ASTM E317-21

Standard Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems without the Use of Electronic Measurement Instruments

SIGNIFICANCE AND USE
5.1 This practice describes procedures applicable to both shop and field conditions. More comprehensive or precise measurements of the characteristics of complete systems and their components will generally require laboratory techniques and electronic equipment such as oscilloscopes and signal generators. Substitution of these methods is not precluded where appropriate; however, their usage is not within the scope of this practice.  
5.2 This document does not establish system acceptance limits, nor is it intended as a comprehensive equipment specification.  
5.3 While several important characteristics are included, others of possible significance in some applications are not covered.  
5.4 Since the parameters to be evaluated and the applicable test conditions must be specified, this practice shall be prescribed only by those familiar with ultrasonic NDT technology and the required tests shall be performed either by such a qualified person or under his supervision.  
5.5 Implementation may require more detailed procedural instructions in the format of the using facility.  
5.6 In the case of evaluation of a complete system, selection of the specific tests to be made should be done cautiously; if the related parameters are not critical in the intended application, then their inclusion may be unjustified. For example, vertical linearity may be irrelevant for a go/no-go test with a flaw gate alarm, while horizontal linearity might be required only for accurate flaw-depth or thickness measurement from the display screen.  
5.7 No frequency of system evaluation or calibration is recommended or implied. This is the prerogative of the using parties and is dependent on application, environment, and stability of equipment.  
5.8 Certain sections are applicable only to instruments having receiver gain controls calibrated in decibels (dB). While these may sometimes be designated “gain,” “attenuator,” or “sensitivity” on various instruments, the term “gain controls” wil...
SCOPE
1.1 This practice describes procedures for evaluating the following performance characteristics of ultrasonic pulse-echo examination instruments and systems: Horizontal Limit and Linearity; Vertical Limit and Linearity; Resolution - Entry Surface and Far Surface; Sensitivity and Noise; Accuracy of Calibrated Gain Controls. Evaluation of these characteristics is intended to be used for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective maintenance. Instrument characteristics measured in accordance with this practice are expressed in terms that relate to their potential usefulness for ultrasonic testing. Instrument characteristics expressed in purely electronic terms may be measured as described in Guide E1324.  
1.2 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated.  
1.3 The procedures are applicable to shop or field conditions; additional electronic measurement instrumentation is not required.  
1.4 This practice establishes no performance limits for examination systems; if such acceptance criteria are required, these must be specified by the using parties. Where acceptance criteria are implied herein, they are for example only and are subject to more or less restrictive limits imposed by customer's and end user's controlling documents.  
1.5 The specific parameters to be evaluated, conditions and frequency of test, and report data required must also be determined by the user.  
1.6 This practice may be used for the evaluation of a complete examination system, including search unit, instrument, interconnections, fixtures and connected alarm and auxiliary devices, primarily in cases where such a system is used repetitively without change or substitution. T...

General Information

• Status: Published
• Publication Date: 31-May-2021
• ICS: 19.100 - Non-destructive testing
• Technical Committee: E07 - Nondestructive Testing
• Drafting Committee: E07.06 - Ultrasonic Method

Relations

• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM E1316-19b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2019
• Refers: ASTM E1316-19 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Mar-2019
• Refers: ASTM E1316-18 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jan-2018
• Refers: ASTM E1316-17a - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2017
• Refers: ASTM E1316-17 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2017
• Refers: ASTM E1316-16a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Aug-2016
• Refers: ASTM E1316-16 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Feb-2016
• Refers: ASTM E1316-15a - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2015
• Refers: ASTM E1316-15 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Sep-2015
• Refers: ASTM E1316-14 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-14e1 - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2014
• Refers: ASTM E1316-13d - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Dec-2013
• Refers: ASTM E1316-13c - Standard Terminology for Nondestructive Examinations
• Effective Date: 15-Jun-2013
• Refers: ASTM E1316-13b - Standard Terminology for Nondestructive Examinations
• Effective Date: 01-Jun-2013

Overview

ASTM E317-21 is a standard practice developed by ASTM International for evaluating the performance characteristics of ultrasonic pulse-echo testing instruments and systems without the need for additional electronic measurement instruments. This standard is critical for nondestructive testing (NDT) applications, enabling both shop and field users to assess the capabilities and stability of their ultrasonic testing equipment efficiently and effectively. ASTM E317-21 guides users through procedures that rely on practical methods rather than laboratory-based electronic instruments like oscilloscopes or signal generators, ensuring usability in diverse environments.

Key Topics

This standard focuses on the following performance characteristics relevant to ultrasonic pulse-echo NDT instruments and systems:

• Horizontal Limit and Linearity: Evaluating the accuracy of depth and thickness measurements along the display’s horizontal axis.
• Vertical Limit and Linearity: Assessing the display or analog/digital output's linear response to varying signal amplitudes.
• Resolution: Measuring the system’s ability to distinguish closely-spaced reflectors, both near the entry surface and the far surface.
• Sensitivity and Noise: Determining the smallest detectable signals against system and material noise, a key factor in flaw detection.
• Accuracy of Calibrated Gain Controls: Verifying that gain adjustments correspond to accurate changes in signal amplitude.

ASTM E317-21 provides practical guidelines on preparing appropriate test set-ups, selecting suitable blocks and fixtures, and interpreting results in ways directly relevant for operational testing environments.

Applications

ASTM E317-21 is widely utilized in industrial sectors where ultrasonic nondestructive testing is fundamental, including:

• Field and Shop Evaluation: Performing system checks on ultrasonic equipment to ensure ongoing reliability without disassembly or lab equipment.
• Periodic Monitoring: Detecting long-term drift or impending failures in pulse-echo systems through regular, on-site comparative measurements.
• Comparative Assessment: Evaluating and comparing the performance of multiple ultrasonic instruments or configurations using consistent criteria.
• Quality Assurance: Supporting compliance with customer or regulatory requirements for NDT equipment readiness.
• System Integration: Assessing full examination systems, including transducers (search units), cables, fixtures, and auxiliary devices, especially when used repetitively in a production setting.

