4 Time-domain Measurement
Thursday, 12 July 2018
8:31 AM
Automatic Time Measurements
Set the FG to a 3 V p-p 20 kHz sinusoid. Set the time base to 200 s/div.

Press Quick Meas. Note that the frequency is automatically displayed. Change the FG wave shape to square. On the FG, turn the Symmetry switch on (up) and turn the Symmetry knob fully clockwise.

Press the Select: softkey. Use the Entry knob     to select Duty Cycle. Press the Measure Duty softkey. Note the duty cycle range of the FG by turning the FG’s Symmetry knob. Change the FG wave shape back to sinusoid, and turn the Symmetry switch off.

Turn Channel 2 on and set the time base to 50.0 ms/div. Set the FG to about 5 kHz, then push the 10 Hz range button to get 5 Hz. 

Press Quick Meas. Use the Entry knob to select Phase. Press the Measure Phase softkey. Measure the phase difference between the two waveforms. Determine which channel is used as the reference by the DSO for the phase measurement. You can set up the way the DSO measures phase by using the softkey Settings.

Automatic Voltage Measurements
Be careful when using the automatic voltage measurements – the DSO can’t differentiate between a noise peak and a signal peak.
Turn Channel 2 off.

Press Quick Meas. Measure the Peak-Peak voltage of Channel 1. Measure the Average of Channel 1. Measure the RMS of Channel 1. Change the FG waveform to triangle, then to square, and observe the change in the measurements.

Set the FG to a sinusoidal wave, and vary the DC offset. Note the effect on the Pk-Pk, Avg and RMS values. Turn the DC offset to ‘off’.
Mini-Lab Amplifier Setup
The function generator has an output resistance of   and so any load that draws considerable current will cause the output to experience a significant internal Ri voltage drop, resulting in a “droop” in the output voltage. The Mini-lab provides us with a “buffer amplifier” that is capable of delivering large currents with minimal voltage drop.
 Mini-lab Amplifier

1.	Identify the section under the power switch labelled “AMPLIFIER OR
BI-POLAR POWER SUPPLY”.
2.	Ensure that the left-most pushbutton is out (F. GEN) so that the internal function generator is selected as the input.
3.	Ensure that the middle pushbutton is out (NORM) so that the output is normal.
4.	Ensure that the right-most pushbutton is out (AMP) so that the unit acts as an amplifier.
5.	Ensure that the knob is fully rotated counter-clockwise to select a gain of “X 1”.
6.	With these settings a “buffered” version of the function generator output is provided directly from the red output terminal.
Cursor Measurements
The cursor keys are useful for making custom time or voltage measurements on a signal.
For example, we would like to measure the time it takes for a particular waveform to respond to a stimulus and reach 63.2% of its final “steady-state” value. We take a measurement of the time T as shown below:

Cursors are used for custom measurements
Set the FG to a 2 V p-p, 5 kHz square wave.
Turn Channel 2 on and set the coupling to DC. Measure the output of the Mini-Lab amplifier with Channel 2 of the DSO.

Press Main/Delayed. Set the Time Ref softkey to Left. Set the Time/Div to 500 ns.

Press Cursors.

Source selects a channel for the cursor measurements. Change the cursors’ source to Channel 2 by pressing the Source softkey.

Press the softkey labelled X Y to select the Y (voltage) cursors.

Press the softkey labelled Y1. Move the Y1 cursor to align with the bottom of the output response by rotating the Entry knob.

Press the softkey labelled Y2 to enable the second Y (voltage) cursor. Move the Y2 cursor to align with the top (steady-state value) of the output response. Check that the cursor measurement displays  .

Now calculate 63.2% of the steady-state value. e.g.  63.2% x 2.000v = 1.264V

Adjust the Y2 cursor so that   is close to the 63.2% value. You will not be able to set the exact value. Choose the closest value available.

Press the softkey labelled X Y to select the X (time) cursors.

Press the softkey labelled X1. Move the X1 cursor to align with the vertical edge of the input square wave.

Press the softkey labelled X2. Move the X2 cursor to align with the intersection of the Y2 cursor and the channel 2 waveform.

Record the following measurement, using the value for  :
15.	Turn the cursors off.