IEEE Geoscience and Remote Sensing Magazine - December 2022 - 279

EARTH OBSERVATION AS A
RADIOCOMMUNICATION SERVICE
categorized according to their sharing scenario with other
systems as shared with active services and as shared with
RADIOCOMMUNICATION SERVICES RELEVANT
TO EARTH OBSERVATION
From the regulatory point of view, EO satellites carry onboard
space stations, defined in the ITU RRs as " one or
more transmitters or receivers or a combination of transmitters
and receivers, including the accessory equipment,
necessary ... for carrying on a radiocommunication service "
[17]. These stations are located on an object that is going,
is intended to go, or has been beyond the major portion of
Earth's atmosphere.
Among the different radiocommunication services relevant
to EO, perhaps the most obvious is the Earth exploration
satellite service (EESS), formally defined in article
1 of the RRs and briefly summarized in the scope of this
contribution as " a radiocommunication service between Earth
stations and one or more space stations, which may include
links between space stations, in which information relating
to the characteristics of the Earth and its natural phenomena,
including data relating to the state of the environment,
is obtained from active sensors or passive sensors on Earth satellites. "
Other services relevant to EO include, for instance,
the meteorological satellite service (MetSat), which is an
EESS for meteorological purposes, and the meteorological
aids service.
RADIO-FREQUENCY ALLOCATIONS
Together, the referenced radiocommunication services have
frequency allocations ranging from 8.3 kHz to 252 GHz as
well as frequency identifications well beyond that, detailed
in article 5 of the RRs in the so-called Table of Frequency
Allocations (TFA). The rank of priorities for using a given
frequency band in the TFA is established by defining primary
and secondary radiocommunication services, with
the first ranking in higher priority with respect to the second,
in which stations can claim protection only from other
stations in secondary services, whose frequencies have
been assigned at a later date.
The frequency allocations used by EO missions may be
generally categorized according to their application, particularly
for communications and measurements. The first
includes the reception of telemetry, space tracking, transmission
of commands to the platform, and payload data
transmission, containing the desired data justifying the
mission in the first place, to designated gateway Earth stations
and directly to service users' Earth stations [18]. The
second includes active and passive sensing of Earth, and,
contrary to what happens with communication links whose
spectrum requirements are driven by engineering factors,
its spectrum requirements are naturally defined by the laws
of nature [14]. Given their unique character, it is not surprising,
then, that some of these, in particular, some for passive
sensing, require ultimate radio protection. In this sense,
frequency allocations for measurements may be further
DECEMBER 2022 IEEE GEOSCIENCE AND REMOTE SENSING MAGAZINE
passive services (only), i.e., subject to RR 5.340, stating that
" all emissions are prohibited "
in these bands. A summary of
the frequency allocations to
EESS and MetSat and relevant
applications enabled by these
services is displayed in Figure
1. The service designation
is listed on the left, and its
applications are on the righthand
side of the figure.
FOR PREVENTIVE RADIO
PROTECTION, SPECTRUM
AUTHORITY OFFICERS
CONDUCT FREQUENT
INSPECTION ACTIONS ON
STATIONS OF DIFFERENT
RADIOCOMMUNICATION
SERVICES UNDER THEIR
JURISDICTION.
RADIO LICENSING AND
SPECTRUM ACCESS
Space stations in the EESS and
MetSat of other administrations
are not subject to any
form of radio licensing and registration in Portugal. Their
conforming frequency assignments are expected, nonetheless,
to have been duly notified to the ITU and recorded
in the Master International Frequency Register. The respective
transceiver Earth stations, in turn, are subject to radio
licensing as well as receiver-only Earth stations operating
in primary frequency bands for which protection against
harmful interference has been required. The licensing of
receiving-only Earth stations is not mandatory, and, although
there is no entitlement to formal radio protection,
such stations may not necessarily operate in any RFI environment.
This will be detailed further.
RADIO PROTECTION AND SPECTRUM
SUPERVISION IN EARTH OBSERVATION
RADIO PROTECTION: DEFINITION
AND INFRASTRUCTURE
By establishing a fundamental common ground for understanding,
the ITU provides international recognition and
protection of the rights of its member states (MSs) to access
and use spectrum and satellite orbits, governing them at
the international level with the objective to ensure such access
and use to be effective (RFI-free), rational, equitable,
efficient, and economical, which is particularly important
given the resources' natural scarcity. For this, the ITU RRs
are the leading international radio regulatory instrument,
providing a stable planning environment for administrations,
manufacturers, operators, users, and other stakeholders.
Being part of the ITU administrative regulations and instruments,
the RRs contain provisions of a technical nature
governing international telecommunications, and they
complement the provisions of the ITU constitution (CS)
and convention (CV) defining the ITU purpose and structure.
These are legal intergovernmental treaties, binding to
all signatory MSs, who must apply their provisions in their
countries by force of law.
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IEEE Geoscience and Remote Sensing Magazine - December 2022

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