IEC 61606-1:2003

INTERNATIONAL IEC
STANDARD
61606-1
First edition
2003-10
Audio and audiovisual equipment –
Digital audio parts – Basic measurement
methods of audio characteristics –
Part 1:
General
Reference number
Publication numbering
As from 1 January 1997 all IEC publications are issued with a designation in the

60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1.

Consolidated editions
The IEC is now publishing consolidated versions of its publications. For example,

edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the

base publication incorporating amendment 1 and the base publication incorporating

amendments 1 and 2.
Further information on IEC publications
The technical content of IEC publications is kept under constant review by the IEC,
thus ensuring that the content reflects current technology. Information relating to
this publication, including its validity, is available in the IEC Catalogue of
publications (see below) in addition to new editions, amendments and corrigenda.
Information on the subjects under consideration and work in progress undertaken
by the technical committee which has prepared this publication, as well as the list
of publications issued, is also available from the following:
• IEC Web Site (www.iec.ch)
• Catalogue of IEC publications
The on-line catalogue on the IEC web site (http://www.iec.ch/searchpub/cur_fut.htm)
enables you to search by a variety of criteria including text searches, technical
committees and date of publication. On-line information is also available on
recently issued publications, withdrawn and replaced publications, as well as
corrigenda.
• IEC Just Published
This summary of recently issued publications (http://www.iec.ch/online_news/
justpub/jp_entry.htm) is also available by email. Please contact the Customer
Service Centre (see below) for further information.
• Customer Service Centre
If you have any questions regarding this publication or need further assistance,
please contact the Customer Service Centre:
Email: custserv@iec.ch
Tel: +41 22 919 02 11
Fax: +41 22 919 03 00
INTERNATIONAL IEC
STANDARD
61606-1
First edition
2003-10
Audio and audiovisual equipment –
Digital audio parts – Basic measurement
methods of audio characteristics –
Part 1:
General
 IEC 2003  Copyright - all rights reserved
No part of this publication may be reproduced or utilized in any form or by any means, electronic or
mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: +41 22 919 02 11 Telefax: +41 22 919 03 00 E-mail: inmail@iec.ch  Web: www.iec.ch
PRICE CODE
Commission Electrotechnique Internationale
T
International Electrotechnical Commission
Международная Электротехническая Комиссия
For price, see current catalogue

– 2 – 61606-1  IEC:2003(E)
CONTENTS
FOREWORD . 4

1 Scope . 6

2 Normative references. 6

3 Terms, definitions, explanations and rated values. 7

4 Measuring conditions .10

4.1 Environmental conditions.10

4.2 Power supply.10

4.2.1 Supply voltage .10
4.2.2 Frequency(ies).10
4.2.3 High-frequency and harmonic components (or ripples) in the power
supply output .10
4.3 Test signal frequencies.10
4.4 Standard setting .11
4.4.1 Standard input conditions for the EUT.11
4.4.2 Standard output conditions for the EUT.11
4.4.3 Standard setting of controls input terminals, and output terminals.12
4.5 Preconditioning.12
4.6 Measuring instruments.12
4.6.1 Signal generator .12
4.6.2 Filter .14
4.6.3 Level meter.15
4.6.4 Distortion meter .16
4.6.5 Frequency meter.17
4.6.6 Group delay meter .17
4.6.7 Analogue spectrum analyzer .18
4.6.8 Digital waveform monitor.18
4.6.9 Voltage amplifier.19
4.6.10 Standard digital player .19
5 Methods of measurement (digital-in/analogue-out).19
5.1 Input/output characteristics.19
5.1.1 Maximum output amplitude .19
5.1.2 Gain difference between channels and tracking error.20

5.2 Frequency characteristics .20
5.2.1 Frequency response .20
5.2.2 Group delay (phase linearity) .20
5.3 Noise characteristics .20
5.3.1 Signal-to-noise ratio (idle channel noise) .20
5.3.2 Dynamic range.21
5.3.3 Out-of-band noise ratio .21
5.3.4 Channel separation.21
5.4 Distortion characteristics .21
5.4.1 Level non-linearity .21
5.4.2 Distortion and noise .22
5.4.3 Intermodulation.22

