CISPR 16-1-1:2010/AMD2:2014

CISPR 16-1-1 ®
Edition 3.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES

BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM
AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring
apparatus
Spécifications des méthodes et des appareils de mesure des perturbations
radioélectriques et de l'immunité aux perturbations radioélectriques –
Partie 1-1: Appareils de mesure des perturbations radioélectriques et de
l'immunité aux perturbations radioélectriques – Appareils de mesure

CISPR 16-1-1:2010-01/AMD2:2014-06(en-fr)

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CISPR 16-1-1 ®
Edition 3.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES

BASIC EMC PUBLICATION
PUBLICATION FONDAMENTALE EN CEM

AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and

methods –
Part 1-1: Radio disturbance and immunity measuring apparatus – Measuring

apparatus
Spécifications des méthodes et des appareils de mesure des perturbations

radioélectriques et de l'immunité aux perturbations radioélectriques –

Partie 1-1: Appareils de mesure des perturbations radioélectriques et de

l'immunité aux perturbations radioélectriques – Appareils de mesure

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX N
ICS 33.100.10 ISBN 978-2-8322-1655-2

– 2 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
FOREWORD
This amendment has been prepared by subcommittee CIS/A: Radio-interference
measurements and statistical methods, of IEC technical committee CISPR: International
special committee on radio interference.
The text of this amendment is based on the following documents:
FDIS Report on voting
CIS/A/1070/FDIS CIS/A/1075/RVD

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 stability 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
_____________
4.4.1 Amplitude relationship (absolute calibration)
Add, after the existing first paragraph, the following new text:
When external preamplifiers are used, refer to Annex J for applicable requirements.

7.5.2 Amplitude relationship
Add, after the existing paragraph and Note, the following new text:
When external preamplifiers are used, refer to Annex J for applicable requirements.

© IEC 2014
Add, after the existing Annex I, the following new annex:
Annex J
(normative)
Requirements when using an external
preamplifier with a measuring receiver
J.1 General
Using an external preamplifier at the input of a measuring receiver shall be considered
carefully as, while it improves system sensitivity, it may invalidate the system’s compliance
with the overload requirements of this standard. Further, an external preamplifier may
invalidate the usability of a spectrum analyzer without preselection for the measurement of
impulsive signals with pulse repetition frequencies down to 20 Hz using the quasi-peak
detector as specified in 4.4.2.
Therefore the operator of a measuring system that includes an external preamplifier shall
determine the limitations of the system and shall apply linearity checks for the test system.
Automated measurement results with external preamplifiers need to be verified using a final
manual linearity check. The information given in this annex provides guidance for the user of
emission measurement systems.
J.2 Considerations for optimum emission measurement system design
Internally, measuring receivers are designed to achieve optimum sensitivity while avoiding
overload. Built-in preselection in the measuring receiver avoids overload by impulsive signals.
In spite of preselection, measuring receivers usually have no linearity reserve for quasi-peak
measurements of a single pulse above the specified indication range. Missing preselection in
measuring receivers causes problems with quasi-peak detection of impulsive signals with low
PRF.
The use of an external broadband preamplifier shall be considered only after all other
possible measures for improving the system sensitivity have been exhausted, e.g. using
measuring receivers with built-in preamplifiers, using antennas of sufficient gain, or using low
loss connecting cables. An external preamplifier need only be added when the disturbance
limit and all of the emissions expected and emissions to be measured are very close to the
system noise level, e.g. for compliance with Class 5 radiated disturbance limits of CISPR 25
[17]. If high emission signals or high ambients are expected, external preamplifiers are not
recommended.
From experience, external preamplifiers are not needed for radiated disturbance
measurements to Class B limits of CISPR 11, CISPR 22 [16] and CISPR 32 [18], either at 3 m
or at 10 m measurement distance, when measuring receivers with built-in preamplifiers
including preselection and low-loss antenna cables are used. The same situation applies for
radiated disturbance measurements to CISPR 14-1, CISPR 15 [15], and the generic emission
standards, as well as for disturbance power measurements.
External preamplifiers are not recommended for conducted disturbance measurements below
30 MHz; their use may cause harmonics in the presence of high-level disturbance at
frequencies below 150 kHz, where many emission standards do not specify disturbance limits.
If an external preamplifier is added for improved sensitivity, the following needs to be
considered:
a) preamplifiers have a wide bandwidth, i.e. they are susceptible to overload by impulsive
signals and high level narrowband signals;

