Tektronix DC 5010 Anleitung Seite 42

Operating Instructions-DC 501 0
46.8525 ns. Ten averages yields 15 counts
(5
counts
+
10
counts). Dividing the total count by the number of averages,
the average (countlinterval) of each count corresponds to
3.1 25 nsec. The answer, is then (1 511 0
x
3.1 25
=
4.68525,
which on the DC 501 0 would be displayed as 4.6 nsec.
Null
Pressing the NULL button stores the present measure-
ment result and then subtracts that number from all subse-
quent measurements (while the button remains lighted). It is
most useful in Time A
--
B measurements, where it can be
used to null out systematic errors (such as unequal cable
lengths and channel mismatches); however, it is available in
all measurement functions.
The averages setting may be changed without losing the
Null stored measurement. If the instrument is subtracting
two numbers of differing resolution, the result of such a sub-
traction has the resolution of the lesser resolution number.
This is the number that the counter automatically uses to
determine how many digits to display.
Pressing the button again will re-null the result.
To exit the Null mode, press any function button (includ-
ing that of the function already chosen).
Events B During A
The EVENTS B DUR A function is basically the same as
WIDTH A; except, instead of clock edges, the counter
counts the selected number of positive-going or negative-
going events (t- SLOPE, CHANNEL B) occurring during a
selected positive or negative pulse width occurring on Chan-
nel A (+ SLOPE, CHANNEL A). Therefore, the internal time
base is not counted for this function. See Fig. 2-7 for a
measurement example. The Channel B events are averaged
over the selected number (AVGS) of Channel A pulse
widths.
Time Manual
The TlME MANUAL function measures and displays the
time interval (to the closest one-hundredth of a second) be-
tween the first and second depressions of the MEASURE-
MENT STARTISTOP pushbutton. The time count can be
reset to zero and restarted by pressing and then releasing
the RESET pushbutton. The AVGS switch has no affect in
the Time Manual mode. When first entering this function, the
measurement is in the STOPped mode, as indicated by the
lighted STARTISTOP button.
CH B Events
Events
~~
CH A INPUT
Counted
(- SLOPE) ------
- I
Fig. 2-7. Measurement example, EVENTS B DURING A.
Totalize A
The Total A function is basically the same as TlME MAN-
UAL except that instead of counting the internal time base
pulses, the counter counts the total number of Channel A
events occurring between two successive depressions of
the MEASUREMENT STARTISTOP pushbutton. The
AVGS switch is active in this mode. With the AVGS expo-
, ,
nent set to 0 or AUTO (-I), whole numbers iare displayed.
For other settings, AVGS operates as a power-of-ten scal-
ing indicator (allowing totalizing to the full fourteen digits of
the internal count chain). For example, with a 1 MHz input
signal and the AVGS switch set to
lo6,
the leisst significant
digit displayed would represent 1
o6
counts and would incre-
ment at one count per second (1
O6
Hz11
o6
==
1 Hz). This
scaling factor may be changed (Refer to Text:) after a mea-
surement is over, effectively moving the display. This allows
the user to view all thirteen digits of the count chain.
Totalize A+B
The TOTAL A+B function is as described for TOTAL A
with the exception that the counter counts the total number
of Channel A events plus the total number 'of Channel B
events. The B count does not begin until after the first valid
A count.
Totalize A
-
B
The TOTAL A- B function is similar to the TOTAL A+ B
function with the exception that the counter counts the total
number of Channel A events minus the total number of
/ T
Channel B events. The
B
count does not begin until after the
first valid A count.