61606-1  IEC:2003(E) – 3 –
6 Methods of measurement (analogue-in/digital-out).22

6.1 Input/output characteristics.22

6.1.1 Analogue to digital level calibration.22

6.1.2 Maximum allowable input amplitude.22

6.1.3 Gain difference between channel and tracking error.23

6.2 Frequency characteristics .23

6.2.1 Frequency response .23

6.2.2 Group delay .23

6.3 Noise characteristics .24

6.3.1 Signal-to-noise ratio (idle channel noise) .24
6.3.2 Dynamic range.24
6.3.3 Folded noise .24
6.3.4 Cross-talk .24
6.3.5 Channel separation.25
6.4 Distortion characteristics .25
6.4.1 Level non-linearity .25
6.4.2 Distortion and noise .25
6.4.3 Intermodulation.25
Figure 1 – Analogue test signal waveform .13
Figure 2 – Digital test signal waveform.14
Table 1 – Actual frequencies used in the measurement.10
Table 2 – Impulse conditions and measuring range .17

– 4 – 61606-1  IEC:2003(E)
INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
AUDIO AND AUDIOVISUAL EQUIPMENT – DIGITAL AUDIO PARTS –

BASIC MEASUREMENT METHODS OF AUDIO CHARACTERISTICS –

Part 1: General
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61606-1 has been prepared by IEC technical committee 100:
Audio, video and multimedia systems and equipment.
IEC 61606-2 and this standard cancel and replace IEC 61606 (1997). This first edition of
IEC 61606-1 constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
100/694/FDIS 100/715/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

61606-1  IEC:2003(E) – 5 –
IEC 61606 consists of the following parts under the general title Audio and audiovisual

equipment – Digital audio parts – Basic measurement methods of audio characteristics:

Part 1: General
Part 2: Consumer use
Part 3: Professional use
The committee has decided that the contents of this publication will remain unchanged until

2006. At this date, the publication will be

• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual edition may be issued at a later date.

———————
Under consideration.
– 6 – 61606-1  IEC:2003(E)
AUDIO AND AUDIOVISUAL EQUIPMENT – DIGITAL AUDIO PARTS –

BASIC MEASUREMENT METHODS OF AUDIO CHARACTERISTICS –

Part 1: General
1 Scope
This part of IEC 61606 deals with the basic methods of measurement of the audio

characteristics of the digital audio part of audio and audiovisual equipment for both consumer
and professional use.
The common measuring conditions and methods, described in this standard, are used for the
measurement of the performance characteristics of equipment having an audio bandwidth
equal to approximately one-half of the sampling frequency of a system, where the audio
information is processed in the form of digital data. CD players, DAT recorders, digital
amplifiers, digital sound broadcast receivers and television broadcast receivers with digital
sound are examples. Methods specified in this standard are not applicable to systems
incorporating bit-rate reduced digital audio signals that have data loss.
This standard describes tests for equipment which has digital input with analogue output and
analogue input with digital output. Future revisions of this standard will cover digital-in/digital-
out and analogue-in/analogue-out tests.
This standard does not apply to power amplifiers.
NOTE 1 A digital audio system having an analogue input and an analogue output with digital signal processing
may have different characteristics from those of a pure analogue audio system due to sampling of the audio signal
and performance of incorporated A/D and D/A converters. Measurement methods described in IEC 60268-3 may
not give correct results when applied to a digital system.
NOTE 2 The methods described are mostly based on sampling frequencies of 32 kHz and higher.
NOTE 3 For tests of those systems of digital-in – digital-out, and analogue-in – analogue-out test, refer to AES 17.
NOTE 4 This standard is planned to provide the industry with a harmonized set of methods of measurements for
digital audio equipment as described in the first edition of IEC 61606 (1997), AES 17 and EIAJ CP-2i50.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.

IEC 60038, IEC standard voltages
IEC 60107-5, Recommended methods of measurement on receivers for television broadcast
transmissions – Part 5: Electrical measurements on multichannel sound television receivers
using the NICAM two-channel digital sound system
IEC 60268-2, Sound system equipment – Part 2: Explanation of general terms and calculation
methods
IEC 60268-3, Sound system equipment – Part 3: Amplifiers
IEC 60958 (all parts), Digital audio interface

61606-1  IEC:2003(E) – 7 –
IEC 61079-4, Methods of measurement on receivers for satellite broadcast transmissions in

the 12 GHz band – Part 4: Electrical measurements on sound/data decoder units for the

digital sub-carrier NTSC system

IEC 61079-5, Methods of measurement on receivers for satellite broadcast transmissions in

the 12 GHz band – Part 5: Electrical measurements on decoder units for MAC/packet systems

IEC 61883-6, Consumer audio/video equipment – Digital interface – Part 6: Audio and music

data transmission protocol
IEC 61938, Audio, video and audiovisual systems – Interconnections and matching values –