– 4 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
b) preamplifiers may produce intermodulation products and harmonics; this is especially
important when measurements are made on an OATS and/or in the presence of radio
transmission equipment;
c) preamplifiers increase the signal level at the receiver input and thus may overload the
receiver input stages, a condition which cannot be avoided entirely by the receiver’s built-
in preselection;
d) the gain in sensitivity will be less than the gain in signal level, thus limiting the dynamic
range of the preamplifier/receiver combination;
NOTE 1 The gain in sensitivity is understood as the difference between the noise figure without preamplifier
and the system noise figure with preamplifier.
e) for maximum sensitivity in the frequency range above 1 GHz, the preamplifier is
mounted/connected directly to the measurement antenna;
f) use of an external preamplifier requires that an accurate gain versus frequency
characterization be accounted for in the measurement result;
g) the uncertainty of the gain as a function of temperature and aging, as well as the
additional mismatch uncertainty between the preamplifier output port and the receiver
input port, shall be included in the uncertainty budget for the measurement; the input
impedance shall, as far as possible, comply with the requirements for the measuring
receiver and shall be included in the uncertainty budget;
h) for CISPR Band E, a system consisting of an external preamplifier and a measuring
receiver shall be designed such that it cannot be overloaded by signals of lower frequency
bands, and/or by any signal whose out-of-band or spurious signals are to be measured;
e.g. the ISM signal of a microwave oven shall not drive the system into overload.
The gain in sensitivity is determined using the following quantities and equations:
P
ie
F= and, (J.1)
kT B
P
o
for an amplifier, (J.2)
F=
gkT B
where
F is the noise factor, with 10 lgF = noise figure (often denoted by the symbol NF);
P is the equivalent noise input power;
ie
P is the noise output power;
o
G/10
g is calculated from the gain, G = 10 lgg, respectively g = 10
–23 –21
k is Boltzmann’s constant = 1,38 × 10 Ws/K and kT = 4 × 10 W/Hz
T is the absolute reference room temperature (293 K);
B is the noise bandwidth (e.g. of the measuring receiver).

© IEC 2014
Receiver
Preamplifier
F , g
1 1 F
a a
c1 c2
IEC  1944/14
Figure J.1 – Receiver with preamplifier
In Figure J.1, assuming that the cable attenuation a = 0 dB, then
c2
 