This standard is especially valuable for professionals in industries such as aerospace, automotive, energy, and manufacturing, where consistent and reliable ultrasonic inspection results are critical for material and structural integrity.

Related Standards

ASTM E317-21 references and complements several other ASTM and industry standards, including:

• ASTM E114 - Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
• ASTM E127 - Practice for Fabrication and Control of Flat Bottomed Hole Ultrasonic Standard Reference Blocks
• ASTM E1316 - Terminology for Nondestructive Examinations
• ASTM E1324 - Guide for Measuring Some Electronic Characteristics of Ultrasonic Testing Instruments
• IEEE Std 100 - IEEE Standard Dictionary of Electrical and Electronic Terms

Users should consult these related documents to ensure comprehensive understanding and proper integration with specific project or quality requirements.

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Keywords: ASTM E317-21, ultrasonic pulse-echo testing, nondestructive testing, ultrasonic testing instruments, performance evaluation, system linearity, sensitivity, resolution, gain control calibration, on-site testing, NDT standards, instrument reliability, quality assurance.

By following ASTM E317-21, NDT professionals and facility managers can maintain and document the reliability and performance of their ultrasonic examination systems, ensuring high standards for safety and structural integrity without relying on complex electronic instrumentation.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E317 − 21
Standard Practice for
Evaluating Performance Characteristics of Ultrasonic Pulse-
Echo Testing Instruments and Systems without the Use of
Electronic Measurement Instruments
This standard is issued under the fixed designation E317; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope* 1.5 The specific parameters to be evaluated, conditions and
frequency of test, and report data required must also be
1.1 This practice describes procedures for evaluating the
determined by the user.
following performance characteristics of ultrasonic pulse-echo
1.6 This practice may be used for the evaluation of a
examination instruments and systems: Horizontal Limit and
Linearity; Vertical Limit and Linearity; Resolution - Entry complete examination system, including search unit,
instrument, interconnections, fixtures and connected alarm and
Surface and Far Surface; Sensitivity and Noise; Accuracy of
Calibrated Gain Controls. Evaluation of these characteristics is auxiliary devices, primarily in cases where such a system is
used repetitively without change or substitution. This practice
intended to be used for comparing instruments and systems or,
by periodic repetition, for detecting long-term changes in the is not intended to be used as a substitute for calibration or
standardizationofaninstrumentorsystemtoinspectanygiven
characteristics of a given instrument or system that may be
indicative of impending failure, and which, if beyond certain material. There are limitations to the use of standard reference
blocks for that purpose.
limits, will require corrective maintenance. Instrument charac-
teristics measured in accordance with this practice are ex-
1.7 Requiredtestapparatusincludesselectedtestblocksand
pressed in terms that relate to their potential usefulness for
a precision external attenuator (where specified) in addition to
ultrasonic testing. Instrument characteristics expressed in
the instrument or system to be evaluated.
purelyelectronictermsmaybemeasuredasdescribedinGuide
1.8 Precautions relating to the applicability of the proce-
E1324.
dures and interpretation of the results are included.
1.2 Ultrasonic examination systems using pulsed-wave
1.9 Alternateprocedures,suchasexamplesdescribedinthis
trains and A-scan presentation (rf or video) may be evaluated.
document,orothers,mayonlybeusedwithcustomerapproval.
1.3 The procedures are applicable to shop or field condi-
1.10 Units—The values stated in inch-pound units are to be
tions; additional electronic measurement instrumentation is not
regarded as standard. The values given in parentheses are
required.
mathematical conversions to SI units that are provided for
1.4 This practice establishes no performance limits for
information only and are not considered standard.
examination systems; if such acceptance criteria are required,
1.11 This standard does not purport to address all of the
these must be specified by the using parties. Where acceptance
safety concerns, if any, associated with its use. It is the
criteria are implied herein, they are for example only and are
responsibility of the user of this standard to establish appro-
subjecttomoreorlessrestrictivelimitsimposedbycustomer’s
priate safety, health, and environmental practices and deter-
and end user’s controlling documents.
mine the applicability of regulatory limitations prior to use.
1.12 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- ization established in the Decision on Principles for the
structive Testing and is the direct responsibility of Subcommittee E07.06 on
Ultrasonic Method.
Current edition approved June 1, 2021. Published June 2021. Originally Beck, K. H., “Limitations to the Use of Reference Blocks for Periodic and
approved in 1967. Last previous edition approved in 2016 as E317 – 16. DOI: Preinspection Calibration of Ultrasonic Inspection Instruments and Systems,”
10.1520/E0317-21. Materials Evaluation, Vol 57, No. 3, March 1999.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E317 − 21
Development of International Standards, Guides and Recom- and the required tests shall be performed either by such a
mendations issued by the World Trade Organization Technical qualified person or under his supervision.
Barriers to Trade (TBT) Committee.
5.5 Implementation may require more detailed procedural
instructions in the format of the using facility.
2. Referenced Documents
3 5.6 In the case of evaluation of a complete system, selection
2.1 ASTM Standards:
ofthespecificteststobemadeshouldbedonecautiously;ifthe
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam
related parameters are not critical in the intended application,
Contact Testing
then their inclusion may be unjustified. For example, vertical
E127 Practice for Fabrication and Control of Flat Bottomed
linearity may be irrelevant for a go/no-go test with a flaw gate
Hole Ultrasonic Standard Reference Blocks
alarm, while horizontal linearity might be required only for
E1316 Terminology for Nondestructive Examinations
accurateflaw-depthorthicknessmeasurementfromthedisplay
E1324 GuideforMeasuringSomeElectronicCharacteristics
screen.
of Ultrasonic Testing Instruments
2.2 Other Standard: 5.7 No frequency of system evaluation or calibration is
IEEE Std 100 IEEE Standard Dictionary of Electrical and recommended or implied. This is the prerogative of the using
Electronic Terms parties and is dependent on application, environment, and
stability of equipment.
3. Terminology
5.8 Certain sections are applicable only to instruments
3.1 Definitions—For definitions of terms used in this
havingreceivergaincontrolscalibratedindecibels(dB).While
