19
Signametrics
2.10 Time Measurements
2.10.1 Threshold DAC (SMU2064)
The Threshold DAC is used for selecting a detection level, providing optimal frequency and time
measurements even at extreme duty cycle values
.
Accuracy ± (% of s volts)
Selected VAC
range [1]
Threshold range (DC
level)
Threshold
DAC
resolution
Highest allowed input
Vp-p
Typical one year setting
uncertainty
240 mV
-1.0 V to +1.0 V
0.5 mV
1.900 V
0.2% + 4 mV
2.4 V
-10.0 V to +10.0 V
5.0 mV
19.00 V
0.2% + 40 mV
24 V
-100.0 V to 100.0 V
50 mV
190.0 V
0.2% + 0.4 V
240 V
-400 V to 400 V
500 V
850.0 V
0.2% + 4 V
[1] This table should be used in conjunction with the AC volts section above.
2.10.2 Frequency and Period Measurements
Input Impedance
1 M
with < 300 pF for voltage, 0.15
to 10
for current.
Ranging
Auto-Ranging (default) or Range-Lock
Maximum acquisition time while in Auto-Ranging mode
7s
Acquisition Time in Range Locked mode
35ms to 2s
Frequency
One Year accuracy (% of
r Hz)
Resolution (Hz)
Minimum amplitued (VRMS)
1Hz – 130Hz
0.025% + 0.0015Hz
1 mHz
130Hz – 640Hz
0.025% + 0.02Hz
6.5 mHz
640Hz – 2.5kHz
0.03% + 0.075Hz
25 mHz
2.5kHz – 40kHz
0.03% + 1.2Hz
0.4 Hz
30mV or 5% of range, whichever is
greater
40kHz – 200kHz
0.05% + 7Hz
2.5 Hz
200kHz – 300kHz
0.07% + 5Hz
1.5 Hz
25% of range
2.10.3 Duty Cycle Measurement
Frequency Range
2 Hz to 100 Hz
100 Hz to 1 kHz
1 kHz to 10 kHz
10 kHz to 100 kHz
Resolution
0.02%
0.2%
2%
20%
Typical Uncertainty is
±0.03% of reading ±
adder shown
0.03%
0.3%
3%
20%
Full scale reading
100.00 %
100.00 %
100.00 %
100.00 %
2.10.4 Pulse Width
± (% of r sec)
Polarity
Frequency range
Resolution
Width range
Typical
Uncertainty
Positive or negative pulse
widths
2 Hz to 100 kHz
1
s
2
s to 1 s
0.01 +/- 4
s
2.10.5 Totalizer (SMU2064)
Selectable edge polarity:
Positive or negative edge transition
Maximum count:
10,000,000,000
Allowed rate:
0.2 to 45,000 events per second
Threshold:
Set Threshold DAC
Accuracy:
±2 counts
