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Table
15-6.
Functions of Miscellaneous Inputs
Input
Function
RF'OVERTEMP
When high,
indicates the
Wattmeter
(A
17A
1)
is
overheated.
WBSIG
PRES
Comes
from
the
Receiver
(AS)- during the
system's
scan-acquisition,
indicates
the
presence
of a
signal at the monitor
input.
ANTSRL
Comes from
the Front Panel
(A18)
-
selects
the
system's
1/0
port.
When
the
variable RF
Level
control
is
pulled
out,
this
signal
goes
high,
selecting
the
Antenna
port.
When
the
control
is
pushed
in
,
this
signal
goes
low,
selecting
the RF
In/Out port.
IF
OVERLOAD
Comes
from
the
Receiver
-
indicates
the monitor
is
being over-d riven.
S
IC;
PRES
Comes
from
t he
Receiver
-
indicates
the
presence
of
a
signal
on
the monitor
input which
is
sufficiently
high to
open
the
Receiver
squelch.
OFFSET
ON/
OFF
Indicates
the position
of
the Duplex
Gen
switch
on
the RF Input module
(A17).
WH/
NH
Indicates
the position
of the
bandwidth
(BW)
switch on the front panel.
CSSG CONT
EN
Indicate
whether
the
front
panel's
Modulation switch
is set
to Cont or Burst,
respectively.
and
CSSG BURST EN
IMAGEHI/LO
Indicates
the position of
the Image/Duplex switch
on
the
front
panel.
MON/
GEN
Indicates
the position
of
the Function switch
on
the front
panel.
15.2.1 .7 Range-Select Inputs
The
0.01 to
10V /Div RNG SEL
inputs
indicate
which
scope
vertical-input sensitivity
has
been
selected.
When
one of
these inputs is
low, t
he
corre-
sponding sensitivity
has
been
selected.
The
micropro-
cessor
programs the appropriate attenuation in
the
range
attenuator via the ATTN X0.001 to
1
signals.
Location
9
on
the AF BUS accesses the 0.01 to
10V
I
Div RNG SEL inputs.
15.2.1.8 Sweep-Select Encoding
The 1
J.lS
to 100
ms/DIV
SWP SEL and
EXT HORIZ
SEL
inputs
indicate the position
of
the Oscilloscope
Horiz
switch
on
the
front
panel. When
one of
these
inputs is
high,
the
corresponding
switch
position
has
been
selected.
These inputs are converted to
a
3-bit
code,
SWP SEL
0-2,
by priority
encoder
U18, accord-
ing to the algorithm in Table
15-7.
Location 10 on the
AF BUS accesses the
SWP
SEL
0-2
outputs.
Table 15-7. Sweep-Select Encoding
SWP
SEL
Lines
EXT
HORIZ
SEL
100
ms/DIV
10
ms/DIV
I
ms/DIV
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
I
()
0
1
0
0
I
0
0
I
0
0
0
15.2.1.9 RF-Scan
Encoding
The
OPTICAL ENC A
and
B
inputs
carry
infor-
mation
from the
RF
Scan optical
encoder
on
the
front
panel.
This encoder is
interfaced
to
the
system
micro-
processor
by
U22,
U23, and
Q16
on the
Front-Panel
Interface.
As
the
RF
Scan control
is
rotated,
each
15-4
SWP
S
EL
Bit~
IOOI!s/
DIV
10
lls/DIV
ll!s/D
IV
2
I
0
0
0
0
0
0
0
0
0
I
0
0
0
0
I
0
0
0
I
1
0
0
0
I
0
0
0
0
0
I
I
0
0
0
1
0
0
0
0
0
1
0
1
0
0
0
I
1
0
change
in
the
OPTICAL ENC A input
causes
the FIRQ
output,
which goes to the
microprocessor, to pull low
for
approximately
10
J.lS.
The OPTO
CCW
output,
which
goes to a
PIA
on the
Processor board
(A14),
indicates
the
direction
of the
scanning.
This output
is
generated
by
latching
the
OPTICAL ENC B
input and
exclusively
ORing it with
the
OPTICAL ENC A input.
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