Nat Res Dev | Stress wave emission analysis systems |
| DE2623892C3 (en) * | 1976-05-28 | 1988-07-28 | Karl Deutsch Prüf- und Meßgerätebau GmbH + Co KG, 5600 Wuppertal | Method for evaluating ultrasonic signals in ultrasonic testing devices for non-destructive material testing |
| GB1534366A (en) * | 1976-07-23 | 1978-12-06 | Emi Ltd | Signal processing arrangements |
| US4058001A (en) * | 1976-08-02 | 1977-11-15 | G. D. Searle & Co. | Ultrasound imaging system with improved scan conversion |
| FR2366546A1 (en) * | 1976-10-01 | 1978-04-28 | Krautkraemer Gmbh | Appts. monitoring operation of ultrasonic testing of tubes and bars - senses echo signals by transmitter probe for amplification and application to threshold circuit |
| US4099416A (en) * | 1977-04-25 | 1978-07-11 | Krautkramer-Branson, Incorporated | Resolution real-time ultrasonic imaging apparatus |
| AU517998B2 (en) * | 1977-05-06 | 1981-09-10 | Commonwealth Of Australia, The | Signal processing system |
| US4216465A (en) * | 1978-03-07 | 1980-08-05 | Hughes Aircraft Company | Programmable analog to digital converter |
-
1979
- 1979-09-29 DE DE2939617A patent/DE2939617C2/en not_active Expired
-
1980
- 1980-09-22 IT IT68464/80A patent/IT1129268B/en active
- 1980-09-23 FR FR8020438A patent/FR2466912A1/en active Granted
- 1980-09-25 BR BR8006147A patent/BR8006147A/en unknown
- 1980-09-26 SE SE8006758A patent/SE449930B/en not_active IP Right Cessation
- 1980-09-29 CA CA000361172A patent/CA1161542A/en not_active Expired
- 1980-09-29 JP JP13450480A patent/JPS5651660A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4829824A (en) * | 1985-11-02 | 1989-05-16 | Deutsche Forschungs- Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. | Method for digital peak value measurement for ultrasonic test pulses |
Also Published As
| Publication number | Publication date |
|---|---|
| SE449930B (en) | 1987-05-25 |
| DE2939617A1 (en) | 1981-04-16 |
| IT8068464A0 (en) | 1980-09-22 |
| FR2466912B1 (en) | 1984-01-06 |
| DE2939617C2 (en) | 1986-02-06 |
| FR2466912A1 (en) | 1981-04-10 |
| BR8006147A (en) | 1981-04-07 |
| IT1129268B (en) | 1986-06-04 |
| JPS5651660A (en) | 1981-05-09 |
| SE8006758L (en) | 1981-03-30 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |