Front Panel Operation
3-27
Crest factor: The crest factor of a waveform is the ratio of its
peak value to its RMS value. Thus, the crest factor specifies
the dynamic range of a true RMS instrument. For sinusoidal
waveforms, the crest factor is 1.414. For a symmetrical
square wave, the crest factor is unity. The crest factor of a
rectangular pulse is related to its duty cycle; as the duty cycle
decreases, the crest factor increases.
For the Model 2001, the additional error term for RMS mea-
surements caused by a high crest factor is specified up to a
value of five. The maximum displayable value is 9.99, or else
it shows “over”.
Note that the crest factor is not calculated if dB or dBm is the
presently selected units.
Low level considerations
For sensitive measurements, external considerations besides
the Model 2001 affect the accuracy. Effects not noticeable
Figure 3-10 (continued)
AC voltage multifunction multiple displays
RMS
RANGE = Set by ACV range (auto or fixed).
Autoranges independently of other functions.
REL = Operates normally.
SPEED = Set by ACV speed.
FILTER = Set by ACV filter.
RESOLUTION = Set by ACV resolution.
UNITS = Set by ACV units.
COUPLING = Set by ACV coupling.
AC-TYPE = Fixed on normal mode RMS.
AVG
RANGE = Set by ACV range (auto or fixed).
Autoranges independently of other functions.
REL = No effect.
SPEED= Set by ACV speed.
FILTER = Unaffected by ACV filter.
RESOLUTION = Fixed at 5.5 digits.
UNITS = Fixed on volts.
COUPLING = Set by ACV coupling.
+000.000 mVAC RMS
AVG=000.000mV Peak=000.0mV
Peak
RANGE = Set by ACV range (auto or fixed).
Autoranges independently of other functions.
REL = No effect.
SPEED = Fixed at 100msec. Peak window has no
effect.
FILTER = Unaffected by ACV filter.
RESOLUTION = Fixed at 4 digits.
UNITS = Fixed on volts.
COUPLING = Set by ACV coupling.
B. AC RMS, average, and peak voltages
when working with higher voltages are significant in micro-
volt signals. The Model 2001 reads only the signal received
at its input; therefore, it is important that this signal be prop-
erly transmitted from the source. The following paragraphs
indicate factors that affect accuracy, including thermal off-
sets and stray pick-up.
Shielding: AC voltages that are extremely large compared
with the DC signal to be measured may produce an errone-
ous output. Therefore, to minimize AC interference, the cir-
cuit should be shielded with the shield connected to the
Model 2001 INPUT LO (particularly for low-level sources).
Improper shielding can cause the Model 2001 to behave in
one or more of the following ways:
• Unexpected offset voltages.
• Inconsistent readings between ranges.
• Sudden shifts in reading.
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