Belar FMHD-1 Operator'S Manual Download Page 9

Page: 9 / 58

FMHD-1 Operator’s Manual

BELAR ELECTRONICS LABORATORY, INC.

Page 1

General Information

1.1

General Description

The

Belar FMHD-1

Modulation Monitor for FM HD Radio™ is a state-of-the-art wideband monitor

designed specifically for the measurement and characterization of FM hybrid In-Band/On-Channel
broadcast signals in the 88-MHz-to-108-MHz band. It simultaneously decodes and meters the
modulation of the analog FM carrier and the Main program audio carried by the IBOC digital sidebands
(subcarrier sets). In its base configuration, the

FMHD-1

provides multiple high-quality audio output

signals for the analog FM program and any one of the digital audio program channels available in an
HD™ broadcast. (Optional hardware permits simultaneous monitoring of up to four digital program
channels.)  The monitor simultaneously presents information about the digital data stream as well as
technical and program-related information carried by the data stream. On-board processing provides real-
time spectral analysis of the hybrid IBOC RF signal. Internally generated calibration signals permit
checking the accuracy of the analog metering at any time.  Diagnostics assist servicing the HD Radio
system.  Communications ports and a graphical user interface enable local or remote operation of the

FMHD-1

via an external PC.

1.2

Physical Description

The

FMHD-1

is constructed on a standard 3½ X 19-inch EIA rack mount panel (2 EIA rack units; 89mm

X 483mm). The unit and rear-panel connectors extend 14¼ inches (362mm) to the rear of the front face of
the rack rails, but additional space should be allowed to accommodate the connectors used to make the
necessary electrical connections and adjust the RF input level controls. The standard XLR audio output
connectors require a total depth of no less than about 16½ inches (419mm) behind the front panel to
easily make connections. The front-panel encoder knob protrudes about one inch (25.4mm) outward from
the rack mounting.

All connections to the

FMHD-1

: the RF input connectors, the instrument communications connectors,

and digital and analog audio outputs are located on the rear panel. The rear-panel connectors include
panel-mounted BNC jacks and XLR output plugs, D-sub connectors, RJ-45 jacks, and an F connector.
Two rear-panel potentiometers facilitate adjustment of the signal level applied to each of the two high-
level RF inputs.

No user adjustments to the monitor circuitry are required to maintain specified performance. All factory
adjustments are located within the shielded compartment of the monitor.

1.3

Electrical Description

The

Belar

FMHD-1

is a precision DSP-based solid-state FM receiver that down-converts and

demodulates FM hybrid In-Band/On-Channel signals in the FM broadcast band. Front-panel tuning spans
the 88-MHz-to-108-MHz FM band in 100-kHz increments. The

FMHD-1

may be driven by either

high-level RF transmission-line samples, or off-air from a receiving antenna. For installations at the
transmitter, the

FMHD-1

provides two isolated, 50-

Ω inputs that accept either a single RF feed from one