Comtech EF Data CDM-425, Инструкция по установке и эксплуатации

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CDM-425 Advanced Satellite Modem
Revision 0
Appendix D D–1 MN-CDM-425
Appendix D. CARRIER ID
(DVB-CID MetaCarrier
®
)
D.1 Overview
The CDM-425 Advanced Satellite Modem incorporates a patent-pending carrier identification
(CID) technique that uses MetaCarrier® spread spectrum technology to embed a unique carrier
identification sequence for the transmitted carrier.
The CDM-425 Advanced Satellite Modem with MetaCarrier® is used in tandem with the Comtech
EF Data MCDD-100 MetaCarrier® Detection Device to provide a complete MetaCarrier
embedding and decoding solution.
Since the initial release of this technology in the CDM-425 Advanced Satellite Modem, the
European Telecommunications Standards Institute (ETSI) has adopted a modified version of
Comtech’s original scheme, which is defined in
ETSI TS 103 129 – Digital Video Broadcasting
(DVB) Framing Structure, Channel Coding and Modulation of a Carrier Identification
System (DVB-CID) for Satellite Transmission.
The CDM-425 Advanced Satellite Modem uses
Firmware Version 1.2.1 or later to fully comply with this new ETSI specification.
D.2 About MetaCarrier
The DVB-CID (MetaCarrier) concept employs a low-speed data sequence containing identifying
information about a host carrier that is spread using Direct Sequence Spread Spectrum (DSSS),
and then combined, at a low power level, directly underneath that host carrier. The composite
signal therefore carries its own embedded identification. The power level and bandwidth of the
MetaCarrier is sufficiently low that it is completely hidden below the host carrier, and has minimal
effect on system Eb/No (approximately 0.1 dB).
DVB-CID operates independent of the modulation and Forward Error Correction (FEC) rate of the
host carrier. In configurations where the carrier is encrypted or uses cryptographic technologies,
the information carried in the DVB-CID is not affected.
Traditionally, the method for identifying an interfering carrier involves using a geo-location system
that, in turn, uses the phase offset from an adjacent satellite to triangulate the approximate
location on the surface of the earth where the interference is being generated. While such “tried-
and-true” geo-locating methods have proven beneficial to satellite operators and service
providers, they are nevertheless imprecise. For example, to find the exact location of the
transmission source in a densely populated area, you must dispatch a helicopter equipped with a
feed horn and spectrum analyzer; the time and cost associated with such methods are significant.