— —
4
Crosstalk
(M
à
S or S
à
M)
:
Processing OUT: nonlinear
crosstalk –55dB or better.
Processing IN: overall crosstalk
–50dB or better
Stereo Pilot:
19kHz, ±1Hz; injection level
adjustable between 6% and 12%,
relative to 100% modulation.
Program Line Inputs:
Active-balanced/bridging;
accommodate nominal “0VU”
input levels between –15dBu and
+15dBu.
SCA / RDS Input:
10K-ohms, unbalanced; accepts
SCA or RDS subcarrier signal
levels between –20dBu and 0dBu
for nominal 5% to 10% injection.
Pre-emphasis:
Integral with split-band audio
processing. May be jumpered for
75µs or 50µs characteristic.
“Bass-Enhance” Equalizer:
Accentuates “perceived” bass
response at user’s option. (See
Figure 4, Page 10.)
AGC Amplifier:
Slow, 0.5dB/sec. correction for
long-term input level variations;
±10dB capture range.
Compressor/Limiter:
Fast-acting peak limiter with
secondary “platform” time
constant to compress dynamic
range with average-value
weighting. Independent high
frequency limiter conforms to
selected pre-emphasis
characteristic. Subsequent
program signal clipping is
relegated to non-repetitive limiter
overshoots 1ms or less in duration.
Composite (Multiplex) Output:
Adjustable between 1V p-p and
8V p-p; 75-ohm source impedance.
Composite Processor:
Adjustable from 0dB to 3dB
clipping of the 100%-modulated
multiplex waveform prior to pilot
injection.
Digital Synthesis Sampling Rate:
608kHz (16X subcarrier
oversampling).
Power Requirements:
105–130VAC or 210–255VAC,
50/60Hz; 15 watts.
Size and Weight:
1¾”H x 19”W x 7”D (1U);
7lbs (shipping).
BLOCK DIAGRAM
A simplified Block Diagram of the
DAVID-II
is shown on the facing
page. Generator circuitry is explained in detail under Circuit
Descriptions, Section V, which references Schematic Diagrams found in
the Appendix, Section VI.
PATENT NOTICE
Low-pass filter overshoot compensation circuitry used in the
DAVID-II
is protected under U.S. Patent No. 4,737,725.