F − 1
 
10lg F = a + 10lg F + (J.3)
tot c1 1
 
g
 
where F is the noise factor of the system at the input cable with a .
tot c1
If a ≠ 0 dB, then the preamplifier gain factor g in Equation (J.3) has to be replaced by
c2 1
( – )/10
G a
10 . Cable attenuation a = 0 dB is achieved by mounting and/or connecting the
1 c2
c1
preamplifier directly to the antenna. If a ≠ 0 dB, then the cable attenuation a adds to the
c1 c1
system noise figure as shown by Equation (J.3).
State-of-the-art preamplifiers typically have noise figures of 3 dB or less, corresponding to a
noise factor of F = 2. Receivers with built-in preamplifiers typically have noise figures around
8 dB, corresponding to a noise factor F = 6,3. This high noise factor is due to attenuation
caused by preselection and other internal insertion losses of the receiver. Receivers without
built-in preamplifiers typically have noise figures around 15 dB, corresponding to a noise
factor F = 31,6.
NOTE 2 The noise figure 10 lgF of a measuring receiver can be determined from the indicated noise level using
10 lgF = V + 67 – 10 lgB –w
2 Nav N Nav
where
V is the receiver noise floor with linear average detection, in dB(µV);
Nav
B is the noise bandwidth of the measuring receiver, in Hz;
N
w is the noise weighting factor for linear average detection, in dB.
Nav
EXAMPLE If V = –10,7 dB(µV), B = 85 kHz (for B = 120 kHz), and w = −1 dB, then the noise figure
Nav N 6 Nav
10 lgF = 8 dB.
The quantity w is the difference between the indications of the linear average detector and
Nav
the r.m.s. detector for Gaussian noise [19]; values for quasi-peak detection w are
Nqp
approximately 4 dB for Band B, and 6 dB for Bands C/D; for peak detection w is up to
Npk
12 dB, depending on measurement time.
The noise bandwidth B is close to the 3 dB bandwidth B of the measuring receiver. A rough
N 3
approximation is given by B = 1,1 B . See [19] for details about specific filter
N 3
implementations.
Considering a given preamplifier noise figure of 3 dB, it will be acceptable to achieve a
system noise figure 10 lgF = 4 dB, corresponding to a noise factor of 2,51. This requires
tot
that (F – 1)/g = 0,51, or g = (F –1)/0,51.
2 1 1 2
• For receivers with a built-in preamplifier, the resulting gain is g = 10,39, or G = 10,2 dB.
1 1
– 6 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
• For receivers without a built-in preamplifier, the resulting gain is g = 60, or G = 17,8 dB.
1 1
For a receiver without a built-in preamplifier, as described above, an external preamplifier with
a noise figure of 3 dB and a gain of 10 dB will give a system noise figure of 7 dB.
From the preceding examples, it can be seen that an improvement in sensitivity of 4 dB
requires a signal gain of around 10 dB for a receiver with a built-in preamplifier. For a receiver
without a built-in preamplifier, an improvement in sensitivity of 11 dB requires a signal gain of
almost 18 dB, and an improvement of 8 dB requires a signal gain of 10 dB. It is evident that a
system noise figure of 3,5 dB cannot easily be achieved with a preamplifier noise figure of
3 dB, because an excessive preamplifier gain would be necessary. Refer to Table J.1 for
example noise figures.
Because it will severely limit the system’s linearity performance, it is not advisable to use
preamplifiers with a gain of 30 dB or more.
Table J.1 – Examples of preamplifier and measuring
receiver data and resulting system noise figures
Preamplifier Measuring receiver System
Noise factor Noise figure Gain factor Gain Noise factor Noise figure Noise figure

10 lgF 10 lgF 10 lgF
F g G F
1 2 tot
1 1 1 2
dB dB dB dB
2 3 10,4 10,2 6,3 8 4
2 3 10 10 31,6 15 7
2 3 60 17,8 31,6 15 4
J.3 Linearity specifications and precautions in measurement
The dynamic range of preamplifiers is defined by the 1 dB compression point, 3 dB
compression point, and saturation point. To avoid distortion caused by the input signal, the
signal should ideally stay below the 1 dB compression point during the entire measurement
time.
An example screenshot of the transfer function of an amplifier is shown in Figure J.2. The
response of such an amplifier using a sinusoidal signal in time domain and frequency domain
is shown in Figure J.3. The numbers on the axes in Figures J.2, J.3 and J.4 are generic in
nature (quantization values) and do not represent specific units.
Figure J.3 shows that the sinusoidal signal is distorted in time domain, which is due to the
nonlinear effects of the preamplifier. The frequency domain display shows that the level is
decreased at 100 MHz, and that further harmonics exist. A corresponding simulation for a
broadband pulse is shown in Figure J.4.

