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**ECC Recommendation (02)05**

# UNWANTED EMISSIONS 

## 

Recommendation adopted by the Working Group \"Spectrum Engineering\"
(SE)

##### INTRODUCTION

Between 1996 and 2001, ITU-R Study Group 1 has developed and adopted a
number of new or revised Recommendations dealing with unwanted
emissions. These Recommendations cover spurious and out-of-band (OOB)
emissions, the boundary between both domains, intermodulation, OOB
falling into adjacent bands and a description of spectra and bandwidth
of emission for modern modulation schemes. Special attention was paid to
the protection of Passive and Safety Services from unwanted emissions.

The aim of this Recommendation is to give guidance about the use of the
whole package of ITU-R Recommendations and their relation to the ERC
Recommendation 74-01 on spurious emissions. This Recommendation on
Unwanted Emissions does not contain special limits for spurious or OOB
domain emissions except those in Annex 2. Fig. 2 illustrates the frame
or "roof" concept of this Recommendation.

Unwanted emissions are composed of OOB and spurious emissions as defined
in Article 1, No. 1.144-146 of the RR. OOB and spurious emissions as
defined there are outside the necessary bandwidth. However, according to
Appendix 3 of the RR (WRC-2000) and to ITU-R Rec. SM.329, the spurious
domain emission limits are generally applicable for frequency ranges
larger than 250 % of the necessary bandwidth. A new terminology, the
domain concept, is introduced, the definition of out-of-band and
spurious domains which overcomes this aforementioned contradiction. This
terminology and the relevant definitions are given ITU-R Rec. SM.329-9
and reproduced in Annex 1 for information and are illustrated in Fig. 1
below.

####### **Figure 1: Illustration of the OOB and Spurious Domains (not part of ITU-R Rec. SM.329)**

Note: The crossover point between OOB and Spurious emissions is not
defined and Figure 1 shows only an example.

These definitions reflect more exactly the scope of the ITU-R Rec.
SM.329 and Rec. SM.1541, which address \"unwanted emissions in the
spurious domain\" and \"in the out-of-band domain\" respectively.

Figure 2: Frame or \"roof\" structure of this ECC Recommendation

"The European Conference on Postal and Telecommunications
Administrations,

*considering*

a)  that the radio frequency spectrum is a common resource and it is
    necessary to keep it as unpolluted as possible, making the best use
    of the most modern and cost-effective techniques;

b)  that a number of ITU-R Recommendations are available for protection
    of other radio systems and services from unwanted emissions;

c)  that Recommendation ITU-R SM.329 (Unwanted Emission in the Spurious
    Domain) relates to effects, measurements, generic and specific
    regional limits to be applied to unwanted emissions in the spurious
    domain;

d)  that Recommendation ITU-R SM.1541 (Unwanted Emissions in the
    Out-of-band Domain) relates to effects, measurements and broadly
    generic limits to be applied to unwanted emissions in the
    out-of-band domain;

e)  that the Recommendations ITU-R SM.329 and SM.1541 provide guidance
    for determining the boundary between the out-of-band and spurious
    domains in a transmitted radio frequency spectrum;

f)  that Recommendation ITU-R SM.1539 deals with variation of the
    boundary between the out-of-band and spurious domains required for
    the application of the Recommendations ITU-R SM.329 and SM.1541;

g)  that Recommendation ITU-R SM.1540 covers unwanted emissions in the
    out-of-band domain falling into adjacent allocated bands;

h)  that the protection of the Passive Services is covered by
    Recommendation ITU-R SM.1542;

i)  that the protection of the Safety Services is covered by
    Recommendation ITU-R SM.1535;

j)  that the Recommendation ITU-R SM.326 deals with intermodulation
    products generated in amplitude-modulated radio transmitters;

k)  that the Recommendation ITU-R SM.1446 deals with definition and
    measurement of intermodulation products in transmitters using
    frequency, phase or complex modulation techniques and related
    background information and mitigation techniques are provided in the
    ITU-R Report SM.2021;

l)  that Recommendation ITU-R SM.328 gives definitions and explanatory
    notes which should be used when dealing with spectra and bandwidth
    of emissions;

*noting*

that the limits for unwanted emissions in the out-of-band domain
(out-of-band domain emission limits) as given in ITU-R Rec SM 1541, are
only generic "safety net limits", since they generally constitute the
least restrictive out-of-band domain emission limits that have been
successfully implemented in national or regional regulations.

