ISO 21460:2015

INTERNATIONAL ISO
STANDARD 21460
Third edition
2015-08-15
Space data and information transfer
systems — Proximity-1 space link
protocol — Physical layer
Systèmes de transfert des informations et données spatiales —
Protocole pour liaisons spatiales de proximité 1 — Couche physique
Reference number
©
ISO 2015
© ISO 2015, Published in Switzerland
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ii © ISO 2015 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 21460 was prepared by the Consultative Committee for Space Data Systems (CCSDS) (as
CCSDS 211.1-B-4, December 2013) and was adopted (without modifications except those stated in clause 2
of this International Standard) by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee
SC 13, Space data and information transfer systems.
This third edition of ISO 21460:2015 cancels and replaces the second edition (ISO 21460:2007), which

has been technically revised.
Recommendation for Space Data System Standards
PROXIMITY-1 SPACE
LINK PROTOCOL—
PHYSICAL LAYER
RECOMMENDED STANDARD
CCSDS 211.1-B-4
BLUE BOOK
December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
AUTHORITY
Issue: Recommended Standard, Issue 4
Date: December 2013
Location: Washington, DC, USA
This document has been approved for publication by the Management Council of the
Consultative Committee for Space Data Systems (CCSDS) and represents the consensus
technical agreement of the participating CCSDS Member Agencies. The procedure for
review and authorization of CCSDS documents is detailed in Organization and Processes for
the Consultative Committee for Space Data Systems (CCSDS A02.1-Y-3), and the record of
Agency participation in the authorization of this document can be obtained from the CCSDS
Secretariat at the address below.

This document is published and maintained by:

CCSDS Secretariat
Space Communications and Navigation Office, 7L70
Space Operations Mission Directorate
NASA Headquarters
Washington, DC 20546-0001, USA
CCSDS 211.1-B-4 Page 1-1 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
STATEMENT OF INTENT
The Consultative Committee for Space Data Systems (CCSDS) is an organization officially
established by the management of its members. The Committee meets periodically to address
data systems problems that are common to all participants, and to formulate sound technical
solutions to these problems. Inasmuch as participation in the CCSDS is completely
voluntary, the results of Committee actions are termed Recommended Standards and are
not considered binding on any Agency.
This Recommended Standard is issued by, and represents the consensus of, the CCSDS
members. Endorsement of this Recommendation is entirely voluntary. Endorsement,
however, indicates the following understandings:
o Whenever a member establishes a CCSDS-related standard, this standard will be in
accord with the relevant Recommended Standard. Establishing such a standard
does not preclude other provisions which a member may develop.
o Whenever a member establishes a CCSDS-related standard, that member will
provide other CCSDS members with the following information:
-- The standard itself.
-- The anticipated date of initial operational capability.
-- The anticipated duration of operational service.
o Specific service arrangements shall be made via memoranda of agreement. Neither
this Recommended Standard nor any ensuing standard is a substitute for a
memorandum of agreement.
No later than three years from its date of issuance, this Recommended Standard will be
reviewed by the CCSDS to determine whether it should: (1) remain in effect without change;
(2) be changed to reflect the impact of new technologies, new requirements, or new
directions; or (3) be retired or canceled.
In those instances when a new version of a Recommended Standard is issued, existing
CCSDS-related member standards and implementations are not negated or deemed to be
non-CCSDS compatible. It is the responsibility of each member to determine when such
standards or implementations are to be modified. Each member is, however, strongly
encouraged to direct planning for its new standards and implementations towards the later
version of the Recommended Standard.
CCSDS 211.1-B-4 Page 1-2 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
FOREWORD
Attention is drawn to the possibility that some of the elements of this document may be the
subject of patent rights. CCSDS shall not be held responsible for identifying any or all such
patent rights.
Through the process of normal evolution, it is expected that expansion, deletion, or
modification of this document may occur. This Recommended Standard is therefore subject
to CCSDS document management and change control procedures, which are defined in
Organization and Processes for the Consultative Committee for Space Data Systems
(CCSDS A02.1-Y-3). Current versions of CCSDS documents are maintained at the CCSDS
Web site:
http://www.ccsds.org/
Questions relating to the contents or status of this document should be addressed to the
CCSDS Secretariat at the address indicated on page i.
CCSDS 211.1-B-4 Page 1-3 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
At time of publication, the active Member and Observer Agencies of the CCSDS were:
Member Agencies
– Agenzia Spaziale Italiana (ASI)/Italy.
– Canadian Space Agency (CSA)/Canada.
– Centre National d’Etudes Spatiales (CNES)/France.
– China National Space Administration (CNSA)/People’s Republic of China.
– Deutsches Zentrum für Luft- und Raumfahrt (DLR)/Germany.
– European Space Agency (ESA)/Europe.
– Federal Space Agency (FSA)/Russian Federation.
– Instituto Nacional de Pesquisas Espaciais (INPE)/Brazil.
– Japan Aerospace Exploration Agency (JAXA)/Japan.
– National Aeronautics and Space Administration (NASA)/USA.
– UK Space Agency/United Kingdom.
Observer Agencies
– Austrian Space Agency (ASA)/Austria.
– Belgian Federal Science Policy Office (BFSPO)/Belgium.
– Central Research Institute of Machine Building (TsNIIMash)/Russian Federation.
– China Satellite Launch and Tracking Control General, Beijing Institute of Tracking
and Telecommunications Technology (CLTC/BITTT)/China.
– Chinese Academy of Sciences (CAS)/China.
– Chinese Academy of Space Technology (CAST)/China.
– Commonwealth Scientific and Industrial Research Organization (CSIRO)/Australia.
– Danish National Space Center (DNSC)/Denmark.
– Departamento de Ciência e Tecnologia Aeroespacial (DCTA)/Brazil.
– European Organization for the Exploitation of Meteorological Satellites
(EUMETSAT)/Europe.
– European Telecommunications Satellite Organization (EUTELSAT)/Europe.
– Geo-Informatics and Space Technology Development Agency (GISTDA)/Thailand.
– Hellenic National Space Committee (HNSC)/Greece.
– Indian Space Research Organization (ISRO)/India.
– Institute of Space Research (IKI)/Russian Federation.
– KFKI Research Institute for Particle & Nuclear Physics (KFKI)/Hungary.
– Korea Aerospace Research Institute (KARI)/Korea.
– Ministry of Communications (MOC)/Israel.
– National Institute of Information and Communications Technology (NICT)/Japan.
– National Oceanic and Atmospheric Administration (NOAA)/USA.
– National Space Agency of the Republic of Kazakhstan (NSARK)/Kazakhstan.
– National Space Organization (NSPO)/Chinese Taipei.
– Naval Center for Space Technology (NCST)/USA.
– Scientific and Technological Research Council of Turkey (TUBITAK)/Turkey.
– South African National Space Agency (SANSA)/Republic of South Africa.
– Space and Upper Atmosphere Research Commission (SUPARCO)/Pakistan.
– Swedish Space Corporation (SSC)/Sweden.
– Swiss Space Office (SSO)/Switzerland.
– United States Geological Survey (USGS)/USA.
CCSDS 211.1-B-4 Page 1-4 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
DOCUMENT CONTROL
Document Title Date Status
CCSDS Proximity-1 Space Link Protocol October Original issue,
211.0-B-1 2002 superseded
CCSDS Proximity-1 Space Link Protocol— April Superseded
211.1-B-1 Physical Layer 2003
CCSDS Proximity-1 Space Link Protocol— May Superseded
211.1-B-2 Physical Layer 2004
CCSDS Proximity-1 Space Link Protocol— March Superseded
211.1-B-3 Physical Layer, Recommended 2006
Standard, Issue 3
CCSDS Proximity-1 Space Link Protocol— December Current issue:
211.1-B-4 Physical Layer, Recommended 2013 This update includes
Standard, Issue 4 several improvements
and clarifications,
accomplishing better
alignment and
consistency with the
other Proximity-1 Blue
Books.
NOTE – Changes from the current issue are too extensive to permit markup.
CCSDS 211.1-B-4 Page 1-5 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
CONTENTS
Section Page
1 INTRODUCTION . 1-1