© IEC 2014
1 000
-200
-400
-600
-800
-1 000
-2 000   -1 500   -1 000   -500     0     500    1 000   1 500   2 000
Quantized value – Input
IEC  1945/14
Figure J.2 – Transfer function of an amplifier
1 000
0 0
-500-500
-1 000
-1000
150 200 250 300 350 400
100 200 300 400 500 600 700
150      200      250      300      350       400
100     200     300     400     500     600     700
Sample n
Frequency / MHz
Sample n Frequency  (MHz)
IEC  1946/14
IEC  1947/14
Green = normalized input signal; red = output signal
Figure J.3 – Response for a sinusoidal signal
1 4001400
1 2001200
1 0001000
-200
-200
4980 4985 4990 4995 5000 5005 5010 5015 5020 5025 0 500 1000 1500 2000 2500
4 980 4 985 4 990 4 995 5 000 5 005 5 010 5 015 5 020 5 025
0       500      1 000      1 500     2 000     2 500
Frequency / MHz
Sample n
Frequency  (MHz)
Sample n
IEC  1948/14 IEC  1949/14
Green = normalized input signal; red = output signal
Figure J.4 – Response for an impulse
Quantized values
Quantized values
Quantized Values
Quantized Values
Quantized value – Output
Relative level  (dB)
Relative level (dB) Relative Level in dB
Relative Level in dB
– 8 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
Comparing Figures J.3 and J.4, it can be seen that the saturation level in the time domain is
exactly the same. However in the frequency domain the effects of saturation of the external
preamplifier are different. For the impulsive signal, the amplitude level is decreased,
invalidating the measurement result. For sinusoidal signals, the amplitude of the fundamental
is decreased, while further harmonics are generated by the nonlinear effect of the external
preamplifier; the measurement result is also invalidated.
The performance of the system, i.e. system noise level and overload capability, will depend
on the characteristics of both the preamplifier and the measuring receiver. For narrowband
signals, generally the 1 dB compression point of the preamplifier output exceeds the 1 dB
compression point of the measuring receiver input. Preselection of the measuring receiver will
improve system linearity for the measurement of broadband impulsive signals. Therefore, two
types of systems are taken into consideration: systems with, and without, preselection at the
measuring receiver input.
A broadband overload detector, which is effective at the input of some measuring receivers
without preselection, is used to detect signal levels at the 1 dB compression point of the first
mixer, to alert the user of linearity problems. The overload detector can also be used as an
indicator to assure valid measurement results. Similar overload detection is recommended for
wideband FFT based measuring systems to avoid over-range of the wideband A/D converter
(see J.4).
Further precautions for measurements include a prediction of the available overload factor for
the measurement of impulsive disturbances. Apart from gain versus frequency and noise
figure, the 1 dB compression point of the preamplifier and the complete system, consisting of
preamplifier and measuring receiver, shall be specified. For CISPR Bands C/D, the
relationship between the 1 dB compression point for sine wave signals and the peak value of
the broadband CISPR pulse signal with a bandwidth of 2 GHz gives a bandwidth factor F of
bw
85 dB [F = 20 lg(2 000/0,12)]. Figures J.5 and J.6 show the deviations from linearity of a
bw
preamplifier with a 1 dB compression point of 112 dB(V), for an unmodulated sine wave and
impulsive signals.
Sinewave signal: deviation from linearity
Sine wave signal: deviation from linearity
0,00
-0,50
-1,00
-1,50
-2,00
-2,50
deviation
-3,00
-3,50
-4,00
-4,50
-5,00
-5,50
100 102 104 106 108 110 112 114 116 118 120
InpuInput levelt Lev / del/dBB (uV(μV))
IEC  1950/14
Figure J.5 – Deviation from linear gain for an unmodulated sine wave (example)
Deviation/dB
© IEC 2014
-0,5
-1
-1,5
-2
Deviation for pos. pulse
-2,5
deviation for neg. pulse
-3
-3,5
-4
-4,5
-5
-5,5
-6
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Input Level/dB(uV)
IEC  1951/14
NOTE Using F = 85 dB, the peak value of the positive pulse signal with a PRF of 100 Hz is at around
bw
37 dB(V) 12 dB  85 dB = 134 dB(V), i.e. around 22 dB above the 1 dB compression point of Figure J.5.
12 dB is the quasi peak weighting factor, i.e. the difference between peak and quasi peak for a PRF of 100 Hz.
Figure J.6 – Deviation from linear gain for a broadband impulsive signal
as measured with the quasi-peak detector (example)
The flatness of the deviation curve for positive pulses in Figure J.6 is misleading, because the
amplifier nonlinearity is masked by the amplifier’s own intermodulation products. This effect
can be demonstrated using a band-stop filter with a notch depth of greater than 40 dB (band-
stop filter as specified in 4.6 of this standard) at the input of the preamplifier. For an
acceptable operation (error contribution less than 1 dB by intermodulation), the notch depth
shall remain at least 20 dB during the intermodulation test. The value of 20 dB is obtained
with quasi-peak measurements at a PRF of 100 Hz; the PRF of 100 Hz is a compromise.
Ideally the 20 dB notch depth would be needed for quasi-peak measurements at all PRFs.
This is shown in Figure J.7 for the preamplifier used above with 10 dB gain, where the 20 dB
depth is retained as long as the peak level of the input signal is less than 37 dB(V), and the
peak level of the output signal is less than 46 dB(V) (blue curve). For a PRF of 100 Hz, a
peak level of 37 dB(V) corresponds to a quasi-peak level of 25 dB(V). Thus while the 1 dB
compression point for the broadband impulsive signal in Figure J.6 “positive pulse” looks like
being at 37 dB(V) quasi-peak, the preamplifier is already overloaded. The input signal should
be at least 12 dB lower, i.e. at 25 dB(V) quasi-peak, to avoid excessive intermodulation.
In Figure J.6 the “positive pulse” also shows that a simple overload test with a switchable
10 dB attenuator at the preamplifier input may not properly indicate the overload in case of
impulsive signals, because the output level can still follow the input level, while the
preamplifier input signal is up to 20 dB above the 1 dB compression point. The simple test
may work for sine wave signals. A better characterization of the system with respect to
impulsive signals is obtained using the band-stop filter intermodulation test. If the band-stop
filter intermodulation test is not available, the 1 dB compression point of the preamplifier,
referred to its input, should be used to characterize the system.
NOTE The band-stop filter intermodulation test is intended to characterize the system, e.g. done by the system
provider. It would be impractical to use a band-stop filter test in each EMC test lab during an emission test.
Note that during the band-stop filter intermodulation test, it shall be assured that the
measuring receiver used as an indicator at the output of the preamplifier is not overloaded.
Figure J.8 shows that the notch depth result from a CISPR intermodulation test of a
measuring receiver with preselection still exceeds 30 dB with an input signal (quasi peak) of
55 dB(V), which corresponds to an input level (quasi peak) of 45 dB(V) to a 10 dB
preamplifier. Using a measuring receiver with built-in broadband preamplifer may not show
Deviation / dB
Deviation/dB
– 10 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
the linearity of the external preamplifier correctly, due to overload of the measuring receiver,
as shown in Figure J.9 and J.10, whereas with preselection the output will be linear.
RBW 120 kHzMarker 1 [T2 ]
MT 1 s     19.16 dBµV
Att 5 dB PREAMP OFF  824.300000000 MHz
ddBBµµVV
1 GHz
1 PK
VIEW
2 PK
VIEW
3 PK
CLRWR
6DB
DC
636 MHz 1 GHz
IEC  1952/14
Figure J.7 – Screenshot of a band-stop filter test for a preamplifier at around 818 MHz

