GB/T 12572-2008 PDF English
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GB/T 12572-2008: Universal requirements and measurement methods of parameters for radio transmitting equipment
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GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 33.060.20
M 36
Replacing GB/T 12572-1990, GB/T 12046-1989, GB 13421-1992
Universal Requirements and Measurement Methods of
Parameters for Radio Transmitting Equipment
ISSUED ON: JUNE 30, 2008
IMPLEMENTED ON: JANUARY 1, 2009
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms, Definitions, Symbols and Abbreviations ... 5
4 Frequency Tolerance of Transmitting Equipment ... 10
4.1 Basic Requirements and Ultimate Design Goals ... 10
4.2 Measurement Methods ... 14
5 Determination of Necessary Bandwidth of Transmitting Equipment ... 15
5.1 AM Emission Signal ... 15
5.2 FM Emission Signal ... 15
5.3 Pulse Modulated Emission Signal ... 15
6 Requirements for Spurious Domain Emission Power Limits of Transmitting
Equipment ... 21
6.1 Applicable Range of Limits ... 21
6.2 Requirements for Spurious Domain Emission Power Limits ... 23
7 Measurement Methods for Spurious Domain Emission Power ... 28
7.1 Measurement Receiver... 28
7.2 Measurement Requirements ... 28
7.3 Measurement Methods ... 29
8 Measurement Methods for Spurious Emission Power of Radar System ... 32
8.1 Overview ... 32
8.2 Measurement System Resolution Bandwidth and Detection Parameter Settings ... 33
8.3 Direct Measurement Method ... 33
8.4 Indirect Measurement Methods ... 37
Appendix A (informative) Units and Conversion Relations of Spurious Domain
Emission ... 40
Appendix B (normative) Supplementary Provisions for Determining the Limits of
Spurious Domain Emissions and Out-of-band Domain Emissions ... 43
Appendix C (normative) Specified Values of Reference Measurement Bandwidth of
Fixed Services ... 47
Appendix D (normative) Specified Values of Reference Measurement Bandwidth of
Land Mobile Services ... 49
Appendix E (normative) Requirements for Test Site ... 51
Bibliography ... 53
Universal Requirements and Measurement Methods of
Parameters for Radio Transmitting Equipment
1 Scope
This Standard specifies the frequency tolerance, spurious domain emission power limit
requirements and general measurement methods for radio transmitting equipment in the
frequency band 9 kHz ~ 300 GHz. Meanwhile, it also determines the calculation formulas for
the necessary bandwidths of different radio emission categories.
This Standard is applicable to radio transmitting equipment of different power levels and
categories in the frequency band 9 kHz ~ 300 GHz. However, it does not apply to the detection
of spurious domain emission indicators of safety services and special services, for example,
survival craft stations or floating transmitters.
2 Normative References
The clauses in the following documents become clauses of this Standard through reference in
this Standard. In terms of references with a specified date, all subsequent amendments
(excluding corrigenda) or revisions do not apply to this Standard. However, parties to an
agreement based on this Standard are encouraged to explore the possibility of adopting the latest
versions of these documents. In terms of references without a specified date, the latest version
applies to this Standard.
GB 9254-1998 Information Technology Equipment - Radio Disturbance Characteristics -
Limits and Methods of Measurement
GB/T 6113.1-1995 Specifications for Radio Disturbance and Immunity Measuring Apparatus
3 Terms, Definitions, Symbols and Abbreviations
The following terms, definitions, symbols and abbreviations are applicable to this Standard.
3.1 Terms and Definitions
3.1.1 frequency tolerance
The maximum allowable deviation of the center frequency of the frequency band occupied by
the emission from the assigned frequency, or the characteristic frequency of the emission from
the reference frequency. The frequency tolerance is expressed in ( 106) or hertz.