practice, see Terminology E1316. Other relevant definitions
these may sometimes be designated “gain,” “attenuator,” or
may be found in IEEE Standard 100.
“sensitivity” on various instruments, the term “gain controls”
will be used in this practice in referring to those which
4. Summary of Practice
specifically control instrument receiver gain but not including
4.1 An examination system to be evaluated comprises an
reject, electronic distance-amplitude compensation, or auto-
ultrasonic pulse-echo instrument, search unit, interconnecting
matic gain control.
cables, and couplant; for immersion examination systems,
5.9 These procedures can generally be applied to any
suitable fixturing is required.
combination of instrument and search unit of the commonly
4.2 When checking an entire system to be used for a given
used types and frequencies, and to most straight-beam
examination, test conditions are selected that are consistent
examination, either contact or immersed. Certain sections are
with the intended end-use as determined by the user.
also compatible with angle-beam, wheel, delay-line, and dual-
search unit techniques.Their use, however, should be mutually
4.3 The ultrasonic response from appropriate test blocks is
agreed upon and so identified in the test report.
obtained, and presented in numerical or graphical form.
5.10 The validity of the results obtained will depend on the
5. Significance and Use
precisionoftheinstrumentdisplayreadings.Thisisassumedto
5.1 This practice describes procedures applicable to both
be 60.04 in. (61 mm), yielding between 1 % and 2 % of full
shop and field conditions. More comprehensive or precise
scale (fs) readability for available instrumentation having
measurements of the characteristics of complete systems and
suitable screen graticules and display sharpness.
their components will generally require laboratory techniques
and electronic equipment such as oscilloscopes and signal
6. Procedures for Obtaining Ultrasonic Response Data
generators. Substitution of these methods is not precluded
6.1 General:
where appropriate; however, their usage is not within the scope
6.1.1 A procedure, using this document as a guide, should
of this practice.
bepreparedforeachspecifictypeofinstrumentorsystemtobe
5.2 This document does not establish system acceptance
evaluated. For each procedure determine from the requesting
limits, nor is it intended as a comprehensive equipment
documents the instrument examination range to be evaluated,
specification.
select the appropriate search unit, fixtures, and test blocks, and
establish the required display conditions. Unless otherwise
5.3 While several important characteristics are included,
others of possible significance in some applications are not required, mid-range values are suggested for most panel
controls and “reject” must be off unless specifically desired to
covered.
be evaluated. It may be desirable to vary the instrument
5.4 Since the parameters to be evaluated and the applicable
controls from these initial values. If so, it is important to
test conditions must be specified, this practice shall be pre-
observe and report any anomalous effects on the parameters
scribed only by those familiar with ultrasonic NDTtechnology
being evaluated when the controls are so varied.
6.1.2 When a procedure requires a change in receiver gain
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
by the use of a calibrated control, it is assumed that those
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
which increase sensitivity with higher panel readings are
Standards volume information, refer to the standard’s Document Summary page on
designated “gain” and those which decrease sensitivity with
the ASTM website.
Published by Wiley-Interscience, New York, NY. higher readings are designated “attenuation.” Fine (reference)
E317 − 21
gain controls, when available, are sometimes not calibrated in 6.2.2 Apparatus—A test block is required that will give
decibels and increase sensitivity with clockwise rotation. several (preferably eleven) noninterfering multiple back reflec-
6.1.3 Although the procedures in this practice do not de-
tions for the sweep range and other test conditions of interest
scribe the use of electronic distance-amplitude compensation, (see Fig. 1). Any block having good ultrasonic transmittivity,
its use is not precluded. If it is used to affect any one or
flat parallel faces, and a thickness of about one tenth of the
combination of characteristics, measured under this document,
specified sweep range will usually be adequate. The aluminum
thenallcharacteristicsshallbeevaluatedwiththesamelevelof
blocks shown in Table 1 will be satisfactory for mid-range
compensation as was used on any one, and this level should be
frequencies and sweep settings on most instruments when the
referenced in the report. If desired by the using parties, a dual
beam is directed through the thickness T. For other test
set of test data may be made both with and without distance-
frequencies or very large search units, different block dimen-
amplitude compensation.
sions or other block designs may be required to eliminate
6.1.4 If the display screen does not provide a suitable
interferences. The couplant system used, either contact or
internal graticule, and deflection measurements are being
immersed, must provide stable indications during the measure-
made, fix the eye relative to the external scale to minimize
ments. A horizontal scale permitting reading accuracy as
parallax.Thispracticeassumesreadingprecisionofwithin2 %
specified in 6.1.4 is required or, if provided, digital readout of
of full scale. If, for any reason, this is not feasible for the
depth indication may be used.
system under test, estimate the probable accuracy and include
NOTE1— Anencapsulatedtransducer-targetsassemblymaybeusedfor
this in the report. Readability can sometimes be improved by
this purpose.
the use of an external scale attached to the display screen
having 50 or 100 divisions for full scale.
6.2.3 Procedure—Couple the appropriate block to the
6.1.5 For instruments that provide digital readout of signal
search unit so that the sound beam does not intercept any test
amplitude, the manufacturer’s specified accuracy, if available,
holes. Adjust the instrument gain, sweep-delay, and sweep-
shall be noted in the report.
length controls to display eleven noninterfering back reflec-
6.1.6 When tests are being done by the contact method,
tions. Set the amplitude of each back reflection at 50 % fs
positionthesearchunitsecurelyandmakecertainthatcouplant
before measurement of its position. Further adjust the sweep
changes are not measurably affecting the results. Refer also to
controls (range, centering, or delay) to position the leading
Practice E114.
edge of the third and ninth back reflections at the 20 % and
6.1.7 When using the immersion method, allow adequate
80 % scale divisions respectively (with each set in turn at 50 %
time for thermal stabilization; remove bubbles and particles
fs). After the third and ninth back reflections are positioned
from search unit and test surfaces; maintain the search-unit
accurately on the 20 % and 80 % divisions as described, read