1.1 PURPOSE . 1-1
1.2 SCOPE . 1-1
1.3 APPLICABILITY . 1-1
1.4 RATIONALE . 1-2
1.5 CONVENTIONS AND DEFINITIONS. 1-2
1.6 REFERENCES . 1-5

2 OVERVIEW . 2-1

2.1 PHYSICAL LAYER OVERVIEW . 2-1
2.2 DATA LINK LAYER OVERVIEW . 2-1

3 GENERAL REQUIREMENTS FOR THE PHYSICAL LAYER . 3-1

3.1 RADIO EQUIPMENT . 3-1
3.2 PHYSICAL LAYER FUNCTIONS . 3-1
3.3 CONTROLLED COMMUNICATIONS CHANNEL PROPERTIES . 3-5
3.4 PERFORMANCE REQUIREMENTS . 3-9

ANNEX A PROTOCOL IMPLEMENTATION CONFORMANCE
STATEMENT PROFORMA (NORMATIVE) . A-1
ANNEX B SECURITY, SANA, AND PATENT CONSIDERATIONS
(INFORMATIVE) .B-1
ANNEX C INFORMATIVE REFERENCES (INFORMATIVE) . C-1
ANNEX D ABBREVIATIONS AND ACRONYMS (INFORMATIVE) . D-1
Figure
1-1 Proximity-1 Rate Terminology . 1-5
2-1 Simplified Overview of Proximity-1 Layers . 2-2
3-1 Control Variables, Signals, and Data Transfers . 3-2
3-2 Oscillator Phase Noise . 3-10
3-3 Discrete Lines Template for the Transmitter (Normalized Power in
dBc vs. Normalized Frequency: (f-f )/A) . 3-10
c
CCSDS 211.1-B-4 Page 1-6 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
CONTENTS (continued)
Table Page
3-1 CATEGORIES OF RADIO EQUIPMENT CONTAINED ON PROXIMITY-1
LINK ELEMENTS . 3-1
3-2 CONTROL VARIABLES FOR TRANSMITTER . 3-3
3-3 CONTROL VARIABLES FOR RECEIVER . 3-4
3-4 PROXIMITY-1 CHANNEL ASSIGNMENTS 0 THROUGH 7 (FREQUENCIES IN
MHZ) . 3-7
A-1  MAJOR CAPABILITIES . A-4