*recommends*

1)  that the ITU-R Recommendations on unwanted emissions should be used
    as general guidance;

2)  that the limits for unwanted emissions in the spurious domain
    (spurious domain emission limits) should be according to the ERC
    Recommendation 74-01 that corresponds to the Category B limits in
    ITU-R Rec. SM.329 and has been derived taking into account ETSI
    standards;

3)  that the variation of the boundary between out-of-band and spurious
    domains should be established according the ITU-R Rec. SM.1539,
    except the boundary for Radar systems designed for Category B
    spurious domain emission limits, for which guidance is provided in
    Annex 2 of this recommendation;

4)  that ITU-R Recs. SM.1535 and SM.1542 should be used for guidance on
    generic mitigation techniques for reduction of unwanted emissions."

*Note:*

*Please check the CEPT web site(http//:www.CEPT.org) for the up to date
position on the implementation of this and other ECC Decisions.*

**Annex 1 (informative)**

### TERMINOLOGY AND DEFINITIONS USED IN ITU-R REC. SM.329 {#terminology-and-definitions-used-in-itu-r-rec.-sm.329 .unnumbered}

The following terms and definitions complement those already defined in
the Radio Regulations (RR). Definitions shown in *italics* are a direct
quotation from the RR.

# 1 Spurious emission (Article 1, No. 1.145 of the RR) {#spurious-emission-article-1-no.-1.145-of-the-rr .Überschrift-2.l2}

Emission on a frequency, or frequencies, which are outside the necessary
bandwidth and the level of which may be reduced without affecting the
corresponding transmission of information. Spurious emissions include
harmonic emissions, parasitic emissions, intermodulation products and
frequency conversion products but exclude out‑of‑band emissions.

### 1.1 Harmonic emissions

Spurious emissions at frequencies which are whole multiples of the
centre frequency emissions.

### 1.2 Parasitic emissions

Spurious emissions, accidentally generated at frequencies which are
independent both of the carrier or characteristic frequency of an
emission and of frequencies of oscillations resulting from the
generation of the carrier or characteristic frequency.

### 1.3 Intermodulation products

Spurious intermodulation products result from intermodulation between:

-   the oscillations at the carrier, characteristic, or harmonic
    frequencies of an emission, or the oscillations resulting from the
    generation of the carrier or characteristic frequency; and

-   oscillations of the same nature, of one or several other emissions,
    originating from the same transmitting system or from other
    transmitters[^1] or transmitting systems.

### 1.4 Frequency conversion products

Spurious emissions, not including harmonic emissions, at the
frequencies, or whole multiples thereof, or sums and differences of
multiples thereof, of any oscillations generated to produce the carrier
or characteristic frequency of an emission.

# 2 Out-of-band emission (Article 1, No. 1.144 of the RR) {#out-of-band-emission-article-1-no.-1.144-of-the-rr .Überschrift-2.l2}

Emission on a frequency or frequencies immediately outside the necessary
bandwidth which results from the modulation process, but excluding
spurious emissions.

# 3 Unwanted emissions (Article 1, No. 1.146 of the RR) {#unwanted-emissions-article-1-no.-1.146-of-the-rr .Überschrift-2.l2}

Consist of spurious emissions and out-of-band emissions.

# 4 Out-of-band and Spurious domains {#out-of-band-and-spurious-domains .Überschrift-2.l2}

The terms \"out-of-band domain\" and \"spurious domain\" have been
introduced in order to remove some inconsistency between, on one hand,
the definitions of the terms \"out-of-band emission\" and \"spurious
emission\" in Article 1 of the Radio Regulations and, on the other hand,
the actual use of these terms in Appendix 3 of the Radio Regulations, as
revised by WRC-2000. Out-of-band and spurious domain emission limits
apply, respectively, to all unwanted emissions in the out-of-band and
spurious domains.

### 4.1 Out-of-band domain

(of an emission): The frequency range, immediately outside the necessary
bandwidth but excluding the *spurious domain*, in which *out-of-band
emissions* generally predominate.

### 4.2 Spurious domain

(of an emission): The frequency range beyond the *out‑of‑band domain* in
which *spurious emissions* generally predominate.

NOTE -- Out-of-band *emissions*, defined based on their source, occur in
the out-of-band domain and, to a lesser extent, in the spurious domain.
Spurious emissions likewise may occur in the out-of-band domain as well
as in the spurious domain.

# 5 Necessary bandwidth (Article 1, No. 1.152 of the RR) {#necessary-bandwidth-article-1-no.-1.152-of-the-rr .Überschrift-2.l2}

For a given class of emission, the width of the frequency band which is
just sufficient to ensure the transmission of information at the rate
and with the quality required under specified conditions.