manipulator and test blocks in stable positions.
and record the scale positions of each other multiple.
Alternatively, if sweep-delay is not available, position the
6.2 Horizontal Limit and Linearity:
second and eighth back reflections at the 20 % and 80 % scale
6.2.1 Significance—Horizontal limit and linearity have sig-
nificance when determination of depth of a discontinuity is divisions respectively; read and record the scale positions of
required. A specified minimum trace length is usually neces- the initial pulse start and of the remaining multiples. To
sary to obtain the horizontal readability desired. Nonlinearity calibrate the digital readout of horizontal position on instru-
of sweep trace may affect accuracy of flaw depth or thickness ments so equipped this procedure will require positioning a
determination made directly from the display screen. “gate” to provide an indication from each desired reflection.
Material: 7075T6 aluminum
Plug drilled holes with water-insoluble plastic.
FIG. 1 Suggested Test Blocks for Evaluation of Horizontal and Vertical Linearity
E317 − 21
TABLE 1 Linearity Test Block Dimensions
Table of Dimensions
US Customary Block (in.) Metric Block (mm)
Dimension Tolerance Dimension Tolerance
A 1.25 0.05 32 1
B 1.00 0.05 25 1
C 0.75 0.05 19 1
D 1.00 0.05 25 1
E 0.75 0.05 19 1
H 3.00 0.05 75 1
T 1.00 0.01 25 0.2
W 2.00 0.05 50 1
d and d 0.047 dia. 0.005 1.2 dia. 0.1
1 2
All surfaces:
Flatness . 0.001 . 0.02
Parallelism . 0.001 . 0.02
Finish 63 µ in. or smoother 1.5 µm or smoother
NOTE 2—Either more or fewer reflections can be used by suitably
the straight line through the set-up points representing ideal
modifying the procedure. For example, six back reflections may be used
linearity. For the test point shown (sixth multiple at 55 % fs),
if interference echoes are obtained with eleven, in which case the second
the error is 5 % fs. Maximum nonlinearity is given by the
back reflection is positioned at the 20 % scale division and the fifth back
“worst case” test point. Linear range is given by the set of
reflection at the 80 % scale division. Measurement of the horizontal
position of each multiple echo, should be made at the same amplitude on contiguous points falling entirely within a specified tolerance.
the leading edge of the indication. Any specific value may be selected if
6.3 Vertical Limit and Linearity:
it is used consistently. Typically used values are baseline break, half
amplitude, or signal peak.
6.3.1 Significance—Vertical limit and linearity have signifi-
cance when echo signal amplitudes are to be determined from
6.2.4 Interpretation of Data:
the display screen or corresponding analog or digital output
6.2.4.1 Horizontal limit is given by the maximum available
signals, and are to be used for evaluation of discontinuities or
trace length falling within the display graticule lines or the
acceptance criteria. A specified minimum trace deflection or
corresponding digital output limits expressed in linear units
digitalequivalentandlinearitylimitmayberequiredtoachieve
(inches or millimetres). Unless otherwise noted, this is also
the desired amplitude accuracy. For other situations, they may
assumed to represent 100 % fs. Failure to obtain full-scale
not be important, for example, go/no-go examinations with
deflection may indicate an equipment malfunction. If an
flaw alarms or evaluation by comparison with a reference level
equipment malfunction is found to be the case, the instrument
using calibrated gain controls. This practice describes both the
shall be repaired before continuing the evaluation.
two-signal ratio technique (Method A) and the input/output
6.2.4.2 Linearity test results may be presented in tabular
attenuator technique (Method B). Both methods assume that
form or, preferably, plotted in the manner shown in Fig. 2. The
the test indications used for measurement are free of interfer-
deviation is given by the displacement (in % full scale) from
ences resulting from nearby signals such as the initial pulse,
interface echo, or adjacent multiples. If linearity is of concern
under such conditions, for example for near-surface signals, it
may be evaluated by the procedure in 6.4.3. Method A (ratio
technique) will disclose only nonlinearity that occurs in the
instrumentcircuitrybetweenthegaincontrolsbeingusedtoset
the amplitudes and the display. Method B (input/output tech-
nique) evaluates the entire receiver/display system at constant
gain as established initially by the panel controls. Because of
this and other differences, the two methods may not give
identical results for linearity range. Further, MethodAmay not
disclose certain types of nonlinear response shown by Method
B.
6.3.2 Method A:
6.3.2.1 Apparatus—This method is only applicable when a
calibrated external attenuator, as described in 6.3.3.1 for
Method B, is not available. A test block is required that
produces two noninterfering signals having an amplitude ratio
of 2 to 1. These are compared over the usable screen height as
the instrument gain is changed. The two amplitudes will be
referredtoas H and H (H > H ).Thetwosignalsmayoccur
FIG. 2 Example of Data Plot for Determination A B A B
of Horizontal Linearity in either screen order and do not have to be successive if part
E317 − 21
of a multiple-echo pattern. Unless otherwise specified in the case, the instrument shall be repaired before continuing the
requesting document, any test block that will produce such evaluation. Linearity test data may be reported in tabular form
signals at the nominal test settings specified can be used. For or preferably presented graphically. Unless otherwise specified
many commonly used search units and test conditions, the test in the requesting document, vertical linearity range should be
block shown in Fig. 1 will usually be satisfactory when the determinedgraphicallyusingthemethodshowninFig.3.Ifthe
beam is directed along the H dimension toward the two holes. preferred set-up condition (H =60% fs, H = 30 % fs) is
A B
The method is applicable to either contact or immersion tests; established initially, the test results may be plotted directly on
however,ifachoiceexists,thelattermaybepreferableforease the scales shown.The limit lines provide a graduated tolerance
of set-up and coupling stability. for H of 61 graph division starting at the set-up point (to
B
provide for reading error) to 66 divisions at the extremes.
NOTE 3—An encapsulated transducer-targets assembly may be used for
Ideal linearity is defined by a straight line extending from the
this purpose.
origin through any set-up point to full scale. The linear range
6.3.2.2 Procedure—To obtain test data, position the search
is determined by interconnecting adjacent data points and
unit so that two echo signals are obtained having amplitudes in
noting the first locations above and below set-up intersecting
theratioofabout2to1.Determinethatthereissufficientrange
the limit lines. The upper linearity limit is given by the
in the gain controls to vary H (the larger) from 10 % fs to
A
corresponding value for H and the lower limit by that for H .
A B
100 % fs. Manipulate the search unit and adjust the instrument
Ifthepreferredset-upvalueswerenotobtained,anewlinearity
