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User Manual 3155
Functional
Description
Output Functions
Frequency Waveform frequency and sample clock are programmed with 10 dig-
Amplitude
Trigger Modes Besides its normal continuous mode, the 3155 responds to a variety
Arbitrary Waveforms
A detailed functional description is given following the general d e-
scription of the features, functions, and options available with the
3155.
Model 3155 is completely digital. There are no analog functions resi-
dent in its hardware circuits. Data has to be downloaded to the i n -
strument to start generating waveforms. The instrument can gener-
ate standard functions such as sine wave, triangular wave and
square wave. Each time that a standard function is required, the i n -
strument calculates its values and places them in waveform memory.
Therefore, every time a standard function is selected, time is re-
quired for the controller to compute the function and load its data into
waveform memory.
its of resolution, limited only by 1µS/s. Frequency accuracy of the
output waveform is determined by the clock reference. The PXIbus
backplane clock provides 100ppm accuracy and stability over time
and temperature. If higher accuracy and/or stability are required, you
may order the 3155 with a 1ppm reference, or connect an external
frequency reference to the front-panel reference input connector.
The output level may be programmed from 160mV to 16Vp-p into
open circuit, or 80mV to 8V into 50Ω. An offset may be applied to the
output to shift the signal either positive or negative. Offset and am-
plitude are inter-related, so make sure you u nderstand the offset-
amplitude ranges before you apply an offset to your signal.
of trigger sources. The output waveform may be gated or triggered to
generate a counted burst of waveforms. A built-in trigger generator
with a programmable period can be used to replace an external trig-
ger source. The internal trigger generator can be programmed with a
resolution of 7 digits. The 3155 can be programmed to output trig-
gers on one or more of 7 trigger lines that are connected to P2, and,
be programmed to respond to these same trigger lines.
The Model 3155 generates arbitrary waveforms with 14 bits of verti-
cal resolution. Any waveform it generates is first loaded into its
waveform memory. The arbitrary waveform memory is a bank of 14-
bit words. Each word represents a point on the horizontal waveform
scale. Each word has a horizontal address that can range from 0 to
1,048,576 and a vertical address that can range from -8192 to +8191
(14 bits). Using a high speed clocking circuit, the digital contents of
the arbitrary waveform memory is extracted and routed to the Digital
to Analog Converter (DAC). The DAC converts the digital data to an
analog signal, and the output amplifier completes the task by ampli-
fying or attenuating the signal at the output connector.
Overview 1-5
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