RBW 120 kHz
MT 10 ms
Att 5 dB PREAMP OFF
ddBBµµVV
1 GHz
1 PK
VIEW
2 PK
CLRWR
6DB
DC
636 MHz 1 GHz
IEC  1953/14
Figure J.8 – Band-stop filter test result with the measuring receiver at 818 MHz

© IEC 2014
IEC  1954/14
Figure J.9 – Band-stop filter test results for the same 10 dB preamplifier but a different
receiver with preselection (black) and without preselection (blue)
IEC  1955/14
NOTE A 15 dB attenuator between external preamplifier and receiver was used to avoid overload of the receiver
without preselection; however the receiver’s noise level then hides the notch.
Figure J.10 – Band-stop filter test results for the same 10 dB preamplifier but with the
receiver of Figure J.9 with preselection (black) and without preselection (green)
When an external broadband preamplifier is used with a measuring receiver, the user cannot
expect proper weighting of broadband impulsive signals by such a measuring system using
average, rms-average and quasi-peak detection at low pulse repetition frequencies.
Therefore, the user shall determine the operating range between noise level and the 1 dB
compression point for broadband impulsive signals for the peak detector of the measurement
system. This determination allows a prediction of the lowest PRF for proper weighting of
broadband impulsive signals using each individual detector.