controls until H and H meet the conditions in Table 2. The
A B
line and corresponding limits shall be constructed following
preferred values are desired because the data may be most
the same approach.
easily presented and evaluated. However, positioning difficul-
NOTE 5—If the requesting document specifies that the test results be
ties or lack of a fine gain or pulse-length control may not
presented in ratio form (that is, H /H versus H ), the necessary values
A B A
permit obtaining the exact values. When optimum set-up
can be calculated from the tabular data and presented in any format
conditions are established, secure the search unit in place,
specified. To establish linearity limits, the desired tolerances must also be
observingtheprecautionsnotedin6.1.Adjustthegaincontrols
stated.
in steps so that H is set in increments of 10 % or less from
NOTE 6—If the instrument graticule cannot be read directly in % of full
A
scale, the recorded values of H and H should be converted to
10 % fs to 100 % fs. Read and record the values of H and H A B
A B
within the accuracies prescribed in 6.1.4.
NOTE 4—To better define the response characteristic, particularly near
the upper and lower limits, additional readings may be taken at smaller
gain increments.
6.3.2.3 Interpretation of Data—Verticallimitisgivenbythe
maximum vertical deflection (baseline to peak for video and
peak to peak for rf) within the usable graticule or digital output
range that can be obtained from a large reflector (for example,
the test block surfaces) as the gain is increased. Report this in
linear units (inches or millimetres) and note equivalent grati-
cule divisions. Unless otherwise stated, this is assumed to
represent 100 % fs. Failure to obtain full-scale deflection may
indicate an equipment malfunction. If this is found to be the
TABLE 2 Vertical Linearity Range by Method A Using Two-Signal
(Ratio) Technique with Initial Values forH andH Giving
A B
Ratios of 1.8 to 2.2
NOTE 1—Preferred setup values permit determination of vertical
linearity range directly from the data plot of Fig. 3.
H % Full Scale H % Full Scale
A B
Preferred Values
60 30
Acceptable
65 30–36
64 29–36
63 29–35
62 28–34
61 27–34
60 27–33
59 27–33
58 26–32
57 26–32
56 25–31
55 25–31 FIG. 3 Data Plot for Determination of Vertical Linearity Range by
Method A (Ratio Technique)
E317 − 21
percentages of full scale before plotting. If that is not done, new manufacturer, and the terminator suitably adjusted. However, when there
coordinates with appropriate scale and limit lines must be constructed. is a question, a minimum of one 20 dB step should always be left in the
attenuator,andterminatorerrorswillbenegligible.Properoperationofthe
6.3.3 Method B:
attenuator can be checked by determining that any combination of steps
6.3.3.1 Apparatus—This method requires the use of an
having an equivalent value, produces the same signal change. For
auxiliary external-step attenuator meeting the following mini-
example, an increase of attenuation from 20 dB to 26 dB should produce
the same display change as the increase from 30 dB to 36 dB.
mum specifications which are usually certified by the supplier:
6.3.3.2 Procedure—With approximately 30 dB of attenua-
Frequency range dc to 100 MHz
Attenuation 0 to 80 dB in 1 dB steps
tion in the external attenuator, adjust the instrument sweep and
Impedance 50 or 75Ω
gain controls to produce a center screen deflection of 50 % fs
Accuracy ±0.2 dB per 20 dB step
within readability tolerance (that is, 2 % fs or better). Decrease
The instrument must be operable in a through-transmission
the external attenuation in 1 dB steps until full-scale deflection
mode with the attenuator inserted between the source of the
is reached and record the signal amplitude for each step in
received signal and the receiver input jack as shown in Fig. 4.
percent of full scale. Reset the external attenuator to again give
Either single-search-unit or the alternative two-search-unit
50 % fs and increase the external attenuation in 2 dB steps for
configuration can be used. The attenuator should be connected
five steps, and then in 4 dB steps thereafter until the signal
to the receiver input with a coaxial cable having the same
essentially disappears; record signal amplitudes for each step.
impedance as the attenuator and the terminator. However,
negligible error will result if short lengths, that is 6 ft (1.8 m) NOTE 8—Smaller attenuation increments may be used to better define
the linearity response. Optional values are given in Table 3.
or less, of common
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E317 − 16 E317 − 21
Standard Practice for
Evaluating Performance Characteristics of Ultrasonic Pulse-
Echo Testing Instruments and Systems without the Use of
Electronic Measurement Instruments
This standard is issued under the fixed designation E317; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This practice describes procedures for evaluating the following performance characteristics of ultrasonic pulse-echo
examination instruments and systems: Horizontal Limit and Linearity; Vertical Limit and Linearity; Resolution - Entry Surface and
Far Surface; Sensitivity and Noise; Accuracy of Calibrated Gain Controls. Evaluation of these characteristics is intended to be used
for comparing instruments and systems or, by periodic repetition, for detecting long-term changes in the characteristics of a given
instrument or system that may be indicative of impending failure, and which, if beyond certain limits, will require corrective
maintenance. Instrument characteristics measured in accordance with this practice are expressed in terms that relate to their
potential usefulness for ultrasonic testing. Instrument characteristics expressed in purely electronic terms may be measured as
described in Guide E1324.
1.2 Ultrasonic examination systems using pulsed-wave trains and A-scan presentation (rf or video) may be evaluated.
1.3 The procedures are applicable to shop or field conditions; additional electronic measurement instrumentation is not required.
1.4 This practice establishes no performance limits for examination systems; if such acceptance criteria are required, these must
be specified by the using parties. Where acceptance criteria are implied herein, they are for example only and are subject to more
or less restrictive limits imposed by customer’s and end user’s controlling documents.
1.5 The specific parameters to be evaluated, conditions and frequency of test, and report data required,required must also be
determined by the user.
1.6 This practice may be used for the evaluation of a complete examination system, including search unit, instrument,
interconnections, fixtures and connected alarm and auxiliary devices, primarily in cases where such a system is used repetitively
without change or substitution. This practice is not intended to be used as a substitute for calibration or standardization of an
instrument or system to inspect any given material. There are limitations to the use of standard reference blocks for that purpose.
1.7 Required test apparatus includes selected test blocks and a precision external attenuator (where specified) in addition to the
