Intro Scope

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Intro Scope#

This intro supports labmanuals 2A, 2B and 4A

  • 2A: measuring with a scope (AC & DC)

  • 2B: triggering on channel 1

  • 4A: Fourier analysis with the scope

The oscilloscope is an indispensable device to test electronic circuits and is an important complement to the DMM. It allows the observation of signals that vary over time and therefore allows to better study certain parameters such as frequency and amplitude for AC signals.

The oscilloscope record a signal on one of its four channels, connected with:

  • a coax cable: a cable with an inner connector (=signal line) and outer shield (=COM, or ground), and can be seen as 2 cables in one

  • a scope probe: a specific cable which has better specifications than just a coac cable.

Watch the movie clip below to get a quick intro into the scope

quick start manual: https://siglentna.com/wp-content/uploads/dlm_uploads/2024/12/SDS800X-HD_QuickStart_EN01B.pdf

user manual: https://siglentna.com/wp-content/uploads/dlm_uploads/2024/11/SigScopeLab_UserManual_EN02A.pdf

## SCR-scope 


from IPython.lib.display import YouTubeVideo
YouTubeVideo('lSHAE_Y6snc', width = 600, height = 450)

Use the scope - basics#

on/off#

After turning on the oscilloscope, you can switch on/ off channels:

  • press once for switching on, one more to switch off.

  • once switch on: you should see the yellow/pink/blue/green colored signal on the screen, plus the current display settings of that channel in the bottom left corner.

channel settings#

  • Correctly adapt a channel (1)’s settings

    • Press button “1” once, to select the channel

    • For a short while a menu should appear, with “C1” written on top.

    • In this menu you can adjust many things, it is a touchscreen, so just tap to select:

      • Coupling : DC coupling means you display the value of the signal, with AC coupling the average is subtracted before display.

      • other default settings are: “BW Limit” at ‘OFF,” “Probe” at “1X”.

Scaling of voltage and timescale#

  • Adjust the vertical and horizontal scale to your likings.

    • the ‘Vertical’ turning knob tunes between V <-> mV

    • the ‘Horizontal’ turning knob tunes between s <-> ns.

Basic Triggering#

The trigger determines when the oscilloscope starts to acquire data and display a waveform.

  • Connect the trigger signal to the channel of your likings. For example signal on CH1, and trigger on CH2.

  • Select the right channel to trigger, via Trigger>Setup, and change the source to C1, C2, C3 or C4.

  • Adjust the trigger level, which controls the voltage point on the waveform where the trigger occurs, by:

    • turn the Level knob. For example to 0.50 V( this doesn’t have to be precise).

    • push the Level knob, and then the trigger level will be set to the average value of the signal.

  • You can adapt the slope via the Trigger Setup menu

Hint: Scope can be a little finicky when adjusting settings with a knob. Don’t get discouraged!

Cursors#

You can use the cursor controls to move along the x and y axes.

  • press the cursors button to switch on the cursors and select:

    • source (CH1,CH2, but also Math)

    • type: x (time) or y (voltage)

  • turn the intenisty/adjust knob to move the selected cursor

  • press the intensity/adjust knob to switch between cursor 1&2

Measure#

Instead of the manual cursors, you can also use ‘Measure’ to automatically determine for example the Vpp or the frequency of a signal. :

  • press the Measure button

  • lots of default values, such as Pk-Pk, Mean, Period, Freq are default measured.

  • more options are available under Measure > Type

Triggering#

The trigger is a very useful function that allows us to control the way in which a signal is displayed by the oscilloscope. The trigger determines when the oscilloscope starts to acquire data and display a waveform.

When a trigger is set up properly, it can convert unstable displays or blank screens into meaningful waveforms. The oscilloscope acquires data while waiting for the trigger condition to occur, which is the measured voltage crossing a set threshold. After a trigger is detected, the oscilloscope continues to acquire enough data to draw the waveform on the display.

Default settings#

In the TRIGGERSteup menu:

  • Type = Edge. An edge trigger occurs when the signal passes through a specified voltage level with the specified slope.

  • source= C1

  • slope= rising. The SLOPE control controls whether the scope starts measuring at the rising edge and the falling edge.

  • holdoff = None

  • Coupling = DC

Fourier Transform#

The Fourier transform states that a signal or waveform can be represented as a sum of sine waves. To observe this on the oscilloscope:

  • Use the Math key, and then select function FFT

  • Via Math > Horizontal or Vertical the axis of th FFT plot can be adapted. The original V-t diagram can still be apated by the Vertical and Horizontal turning knobs.

  • On the scope you only see the positive frequency axis, so only one peak is shown for a recorded sine.

Suggestion: try to see the FFT of a block wave on the scope.

Scope probe#

If the bandwidth of the measurement with a coax cable is too limited, you can use a scope probe:

  • adapt the channel accordingly by selecting the channel and set the Probe to 10x. Don’t forget to revert to 1x after removal of the probe

  • the (top) hook should be connected to the signal in, the crocodile clip at the side is to be connected to either common ground or somewhere else in your system

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