3.1.2 assigned frequency
the frequency meter or spectrum analyzer through an attenuator or appropriate coupling
device (the spectrum analyzer of frequency meter shall have sufficient frequency
accuracy);
---Set the operating frequency of the transmitter and set the transmitter to operate in
continuous wave (CW) state;
---On the premise that the transmitter maintains normal operating status, read the
frequency value as f. In accordance with the following formula, calculate the frequency
deviation:
Deviation = (f f0) / f0, in which, f0 is the nominal transmission frequency;
---For systems like TDMA, if the system cannot output a single carrier, a vector signal
analyzer with a high-stable time base shall be used for testing through the modulation
domain.
5 Determination of Necessary Bandwidth of Transmitting
Equipment
The following provisions clarify the calculation formulas, calculation examples and
corresponding emission identification of necessary bandwidths for various emission categories.
5.1 AM Emission Signal
The calculation formula, calculation example and corresponding emission identification of the
necessary bandwidth of AM emission signal are shown in Table 3.
5.2 FM Emission Signal
The calculation formula, calculation example and corresponding emission identification of the
necessary bandwidth of FM emission signal are shown in Table 4.
In the multi-channel emission signal of FM frequency division multiplexing (FM / FDM), the
calculation and determination of the multiplication factor used for the D value (peak frequency
deviation) are shown in Table 5.
5.3 Pulse Modulated Emission Signal
The calculation formula, calculation example and corresponding emission identification of the
necessary bandwidth of pulse modulated emission signal are shown in Table 6.
7 Measurement Methods for Spurious Domain Emission
Power
7.1 Measurement Receiver
During the test, a measurement receiver or spectrum analyzer that satisfies the requirements of
this test may be selected for the measurement of the spurious emission power of the transmitter.
The basic requirements that shall be satisfied are:
a) All measurement receivers must have r.m.s and peak detection modes.
b) Provide multiple resolution bandwidth selection modes. During measurement, the
resolution bandwidth of the measurement receiver (referring to the intermediate
frequency final stage 3 dB bandwidth) shall be as close as possible to the reference
measurement bandwidth recommended in 6.2.1. For measurement of emissions close
to the operating frequency, a narrower resolution bandwidth needs to be selected.
When the selected resolution bandwidth is much smaller than the reference
measurement bandwidth, the power measurement result is the integrated power within
the reference measurement bandwidth. When the selected resolution bandwidth is
much larger than the reference measurement bandwidth, the broadband spurious
emission power measurement result is the normalized power corresponding to the
bandwidth ratio. However, the above principles are not suitable for spurious domain
emission power measurement of discrete spectrum signals. In addition, the resolution
bandwidth calibration factor must be provided based on the specific resolution
bandwidth type of the measurement receiver (i.e., 6 dB resolution bandwidth) and
the specific measurement spurious emission signal category (i.e., pulse signal or
Gaussian noise).
c) The video bandwidth cannot be smaller than the resolution bandwidth, and the video
bandwidth is usually selected to be 3 ~ 5 times the resolution bandwidth.
d) Provide a suitable filter waveform factor. The size of the filter waveform factor is
mainly determined by the filter category selected by the receiver. In principle, try to
use a highly selective filter. Generally, the typical range of the filter waveform factor
(60 dB/3 dB ratio) of the spectrum analyzer using a 4-stage or 5-stage analog filter
circuit is 5 : 1 to 15 : 1, and the typical value of the Gaussian digital filter waveform
factor is 4.6.
7.2 Measurement Requirements
7.2.1 Resolution bandwidth requirements
In accordance with the provisions of 6.1 in this Standard, usually, the spurious emission power
measurement starts at a frequency beyond the necessary bandwidth of the emission that is
separated by 250% from the emission operating frequency. However, in some cases,
measurement using this frequency limit will include non-spurious emission signals, resulting
in erroneous measurement results, and it will be necessary to re-determine this frequency limit.