instrument or system to be evaluated.
This practice is under the jurisdiction of ASTM Committee E07 on Nondestructive Testing and is the direct responsibility of Subcommittee E07.06 on Ultrasonic Method.
Current edition approved June 1, 2016June 1, 2021. Published June 2016June 2021. Originally approved in 1967. Last previous edition approved in 20112016 as
E317 - 11.E317 – 16. DOI: 10.1520/E0317-16.10.1520/E0317-21.
Beck, K. H., “Limitations to the Use of Reference Blocks for Periodic and Preinspection Calibration of Ultrasonic Inspection Instruments and Systems,” Materials
Evaluation, Vol 57, No. 3, March 1999.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E317 − 21
1.8 Precautions relating to the applicability of the procedures and interpretation of the results are included.
1.9 Alternate procedures, such as examples described in this document, or others, may only be used with customer approval.
1.10 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are
mathematical conversions to SI units that are provided for information only and are not considered standard.
1.11 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.12 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E127 Practice for Fabrication and Control of Flat Bottomed Hole Ultrasonic Standard Reference Blocks
E428 Practice for Fabrication and Control of Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic Testing
(Withdrawn 2019)
E1316 Terminology for Nondestructive Examinations
E1324 Guide for Measuring Some Electronic Characteristics of Ultrasonic Testing Instruments
2.2 Other Standard:
IEEE Std 100 IEEE Standard Dictionary of Electrical and Electronic Terms
3. Terminology
3.1 Definitions—For definitions of terms used in this practice, see Terminology E1316. Other relevant definitions may be found
in IEEE Standard 100.
4. Summary of Practice
4.1 An examination system to be evaluated comprises an ultrasonic pulse-echo instrument, search unit, interconnecting cables, and
couplant; for immersion examination systems, suitable fixturing is required.
4.2 When checking an entire system to be used for a given examination, test conditions are selected that are consistent with the
intended end-use as determined by the user.
4.3 The ultrasonic response from appropriate test blocks is obtained, and presented in numerical or graphical form.
5. Significance and Use
5.1 This practice describes procedures applicable to both shop and field conditions. More comprehensive or precise measurements
of the characteristics of complete systems and their components will generally require laboratory techniques and electronic
equipment such as oscilloscopes and signal generators. Substitution of these methods is not precluded where appropriate; however,
their usage is not within the scope of this practice.
5.2 This document does not establish system acceptance limits, nor is it intended as a comprehensive equipment specification.
5.3 While several important characteristics are included, others of possible significance in some applications are not covered.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Published by Wiley-Interscience, New York, NY.
E317 − 21
5.4 Since the parameters to be evaluated and the applicable test conditions must be specified, this practice shall be prescribed only
by those familiar with ultrasonic NDT technology and the required tests shall be performed either by such a qualified person or
under his supervision.
5.5 Implementation may require more detailed procedural instructions in the format of the using facility.
5.6 In the case of evaluation of a complete system, selection of the specific tests to be made should be done cautiously; if the
related parameters are not critical in the intended application, then their inclusion may be unjustified. For example, vertical linearity
may be irrelevant for a go/no-go test with a flaw gate alarm, while horizontal linearity might be required only for accurate
flaw-depth or thickness measurement from the display screen.
5.7 No frequency of system evaluation or calibration is recommended or implied. This is the prerogative of the using parties and
is dependent on application, environment, and stability of equipment.
5.8 Certain sections are applicable only to instruments having receiver gain controls calibrated in decibels (dB). While these may
sometimes be designated “gain,” “attenuator,” or “sensitivity” on various instruments, the term “gain controls” will be used in this
practice in referring to those which specifically control instrument receiver gain but not including reject, electronic distance-
amplitude compensation, or automatic gain control.
5.9 These procedures can generally be applied to any combination of instrument and search unit of the commonly used types and
frequencies, and to most straight-beam examination, either contact or immersed. Certain sections are also compatible with
angle-beam, wheel, delay-line, and dual-search unit techniques. Their use, however, should be mutually agreed upon and so
identified in the test report.
5.10 The validity of the results obtained will depend on the precision of the instrument display readings. This is assumed to be
60.04 in. (61 mm), yielding between 1 % and 2 % of full scale (fs) readability for available instrumentation having suitable screen
graticules and display sharpness.
6. Procedures for Obtaining Ultrasonic Response Data
6.1 General:
6.1.1 A procedure, using this document as a guide, should be prepared for each specific type of instrument or system to be
evaluated. For each procedure determine from the requesting documents the instrument examination range to be evaluated, select
the appropriate search unit, fixtures, and test blocks, and establish the required display conditions. Unless otherwise required,
mid-range values are suggested for most panel controls and “reject” must be off unless specifically desired to be evaluated. It may
be desirable to vary the instrument controls from these initial values. If so, it is important to observe and report any anomalous
effects on the parameters being evaluated when the controls are so varied.
6.1.2 When a procedure requires a change in receiver gain by the use of a calibrated control, it is assumed that those which
increase sensitivity with higher panel readings are designated “gain” and those which decrease sensitivity with higher readings are
designated “attenuation.” Fine (reference) gain controls, when available, are sometimes not calibrated in decibels and increase
sensitivity with clockwise rotation.
6.1.3 Although the procedures in this practice do not describe the use of electronic distance-amplitude compensation, its use is
not precluded. If it is used to affect any one or combination of characteristics, measured under this document, then all
characteristics shall be evaluated with the same level of compensation as was used on any one, and this level should be referenced
in the report. If desired by the using parties, a dual set of test data may be made both with and without distance-amplitude
compensation.
6.1.4 If the display screen does not provide a suitable internal graticule, and deflection measurements are being made, fix the eye
