HP 5328A User Manual

Model 5328A
Operation
CASE NO. 1 CASE NO. 2
SIGNAL INPUT
TO MAIN GATE
I I
1 I
I I I
I I I
"I
GATE OPENING
SIGNAL COUNTED
n 2
I
Figure 3-6. +I Count Ambiguity
NOTE
The main gate is open for the same time tm in both
cases. Incoherence between the clock and the input
signal can result in two different counts which for this
example are 1 for case No. 1 and 2 for case No. 2.
3-38.
FREQUENCY MEASUREMENT ERROR. The error caused by the ambiguity is in absolute
terms,
+I of the accumulated count. For a frequency measurement the signal counted is the
input signal of frequency fin Thus the relative error
is given by
?I count error, relative frequency measurement error
3-39.
PERIOD MEASUREMENT ERROR. For period measurement, on theother hand, thesignal
counted
is the internal time base clock of period tc. Hence the relative error becomes
3 count error; relative period measurement error
AT
ktc
-
-- -
Tin
3-40. MAIN GATE REQUIREMENTS. The
+I count error described above assumes the main gate
itself does not contribute any error. As with any gate, however, the main gate does exhibit
propagation delays and takes finite times to both switch on and off. Any differential between the
times taken for the main gate to switch on and off show up as uncertainties in the length of time
the gate isopen. This uncertainty in turn translates intoa measurement error that increases the?I
count. However, the uncertainty in the main gateof the 5328A issubstantially less than the period
of the highest frequency counted, so this error
is not appreciable.
3-41. Time Base Error
3-42.
Any error in the time base oscillator directly translates itself into a measurement error.
Thus, if the total of all the oscillator errors amount to 1 x 10-6, the total error contributed by the
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HP 5328A Specifications

General

Brand	HP
Model	5328A
Category	Cash Counter
Language	English