Belar FMHD-1, Operator'S Manual

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FMHD-1 Operator’s Manual
Page 36 FMHD-1
Injection
The “injection” of a signal is that modulation of the FM carrier caused by the signal’s presence as part of
the complete baseband signal modulating the FM carrier. It typically refers to the modulation due to the
lesser, sine-wave-like components of the baseband signal, such as the Pilot, or RDS and SCA
sub-carriers. It may be measured in percent or in kHz-peak-deviation.
IF
This stands for “intermediate frequency.” In the FMHD-1 , IF refers to the down-converted
FM-modulated RF signal present at the output of the tuner employed to recover broadcast signals applied
to the antenna input. The IF is centered at approximately 10.7 MHz.
LAN
This stands for “local-area network”. The FMHD-1 bases its LAN communications on the
10/100-Base-T/TX standard.
L+R
The sum of the left and right channel audio signals in an FM Stereo signal. The L+R fills the portion of
the composite signal below 15 kHz. It is sometimes referred to as the “main channel.”
L–R
The difference between the left and right channel audio signals in an FM Stereo signal. It is multiplied by
a 38-kHz sine wave to generator the stereo sub-channel of the composite signal. The stereo sub-channel,
or “difference channel,” falls between 23 kHz and 53 kHz in the composite signal. “L–R” is also used to
refer to the modulated difference channel.
Low-level Combining
In FM hybrid IBOC transmitter facilities, this refers to the situation where the analog and digital carriers
are combined at low-level then amplified in a common power amplifier. The output of the power
amplifier is fed to the antenna on one transmission line. This is a “common-line” transmitter facility.
LVDS
This is the abbreviation for “low-voltage differential signaling”. This is a standard distribution system for
high-speed data over multiple copper twisted pairs.
MAC
Stands for “Media Access Control”. The MAC address is relevant to physical-layer communications
between the Ethernet and IP realms.
NRSC
The National Radio Standards Committee, which is a non-governmental, radio broadcast standards
organization functioning in the United States.
OFDM
Orthogonal frequency-division multiplexing. A method of encoding data on multiple carriers at different
frequencies.
PAD
In the HD Radio context, this refers to “Program Associated Data”. This is another expression for
Program Service Data, defined directly below.