The measurement bandwidth adopts the reference measurement bandwidth of spurious
emission, and it is necessary to adjust and re-determine the frequency measurement limit that
is different from the necessary emission bandwidth of 250%. To adopt the frequency limit of
the necessary bandwidth of the emission that is separated by 250% from the emission
operating frequency, it is necessary to select a smaller measurement resolution bandwidth. The
correlation between the measurement resolution bandwidth and the spurious domain emission
measurement frequency limit (out-of-band domain limit) is shown in Formula (1):
Measurement resolution bandwidth (RBW) (filter waveform factor 1) 2 (out-of-band
limit necessary bandwidth/2) ……………………………………….…………………… (1)
It can be seen from Formula (1) that if the measurement resolution bandwidth has been
determined, then, calculate and determine the spurious domain emission measurement
frequency limit; and vice versa. For example, for a measurement signal with a necessary
bandwidth of 16 kHz, the frequency limit (i.e., 40 kHz) of the necessary emission bandwidth
of 250% does not change, and the measured intermediate-frequency filter waveform factor
(60 dB/3 dB) is equal to 15 : 1. Utilize Formula (1) to calculate and obtain that the
measurement resolution bandwidth (RBW) is 4.5 kHz (RBW 2 (40 16/2)/(15 1) ≌ 4.5
kHz). On the contrary, for the same measurement signal, it is determined that the measurement
resolution bandwidth is 100 kHz, then utilize Formula (1) to calculate and obtain that the out-
of-band frequency limit (OOB) is 708 kHz (OOB 100 (15 1)/2 + 16/2 = 708 kHz).
7.2.2 Requirements for measurement sensitivity
Under certain conditions, adopting a conventional spectrum analyzer and considering the loss
of the connecting cable will cause the measurement sensitivity to not satisfy the test
requirements. Using a low-noise amplifier can solve this problem. In extreme situations in the
frequency band above 26 GHz, the test system usually uses an external mixer. Sometimes the
test system cannot provide the appropriate sensitivity to measure the equipment under test (EUT)
under specific modulation conditions. The calibration measurement of the spurious domain
emission power can be carried out under the carrier frequency state, and the measurement
results must consider the modulation loss of the EUT.
7.2.3 Modulation requirements
Under normal test conditions, spurious domain emission power measurement is best performed
in the maximum modulation mode of the EUT. In order to detect certain specific spurious
emission frequencies, it is sometimes necessary to carry out measurements without modulation.
However, it shall be noted that in this case, all spurious emission frequencies may not be
detected, and new spurious emission products may be generated after modulation.
7.3 Measurement Methods
7.3.1 Measurement method 1---spurious domain emission power measurement provided
with antenna ports
Ksf---the calibration factor of the test system at the measurement frequency f, expressed in (dB);
Gf---the standard gain of the measurement antenna at the measurement frequency f, expressed
in (dB);
f---the spurious radiated emission frequency point, expressed in (MHz);
D---the measurement distance between the transmitter antenna and the measurement standard
antenna, expressed in (m).
7.3.2.3 Alternative measurement method
When alternative measurement method is adopted, calibration of individual components of the
test system is not required. In accordance with Figure 2 of test connection, change the height
and polarization mode of the measurement antenna. The measurement receiver records the
maximum test value of all spurious radiated emission power of the transmitter under test. Then,
use the calibration generator and alternative antenna to equivalently replace the transmitter
under test; repeat the above-mentioned measurement process, and meanwhile, adjust the output
frequency and level of the calibration generator, so that the measurement receiver can obtain
consistent spurious radiated emission power test values for all corresponding frequencies. In
this way, the output power from the calibration generator at each recording frequency plus the
alternative antenna gain equals the e. i. r. p. measurement values of all spurious emissions from
the transmitter under test.
