TM11-5840-360-14-1-1
4.4.1.4 Sweep Drive and Output Circuits. - The X and Y
4.4.1.2 Position Transmission Circuits. - The position
sweep outputs are amplified in deflection amplifiers and
transmission circuits provide the following outputs:
applied to the CRT deflection yoke. The currents
through the deflection yoke generate a net magnetic
a.
Resolver drive signal
field which deflects the CRT sweep in synchronism with
b.
Sample pulses
the antenna position. The CRT sweep is terminated at
c.
X/Y reference signals
the end of the sweep gate, or if the sweep is deflected
d.
Display offset
10% beyond the CRT radius (whichever occurs earlier).
e.
Unblanking signal
4.4.2 Video Processing
When an indicator is designated master
indicator by a command from the interswitch, the
position transmission circuits produce the resolver drive
4.4.2.1 Data Storage Circuits. - Video signals from the
signal for the antenna resolver and sample pulses for
receiver are converted to digital form and stored. High
the slave indicators. The resolver drive signal is
and low level signals are processed separately to
modulated by the antenna position and returned, via the
provide two-level video display. The stored digital video
NSK circuits to the position transmission circuits in the
is applied to the interference rejection circuits coincident
master and slave indicators. The sample pulses from
with the beginning of the CRT sweep, at a rate
the master indicator are sent to the slave indicators
determined by the range-scale selected sweep rate.
position transmission circuits to control sampling of
High and low level video data is applied separately to
antenna position data.
the interference rejection circuits.
The resolver drive circuit of the slave
indicator(s) is disabled by the absence of the master
4.4.2.2 Interference Rejection Circuits. - The operation
command signal from the digital processor.
of the interference rejection (IR) circuits is selected by
The X/Y reference signals, derived by
the INTRF REJECT switch on the indicator control
combining antenna position data and sampled/stored
panel. In the OFF position, video data is forwarded to
data, are applied to the sweep generator circuits via the
the video amplifier for CRT display. In the ON position,
EBL switching circuits.
the video data is forwarded to the video amplifier and
The display offset signal, enabled by the
also stored in IR memory. At the beginning of the next
OFFSET switch on the indicator bezel, is coupled
CRT sweep, the incoming video is compared with the
through the EBL switching circuit to the Y-axis deflection
stored video from the previous sweep. If the incoming
amplifier in the sweep drive and output circuits.
and stored video are coincident (indicating true targets),
The unblanking signal applied to the video
the video is forwarded for display. If the incoming and
amplifier is used to unblank the CRT for video display.
stored video are not coincident (indicating random
The unblanking signal is derived from the modified
interference), the video signal is inhibited.
sweep gate and the 85 percent signal from the sweep
generator circuits. Burn protection is provided for the
4.4.2.3 Video Amplifier Circuits. - The video amplifier
CRT by inhibiting CRT unblanking for subsequent
circuits provide video amplification, signal mixing, CRT
sweeps when the sweep does not reach 85 percent of
unblanking and processing of front panel control signals.
the CRT radius. When the INTRF REJECT switch is set
Video amplification and signal mixing are provided for
to the ON position, the delayed sweep gate from the
the following:
interference rejection circuits delays the unblanking
signal by one range cell.
a.
Digital video (high and low level)
b.
Real time video
4.4.1.3 Sweep Generation Circuits. - The X and Y
c.
Fixed range marks
reference signals from the position transmission circuits
d.
EBL (electronic bearing line) video
are applied as sweep charging voltages to separate
e.
VRM (variable range mark)
sawtooth generators. The charging rate (fast, medium
f.
Heading flash
or slow) is determined by the setting of the RANGE
The CRT is unblanked in response to the
SELECT switch. Sweep charging is initiated by the
unblank command from the position transmission
delayed sweep gate from the interference rejection
circuits.
circuits. The X and Y sawtooth outputs are applied to
the sweep drive and output circuits.
4-7
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