The Agilent 54622A Digital Oscilloscope
An oscilloscope is a device that will provide you with a plot of a fluctuating voltage versus
time. Voltage is plotted on the vertical axis, and the scale of this axis is controlled by the
Vertical adjustment. Time is plotted on the 
horizontal axis, and the scale of this axis is controlled
by the horizontal adjustments. The scope may be configured so that both axes are adjusted automatically.
You should think of an oscilloscope as being a voltmeter with the capability to plot changing voltage values vs. time. For example, oscilloscopes have very high internal resistances to all parallel measurements. Oscilloscopes cannot measure current directly.
In a digital oscilloscope, the analog voltages measured at the input are converted into digital values by an analog-to-digital converter. The Agilent 54622A uses an 8-bit A/D converter, which means that a full-scale signal at the input is converted into 256 digital values – smaller signals will correspond to a smaller number of bits.
The full-scale signal value depends on the Vertical setting. For example, a Vertical setting of 50
mV, means that each vertical division on the screen corresponds to 50 x 10-3 Volts. Notice that there
are 8 divisions on the vertical scale, so with this setting, the full-scale voltage is 0.4 volts. Thus,
the bit-resolution for this Vertical setting is
0.400/256 or 1.5625 mV. Analog voltage increments of 1.5625 mV will cause the digital value to increase
by one.
Note: the Agilent 54622A may operate in an averaging mode that results in an enhanced
bit-resolution of up to 12 bits (4096 digital values per full scale reading).
A digital oscilloscope samples specific voltage values at specific instants of time, determined by the
sample-rate. This is a set rate, and for the Agilent 54622A, it is 200 x 106 samples per second.
The data samples are then averaged and converted to display points on the oscilloscope screen.
The Agilent 54622A has a LCD screen that utilizes 1000 pixels for the plotting area. The total time
interval of the plotted region is determined by the Horizontal setting. For example, a Horizontal
setting of 1.0 ms means that each horizontal division on the screen corresponds to 10-3 seconds.
Notice that there are 10 divisions on the horizontal scale, so with this setting, there are 0.01
seconds displayed across the entire plot. The Agilent 54622A will take all data points acquired over
that total time interval, and average them into a 1000 point display record.
Agilent 33120A 15MHz Arbitrary Waveform Generator
This function generator will output a variety of waveforms - including sine and cosine waves - at frequencies up to 15MHz.
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