CISPR TR 16-3:2003/AMD2:2006
(Amendment)Amendment 2 - Specification for radio disturbance and immunity measuring apparatus and methods - Part 3: CISPR technical reports
Amendment 2 - Specification for radio disturbance and immunity measuring apparatus and methods - Part 3: CISPR technical reports
General Information
Relations
Standards Content (Sample)
TECHNICAL
CISPR
REPORT
16-3
AMENDMENT 2
2006-11
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
Amendment 2
Specification for radio disturbance and immunity
measuring apparatus and methods –
Part 3:
CISPR technical reports
© IEC 2006 Droits de reproduction réservés ⎯ Copyright - all rights reserved
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 X
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
For price, see current catalogue
– 2 – TR CISPR 16-3 Amend. 2 © IEC:2006(E)
FOREWORD
This amendment has been prepared by CISPR subcommittee A: Radio interference
measurements and statistical methods.
The text of this amendment is based on the following documents:
DTR Report on voting
CISPR/A/659/DTR CISPR/A/681/RVC
CISPR/A/662/DTR CISPR/A/678/RVC
Full information on the voting for the approval of this amendment can be found in the report on
voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the publication
will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
_____________
Page 7
3 Definitions
Add, on page 9, after 3.11, the following new definitions:
3.12
weighting (e.g. of impulsive disturbance)
the pulse-repetition-frequency (PRF) dependent conversion (mostly reduction) of a peak-
detected impulse voltage level to an indication which corresponds to the interference effect on
radio reception
NOTE 1 For the analog receiver, the interference effect is the psychophysical annoyance, i.e. a subjective quantity
(audible or visual, usually not a certain number of misunderstandings of a spoken text).
For the digital receiver, the interference effect may be defined by the critical Bit Error Ratio (BER) (or Bit Error
Probability (BEP)), for which perfect error correction can still occur, or by another objective and reproducible
parameter.
3.13
weighting characteristic
the peak voltage level as a function of PRF for a constant effect on a specific radio-
communication system, i.e., the disturbance is weighted by the radio communication system
itself
TR CISPR 16-3 Amend. 2 © IEC:2006(E) – 3 –
3.14
weighting function
weighting curve
the relationship between input peak voltage level and PRF for constant level indication of a
measuring receiver with a weighting detector, i.e. the curve of response of a measuring receiver
to repeated pulses
3.15
weighting factor
the value in dB of the weighting function relative to a reference PRF or relative to the peak value
3.16
weighting detector
detector which provides an agreed weighting function
3.17
weighted disturbance measurement
measurement of disturbance using a weighting detector
Page 10
4 Technical Reports
Add, after the existing subclause 4.7 published in Amendment 1, the following new subclauses
4.8 and 4.9:
4.8 Background material on the definition of the r.m.s.-average weighting detector
for measuring receivers
4.8.1 Introduction – purpose of weighted measurement of disturbance
Generally, a weighted measurement of impulsive disturbance serves the purpose of minimizing
the cost of disturbance suppression, while keeping an agreed level of radio protection. The
weighting of a disturbance for its effect on modern digital radiocommunication services is
important for the definition of emission limits that will protect these services. Amendment 1 of
CISPR 16-1-1 defines a detector that is a combination of an r.m.s. and an average detector. The
selection of the type of detector and of the transition between these detector functions is based
on measurements and theoretical investigations.
4.8.2 General principle of weighting – the CISPR quasi-peak detector
The effect on radiocommunication services depends on the type of interference (e.g. broadband
or narrowband, pulse rate etc.) and on the type of service itself. The effect of the pulse rate was
recognized a short time after the CISPR was founded in 1933. As a result, the quasi-peak
weighting receiver for the frequency range of 150 kHz to 1 605 kHz was defined as shown for
band B in Figure 4.8.1. However in CISPR 1 [1] it was already accepted that “Subsequent
experience has shown that the r.m.s. voltmeter might give a more accurate assessment” but the
quasi-peak type of voltmeter has been retained for certain reasons – mainly for continuity.