CCSDS 211.1-B-4 Page 1-7 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
1 INTRODUCTION
1.1 PURPOSE
The purpose of this Recommended Standard is to specify Physical Layer procedures used
with the Proximity-1 Data Link Layer (references [3] and [2]). Proximity space links are
defined to be short-range, bi-directional, fixed or mobile radio links, generally used to
communicate among probes, landers, rovers, orbiting constellations, and orbiting relays.
These links are characterized by short time delays, moderate (not weak) signals, and short,
independent sessions.
1.2 SCOPE
This Recommended Standard defines the Proximity-1 Space Link Protocol Physical Layer.
The specification for the channel connection process, provision for frequency bands and
assignments, hailing channel, polarization, modulation, data rates, and performance
requirements are defined in this document.
Currently, the Physical Layer only defines operations at UHF frequencies for the Mars
environment.
The Data Link Layer is defined in the two separate CCSDS Recommended Standards entitled,
Proximity-1 Space Link Protocol—Coding and Synchronization Sublayer (reference [2]), and
Proximity-1 Space Link Protocol—Data Link Layer (reference [3]).
This Recommended Standard does not specify
a) individual implementations or products;
b) implementation of service interfaces within real systems;
c) the methods or technologies required to perform the procedures; or
d) the management activities required to configure and control the protocol.
1.3 APPLICABILITY
This Recommended Standard applies to the creation of Agency standards and to future data
communications over space links between CCSDS Agencies in cross-support situations. It
applies also to internal Agency links where no cross-support is required. It includes
specification of the services and protocols for inter-Agency cross support. It is neither a
specification of, nor a design for, systems that may be implemented for existing or future
missions.
The Recommended Standard specified in this document is to be invoked through the normal
standards programs of each CCSDS Agency and is applicable to those missions for which
cross support based on capabilities described in this Recommended Standard is anticipated.
Where mandatory capabilities are clearly indicated in sections of the Recommended
CCSDS 211.1-B-4 Page 1-1 December 2013
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
Standard, they must be implemented when this document is used as a basis for cross support.
Where options are allowed or implied, implementation of these options is subject to specific
bilateral cross support agreements between the Agencies involved.
1.4 RATIONALE
The CCSDS believes it is important to document the rationale underlying the
recommendations chosen, so that future evaluations of proposed changes or improvements
will not lose sight of previous decisions. Concept and rationale behind the decisions that
formed the basis for Proximity-1 are documented in the CCSDS Proximity-1 Space Link
Protocol Green Book, reference Error! Reference source not found.
1.5 CONVENTIONS AND DEFINITIONS
1.5.1 DEFINITIONS
1.5.1.1 Terms from the Open Systems Interconnection (OSI) Basic Reference Model
This Recommended Standard makes use of a number of terms defined in reference [1]. In
this Recommended Standard those terms are used in a generic sense, i.e., in the sense that
those terms are generally applicable to any of a variety of technologies that provide for the
exchange of information between real systems. Those terms are as follows:
a) connection;
b) Data Link Layer;
c) Physical Layer;
d) protocol data unit;
e) real system;
f) service;
g) service data unit.
1.5.1.2 Terms Defined in This Recommended Standard
For the purposes of this Recommended Standard, the following definitions also apply. Many
other terms that pertain to specific items are defined in the appropriate sections.
caller and responder: Initiator and receiver, respectively, in a Proximity space link session.
CCSDS 211.1-B-4 Page 1-2 December 2013
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NOTE – A caller transceiver is the initiator of the link establishment process and
manager of negotiation (if required) of the session. A responder transceiver
typically receives link establishment parameters from the caller. The caller
initiates communication between itself and a responder on a prearranged
communications channel with predefined controlling parameters. As necessary,
the caller and responder may negotiate the controlling parameters for the session
(at some level between fully controlled and completely adaptive).
forward link: That portion of a Proximity space link in which the caller transmits and the
responder receives (typically a command link). The term ‘forward’ is used in
