Racal Instruments 2461 User Manual page 164

User Manual 2461 Type C
Accuracy:
(Relative to the trigger point as queried with INP[1|2]:COMP:LEV?)
Output Impedance:
Connector:
Automatic Trigger
In the automatic trigger mode the maximum and minimum values of the input waveform are
measured and the trigger points are set nominally halfway between these values. The
peak values are available via the DMM function.
The input signal must be continuously repetitive and be ≥ 5ns (pulse) or ≤ 20MHz
sinewave. The UCT will also auto-trigger to a DC level (i.e. any signal with an AC content
of < 150mV pk-pk). In this case, the processor will return zero for the peak values and will
set the trigger level to the nominal DC voltage at the input. The lowest frequency of auto-
trigger can be set to 50Hz or 1kHz in order to minimize auto-trigger acquisition times.
Selectable Auto-Trigger Minimum Frequency
The auto-trigger algorithm is optimised for the lowest AC frequency to be acquired. In
general, the lower the frequency that the algorithm has to process, the longer will be the
maximum and typical acquisition times. For this reason, the user is given the ability to
program the lowest input frequency that must be acquired, thereby reducing to a minimum
the auto-trigger acquisition time. The algorithm will accept a programmable lower
acquisition frequency of 50Hz or 1kHz (note that a lower limit of more than 1kHz would
provide no further reduction in maximum or typical acquisition times). The following table
shows how acquisition time is affected by input frequency. The default setting is 1kHz.
Minimum Input
Frequency Set
50Hz
50Hz
1kHz
1kHz
Auto Attenuation
The auto-trigger selects the appropriate attenuator automatically, and the following
conditions apply:
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x1 (Measured output not scaled by user)
x10 (Measured output scaled by user)
10 kΩ nominal.
MCX female jacks for both Channel 1 and 2 trigger level outputs.
Outputs are labelled VT1 for Channel 1 and VT2 for Channel 2.
Actual Input
Frequency
50Hz
1kHz
1kHz
20MHz
± 1% setting ± 10mV
± 1% (setting × 10) ± 100mV
Maximum Typical Acquisition
Acquisition Time Time
13s ---
--- 2s
1.5s ---
--- 0.4s
A-5