– 12 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
Figure J.11 shows the weighting functions of the detectors specified in CISPR 16-1-1 for
CISPR Bands C/D, and an example ‘Noise’ line to illustrate the operating range between
noise level and 1 dB compression point. In the example, the peak detector noise level is
15 dB below the 1 dB compression point. For the quasi-peak detector, the noise level is
approximately 5 dB lower, i.e. the operating range is approximately 5 dB wider. For the rms-
average and average detectors, the noise level is approximately 10 dB lower, which increases
the operating range to about 25 dB in the example.
To draw the noise line shown in Figure J.11, the peak level V is used from the band-stop
p
filter test in Figure J.7 and the average detector noise level V determined. The difference
Nav
V – V marks the crossing of the “Noise” line with the “Average” line. For the 10 dB
p Nav
preamplifier above, V = 37 dB(V), V = –14 dB(V) for a noise figure of 4 dB and V – V
p Nav p Nav
= 51 dB. The noise line in Figure J.11 is drawn from an example where V – V = 27 dB.
p Nav
Weighting functions with noise levels
Weighting
(for Bands C and D)
factor/dB
0 Peak
Average
RMS-AV
Quasi-Peak
-10
Peak
Noise
-20
Noise
-30
Quasi-Peak
-40
-50
Average
RMS-AV
-60
f /Hz
p
-70
1 10 100 1 000 10 000 100 000 1 000 000
IEC  1956/14
Figure J.11 – Weighting functions of the various CISPR detectors with a noise curve to
illustrate the remaining operating ranges for broadband impulsive signals (example)
From Figure J.11, the critical PRF can be seen at which the impulsive signal level, with peak
level at the 1 dB compression point, is equal to the noise level. However for an accurate
measurement, the signal level needs to be approximately 6 dB above the noise level (the
actual value depends on the PRF). As a consequence, in this example quasi-peak
measurements can be carried out above a PRF of about 60 Hz. For the rms-average and
average detectors, the critical PRFs are near 1 kHz and 10 kHz, respectively. For practical
measurements, a linearity check is recommended using the weighting factor at the critical
PRF. For this example, the linearity check is as follows:
a) For the quasi-peak measurement: the critical PRF of 60 Hz is exceeded if the difference
between peak and quasi-peak values is less than 15 dB.
b) For the rms-average and average measurements: the critical PRFs of 1 kHz and 10 kHz
are exceeded if the difference between peak and rms-average or average detector results
are less than 20 dB.
However, if the measurements are made close to the noise level, the differences might be
reduced by the noise level, which will give the impression of PRFs higher than actual.

© IEC 2014
J.4 Detecting the overload of an external preamplifier in a wideband FFT based
measuring system
Detecting whether the preamplifier is in the linear range during the measurement can be
performed for sinusoidal as well as impulsive signals, by taking the maximum of the
preamplifier output signal then comparing it with a given threshold level corresponding to the
1 dB compression point. The maximum (positive) and minimum (negative) voltage of the
signal in the time domain shall be sampled continuously during the measurement time, and
compared to that threshold level. The 1 dB compression point is defined for a sinusoidal
signal yielding an output 1 dB lower than expected, as shown in Figure J.5.
During a measurement, a measuring apparatus that digitizes the signal of the output of the
external preamplifier can be used to detect whether an over-range has occurred. For the
preceding example, a threshold level of a normalized value in Figure J.2 ‘Input’ of about 900
would be appropriate to avoid nonlinear effects. The threshold level should be identified by
the system manufacturer depending on the application. For example, the measurement of
harmonics of intentional radiators requires a better linearity (lower threshold) than the
measurement of impulsive disturbance. A measuring apparatus that digitizes the input signal
shall fulfil the following requirements, to allow a correct decision:
a) continuous (gapless) acquisition during the measurement time;
b) selectable threshold level;
c) broadband acquisition of the entire measurement band, e.g. up to 1 GHz.
Typical instruments that fulfil such requirements include broadband FFT-based measurement
instruments with over-range detection, as described in CISPR/TR 16-3, and oscilloscopes in
single-shot trigger mode. Over-range detection is used to avoid exceeding the operating
range of the wideband A/D converter.
Bibliography
Add, after the existing reference [14], the following new references [15], [16], [17], [18] and
[19]:
[15] CISPR 15, Limits and methods of measurement of radio disturbance characteristics of
electrical lighting and similar equipment
[16] CISPR 22, Information technology equipment – Radio disturbance characteristics –
Limits and methods of measurement
[17] CISPR 25, Vehicles, boats and internal combustion engines – Radio disturbance
characteristics – Limits and methods of measurement for the protection of on-board
receivers
[18] CISPR 32, Electromagnetic compatibility of multimedia equipment – Emission
requirements
[19] RAUSCHER, C., Fundamentals of Spectrum Analysis, 5th edition, 2011,
ISBN 978-3-939837-01-5 (available from Rohde & Schwarz Bookshop,
http://www.books.rohde-schwarz.com/).

