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ITU-R SM.329-10 虚假域中的无用发射
标准号 SM.329-10     登录可关注该标准
中文名称 虚假域中的无用发射
英文名称 Unwanted emissions in the spurious domain
发布日期 2003-02-01
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摘要 The ITU Radiocommunication Assembly,
considering
a) that Recommendation ITU-R SM.328 gives definitions and explanatory notes which should
be used when dealing with bandwidth, channel spacing and interference scenarios; when
distinguishing between out-of-band emissions and spurious emissions; and when specifying limits
for out-of-band domain emissions;
b) that a difficulty faced in applying the limits for unwanted emissions in the spurious domain
is knowing precisely the value of the necessary bandwidth and exactly where in the spectrum the
limits for spurious domain should begin to apply, particularly for services using broadband or
digitally-modulated emissions which may have both noise-like and discrete spurious components;
c) that limitation of the maximum permitted level of spurious domain emissions 1 at the
frequency, or frequencies, of each spurious domain emission is necessary to protect all radio
services;
d) that stringent limits may lead to an increase in size or in complexity of radio equipment, but
will in general increase protection of other radio services from interference;
e) that every effort should be made to keep limits for unwanted emissions in out-of-band and
spurious domains, both for existing and new services, at the lowest possible values taking account
of the type and nature of the radio services involved, economic factors, and technological
limitations, and the difficulty of suppressing harmonic emissions from certain high power
transmitters;
f) that there is a need to define the methods, units of measurements and bandwidth, and the
bandwidths to be used for measurement of power at frequencies other than the centre frequency.
This will encourage the use of rational, simple, and effective means of reducing unwanted
emissions;
g) that the relation between the power of the spurious domain emission supplied to a
transmitting antenna and the field strength of the corresponding signals, at locations remote from
the transmitter, may differ greatly, due to such factors as antenna characteristics at the frequencies of the spurious domain emissions, propagation anomalies over various paths and radiation from
parts of the transmitting apparatus other than the antenna itself;
h) that field-strength or pfd measurements of unwanted emissions, at locations distant from the
transmitter, are recognized as the direct means of expressing the intensities of interfering signals
due to such emissions;
j) that in dealing with emissions on the centre frequencies, administrations customarily
establish the power supplied to the antenna transmission line, and may alternatively or in addition
measure the field strength or pfd at a distance, to aid in determining when a spurious domain
emission is causing interference with another authorized emission, and a similar, consistent
procedure would be helpful in dealing with spurious domain emissions (see Article 15, No. 15.11 of
the RR);
k) that for the most economical and efficient use of the frequency spectrum, it is necessary to
establish general maximum limits of spurious domain emissions, while recognizing that specific
services in certain frequency bands may need lower limits of spurious domain emissions from other
services for technical and operational reasons as may be recommended in other ITU-R Recommen-dations
(see Annex 4);
l) that transmitters operating in space stations are increasingly employing spread-spectrum
and other broadband modulation techniques that can produce out-of-band and spurious emissions at
frequencies far removed from the carrier frequency, and that such emissions may cause interference
to passive services, including the radio astronomy service, recognizing however, that spectrum
shaping techniques, which are widely used to increase the efficiency of spectral usage, result in an
attenuation of side band emissions;
m) that spurious domain emission limits applicable to transmitters are a function of:
?C the radiocommunication services involved and the minimum protection ratio determined in
every frequency band;
?C the type of environment where transmitters could be found (urban, suburban, rural, etc.);
?C the type of transmitter;
?C the minimum distance between the transmitter in question and the potential victim radio
receiver;
?C all possible decouplings between the antenna of the interfering transmitting antenna at the
reception frequency and the receiving antenna of the radio receiver including the
propagation model, polarization decoupling and other decoupling factors;
?C the probability of occurrence of the spurious radiation of the transmitter when the receiver
is active;
?C the fact that a transmitter is active or idle, or that there are simultaneous active transmitters;
n) that some space stations have active antennas and the measurement of power as supplied to
the antenna transmission line cannot cover emissions created within the antenna. For such space
stations, the determination of field strength or pfd at a distance should be established by
administrations to aid in determining when an emission is likely to cause interference to other
authorized services;
o) that spurious domain emissions may exist in the whole radio spectrum, but practical
difficulties may dictate a frequency limit above which they need not to be measured;
p) that Recommendation ITU-R SM.1539 deals with variation of the boundary between the
out-of-band and spurious domains,
noting
a) that the studies required by the new Question ITU-R 222/1, approved by the
Radiocommunication Assembly 2000, could have formal and substantial impact to basic definitions
used in this Recommendation. It may be necessary to revise this Recommendation in the future to
reflect the results of these studies,
recommends
that the following should be used when spurious domain emission limits, and their methods of
measurement, are applied: 本标准中的术语
页数 40
全文上线日期 2003-02-01
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