1.0 INTRODUCTION:
GENERAL DESCRIPTION
The FMU622CA is designed to receive and process into the FM stereo
broadcast band any one of the stereo audio programs delivered by satellite as
narrow-band frequency modulated sub carriers, normally above video, on selected
transponders, such as fine arts radio WFMT on Satcom 3, transponder 3, along with
TV Super station WGN in Chicago. This system incorporates complimentary
dynamic range expansion to optimize the signal to noise ratio by a sliding frequency
cut-off (variable de-emphasis process).
The RF output frequency of these units, like other FM SYSTEMS, INC.
products, is adjustable in the field without changing crystals. This state of the art
design uses a master crystal oscillator and a programmable phase-lock-loop (PLL)
system to precisely set the output to any standard frequency in the FM Broadcast
Band. Other frequencies outside the 88-108 MHz Band are available upon special
request. The program output is also available as Base-band Audio, with separate
balanced outputs for left and right channels.
2.0 INSTALLATION AND OPERATING INSTRUCTIONS:
NOTE: This section assumes that the FMU622CA is tuned to the desired sub-
carrier frequency and FM channel output frequency. If not, proceed to section 6.5,
Tuning Procedures.
Remove the unit from its shipping container and inspect for shipping damage.
The FMU622CA is usually shipped already mounted in a PMS610 panel (1-¾” high x
19” standard rack width). The FMU622CA is mounted in a PMS610 mainframe
power supply, if you have purchased a separate FMU622CA module to be installed
in an existing PMS610, refer to Appendix B of this instruction set for the installation
procedure.
When power is applied, observe that the red “OFF FREQ” LED illuminates and
flickers off, indicating that the RF output is locked on frequency.
Connect an RG59U cable between the “COMPOSITE” output of the satellite
receiver and the “SUBCARRIER INPUT-IN” on the rear of the FMU622CA.
Terminate the “SUBCARIER INPUT-OUT” with 75 ohms, either a resistor, or looped
through into another unit with 75 ohms resistive termination.
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