7.3.3 Spurious radiated emission measurement of designated cabinet
The designated cabinet refers to the main part of the transmitting equipment that does not
contain the transmitting antenna. Using the measurement method of 7.3.2 can complete the
spurious radiated emission power measurement of the transmitter cabinet. In the specific
measurement, use a standard load to replace the transmitter antenna under test, and use the
measurement method of 7.3.2 to obtain the e. i. r. p. measurement value of spurious radiated
emission of the transmitter cabinet. However, during the measurement process, it shall be
ensured that the radiated emissions of the alternative standard load and its RF cable do not affect
the measurement results.
8 Measurement Methods for Spurious Emission Power of
Radar System
8.1 Overview
For the spurious emission power measurement of radar system, two methods are provided:
direct measurement and indirect measurement.
The direct measurement method is applicable to spurious emission power measurement of
integrated design radar systems that are inconvenient to be measured at intermediate points, for
example, those radar systems that use distributed transmitter arrays to constitute a shared
antenna, etc.
The indirect measurement method is to respectively measure each constituent part of the radar
system and add them together to obtain the final measurement result. It is usually specified that
the radar system under test is separated at the “coupling” to measure the spurious emission
output power of the transmitter at the “coupling” and synthesize the gain characteristic value of
the transmitting antenna. When the indirect measurement method is used, the measurement
frequency band can be easily extended to 40 GHz or a higher frequency band.
Under the same measurement conditions, re-measure the specified radar emission spectrum. At
any given frequency, the repeated measurement error of these measurement methods is required
to be within 2 dB.
8.2 Measurement System Resolution Bandwidth and Detection Parameter Settings
When conducting the spurious emission measurement on a radar system, the measurement
resolution bandwidth must be calculated and determined based on the specific radar system.
For three common types of pulse modulated radars used for radio navigation, radio positioning,
acquisition, tracking and other radio determination functions, the measurement resolution
bandwidth is calculated as follows:
---For fixed-frequency non-pulse coded radar, it is equal to the reciprocal of the radar pulse
width (i.e., if the radar pulse width is 1 s, then, the measurement resolution bandwidth
is 1/(1 s) = 1 MHz);
---For fixed-frequency phase-coded pulse radar, it is equal to the reciprocal of the phase
slice width (i.e., if the phase slice width is 2 s, then, the measurement resolution
bandwidth is 1/(2 s) = 500 kHz);
---For frequency modulation (FM) or chirp frequency scanning radar, it is equal to the
square root value of the frequency scanning width divided by the pulse length (i.e., if
the frequency scanning range is from 1,250 MHz to 1,280 MHz or 30 MHz, the pulse
length is 10 s, then, the measurement resolution bandwidth is (30 MHz/10)1/2 = 1.73
MHz).
When the measurement resolution bandwidth determined in accordance with the above method
is greater than 1 MHz, then, the measurement resolution bandwidth shall be 1 MHz. The video
measurement bandwidth shall be greater than or equal to the measurement resolution bandwidth;
the detection mode is set to positive peak detection.
8.3 Direct Measurement Method
8.3.1 Composition and requirements of measurement system
The typical configuration and measurement block diagram of the measurement system for
direct measurement are shown in Figure 3, and the radar antenna can be normally rotated. The
functions and requirements of each constituent part of the measurement system are as follows:
a) Select a parabolic antenna with a special-purpose feed source as the measurement
receiving antenna. The measurement receiving antenna shall have a good broadband
frequency response, at least satisfying the basic requirements of the measurement
frequency band; the antenna gain must be high; the main lobe beam of the antenna
must be narrow; the polarization selection of the antenna feed source must maximize
the response level of the received radar signal. When the polarization mode of the
radar signal cannot be determined, it is best to use circular polarization as the antenna
feed source. In addition, a low-loss RF cable shall be selected as the connecting cable
between the measurement antenna and the RF front-end of the measurement system.