– 4 – TR CISPR 16-3 Amend. 2 © IEC:2006(E)
30 MHz-1000 MHz (band C and D)
0,15 MHz-30 MHz (band B)
9 kHz-150 kHz (band A)
43,5 dB
–4
–8
–12
100 1 kHz
Single pulse Pulse rate
1 10
IEC 2010/06
Figure 4.8.1 – Weighting curves of quasi-peak measuring receivers
for the different frequency ranges as defined in CISPR 16-1-1.
The weighting factor is shown relative to a reference pulse rate (25 Hz or 100 Hz)
4.8.3 Other detectors defined in CISPR 16-1-1
• Peak detector
The peak detector follows the signal at the output of the IF envelope detector and holds the
maximum value during the measurement time (also called dwell time) until its discharge is
forced. This indication is independent of the pulse repetition frequency (PRF).
• Average detector
The average detector determines the linear average of the signal at the output of the IF envelope
detector. It should be kept in mind that for low PRFs, CISPR 16-1-1 specifies the average
detector measurement result as the maximum scale deflection of a meter with a time constant
specified for the quasi-peak detector. This is necessary to avoid reduced level indication for a
pulse modulated disturbance by using long measurement times. The weighting function varies
with 20 dB per decade of the PRF (see Figure 4.8.2).
• RMS detector
The r.m.s. detector determines the r.m.s. value of the signal at the output of the IF envelope
detector. Despite being mentioned in [1] and being described in CISPR 16-1-1, at the time of
writing of this report it has not been put to practical use in CISPR product standards. The
weighting function varies with 10 dB per decade of the PRF (see Figure 4.8.2). Up to now, no
meter time constant applies for the r.m.s. detector for intermittent, unsteady and drifting
narrowband disturbances.
Rel. input level for constant indication dB
TR CISPR 16-3 Amend. 2 © IEC:2006(E) – 5 –
Comparison of detector weighting functions
(example for bands C and D with 120 kHz bandwidth)
60 Average
RMS
Quasi-Peak
Peak
1 10 100 1 000 10 000 100 000 1 000 000
f /Hz
p
IEC 2011/06
Figure 4.8.2 – Weighting curves for peak, quasi-peak, r.m.s. and linear average detectors
for CISPR bands C and D
4.8.4 Procedures for measuring pulse weighting characteristics of digital
radiocommunications services
All modern radio services use digital modulation schemes. This is not only true for mobile radio
but also for audio and TV. Procedures for data compression and processing of analog signals
(voice and picture) are used together with data redundancy for error correction. Usually, up to a
certain critical bit-error ratio (BER) the system can correct errors so that perfect reception
occurs.
Whereas analog radio systems require signal-to-noise ratios of as much as 50 dB for satisfactory
operation, in general, digital radio communication systems allow error-free operation down to
signal-to-noise ratios of approximately 10 dB. However the transition region from error-free
operation to malfunction is small. Therefore planning guidelines for digital radio are based on
almost 100 % coverage. When a digital radio receiver operates at low input levels, the
susceptibility to radio disturbance is important. In mobile radio reception, the susceptibility to
radio disturbance is combined with the problem of multi-path propagation.
4.8.4.1 Principles of measurement
The significance of the weighting curve for band B in Figure 4.8.1 is as follows: to a listener the
degradation of reception quality, caused by a 100-Hz pulse, is equivalent to the degradation from
a 10-Hz pulse, if the pulse level is increased by an amount of 10 dB. In analogy to the above, an
–3
interference source with certain characteristics will produce a certain BER, e.g. 10 in a digital
radiocommunication system, when the interfering signal is received in addition to the radio
signal. The BER will depend e.g. on the pulse repetition frequency (PRF) and the level of the
interfering signal. In order to keep the BER constant, the level of the interfering signal will have
to be readjusted while the PRF is varied. This level variation vs. PRF determines the weighting
characteristics. Measurement systems with BER indication are needed to determine the required
level of the interfering signal for a constant BER as e.g. shown in Figure 4.8.3.
Weighting factor/dB
– 6 – TR CISPR 16-3 Amend. 2 © IEC:2006(E)
BER
Radio signal
generator
Radio
receiver
Interference
source
IEC 2012/06
Figure 4.8.3 – Test setup for the measurement of the pulse weighting characteristics
of a digital radiocommunication system
The test setup shown in Figure 4.8.3 consists of a radio signal generator that transmits the
wanted radio signal to the receiver. For the determination of the BER, the radio receiver either
has to know the original bit sequence for comparison with the detected bit sequence or the latter
must be looped back to the radio signal generator for comparison with the original. Both systems
are available and have been used for tests. Mobile radio testers, e.g., apply the loop-back
principle.
