4/18/11
888-2587-001
1-13
WARNING: Disconnect primary power prior to servicing.
Section 1 Introduction/Specifications
FM HD Radio System
1.9
General IBOC Information
There are several methods of combining the analog (FM) and digital (HD) RF to create
an IBOC signal, and there may be up to four possible modes of operation - also known
as Modulation Format - that may be used in a typical IBOC system including a backup
mode. The four modes of operation are:
FM -
Analog RF only; this could be the analog backup mode in the event of a
digital failure.
FM+HD
- Analog & digital (at -20dB) RF, also known as Common Combining.
HD
- Digital RF only, used for Separate Combining, such as 10dB combined, dual-
feed and interleaved antenna, and dual antennas.
SLC
- Analog & digital (at various ratios) RF, also known as Split-level or Mid-
level Combining.