Input Switching; Rf-Attenuator Encoding - Motorola R-20010 Maintenance Manual

Table 15-3. Range-Attenuator Switching
ATTENLines Gain from Selected Input to
Sensitivity of EXT FREQ.
Gain from Selected Input
to VERT FROM RNG SW Output
CNTR and EXT FREQ. CNTR
Attenuation XO.OO I XO.OI XO.I X1 DVM FROM RNG SW Output
(VERNIER CAL POS) Outputs
to
Selected Input
XI 0 0 0 I 1
XO.I 0 0 I 0 0.1
XO.OI 0 I 0 0 0.01
XO.OOI I 0 0 0 0.001
15.2.1.4 Input-Switching Control
Location 4 of the AF BUS accesses outputs which
control selection of t he external (P1-1) or internal (P1-
24) inputs and ac or de coupling of the external input.
This control is achieved with data-bus bits 0 and 1 as
R hown in Table 15-4.
Table 15-4. Input Switching
EXT INPUT DC
S ELECT SELECT Input Source Coupling
I
I EXT INPUT de
I 0
EXT INPUT
ac
0 X INT SCOPE TO RNG SW de
50 30MV
5 300 MV
0.5 3V
0.05 30V
15.2.1.5 RF-Attenuator Encoding
The RF ATTEN 0-130 dB inputs indicate the set -
ting of the RF step attenuator in the RF Input module
(Al7). When one of t hese inpu ts is driven high, the
corresponding attenuation has been selected. These
fo urteen inputs are converted to a 4-bit code (RF
ATTEN 0-3) by priority encoders UlO and Ul 2 and
OR gates U12. Location 5 of t he AF BUS accesses these
outputs. Table 15-5 shows the encoding of the RF
A TTEN 0-130 dB inputs into t he RF A TTEN 0-3 out-
put.
Table 15-5. RF -Attenuator Encoding
RF A TTEN Lines
I:IOdB 120 dB llOdB IOOdB 90dB SO dB
70dB 60dB
()
0 0 0 0 0 0 0
0
0 0 0 0 0 0 0
0 0
0 0 0
0
0 0
0 0 0 0 0 0
0
0
0
0 0 0 0 0 0 0
0
0 0 0 0 0 0 0
0
0
0
0
0 0
0 0
0 0 0 0 0
0 0
1
0
0 0 0 0 0 1 0
0 0 0 0 0 1 0 0
0 0 0 0 1 0 0 0
0
0
0
I 0 0 0 0
0 ()
I 0 0 0 0 0
0
I
0 0 0 0
0 0
I 0 0 0 0
0 0 0
15.2.1.6 Miscellaneous Inputs
Locations 6-8 of the AF BUS access miscellaneous
RF ATTEN Bits
50 dB 40dB 30dB 20 dB IOdB OdB 3 2 I 0
0 0 0
0 0 0 0 0
0 0
0 0 0 0
0
1 0 0 0 0
0 0 0 0
1
0 0 0 0
I
0 0 0
1
0 0 0
0 I
0
0 0 I 0 0 0 0 0 1 1
0 1 0 0 0 0 0 1 0 0
1 0 0 0
0 0
0 1 0
I
0 0 0 0 0 0 0 1 1
0
0 0 0 0 0 0 0
I 1 1
0 0 0 0 0 0 I 0 0 0
0 0 0 0 0 0 1 0 0 1
0 0 0
0 0 0
1
0
l
0
0
0
0 0 0 0 1 0 1 1
0 0 0 0 0 0
1 1
0 0
0 0 0 0
0 0
1
I
0
1
data inputs. Table 15-1 gives the specific location of
each input on the bus. Table 15-6 gives a brief descrip-
tion of each input.
15-3