relative to the external scale to minimize parallax. This practice assumes reading precision of within 2 % of full scale. If, for any
reason, this is not feasible for the system under test, estimate the probable accuracy and include this in the report. Readability can
sometimes be improved by the use of an external scale attached to the display screen having 50 or 100 divisions for full scale.
E317 − 21
6.1.5 For instruments that provide digital readout of signal amplitude, the manufacturer’s specified accuracy, if available, shall be
noted in the report.
6.1.6 When tests are being done by the contact method, position the search unit securely and make certain that couplant changes
are not measurably affecting the results. Refer also to Practice E114.
6.1.7 When using the immersion method, allow adequate time for thermal stabilization; remove bubbles and particles from search
unit and test surfaces; maintain the search-unit manipulator and test blocks in stable positions.
6.2 Horizontal Limit and Linearity:
6.2.1 Significance—Horizontal limit and linearity have significance when determination of depth of a discontinuity is required. A
specified minimum trace length is usually necessary to obtain the horizontal readability desired. Nonlinearity of sweep trace may
affect accuracy of flaw depth or thickness determination made directly from the display screen.
6.2.2 Apparatus—A test block is required that will give several (preferably eleven) noninterfering multiple back reflections for the
sweep range and other test conditions of interest (see Fig. 1). Any block having good ultrasonic transmittivity, flat parallel faces,
and a thickness of about one tenth of the specified sweep range will usually be adequate. The aluminum blocks shown in Table
1 will be satisfactory for mid-range frequencies and sweep settings on most instruments when the beam is directed through the
thickness T. For other test frequencies or very large search units, different block dimensions or other block designs may be required
to eliminate interferences. The couplant system used, either contact or immersed, must provide stable indications during the
measurements. A horizontal scale permitting reading accuracy as specified in 6.1.4 is required or, if provided, digital readout of
depth indication may be used.
NOTE 1—An An encapsulated transducer-targets assembly may be used for this purpose.
6.2.3 Procedure—Couple the appropriate block to the search unit so that the sound beam does not intercept any test holes. Adjust
the instrument gain, sweep-delay, and sweep-length controls to display eleven noninterfering back reflections. Set the amplitude
of each back reflection at 50 % fs before measurement of its position. Further adjust the sweep controls (range, centering, or delay)
to position the leading edge of the third and ninth back reflections at the 20 % and 80 % scale divisions respectively (with each
set in turn at 50 % fs). After the third and ninth back reflections are positioned accurately on the 20 % and 80 % divisions as
described, read and record the scale positions of each other multiple. Alternatively, if sweep-delay is not available, position the
second and eighth back reflections at the 20 % and 80 % scale divisions respectively; read and record the scale positions of the
initial pulse start and of the remaining multiples. To calibrate the digital readout of horizontal position on instruments so equipped
this procedure will require positioning a “gate” to provide an indication from each desired reflection.
NOTE 2—Either more or fewer reflections can be used by suitably modifying the procedure. For example, six back reflections may be used if interference
Material: 7075T6 aluminum
Plug drilled holes with water-insoluble plastic.
FIG. 1 Suggested Test Blocks for Evaluation of Horizontal and Vertical Linearity
E317 − 21
TABLE 1 Linearity Test Block Dimensions
Table of Dimensions
US Customary Block (in.) Metric Block (mm)
Dimension Tolerance Dimension Tolerance
A 1.25 0.05 32 1
B 1.00 0.05 25 1
C 0.75 0.05 19 1
D 1.00 0.05 25 1
E 0.75 0.05 19 1
H 3.00 0.05 75 1
T 1.00 0.01 25 0.2
W 2.00 0.05 50 1
d and d 0.047 dia. 0.005 1.2 dia. 0.1
1 2
All surfaces:
Flatness . 0.001 . 0.02
Parallelism . 0.001 . 0.02
Finish 63 μ in. or smoother 1.5 μm or smoother
echoes are obtained with eleven, in which case the second back reflection is positioned at the 20 % scale division and the fifth back reflection at the 80 %
scale division. Measurement of the horizontal position of each multiple echo, should be made at the same amplitude on the leading edge of the indication.
Any specific value may be selected if it is used consistently. Typically used values are baseline break, half amplitude, or signal peak.
6.2.4 Interpretation of Data:
6.2.4.1 Horizontal limit is given by the maximum available trace length falling within the display graticule lines or the
corresponding digital output limits expressed in linear units (inches or millimetres). Unless otherwise noted, this is also assumed
to represent 100 % fs. Failure to obtain full-scale deflection may indicate an equipment malfunction. If an equipment malfunction
is found to be the case, the instrument shall be repaired before continuing the evaluation.
6.2.4.2 Linearity test results may be presented in tabular form or, preferably, plotted in the manner shown in Fig. 2. The deviation
is given by the displacement (in % full scale) from the straight line through the set-up points representing ideal linearity. For the
test point shown (sixth multiple at 55 % fs)fs), the error is 5 % fs. Maximum nonlinearity is given by the “worst case” test point.
Linear range is given by the set of contiguous points falling entirely within a specified tolerance.
6.3 Vertical Limit and Linearity:
6.3.1 Significance—Vertical limit and linearity have significance when echo signal amplitudes are to be determined from the
display screen or corresponding analog or digital output signals, and are to be used for evaluation of discontinuities or acceptance
FIG. 2 Example of Data Plot for Determination
of Horizontal Linearity
E317 − 21
criteria. A specified minimum trace deflection or digital equivalent and linearity limit may be required to achieve the desired
amplitude accuracy. For other situations, they may not be important, for example, go/no-go examinations with flaw alarms or
evaluation by comparison with a reference level using calibrated gain controls. This practice describes both the two-signal ratio
technique (Method A) and the input/output attenuator technique (Method B). Both methods assume that the test indications used
for measurement are free of interferences resulting from nearby signals such as the initial pulse, interface echo, or adjacent
multiples. If linearity is of concern under such conditions, for example for near-surface signals, it may be evaluated by the
procedure in 6.4.3. Method A (ratio technique) will disclose only nonlinearity that occurs in the instrument circuitry between the
gain controls being used to set the amplitudes and the display. Method B (input/output technique) evaluates the entire
receiver/display system at constant gain as established initially by the panel controls. Because of this and other differences, the two