association with any parameters referring to the forward link.
hailing: The persistent activity used to establish a Proximity link by a caller to a responder
in either full or half duplex. It does not apply to simplex operations.
hailing channel: The forward and return frequency pairs that a caller and responder use to
establish physical link communications.
physical channel: The RF channel upon which the stream of channel symbols is transferred
over a space link in a single direction.
PLTU: Proximity Link Transmission Unit, the data unit composed of the Attached
Synchronization Marker, the Version-3 Transfer Frame, and the attached Cyclic
Redundancy Check (CRC)-32.
Proximity link: A full-duplex, half-duplex, or simplex link for the transfer of data between
Proximity-1 entities in a session.
return link: That portion of a Proximity space link in which the responder transmits and the
caller receives (typically a telemetry link). The term ‘return’ is used in association
with any parameters referring to the return link.
session: A dialog between two or more communicating Proximity link transceivers.
NOTE – A session consists of three distinct operational phases: session establishment,
data services (which may include resynchronization and/or reconnect subphases),
and session termination. Session termination can be coordinated (through the
exchange of no-more-data-to-send directives), or, if communication is lost
(inability to resynchronize or reconnect), the transceivers will eventually
independently conclude the dialog is over.
space link: A communications link between transmitting and receiving entities, at least one of
which is in space.
working channel: A forward and return frequency pair used for transferring User
data/information frames (U-frames) and Protocol/supervisory frames (P-frames)
during the data service and session termination phases.
CCSDS 211.1-B-4 Page 1-3 December 2013
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1.5.2 NOMENCLATURE
1.5.2.1 NORMATIVE TEXT
The following conventions apply for the normative specifications in this Recommended
Standard:
a) the words ‘shall’ and ‘must’ imply a binding and verifiable specification;
b) the word ‘should’ implies an optional, but desirable, specification;
c) the word ‘may’ implies an optional specification;
d) the words ‘is’, ‘are’, and ‘will’ imply statements of fact.
NOTE – These conventions do not imply constraints on diction in text that is clearly
informative in nature.
1.5.2.2 INFORMATIVE TEXT
In the normative section of this document (section 3), informative text is set off from the
normative specifications either in notes or under one of the following subsection headings:
– Overview;
– Background;
– Rationale;
– Discussion.
1.5.3 CONVENTIONS
Throughout this Recommended Standard, directive, parameter, variable, and signal names
are presented with all upper-case characters; data-field and MIB-parameter names are
presented with initial capitalization; values and state names are presented with predominantly
lowercase italic characters.
In Proximity-1, data rate (R ), coded symbol rate (R ) and channel symbol rate (R ) are
d cs chs
used to denote respectively:
– the data rate of the bitstream composed by PLTUs and Idle data measured at the
encoder input;
– the coded data rate measured at the interface between the Coding and
Synchronization Sublayer and the Physical Layer; and
– the rate measured at the output of the transmitter.
CCSDS 211.1-B-4 Page 1-4 December 2013
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PHYSICAL LAYER
The terms are used as shown in figure 1-1.
BITSTREAM CODED CHANNEL
FOR ENCODING SYMBOLS
SYMBOLS
ENCODER RF POWER AMPLIFIER
Bi-Phase-L
(or Bypass) MODULATOR & RF CHAIN
CHANNEL
SYMBOL RATE
DATA RATE CODED SYMBOL RATE
REFERENCE
REFERENCE POINT REFERENCE POINT
POINT
(R ) (R )
d cs
(R )
chs
Figure 1-1: Proximity-1 Rate Terminology
With respect to the modulation scheme specified in 3.3.5.1, the following relationship applies
for the purpose of the present standard:
R = R
chs cs
1.6 REFERENCES
The following publications contain provisions which, through reference in this text,
constitute provisions of this document. At the time of publication, the editions indicated
were valid. All publications are subject to revision, and users of this document are
encouraged to investigate the possibility of applying the most recent editions of the
publications indicated below. The CCSDS Secretariat maintains a register of currently valid
CCSDS publications.
[1] Information Technology—Open Systems Interconnection—Basic Reference Model: The
Basic Model. International Standard, ISO/IEC 7498-1:1994. 2nd ed. Geneva: ISO,
1994.
[2] Proximity-1 Space Link Protocol—Coding and Synchronization Sublayer. Issue 2.
Recommendation for Space Data System Standards (Blue Book), CCSDS 211.2-B-2.
