HP 5326A - Operating Modes

Model 5326/27A
Operation
SECTION IS
3-1. INTRODUCTION
3-2. Section III contains the operating information
required to obtain the most effective performance
from the instrument. This includes a general descrip¬
tion of the operating modes, the function of ail con¬
trols and indicators, a self-check procedure, and setup
procedures for making basic measurements.
3-3. OPERATING MODES
3-4. The following paragraphs describe the operating
modes of totalize, frequency, period, time interval,
and ratio.
3-5. Totalize Mode
3-6. START and STOP positions on the FUNCTION
selector allow manual opening and closing of the
counter’s main gate. When the switch is in the START
position, the counter does not measure frequency, but
instead, counts the number of times the signal passes
through the trigger point. The input signal, connected
to the front-panel CHANNEL A jack, is divided by the
MULTIPLIER switch setting prior to counting. For
example, when the MULTIPLIER switch is set to the
1 position, every pulse is counted. When the switch is
set to 10 ;i , the counter registers every thousandth
pulse. When the FUNCTION switch is set to STOP,
the counter stops totalizing and holds the displayed
count until the RESET switch is pressed or the
MULTIPLIER switch setting is changed. If the
FUNCTION switch is again set to START before a
reset is generated, the count continues to totalize
from the previously displayed value. With the FUNC¬
TION switch set to START, the scaled input signal
is available at the rear-panel TIME BASE OUTPUT
jack. The unit indicators and decimal points are
blanked during the totalize mode. The C light is
on (in START), indicating counting is taking place.
3-7. Frequency Modes
3-8. Three frequency modes are available in the
5327A: Frequency A, Frequency C prescaled, and Fre¬
quency C direct, (The prescale operation is not in¬
cluded in the 5326A.) In the Frequency A mode, the
input signal connects to the high impedance
CHANNEL A input jack and can be conditioned with
the LEVEL, SLOPE, and ATTEN controls. In the Fre¬
quency C modes, the input signal is connected to the
INPUT C jack (50 ohm). The signal is not conditioned
by any front-panel controls but may be counted either
directly (50 MHz) or by prescaling (550 MHz),
depending on the setting of the INPUT C switch.
The G channel of the 5326A model counts the signal
directly.
3-9. Period Modes
3-10. The period and period average modes allow
single period measurements or multiple period
averages to be made with input frequencies into
CHANNEL A of up to 10 MHz. These modes are use¬
ful for making low frequency measurements where
maximum resolution is desired.
3-11. For single period measurements, the MULTI¬
PLIER switch scales the time base frequency and
selects the placement of the decimal point and deter¬
mines the resolution of the measurement.
3-12. The period average mode is used for increased
resolution and reduced inaccuracies. For example, if
10 2 period averaging is selected, the counter will dis¬
play the average of 100 periods with the proper decimal
point. In this example, trigger error is 100 times less
than in a single period measurement.
3-13. Time Interval Modes
3-14. Two modes of time interval measurements can
be selected: time interval and time interval average.
The time interval modes measure the time between
points on a single waveform or between separate in¬
put signals; thus, pulse width and phase differences
can be measured. Separate slope and level controls
allow variable triggering levels on either the + or -
slope. Marker A and B outputs are available at
the rear panel to intensity-modulate an HP I BOA
oscilloscope. The markers indicate the trigger point
of the counter’s input circuits and provide a visual
means of adjusting the trigger points to measure
the time interval between any two points and are
useful to about 100 kHz.
3-15. In time interval measurements, Channel A
opens the main gate and Channel B closes the main
gate. While the main gate is open, the internal oscil¬
lator, divided by the setting of the MULTIPLIER
switch, is totalized by the counter and readout on the
display. The less the division factor, the more pulses
of the internal oscillator there are to count and, there¬
fore, the better the resolution and accuracy.
3-16. With time interval average, the main gate is
open for the number of time intervals selected by the
MULTIPLIER switch. The internal oscillator pulses
(not divided) are totalized only during the individual
time intervals. Once Channel B triggers, there must
3-1