If the environment and site allow, reduce the connection length of low-loss RF cable
as much as possible.
b) Configure special-purpose RF front-end part. The RF front-end consists of three parts:
a variable RF attenuator, a frequency-tuned bandpass filter (tuned tracking variable
filter), and a low-noise amplifier (LNA). Each component shall have good broadcast
frequency response characteristics. The RF attenuator shall provide a variable
attenuation range with a fixed step size. The use of RF attenuators can extend the
dynamic range of the measurement system. The RF attenuator can be manually
controlled or automatically controlled by a computer. When measuring the low-level
spurious emission spectrum beyond the radar signal band, using a frequency-tuned
bandpass filter can suppress the high-power radar fundamental frequency signal and
achieve the linear characteristic measurement requirements of the measurement
system. The frequency-tuned bandpass filter can be manually controlled, or it can be
automatically controlled by a computer or a frequency-controlled voltage generated
by the spectrum analyzer. Using a low-noise amplifier can enhance the receiving
sensitivity of the measurement system, and usually, it can reduce the noise coefficient
by about 10 dB ~ 15 dB.
c) Select a wide-band spectrum analyzer to complete the measurement of all spurious
emission signals in the frequency band that needs to be measured. The computer is
controlled through the GPIB bus and adopts the step frequency algorithm to complete
automatic measurement. Reasonably set the attenuator and preselector parameters
built into the spectrum analyzer, so as to ensure that the spectrum analyzer is used to
satisfy the measurement requirements for sensitivity and linear dynamic range of the
measurement system.
---Set the spectrum analyzer frequency span: 0 Hz. (the spectrum analyzer is set to work
in the time domain)
---Set the spectrum analyzer scanning time: greater than the radar beam rotation gap. (For
example, if the radar rotational speed is 40 r. p. m., that is, each rotation is 1.5 s, then,
the scanning time needs to be greater than 1.5 s, usually 2 s is selected)
The system measurement procedure is:
a) The radar antenna system rotates in accordance with the normal requirements. In
accordance with the above requirements, connect the measurement system and set the
measurement parameters. Start the measurement of the first set of data. Each set of
data contains measured power levels and corresponding frequency points. For
example, if the measurement result of the first set of data is a power value of 93 dBm
measured at the 2,000 MHz frequency point, this power value is the radar emission
power level corresponding to the measurement frequency point, which is obtained
when the measurement gap is larger than the radar rotational speed period and the
frequency span is 0 Hz. The test displays the time / level trajectory of the radar beam
rotation on the spectrum analyzer display screen, where the maximum trajectory level
value represents the received power level value when the radar beam is facing the
measurement system. The control computer automatically records the maximum
received power level value. In addition, the calibrated measurement result is obtained
from the gain calibration characteristic value of the above-mentioned measurement
system.
b) Set the measurement frequency to the second frequency point and start the
measurement of the second set of data. The measurement center frequency is best set
to the result of the first measurement frequency plus the measurement bandwidth (if
the first measurement frequency is 2,000 MHz and the measurement bandwidth is 1
MHz, then, the second measurement center frequency is 2,001 MHz). At the second
measurement frequency, repeat the measurement process in Step 1 to obtain the
second set of calibrated measurement results.
c) Step by step in sequence in accordance with the measurement bandwidth, repeat the
measurement process of Step 1 and Step 2, until all the frequencies that need to be
measured are tested, and the spurious emission power measurement results of all radar
systems corresponding to each measurement frequency are obtained.
NOTE: adopt the step measurement method, when the measurement frequency is close to the
central fundamental wave frequency of the radar system, a fixed RF attenuator can be
inserted at the front end of the measurement system to increase the attenuation of the
fundamental wave signal and expand the dynamic measurement range of the measurement
system, so as to achieve the measurement of adjacent low-power spurious emission signals.
Undoubtedly, the best mode is to insert a fundamental-wave trap or bandpass filter at the
front end of the measurement system to suppress the fundamental wave high-power signal
without affecting the measurement of low-power spurious emission signals.