Preferred matching values of analogue signals
ISO 266, Acoustics – Preferred frequencies
ITU-R BS 468-4, Measurement of audio-frequency noise voltage level in sound broadcasting
AES 17, AES standard method for digital audio engineering – Measurement of digital audio
equipment
3 Terms, definitions, explanations and rated values
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1.1
digital audio signal
series of digital signals expressed by sampled data
NOTE This data is constructed with LPCM (Linear Pulse Code Modulation) data.
3.1.2
coding format
series of data bit stream with control information in accordance with the standard for which
the EUT is designed, such as IEC 60958, IEC 61883-6 or some kind of AV interface
NOTE A coding word is arranged as a 2’s complimentary binary form in this standard.
3.1.3
digital interface for measurement

type of input or output digital interface which is used for measurement, such as IEC 60958,
IEC 61883-6 or some kind of AV interface
NOTE Details are defined in IEC 61606-2 (consumer use) or IEC 61606-3 (professional use)
3.1.4
word length
the number of bits of a data element
NOTE The least significant bit of the data element should not be ignored.
———————
Under consideration.
– 8 – 61606-1  IEC:2003(E)
3.1.5
sampling frequency
f
s
the number of samples of a signal taken per unit time

3.1.6
full-scale level
FS
signal level of a sine wave whose positive peak value reaches the positive digital full scale,

leaving the negative maximum code unused

EXAMPLE The largest positive value is 7FFF and the largest negative value is 8001 in
H H
16 bit data.
3.1.7
signal level
dB
FS
the result obtained from the following equation:
signal level (dB ) = 20 log (A/B)
FS 10
where A is the r.m.s. value of the signal whose level is to be determined, and B is the r.m.s.
value of a sine wave which corresponds to full-scale level in digital data or to analogue full-
scale level in analogue signals
3.1.8
analogue full-scale amplitude
nominal signal level at the analogue input of an EUT corresponding to the digital full-scale
level
3.1.9
digital zero
signal that has a value consisting of all zeros for all samples
3.1.10
normal measuring level
signal level equal to –20 dB
FS
3.1.11
normal source impedance
impedance which is connected to input terminals of EUT The concrete value is defined in IEC
61606-2 (consumer use) or IEC 61606-3 (professional use). For example, IEC 61938 is
applied in IEC 61606-2
3.1.12
normal load impedance
impedance which is connected to output terminals of EUT. The concrete value is defined in
IEC 61606-2 (consumer use) or IEC 61606-3 (professional use). For example, IEC 61938 is
applied in IEC 61606-2
3.1.13
folding frequency
one half the sampling frequency of the digital system
NOTE Signals applied to the input with frequency components higher than this frequency are subject to aliasing.

61606-1  IEC:2003(E) – 9 –
3.1.14
in-band frequency range
frequency range from 4 Hz to upper band-edge frequency (see 3.1.15)

3.1.15
upper band-edge frequency
f × 0,46
s
NOTE If fs is higher than 44,1 kHz, the manufacturer may define the upper band-edge frequency between 20 kHz

and f × 0,46. In this case, the upper band-edge frequency should be stated in the system description by the
s
manufacturer.
3.1.16
out-of-band frequencies
frequency range from folding frequency to 500 kHz.
NOTE Signals applied to the input in this frequency range are subject to aliasing.
3.1.17
aliasing components
frequency components produced below the folding frequency due to sampling of input signals
above the folding frequency
3.1.18
digital signal generator
all types of digital generators, which including digital sine signal generators or package media
or RF signal generators
3.1.19
equipment under test
EUT
equipment to be measured using the methods described in this standard
3.1.20
jitter
deviation of the timing of the transitions of a clock signal from their ideal or nominal times
3.2 Explanation of term “jitter”
The performance of conversion processes are potentially affected by jitter present on the
synchronization input, the digital audio inputs, or both. For example, if the sampling clock for

the analogue-to-digital converter inside the EUT is derived from or locked to either the
synchronization input or a digital audio input, jitter present on that input can degrade
conversion accuracy.
There are various types of jitter susceptibility to be considered such as analogue-to-digital
jitter susceptibility, digital-to-analogue susceptibility, and digital-to-digital susceptibility. See
AES 17 for detailed discussion on the subject.
3.3 Rated values
For a full explanation of these terms, see IEC 60268-2. The following are rated conditions for
digital audio equipment and should be specified by the manufacturer:
• rated supply voltage;
• rated supply frequency;
• rated pre-emphasis and de-emphasis characteristics;

– 10 – 61606-1  IEC:2003(E)
• rated digital input word length;

• rated sampling frequencies.
4 Measuring conditions
4.1 Environmental conditions
Air pressure 96 kPa ± 10 kPa
Ambient temperature 15 °C to 35 °C