methods may not give identical results for linearity range. Further, Method A may not disclose certain types of nonlinear response
shown by Method B.
6.3.2 Method A:
6.3.2.1 Apparatus—This method is only applicable when a calibrated external attenuator, as described in 6.3.3.1 for Method B,
is not available. A test block is required that produces two noninterfering signals having an amplitude ratio of 2 to 1. These are
compared over the usable screen height as the instrument gain is changed. The two amplitudes will be referred to as H and H
A B
(H > H ). The two signals may occur in either screen order and do not have to be successive if part of a multiple-echo pattern.
A B
Unless otherwise specified in the requesting document, any test block that will produce such signals at the nominal test settings
specified can be used. For many commonly used search units and test conditions, the test block shown in Fig. 1 will usually be
satisfactory when the beam is directed along the H dimension toward the two holes. The method is applicable to either contact or
immersion tests; however, if a choice exists, the latter may be preferable for ease of set-up and coupling stability.
NOTE 3—An encapsulated transducer-targets assembly may be used for this purpose.
6.3.2.2 Procedure—To obtain test data, position the search unit so that two echo signals are obtained having amplitudes in the ratio
of about 2 to 1. Determine that there is sufficient range in the gain controls to vary H (the larger) from 10 % fs to 100 % fs.
A
Manipulate the search unit and adjust the instrument controls until H and H meet the conditions in Table 2. The preferred values
A B
are desired because the data may be most easily presented and evaluated. However, positioning difficulties or lack of a fine gain
or pulse-length control may not permit obtaining the exact values. When optimum set-up conditions are established, secure the
search unit in place, observing the precautions noted in 6.1. Adjust the gain controls in steps so that H is set in increments of 10 %
A
or less from 10 % fs to 100 % fs. Read and record the values of H and H within the accuracies prescribed in 6.1.4.
A B
NOTE 4—To better define the response characteristic, particularly near the upper and lower limits, additional readings may be taken at smaller gain
increments.
6.3.2.3 Interpretation of Data—Vertical limit is given by the maximum vertical deflection (baseline to peak for video and peak
to peak for rf) within the usable graticule or digital output range that can be obtained from a large reflector (for example, the test
TABLE 2 Vertical Linearity Range by Method A Using Two-Signal
(Ratio) Technique with Initial Values for H andH Giving
A B
Ratios of 1.8 to 2.2
NOTE 1—Preferred setup values permit determination of vertical
linearity range directly from the data plot of Fig. 3.
H % Full Scale H % Full Scale
A B
Preferred Values
60 30
Acceptable
65 30–36
64 29–36
63 29–35
62 28–34
61 27–34
60 27–33
59 27–33
58 26–32
57 26–32
56 25–31
55 25–31
E317 − 21
block surfaces) as the gain is increased. Report this in linear units (inches or millimetres) and note equivalent graticule divisions.
Unless otherwise stated, this is assumed to represent 100 % fs. Failure to obtain full-scale deflection may indicate an equipment
malfunction. If this is found to be the case, the instrument shall be repaired before continuing the evaluation. Linearity test data
may be reported in tabular form or preferably presented graphically. Unless otherwise specified in the requesting document,
vertical linearity range should be determined graphically using the method shown in Fig. 3. If the preferred set-up condition
(H = 60 % fs, H = 30 % fs) is established initially, the test results may be plotted directly on the scales shown. The limit lines
A B
provide a graduated tolerance for H of 61 graph division starting at the set-up point (to provide for reading error) to 66 divisions
B
at the extremes. Ideal linearity is defined by a straight line extending from the origin through any set-up point to full scale. The
linear range is determined by interconnecting adjacent data points and noting the first locations above and below set-up intersecting
the limit lines. The upper linearity limit is given by the corresponding value for H and the lower limit by that for H . If the
A B
preferred set-up values were not obtained, a new linearity line and corresponding limits shall be constructed following the same
approach.
NOTE 5—If the requesting document specifies that the test results be presented in ratio form (that is, H /H versus H )), the necessary values can be
A B A
calculated from the tabular data and presented in any format specified. To establish linearity limits, the desired tolerances must also be stated.
NOTE 6—If the instrument graticule cannot be read directly in % of full scale, the recorded values of H and H should be converted to percentages of
A B
full scale before plotting. If that is not done, new coordinates with appropriate scale and limit lines must be constructed.
6.3.3 Method B:
6.3.3.1 Apparatus—This method requires the use of an auxiliary external-step attenuator meeting the following minimum
specifications which are usually certified by the supplier:
FIG. 3 Data Plot for Determination of Vertical Linearity Range by Method A (Ratio Technique)
E317 − 21
Frequency range dc to 100 MHz
Attenuation 0 to 80 dB in 1-dB steps
Attenuation 0 to 80 dB in 1 dB steps
Impedance 50 or 75 Ω
Accuracy ±0.2 dB per 20-dB step
Accuracy ±0.2 dB per 20 dB step
The instrument must be operable in a through-transmission mode with the attenuator inserted between the source of the received
signal and the receiver input jack as shown in Fig. 4. Either single-search-unit or the alternative two-search-unit configuration can
be used. The attenuator should be connected to the receiver input with a coaxial cable having the same impedance as the attenuator
and the terminator. However, negligible error will result if short lengths, that is 6 ft (1.8 m) or less, of commonly used
low-capacitance cables are used at mid-range test frequencies. The terminator should be a shielded, noninductive resistor
preferably mounted in a coaxial connector. Refer to Note 7 regarding termination errors. In the single-search-unit configuration
the pulser is shunted by the attenuator input. Therefore, to isolate the pulser and protect the attenuator if its input rating is exceeded,
a dropping resistor may be desirable. If the two-search-unit arrangement is used, no further isolation is required. The path length
provided by the test medium shall be adequate to separate the initial pulse (or any instrument cross-talk) from the desired signal,
usually that from the first back reflection or interface echo (single-search-unit method) or the first transmitted signal
(two-search-unit method). For most test situations, a total material path of 2 in. (50 mm) of water or 6 in. (150 mm) of metal such
as aluminum will be satisfactory.
NOTE 7—It is assumed that, as is typical of most commercial instruments when operated in the through-transmission mode, the receiver input impedan
...