Inovonics 540, Operating And Maintenance Instruction Manual

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Section IV
RDS-DECODE OPTION
The Model 540 accommodates an optional plug-in assembly which
independently demodulates digital “radiodata” broadcast by stations
supporting RDS, the Radio Data System. RDS transmissions serve a
number of purposes: automatic receiver tuning to search for specific
formats, “radiotext” displays for station promos or advertising, personal
paging services, and “housekeeping” functions which enhance a
broadcaster’s service to his listeners.
The RDS data channel is transmitted as a low-level, double-sideband,
suppressed-carrier “subcarrier” at 57kHz, just above the spectrum of the
composite stereo program signal in the FM baseband. The data
transmission (baud) rate is modest, yet it is “robust,” thanks to data
redundancy and error correction.
The plug-in RDS Option for the Model 540 demodulates the 57kHz
subcarrier and reformats the RDS data stream into RS-232 serial digital
data which may be fed to any IBM-compatible computer. Supplied
software decodes the RDS data so that it may be read.
INSTALLING THE OPTIONAL PLUG-IN RDS CARD
If the Model 540 was supplied without the RDS Option, the rear-panel
RDS DATA OUT
connector cutout will have been covered by a plastic
escutcheon. This may be removed, and the plug-in Option card installed
as follows.
First, remove two jackscrews from the DB-9 connector of the plug-in
Option card, and the spare 4-40 screw from the single threaded standoff
on the back of the board. Angle the Option card downward so that the
DB-9 connector pokes through the back-panel cutout. While gently
forcing the six Option connecting pins toward the back panel with your
thumb, align these pins with the mating connector strip on the main
circuit board and push the Option into its seated position. Re-install the
two jackscrews and the 4-40 screw to complete the installation.
COMPUTER REQUIREMENTS
RDS decoding and analysis software runs under DOS on any IBM-
compatible computer with a 286-or-better processor. The program will
run equally well on an old DOS machine, or under Windows
®
from the
MS-DOS Prompt command.