Washington, D.C.: CCSDS, December 2013.
[3] Proximity-1 Space Link Protocol—Data Link Layer. Issue 5. Recommendation for
Space Data System Standards (Blue Book), CCSDS 211.0-B-5. Washington, D.C.:
CCSDS, December 2013.
CCSDS 211.1-B-4 Page 1-5 December 2013
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2 OVERVIEW
2.1 PHYSICAL LAYER OVERVIEW
Proximity-1 is a bi-directional Space Link Layer protocol for use by space missions. It
consists of a Physical Layer (the subject of this document) and a Data Link Layer (references
[2] and [3]). This protocol has been designed to meet the requirements of space missions for
efficient transfer of space data over various types and characteristics of Proximity space
links.
Proximity-1 activities are divided between a send side and a receive side. The send side is
concerned with the transmitted physical channel, and also with the acquisition of the received
physical channel in order to establish a Proximity-1 link. The operation of the transmitter is
state-driven. The receive side is concerned with the reception of data on the received
physical channel: the input symbols stream and the protocol data units it contains. Once the
receiver is turned on, its operation is modeless. It accepts and processes all valid local and
remote directives and received service data units.
On the send side, the Physical Layer:
– accepts control variables from the MAC Sublayer of the Data Link Layer for control
of the transceiver;
– accepts a coded symbols stream from the Coding & Synchronization Sublayer
(reference [2]) of the Data Link Layer for modulation onto the radiated carrier.
On the receive side, the Physical Layer:
– provides status signals (CARRIER_ACQUIRED and SYMBOL_INLOCK_STATUS)
to the MAC Sublayer of the Data Link Layer.
2.2 DATA LINK LAYER OVERVIEW
This subsection provides a brief overview of the Data Link Layer, with emphasis on the
features relevant to the Physical Layer. For a fuller description of the overall Proximity-1
system, of the Data Link Layer and of its sublayers (see reference [3]).
On the send side, the Data Link Layer is responsible for providing the coded symbols to be
transmitted by the Physical Layer. On the receive side, the Data Link Layer accepts the
serial coded symbols stream output from the receiver in the Physical Layer and processes the
Protocol Data Units contained in it.
Within the Data Link Layer, the Medium Access Control (MAC) Sublayer (reference [3])
and the Coding and Synchronization (C&S) Sublayer (reference [2]) have interfaces to the
Physical Layer.
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The Medium Access Control (MAC) Sublayer controls the establishment, maintenance, and
termination of communications sessions for point-to-point communications between
Proximity entities. It controls the operational state of the Data Link and Physical Layers,
using control variables. It accepts Proximity-1 directives both from the local vehicle
controller and across the Proximity link to control its operations. The MAC Sublayer is also
responsible for the storage and distribution of the Management Information Base (MIB)
parameters.
On the send side, the C&S Sublayer generates the output coded symbols stream, containing
Proximity Link Transmission Units (PLTUs) and Idle data, which is delivered to the Physical
Layer for modulation onto the radiated carrier. On the receive side, the C&S Sublayer
accepts the incoming serial coded symbols stream from the Physical Layer and delimits each
PLTU contained in the symbol stream.
Figure 2-1 gives a simplified view of the relationship of the Data Link Layer to the Physical
Layer. (For a more detailed view of the Proximity-1 system, see reference [3].)
Local S/C
INPUT of USER DATA
USER DATA
Controller
+ Routing information
Delivery
SEND     RECEIVE
I/O Sublayer
MAC
Sublayer
Data Services
(MIB)
Sublayer
Frame Sublayer
Coding & Synchronization Layer
Physical Layer
Figure 2-1: Simplified Overview of Proximity-1 Layers

CCSDS 211.1-B-4 Page 2-2 December 2013
Data Link Layer
CCSDS RECOMMENDED STANDARD FOR PROXIMITY-1 SPACE LINK PROTOCOL—
PHYSICAL LAYER
3 GENERAL REQUIREMENTS FOR THE PHYSICAL LAYER
3.1 RADIO EQUIPMENT
3.1.1 OVERVIEW
The Proximity-1 Link system supports the communication and navigation needs between a
variety of network elements, e.g., orbiters, landers, rovers, microprobes, balloons, aerobots,
gliders. The categories of radio equipment in network elements (E1, E2,…) are listed in
table 3-1.
3.1.2 COHERENCY REQUIREMENT
Link elements in category E2c (table 3-1), for which range and range-rate measurements are
needed, shall have transmit/receive frequency coherency capability. (See 3.4.5 for Doppler
tracking and acquisition requirements.)
Table 3-1: Categories of Radio Equipment Contained on Proxi
...