Measurement
Uncertainties
Random Uncertainties (1
)
■
Quantization Error
(E
q)
E
q
= 100 ps rms
■
Start/Stop Trigger Error
(E
ss)
E
jitter
= Single Period Jitter (rms)
(s)
V
noise-input:
500 V
rms
internal noise
(200 V
rms typical)
V
noise-signal: The rms noise of the
applied signal
Systematic Uncertainties
■ Trigger Level Timing Error
(E
tl
)
Time Interval, Rise/Fall Time, Pulse
Width,
Duty Factor, Phase (attenuator setting
xl)
where:
Sx = Slew rate at start trigger point (V/s)
Sy = Slew rate at stop trigger point (V/s)
TLU = Trigger level uncertainty (V)
Hyst = Hysteresis window (V)
Hyst = 30 mV ± 1% of trig lvl (DC to 1 kHz)
for Pulse Width & Duty Factor
Hyst = 6 mV ± 1 % of trig lvl (DC to l kHz)
for other measurement functions.
■ Timebase Error
(TBE)
TBE is the relative error of the timebase
oscillator (dimensionless) and depends on the
actual oscillator used. See Timebase Options
on page 8-29.
Total Uncertainty (2
)
The general formula for all measurement
functions is:
Time Interval, Pulse Width,
Rise/Fall Time
■ Random Uncertainty
(rms)
■ Systematic
Uncertainty
where:
Etl = trigger level timing error
500 ps = maximum channel difference
TBE = timebase error
TIME = measurement result
Frequency & Period A, B
■ Random Uncertainty
(rms)
For measuring times <200 ms and if Smart
Freq = AUTO or OFF:
x Measurement Result
[Hz or s]
For measuring times >=200 ms and if Smart
Freq = AUTO or ON:
x Measurement Result [Hz or s]
N = 800 /Measuring Time, however, 6 < N <
1000 and
N < (Freq/2) * Measuring Time - 2
■ Systematic
Uncertainty
[Hz
or
s]
where:
MR = Meas. Result (Freq or Per)
MT = Meas. Time
Frequency & Period C
■ Random Uncertainty
(rms)
where:
F = Meas. Result expressed as frequency
rounded up to the nearest whole GHz.
Example: 14.2... GHz should be inserted as
15*10
9
■ Systematic
Uncertainty
F is calculated as under Random Uncertainty
above.
Specifications
USER MANUAL ● CNT 9x Series ● Rev.22 February 2020
8-22
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