Counter/Timer; Cit Measurement Menu - Tektronix 2247A Operator's Manual

Operators Familiarization
SET ZERO REF is a measurement modifier that toggles on (undorlln
cf)
or off whenever this menu Item button Is pushed. When turn ed on, n
Initial propagation measurement Is made by the CIT , and saved
zero reference. Thereafter (until toggled off), all propagation d I, y
measurements will have this zero reference value subtracted from
them . This Is useful for zeroing out delay mismatches b tw n
channels and probes.
NOTE
For PROPDL Y measurement , if the START measurement
channel is the same as the A Trigger channel , than A Trig
ger level is automatically adjusted to try to guarantee that
the measurement will trigger properly, as follows :
If
A Trigger SLOPE Is the same as the measure-
ment ' s B START slope , the A Trigger level Is set
near the B ST ART trigger level.
If A Trigger SLOPE is \.... and B ST ART SLOPE Is
...r,
or if A Trigger SLOPE is
...r
and B ST ART
SLOPE is \...., A Trigger level is set near the 50%
level.
(TO TIMER CONTROL MENU)-selects a menu th t
resolution magnifiers to be selected for the CIT- based version of th
time measurements. Only one of the three resolution m agnlfl r m y
be selected at a time. The selected resolution magnifier get und ,
lined. See the C/T Control Menu discussion for a description
resolutlon magnifier operation.
(TIMER CONTROL) AUTO RESOL
X10 RESOL
X100 RESOL
C/T TRIG TIMEOUT
(BACK TO TIME MENU)
Timer Control menu
Each press of the CIT TRIG TIMEOUT Item button to ggles thl fun ti ,
on and off. Timeout mode gets underlined when It Is toggl d
Toggling timeout mode In this menu also chang es It In th (
CONTROL) menu. The (TIMER CONTROL) menu stays up, uni
(BACK TO TIME MENU) Is selected . See the C IT Control M
discussion for the description of this function.
3-24
l,
Operators Familiarization
Counter/Timer
Press the COUNTER TIMER button to call up the CIT measurement
choices .
In the (CTR/TIMER) menu, selecting a measurement will cause the menu to
disappear (If menus are configured to clear after selection). Selecting
TOT ALIZE causes the totalize RESET label to appear by the top menu Item
button (If menus are configured to disappear). While the totallze measure-
ment Is running , the RESET label will stay on screen In the absence of any
other menu . Canceling the totalize measurement will also cancel the RESET
label . The RESET function Is momentary , so the label never gets under-
lined . If al'}other menu Is called up then canceled , the RESET label
reappears.
CIT Measurement Menu Page 1
(CTR/TIMER) FREQ
PERIOD
WIDTH
TOTALIZE
FREQ RATIO
(TO GATED MEASMT MENU)
Counter/Timer Menu
RESET
Totallze R~set Menu
_, 1
For these measurements , all B trigger modes aper.ate as usual for trig-
gering the CIT. B source LEDs are turned off : The measurement source
channels can be altered In the SET MEAS' MT ,CHANNEL menu . All B
coupling modes may be used, and B slope may be changed to control which
edge polarity triggers the CIT. The B trigger light remains off during CIT
measurements. However, Indication of proper triggering Is shown with a
steadily blinking "Ct" character In the top line of ihe readout. If an external
frequency reference source Is plugged Into , the rear-panel EXT CIT
REFERENCE INPUT BNC, the " Ct" character will have the "ET" character
above It.
In TOT ALIZE, the "Ct" character stays on continuously, and B AUTO
LEVEL MODE only works when measurement Is first selected. After that,
no Indication Is given If B trigger Is lost. However, B AUTO LEVEL MODE
may be reselected to acquire a new trigger level.
2247 A Operators
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