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Step One - Creating a Sinewave With No DC Offset Voltage, High Z Load Resistance
1. A basic waveform you will now produce is a 1 kHz, 100 mVpp sine wave with no DC offset.
Connect the Output (a BNC connector on the front panel) to the vertical input of an
oscilloscope.
2. Turn the power on by pressing the white button at the lower left of the front panel. You are
reminded that you can get Help for any key by holding it down.
3. The display says 1.000,000,0 kHz, with a picture of a sinewave on the right. It also says
"Output Off", so the first thing we need to do is press the Output button. Press it now.
4. Press AutoScale on the mixed-signal oscilloscope (MSO) (or adjust its controls manually) to
display the sinewave. Press QuickMeas on the MSO to measure the frequency and peak-
to-peak voltage (should be very close to 1.000 kHz and 200 mVpp). You may want to turn
on Averaging on the MSO to minimize noise and get more accurate readings.
5. Now, press the Softkey labeled Ampl; it should say 100.0 mVpp. Wait a minute! What's
going on here - we just measured 200 mVpp? The reason for this discrepancy is that the
oscilloscope input resistance is 1M Ω (High Z), not the 50 Ω the AWG assumed was the
load resistance connected to the AWG output connector. How do we fix this discrepancy?
6. Since we are going to be using the MSO as our "Device Under Test" (i.e. the load connected
to the AWG), and the MSO resistance is 1M Ω, not the 50 Ω the MSO "expected", we will tell
the AWG what its load is.
7. Press the Utility hardkey, then the Output Setup softkey, and the Load softkey. This
changes the AWG to "High Z" mode, and it will now display the correct output amplitude.
8. Press the Sine hardkey; the amplitude now displayed is 200.0 mVpp, which agrees with the
amplitude as measured on the oscilloscope.
Be aware of the load resistance of the circuit or instrument you connect to the AWG. If you
were connecting the AWG output to a logic circuit (which could be damaged by an input voltage
that is too big) and did not change the AWG to "High Z" mode, the actual AWG output voltage
can be twice what the AWG display indicates.
Step Two - Creating a Sinewave With DC Offset Voltage, High Z Load Resistance
1) Leave the AWG in "High Z" mode. Now we will add some DC offset to our 1 kHz sinewave,
200 mVpp. This can be done two ways.
2) Method 1: Press the Offset softkey. Use the right "Navigation Arrow Key" to move the
cursor one place to the right on the amplitude display. Rotate the Knob one click
clockwise; this will add +100 mVDC to the 200 mVpp sinewave. See the display below.
(66 paginas)
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