_____________
– 14 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
AVANT-PROPOS
Le présent amendement a été établi par le sous-comité CIS/A: Mesures des perturbations
radioélectriques et méthodes statistiques, du comité d'études CISPR de la CEI: Comité
international spécial des perturbations radioélectriques.
Le texte de cet amendement est issu des documents suivants:
FDIS Rapport de vote
CIS/A/1070/FDIS CIS/A/1075/RVD

Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant
abouti à l'approbation de cet amendement.
Le comité a décidé que le contenu de cet amendement et de la publication de base ne sera
pas modifié avant la date de stabilité indiquée sur le site web de l'IEC sous
"http://webstore.iec.ch" dans les données relatives à la publication recherchée. A cette date,
la publication sera
• reconduite,
• supprimée,
• remplacée par une édition révisée, ou
• amendée.
IMPORTANT – Le logo "colour inside" qui se trouve sur la page de couverture de cette
publication indique qu'elle contient des couleurs qui sont considérées comme utiles à
une bonne compréhension de son contenu. Les utilisateurs devraient, par conséquent,
imprimer cette publication en utilisant une imprimante couleur.

_____________
4.4.1 Réponse en amplitude (étalonnage absolu)
Ajouter, après le premier alinéa existant, le nouveau texte suivant:
Lorsque des préamplificateurs externes sont utilisés, se référer à l'Annexe J pour les
exigences applicables.
7.5.2 Réponse en amplitude
Ajouter, après l'alinéa et la Note existants, le nouveau texte suivant:
Lorsque des préamplificateurs externes sont utilisés, se référer à l'Annexe J pour les
exigences applicables.
Ajouter, après l'Annexe I existante, la nouvelle annexe suivante:

© IEC 2014
Annexe J
(normative)
Exigences relatives à l'utilisation d'un préamplificateur
externe avec un récepteur de mesure
J.1 Généralités
L'utilisation d'un préamplificateur externe à l'entrée d'un récepteur de mesure doit être
soigneusement étudiée, car, bien que cela améliore la sensibilité du système, il peut en
résulter une invalidation de la conformité du système aux exigences relatives à la surcharge
présentées dans la présente norme. En outre, un préamplificateur externe peut invalider
l’aptitude à l'utilisation d'un analyseur de spectre sans présélection pour la mesure des
signaux impulsionnels avec des fréquences de répétition des impulsions descendant jusqu'à
20 Hz en utilisant le détecteur de quasi-crête.
Par conséquent, l'opérateur d'un système de mesure qui comporte un préamplificateur
externe doit déterminer les limitations du système et doit effectuer des vérifications de
linéarité pour le système d'essai. Les résultats de mesures automatisées obtenus avec des
préamplificateurs externes ont besoin d'être contrôlés par une vérification manuelle finale de
la linéarité. Les informations données dans la présente annexe fournissent des conseils pour
l'utilisateur des systèmes de mesure d'émissions.
J.2 Considérations concernant la conception d'un système optimal de mesure
d'émissions
Intérieurement, les récepteurs de mesure sont conçus pour obtenir une sensibilité optimale
tout en prévenant les surcharges. La présélection intégrée dans le récepteur de mesure
prévient la surcharge par des signaux impulsionnels. En dépit de la présélection, les
récepteurs de mesure n'ont habituellement aucune réserve de linéarité pour les mesures de
quasi-crête d'une seule impulsion au-dessus de la plage de lecture spécifiée. L'absence de
présélection dans les récepteurs de mesure cause des problèmes avec la détection de quasi-
crête des signaux impulsionnels avec une valeur basse de la PRF ('Pulse Repetition
Frequency' («Fréquence de répétition des impulsions»)).
L'utilisation d'un préamplificateur externe à large bande ne doit être envisagée qu'après avoir
épuisé toutes les autres mesures possibles (par exemple, l'utilisation de récepteurs de
mesure préamplificateurs intégrés, l'utilisation d'antennes de gain suffisant, ou l'utilisation de
câbles de raccordement à faibles pertes) permettant d'améliorer la sensibilité du système. Un
préamplificateur externe a besoin d'être ajouté seulement si la limite des perturbations et
l'ensemble de toutes les émissions prévues et de toutes les émissions devant être mesurées
sont très proches du niveau de bruit du système, par exemple, pour la conformité aux limites
de perturbations rayonnées de Classe 5 selon la CISPR 25 [17]. Si des niveaux élevés sont
prévus pour les signaux d'émissions ou les bruits ambiants, les préamplificateurs externes ne
sont pas recommandés.
L'expérience montre que les préamplificateurs externes ne sont pas nécessaires pour les
mesures de perturbations rayonnées en ce qui concerne les limites de Classe B selon la
CISPR 11, la CISPR 22 [16] et la CISPR 32 [18], à une distance de mesure soit de 3 m, soit
de 10 m, lorsque sont utilisés les récepteurs de mesure à préamplificateurs intégrés avec
présélection et câbles d'antenne à faibles pertes. La même situation s'applique pour ce qui
concerne les mesures des perturbations rayonnées selon la CISPR 14-1, la CISPR 15 [15], et
les normes d'émissions génériques, ainsi que pour ce qui concerne les mesures de puissance
perturbatrice.
Les préamplificateurs externes ne sont pas recommandés pour les mesures de perturbations
conduites effectuées en dessous de 30 MHz; leur utilisation peut générer des harmoniques en

