Comtech EF Data CDM-625 - Manual (Page 427)

19–1
Chapter 19. CARRIER ID
(MetaCarrier ® )
19.1 Overview
CDM-625 Advanced Satellite Modems running Firmware Version 2.2.1 or later incorporate 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-625 with MetaCarrier® provides a subset of the functionality of the Comtech EF Data
MCED-100 MetaCarrier® Embedding Device. It is used in tandem with the Comtech EF Data
MCDD-100 MetaCarrier® Detection Device to provide a complete MetaCarrier embedding and
decoding solution.
19.2 About MetaCarrier
The MetaCarrier concept employs a low-speed data sequence containing information about the
transmission carrier that is spread using Direct Sequence Spread Spectrum (DSSS), and then
combined with the transmission “desired” carrier to produce a composite carrier with an
embedded CID. The power level and bandwidth of the MetaCarrier is sufficiently low that it is
completely hidden below the desired carrier, and has minimal effect on system Eb/No
(approximately 0.1 dB).
The MetaCarrier operates independent of the modulation and forward error correction rate of
the transmitted carrier. In configurations where the carrier is encrypted or uses cryptographic
technologies, the CID contained in the MetaCarrier 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, in densely populated areas,
a helicopter equipped with a feed horn and spectrum analyzer must be used to find the exact
location of the transmission source; the time and costs associated with such methods are
significant.