Appendix A
(informative)
Units and Conversion Relations of Spurious Domain Emission
A.1 Representation of Spurious Domain Emission
Under the specified measurement bandwidth conditions, the size of spurious domain emissions
is usually expressed in units, such as: power level, electric field intensity at a specified
measurement distance, power flux density (pfd) at a specified measurement distance, etc.
A.1.1 Power magnitude
There are many modes to express the power level of the measured spurious emissions, which
mainly depend on the measurement connection mode and measurement method. Commonly
used expressions include:
1) Feed-in antenna power (p. s. a): often used in equipment with antenna connectors
operating below 30 MHz and above 30 MHz. The feed-in antenna power
measurement reflects the actual power level of the spurious signal transmitted by the
transmitter to the antenna. However, it does not consider the impact of the antenna
and cannot obtain the radiated emissions at non-antenna operating frequencies.
2) Equivalent isotropic radiated power (e. i. r. p.): mainly used in equipment operating
above 30 MHz (more often above 80 MHz). Equivalent isotropic rated power
measurement better reflects the radiation of spurious emission signals from the
transmitter system (including the antenna part) and the harmful interference caused
to other wireless services. However, the conversion relations between the feed-in
antenna power and the equivalent isotropic radiated power are not easy to obtain,
mainly because the radiation characteristics beyond the antenna’s operating frequency
band are unknown. Equivalent isotropic radiated power is a power parameter
commonly used in integrated antenna transmitting equipment to represent spurious
emission characteristics.
3) Effective radiated power (e. r. p.): the difference between e. r. p and e. i. r. p. is that a
half-wave dipole tuned antenna is used instead of an isotropic antenna. The
conversion relations between them are as follows: e. i. r. p. (dBm) = e. r. p. (dBm) +
2.15.
A.1.2 Electric field intensity
It is theoretically possible to measure the interference field strength E or H value of spurious
emissions at the receiving antenna. However, it is extremely difficult to obtain the
corresponding relations between e. i. r. p. and electric field intensity suitable for various
occasions, because the phenomena of radio wave propagation and inductive coupling are
extremely complex. On the test site, the electric field intensity value is usually measured at a
specified distance. For the measurement of unwanted radiated emissions and interference field
strength from radio equipment and information technology equipment (ITE), CISPR stipulates
that the electric field intensity value shall be measured at a distance of 10 m on a calibrated
open area test site (OATS) with a flat reflective ground.
A.1.3 Power flux density
Power flux density (pfd) is suitable for spurious emission measurements from transmitting
equipment operating above 1 GHz, such as: wireless satellite links and radio astronomy services.
A.2 Parameter Units and Mutual Relations
A.2.1 Parameter units
The international standard measurement unit of power is watt (W). The power parameters often
used in spurious emission measurements are as follows: feed-in antenna power (p. s. a.),
equivalent isotropic radiated power (e. i. r. p.) and effective radiated power (e. r. p.). The power
units include: dBpW, dBnW, dBm, dBW or power density of a specified reference bandwidth.
The standard unit of electric field intensity E is V/m, and the commonly used units are V/m
and dBV/m. The standard unit of magnetic field intensity H is A/m, and the commonly used
units are A/m and dBA/m. The standard unit of power flux density (pfd) is W/m2, and the
commonly used unit is dBW/m2.
A.2.2 Interrelations among different units
Under ideal conditions (referring to satisfying free space propagation and far-field measurement
conditions), the mutual conversion relations among electric field intensity, measurement
distance, equivalent isotropic radiated power and power flux density parameters are as follows:
Where,
E---the electric field intensity, expressed in (V/m);
D---the measurement distance, which refers to the distance between the radio transmitting
equipment and the measurement point, expressed in (m);
e. i. r. p.---the equivalent isotropic radiated power, expressed in (W);
pfd---the power flux density, expressed in (W/m2).
Calculate the maximum value (E) of the electric field intensity, which represents the maximum
measurement value that can be achieved in the calibrated open area test site by adjusting the
height of the measurement antenna, that is:
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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