– 16 – CISPR 16-1-1:2010/AMD2:2014
© IEC 2014
présence de perturbation de haut niveau à des fréquences inférieures à 150 kHz, lorsque de
nombreuses normes d'émission ne spécifient pas de limites de perturbations.
Si un préamplificateur externe est ajouté pour améliorer la sensibilité, les aspects suivants
ont besoin d'être pris en considération:
a) les préamplificateurs ont une grande largeur de bande, c'est dire qu'ils sont susceptibles à
la surcharge par les signaux impulsionnels et les signaux à bande étroite de niveau élevé;
b) les préamplificateurs peuvent générer des produits d'intermodulation et des harmoniques;
cela est notamment important lorsque les mesures sont effectuées sur un OATS ("Open
Area Test Site" («Site d'essai ouvert étalonné»)) et/ou en présence d'un matériel
d'émission radio;
c) les préamplificateurs augmentent le niveau de signal à l'entrée du récepteur et peuvent
donc surcharger les étages d'entrée du récepteur, état qui ne peut pas être totalement
évité par la présélection intégrée du récepteur;
d) le gain de sensibilité sera inférieur au gain de niveau de signal, ce qui limite la plage
dynamique de la combinaison préamplificateur/récepteur;
NOTE 1 Le gain de sensibilité est compris comme étant la différence entre le chiffre de bruit sans
préamplificateur et le chiffre de bruit du système avec préamplificateur.
e) pour une sensibilité maximale dans la bande de fréquences au-dessus de 1 GHz, le
préamplificateur est monté/relié directement à l'antenne de mesure;
f) l'utilisation d'un préamplificateur externe exige que le résultat de mesure rende compte de
la caractéristique précise du gain en fonction de la fréquence;
g) l'incertitude du gain en fonction de la température et du vieillissement, ainsi que
l'incertitude complémentaire de discordance entre le port de sortie du préamplificateur et
le port d'entrée du récepteur, doivent être incluses dans le bilan d'incertitude pour la
mesure; l'impédance d'entrée, dans le cadre de la présente norme, doit être conforme aux
exigences pour le récepteur et doit être incluse dans le bilan d'incertitude de mesure;
h) pour la bande E selon le CISPR, un système constitué d'un préamplificateur externe et
d'un récepteur de mesure doit être conçu de façon qu'il ne puisse pas être surchargé par
des signaux des bandes de fréquences inférieures, et/ou par un signal quelconque dont
des signaux hors bande ou parasites doivent être mesurés; par exemple, le signal ISM
d'un four à micro-ondes ne doit pas conduire le système à la surcharge.
Le gain de sensibilité est déterminé en utilisant les grandeurs et équations suivantes:
P
ie
F= et, (J.1)
kT B
P
o
pour un amplificateur, (J.2)
F=
gkT B
où
F est le facteur de bruit, avec 10 lgF = chiffre de bruit (souvent désigné par le symbole NF);
P est la puissance de bruit équivalente en entrée;
ie
P est la puissance de bruit en sortie;
o
G/10
g est calculé à partir du gain, G = 10 lgg, soit g = 10
-23 -21
k est la constante de Boltzmann = 1,38×10 Ws/K et kT = 4×10 W/Hz
T est la température ambiante absolue de référence (293 K);
B est la largeur de bande de bruit (du récepteur de mesure, par exemple).

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