For application to multi-channel or multi-carrier
transmitters/transponders, where several carriers may be transmitted
simultaneously from a final output amplifier or an active antenna, the
necessary bandwidth is taken to be the transmitter\'s or transponder\'s
3 dB bandwidth. This does not apply to base stations in the mobile
service or to fixed wireless access base stations using mobile
technology.

For fixed service, Recommendation ITU-R F.1191 is to be used to
calculate the necessary bandwidth in the case of fixed digital radio
multi-carrier systems.

For the radiodetermination service, the necessary bandwidth of
frequency-agile radars is taken to be the part of the allocated band
over which the carrier frequencies of those radars tune.

#### **Annex 2**

#### **BOUNDARY AND LIMITS FOR PRIMARY RADAR EMISSIONS**

This Annex defines limits for unwanted emissions in the out-of-band
domain for fixed radar stations for which ERC Rec. 74-01 applies the
more stringent Category B Limits of ITU-R Recommendation SM.329. By
providing these limits the boundary between the out-of-band domain and
the spurious domain is also hereby defined for this type of systems.

The limits of unwanted emissions in the out-of-band domain for any other
radar systems are given in Annex 8 of ITU-R SM.1541.

Two spectrum masks are given in Fig. A2.1, one based on the roll-off of
20 dB/decade and one based on the design objective; both are taken from
the Rec. ITU-R SM.1541. The mask based on an initial 20 dB roll-off is
applicable to all radars, which fall under the definition of this Annex.
New radar designs should aim to meet the design objectives as soon as
possible. In the future it is intended to apply a more stringent mask
based upon the design objective limits.

![](media/image3.wmf)

**Figure A2.1: Emission masks for radars**

(The dashed line shows the limit for unwanted emissions in the
out-of-band domain.

The solid line represents the proposed design objective)

For the ITU-R Rec. SM.329 Category B limit the mask has a roll-off at 20
dB/dec from the calculated 40 dB bandwidth (B~-40~) to a level of --60
dB~pp~. The mask then continues to roll-off at 60 dB/dec to the -100 dB
level. For the design objective the mask has a roll-off at 40 dB/dec
from the calculated B~-40~to a level of --80 dB~pp~. The mask then
continues to roll-off at 60 dB/dec to the -100 dB level. The equations
for determining the B~-40~bandwidth are given in Annex 8 of ITU-R
SM.1541.

The first mask limit will result in the out-of-band emission domain
width of 46.4 times B~-40~. The design objective mask limits will reduce
the out-of-band emission domain to the width of 21.5 times B~-40~.

These two masks have the characteristics listed in the following Tables
1 and 2. The limits are specified for the offset frequencies being
multiple of the B~-40~ bandwidth.

**Table 1: Limits for unwanted emissions**

+----------------------------+-------------+---------------------------+
| **Offset**                 | **Limit**   | **Slope**                 |
|                            |             |                           |
| **Frequency x B~-40~**     | **dB**      | **dB/decade**             |
+----------------------------+-------------+---------------------------+
| 0 to 0.5                   | 0           | 0                         |
+----------------------------+-------------+---------------------------+
| 0.5                        | 40          | ∞                         |
+----------------------------+-------------+---------------------------+
| 0.5 to 5                   | 40 to 60    | 20                        |
+----------------------------+-------------+---------------------------+
| 5 to 23.2                  | 60 to 100   | 60                        |
+----------------------------+-------------+---------------------------+
| 23.2 to ∞                  | 100         | 0                         |
+----------------------------+-------------+---------------------------+

**Table 2: Design objective limits for unwanted emissions**

+---------------------------+--------------+--------------------------+
| **Offset**                | **Limit**    | **Slope**                |
|                           |              |                          |
| **Frequency x B~-40~**    | **dB**       | **dB/decade**            |
+---------------------------+--------------+--------------------------+
| 0 to 0.5                  | 0            | 0                        |
+---------------------------+--------------+--------------------------+
| 0.5                       | 40           | ∞                        |
+---------------------------+--------------+--------------------------+
| 0.5 to 5                  | 40 to 80     | 40                       |
+---------------------------+--------------+--------------------------+
| 5 to 10.75                | 80 to 100    | 60                       |
+---------------------------+--------------+--------------------------+
| 10.75 to ∞                | 100          | 0                        |
+---------------------------+--------------+--------------------------+

[^1]: Signals coupled through the antenna radiation system.