Relative humidity 60 % ± 15 %
4.2 Power supply
4.2.1 Supply voltage
The rated power supply voltage, as specified in IEC 60038, shall be used. The tolerance of
the supply voltage should be ±1 % or less. A tolerance of up to +10 % or –10 % may be
allowed if the results of the measurements are not noticeably affected.
4.2.2 Frequency(ies)
The power supply frequency(ies) specified by the manufacturer shall be used. The tolerance
of the frequency should be ±2 % or less. A d.c. power supply may be used if specified.
4.2.3 High-frequency and harmonic components
(or ripples) in the power supply output
High-frequency components in the power supply output should be less than the level which
affects the result of measurement.
4.3 Test signal frequencies
The frequency of the test signal shall be selected from the actual values in Table 1. In
catalogues and other documents, where precision is not required or implied in the description,
it is permitted to use the normal figures shown in this table. Unless otherwise specified, the
reference frequency for measurements shall be 997 Hz, which may be stated in non-critical
contexts, as 1 kHz.
Table 1 – Actual frequencies used in the measurement
Actual frequency
Hz
Nominal
Hz
f = f = f = f = f = f = f =
s s s s s s s
32 kHz 44,1 kHz 48 kHz 88,2 kHz 96 kHz 176,4 kHz 192 kHz
44 4 444 4 4
87 7 777 7 7
16 17 17 17 17 17 17 17
32 31 31 31 31 31 31 31
63 61 61 61 61 61 61 61
125 127 127 127 127 127 127 127
250 251 251 251 251 251 251 251
500 499 499 499 499 499 499 499
1 K 997 997 997 997 997 997 997
2 K 1 999 1 999 1 999 1 999 1 999 1 999 1 999

61606-1  IEC:2003(E) – 11 –
Actual frequency
Hz
Nominal
Hz
f = f = f = f = f = f = f =
s s s s s s s
32 kHz 44,1 kHz 48 kHz 88,2 kHz 96 kHz 176,4 kHz 192 kHz

4 K 3997 3 997 3 997 3 997 3 997 3 997 3 997

8 K 7 993 7 993 7 993 7 993 7 993 7 993 7 993

10 K 10 007 10 007 10 007 10 007 10 007 10 007 10 007

12 K 12 503 - - - - - -
14 K 13 999 - - - - - -
14,5 K 14 501 - - - - - -
16 K - 16 001 16 001 16 001 16 001 16 001 16 001
18 K - 17 997 17 997 - - -
20 K - 19 997 19 997 19 997 19 997 19 997 19 997
22 K - - 22 001 - - - -
30 K - - - 30 011 30 011 - -
35 K - - - 34 981 34 981 - -
40 K - - - 40 009 40 009 40 009 40 009
44K - - - - 43 997 - -
50 K - - - - - 49 999 49 999
70 K - - - - - 70 001 70 001
80 K - - - - - 79 999 79 999
88 K - - - - - - 88 001
If a sweep signal is used in the measurement, the sweep frequency range is from 16 Hz to
1/2 x fs.
4.4 Standard setting
4.4.1 Standard input conditions for the EUT
4.4.1.1 Analogue input
Connect the EUT with the source equipment which has normal source impedance.
4.4.1.2 Digital input
Connect the EUT to the digital interface, for which the EUT is designed.
4.4.1.3 RF input
See IEC 60107-5, IEC 61079-4 and IEC 61079-5.
4.4.2 Standard output conditions for the EUT
4.4.2.1 Analogue output
Analogue output terminals which are connected to subsequent equipment shall be terminated
with the normal load impedance.

– 12 – 61606-1  IEC:2003(E)
4.4.2.2 Digital output
Digital audio output terminals shall be terminated in a manner appropriate to the output

interface format.
4.4.3 Standard setting of controls input terminals, and output terminals

a) Each channel of the EUT is set to the standard input and output conditions.

b) Setting of level controls
For analogue input signal: adjust the level control so as to obtain the normal measurement

level signal across the digital output when a sinusoidal input signal of 997 Hz and the

normal measurement level is applied to the input terminals of the EUT. The level control
shall be set to the maximum position if these settings cannot be obtained.
For digital input signal: adjust the level control so as to obtain an analogue output signal
at the normal measurement level across the analogue output terminals terminated with a
normal load impedance when a sinusoidal signal of 997 Hz and the normal measurement
level is applied to the digital input terminal of the EUT.
c) If the EUT is equipped with a balance control, it shall be set to the centre position.
d) Setting of the pre-emphasis and de-emphasis: If pre-emphasis and/or de-emphasis are
optional then they shall be turned off, if possible. If results with pre-emphasis or de-
emphasis are required these shall be stated separately
...