Fluke 93 - Page 56

3-22
CIRCUIT DESCRIPTIONS
Table 3.7 Frequencies
of A-ASIC signals In various modes^
Time Base TRACKN freq
1)
CHA freq
1)
MODE
horizontal vertical
60 s/div 0.8333 Hz
0.416 Hz
~r
_
20 s/drv 2.5 Hz
1.25 Hz roll
i
10 s/div
5 Hz 2.5 Hz
,
5
s/div
10 Hz
5
Hz
-
-
T
2 $/div
25 Hz 12.5 Hz
i
1 s/dIv
50 Hz 25 Hz
C
.5 s/div
100 Hz 50 Hz
H
.2 s/div
250 Hz 125 Hz
s 0
.1 s/div
500 Hz 269 Hz
p
50 ms/dlv 1 kHz 500 Hz
N
20 ms/div 2.5 kHz 1.25 kHz
G F
10 ms/div
5 kHz 2.5 kHz L
z
5
ms/div
10 kHz
5
kHz
E
z
i\
2
ms/div 25 kHz 12.5 Id-fz
_
1 ms/div
50 kHz 25 kHz
.5 ms/div
100 kHz 50 kHz f
•
r
.2 ms/div 260
kHz 125 kHz Ei
.1 ms/dlv
600 kHz 250 kHz C
50
ps/div
1 MHz 500 kHz
U
1
z
20
ps/div
1.25 MHz
“
r
R
-
10
ps/div
2.5
MHz
R
5
ps/div
5 MHz Trigger E
z
2
ps/div 12.5
MHz N
A
.
'
1
ps/dfv 25 MHz
dependent T
_
.5
ps/div
25 MHz
1
r
.2
ps/div
25 MHz
f
.1 ps/div
25 MHz
m
50 ns/div 25 MHz
20 ns/div 25 MHz
f
1 f
10 ns/div 25 MHz
1
)
In MtN/MAX mod^
(only possible for one channel), the frequency
of CHA is zero and the sample
frequency TRACK Is always
25 MHz.
Clamp
To prevent the
Track & Hold circuit from overdrive,
the signal is damped. The level of the output
signal
can be adjusted by means of VREF
(input 23). VREF is the reference voltage, made
by
ihe circuit
consisting of V2301, V2302 and R2323,
R2324, and R2325 (see ADC section).
Track A Hold
The maximum sampling frequency
of the ADC used in the ScopeMeter is 25
MHz.
This
means that
the ADC can only handle signals with
frequencies up to 12.5 MHz (half the sample frequency).
Because of this a Track & Hold circuit
Is
incorporated
In the A-ASIC. The Track & Hold circuit
determines the frequency
range of the whole system.
The timing in this part of
the A-ASlC (s determined by clock signal
TRACKN (input 1
2).
The frequency
of the TRACKN signal
depends on the selected timebase
speed (see table 3.7).