— 14 —
not surprisingly labeled
MPX OUT 1
and MPX
OUT 2
. Their
source impedance is a resistive 75 ohms.
The level of the multiplex signal at each output is adjusted un-
der the
Setup / Stereo Generator / Multiplex Output
menu (Page 37).
The level in open-circuit peak-to-peak volts is indicated in the
menu, and can be adjusted between 0.8V p-p and 8V p-p
(+11dBu), corresponding to program peak modulation.
RDS COMBINING PROVISION
19kHz Sync
Output
The
19kHz SYNC
BNC connector gives a TTL-compatible square-
wave output at the 19kHz stereo pilot frequency when RDS
combining is enabled. This is a 5V p-p square wave with a 50%
duty cycle, in-phase with the stereo pilot component of the FM
multiplex signal. This waveform may be used to synchronize
an RDS (Radio Data System) encoder with the stereo pilot.
RDS Input
The
RDS INPUT
BNC connector accepts the 57kHz RDS subcar-
rier for combining with the FM multiplex program signal. The
p-p level of the subcarrier can range from 0.5V to 5V, corre-
sponding to a typical injection level that’s approximately 5% of
total carrier deviation.
Internal
Metering
The DAVID IV has an accurate and helpful internal metering
utility for adjusting the RDS subcarrier injection. The actual
injection level is shown directly as a percentage of total carrier
modulation under the
Setup / Stereo Generator / RDS Input
menu
(Page 38). This is very useful during installation of the RDS en-
coder, especially when a modulation monitor that displays ac-
tual RDS subcarrier injection is not available.
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