4.8.4.2 Generation of the interference signal
A signal generator with pulse-modulation capability can be used to generate the interference
signal. For correct measurements, the pulse modulator requires a high ON/OFF ratio of more
than 60 dB. Using the appropriate pulse width, the interference spectrum can be broadband or
narrowband, where the definition of broadband and narrowband is relative to the communication
channel bandwidth. Figure 4.8.4 gives an example of an interference spectrum used for the
determination of weighting characteristics.
* RBW 9 kHz Marker 1 [T1]
VBW 30 kHz 61,89 dBμV
Ref. 90 dBμV *
Att. 0 dB SWT 3,1 s 128 000 000 000 MHz
B
1 PK*
CLRWR
PRN
–10
Center 128 MHz 5 MHz Span 50 MHz
IEC 2013/06
Figure 4.8.4 – Example of an interference spectrum: pulse modulated carrier
with a pulse duration of 0,2 μs and a PRF < 10 kHz
TR CISPR 16-3 Amend. 2 © IEC:2006(E) – 7 –
With increasing pulse duration, the main lobe of the spectrum becomes narrower. This is also
used to study the effect of narrowband pulses on radiocommunication systems. The advantage
of using a band-limited pulse spectrum instead of a broadband pulse generator is to avoid
overloading the receiver under test. Otherwise non-linearity effects could cause deterioration of
the weighting characteristics. In addition to pulse-modulated carriers, unmodulated carriers can
be used to determine the sensitivity of different systems to narrowband (CW signal) EMI.
Extensive measurements have also been presented in [2] with on/off-keying of a QPSK-
modulated signal, thus keeping the spectrum width wider than the system bandwidth even with
longer pulse durations. Since actual receivers do not provide BER indication, the method
described in the ITU Recommendation 1368 was used as the failure criteria: DVB-T reception
was regarded as distorted when more than one visible erroneous block was shown on the screen
within an observation period of 20 s. Alternatively, any picture-freeze, also for short periods, was
regarded as a failure. For DRM, the reception was considered as distorted when the system
showed more than one dropout in a 20 s observation time.
Further measurements have been made with spread-spectrum modulated carriers in order to
study the effect of spread-spectrum clock interference on wideband radiocommunication services
(see [3] and [4]).
Table 4.8.1 – Overview of types of interference used in the experimental study
of weighting characteristics
Interference signals Pulse-modulated On/Off-keyed QPSK- Spread-spectrum
modulated modulated
Pulse width in relation T < 1/B to 100/B T < 1/B to 100/B Continuous
to signal bandwidth
T = pulse width, B = radio signal bandwidth
4.8.4.3 Other principles of measurement
The receiver under test should receive a signal that is just sufficient to give quasi error-free
–7 –3
reception (e.g. a BER = 10 or a factor of 10 lower than the critical BER). Thus the receiver
operates like a receiver at the rim of a coverage area, where a disturbance above the emission
limit can easily cause interference.
For radio telephone systems, where the downlink (to the mobile) and uplink (to the base station)
frequencies are in different bands, the use of a pulse modulated carrier helps to concentrate the
interference on the mobile receiver and thus avoids interference with the loop-back connection.
4.8.5 Theoretical studies
The work of developing measurement procedures considering a digital radio receiver as a
disturbance victim, is a very complex problem since there are many different modulation and
coding schemes to consider as digital communication services are undergoing rapid
development. The results of theoretical studies for radio systems using error correction have
been presented in [5] and [6]. These studies are based on the same fundamental assumptions
that are explained above:
• the BER is the performance parameter of interest for the digital communication system;
• the repetitive pulsed disturbance is the waveform of particular interest;
• the disturbance pulses have a pulse duration that is short compared to the digital symbols
transmitted.
Results for some selected convolutional codes (for more details, see [5]):
– 8 – TR CISPR 16-3 Amend. 2 © IEC:2006(E)
A convolutio
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.