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SECTION3
Operation
Frequency to period: Press the set or ms key when the
Model 3930A is displaying
frequency.
The actual, specified value is always displayed for the in-
ternal rate period, and the period accuracy specifications
stated in Appendix
B apply. However, the frequency dis-
played is the result obtained by rounding
off the recipro-
cal of a given period to the predetermined
number of dig-
its according to the selected resolution
(the reciprocal is
truncated for values lower than the resolution),
and the
result is displayed.
Note, therefore, that the frequency
displayed
as the result of units conversion
contains a
larger error when the programmed
period is high.
Example:
A rate period of 2,350.Osec is converted to a frequency of
0.0004H2, an error of -6% when compared to the cor-
rectly converted frequency
Amplitude
Units Conversion
p-p or rms to dBV: Press the dBV key when the Model
3930A displays the p-p or rms value.
p-p or dBV to rms: Press the Vrms or mVrms key when
the Model 3930A displays the p-p or dBV value.
rms or dBV to p-p: Press the V or mVrms key when the
Model 3930A displays the rms or dBV value.
NOTE
Amplitude
units conversion
is possible only
in the AUTO output
range mode. Only p-p
units can be suecified in the FXD (fixed) out-
put range mo&. See paragraph 3..612 for de-
tails on the output range mode.
For amplitude,
no one-to-one correspondence
for actu-
ally specified
values exists. Because a given value is
rounded
off according to restrictions
on the number of
display digits and the resolution
for each type of units,
the amplitude
display may not return to exactly the same
value after conversion from one type of units to another
and back to the original units.
3.5.5
Frequency
Programming
Pressing the FREQ key displays the current frequency
and enables frequency programming.
(During
a sweep
or sweep hold, however,
the frequency
cannot be pro-
grammed,
but the current
frequency
can still be dis-
played by pressing FREQ.)
To program the frequency using the numeric keys, press
the kHz, or Hz key after entering the value. The resolu-
tion of a frequency value is O.lmHz. When the specified
frequency is below IkHz, the value will be displayed
in
Hz units. For 1kHz and above, the frequency will be dis-
played in kHz units. To specify the frequency in period
units instead of frequency units, press one of the time pe-
riod keys (set or ms). Frequency programming
for sweep
operations is identical.
The allowed frequency range for sine and square waves
(withfixed50%
dutycycle)isfromO.OOOlHz
tol,ZOOkHz;
for other waveforms,
the upper limit is is 1OOkHz for
good quality
waveforms.
The absolute upper limit for
variable duty cycle square waves is lOOkHz, but the fre-
quency can be set as high as 1,ZOOkHz for 2/,n,and
u waveforms
of reduced quality.
The unit accepts a maximum
of six digits and has a reso-
lution of 1Onsec for the frequency parameter. The actual
oscillation
frequency is obtained by truncating
the recip-
rocal of the given value to an acceptable number of digits
on the part of the value smaller than O.lmHz.
When frequency
programming
is enabled,
you can
change the present value with the MODIFY
knob. The
knob can be used to change the value during both fre-
quency display and period display. When the step size is
il
or f5, you can select the digit to change by placing
flashing
underline
cursor under the appropriate
digit
and turning
the MODIFY knob to the right or left. When
the step size is x+2 or x+10, the cursor will disappear, and
you can divide or multiple
the value by 2 or by 10 by tin-
ing the knob to the left or right.
Note that when the displayed
period is obtained from a
frequency specified with an insufficient
number of digits,
the actual oscillation frequency may not be changed even
if the value is changed with the numeric
keys or the
MODIFY knob. The Model 3930A always displays a cor-
rect value for frequency.
3-20
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