Tektronix DPScope II User Manual
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Tektronix DPScope II User Manual

Tektronix DPScope II User Manual

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DPScope II User Manual
Version 1.1
Feb. 11, 2017

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Summary of Contents for Tektronix DPScope II

  • Page 1 DPScope II User Manual Version 1.1 Feb. 11, 2017...

  • Page 2: Table Of Contents

    Contents Introduction ..........................1 General Remarks ......................1 Software Startup....................... 1 The Main Screen ......................3 First Acquisition ........................ 4 Acquisition Modes ......................4 1.5.1 Normal Mode......................5 1.5.2 Pretrigger Mode ......................5 1.5.3 Equivalent Time Sampling Mode: ................6 1.5.4 Datalogger (Roll) Mode: ....................
  • Page 3 File Menu ........................22 2.7.1 Load Setup ......................22 2.7.2 Save Setup As ......................22 2.7.3 Export Data ......................22 2.7.4 Exit .......................... 23 Measure Menu ....................... 23 2.8.1 Measurements ......................23 2.8.2 Spectrum Analysis ....................25 2.8.3 DMM Display ......................26 Generator Menu ......................

  • Page 4: Introduction

    (http://www.ftdichip.com/Drivers/VCP.htm ). After you installed the USB driver and the DPScope II software, plug in your DPScope II and wait a short time so the computer has a chance to recognize the scope. The DPScope II’s power LED on the front panel should blink quickly a few times and then stay solidly on –...
  • Page 5 DPScope II program should appear on the screen. If the program cannot connect to the DPScope II you will get a popup (see below) that you need to confirm in order to continue. The software will still start after that, but you will not be able to run the acquisition. In this case, close the software, unplug the oscilloscope, plug it in again (you may want to try a different USB port if that does not help), and launch the software again.

  • Page 6: The Main Screen

    (e.g. to determine the signal amplitude or frequency). On the top of the screen you find the menu containing several items:  File (to save the displayed waveforms in numerical format, and to save and restore the DPScope II’s software settings)

  • Page 7: First Acquisition

    Congratulations – you have just measured your first signal with the DPScope II! 1.5 Acquisition Modes The DPScope II’s acquisition engine has four different modes (again, refer to the “XYZ of Oscilloscopes” document for further details):...

  • Page 8: Normal Mode

    1.5.1 Normal Mode Acquisition is started by a trigger event (or automatically right after the previous acquisition if the trigger mode is “Auto”) and samples the signal in real time. This is very similar to how a classic analog oscilloscope operates. Real-time acquisition means the acquisition is very fast (up to approx.

  • Page 9: Equivalent Time Sampling Mode

    Once the delay has spanned one full real-time sampling interval (one microsecond or half a microsecond, respectively), the DPScope II restarts the acquisition delay from zero delay.

  • Page 10: Probe, Vertical Gain Setup And Trigger Setup

    Whenever you use a new 1:10 probe, first perform a probe calibration (described in section “Calibration”). 1:1 probes should not need any calibration because the DPScope II’s input has been calibrated for them as part of the scope assembly.

  • Page 11: Undersampling / Aliasing

    CH1 or CH2 – you want to trigger on) and turn the trigger on. Switching on the “Levels” display can be helpful there as well. To quickly move a slider back to center just press the button labeled “X” (“center”) above the respective slider.

  • Page 12: Description Of User Controls

    2 Description of User Controls 2.1 Acquisition 2.1.1 Run Starts the acquisition process – data is captured (if trigger event occurs) and displayed on the screen. If “continuous” is selected the acquisition will repeat until “Stop” is pressed. In case of “single shot”...

  • Page 13: Continuous / Single Shot

    This function is only available in datalogger mode. It allows you to write all the captured samples directly into a file. This way you can record signals of arbitrary time spans and with an arbitrary number of sample points, no longer restricted to the DPScope II’s 800 points per channel record length.

  • Page 14: Display

    SPI bus consisting of clock, data, and chip select. In this case you can first set up the DPScope II so CH1 looks at the chip select and CH2 looks at the clock signal, and it triggers on the falling edge of the chip select signal.

  • Page 15: Persist

    display mode – if the signals change fast compared to the sample rate, connecting subsequent sample points with lines can result in a messy, difficult-to-interpret picture on the screen. 2.2.5 Persist Normally the screen is cleared whenever the scope has a new acquisition to display. Checking this option will make the scope keep all waveforms on the screen until you either press “Stop”...

  • Page 16: X/Y Mode

    Levels: amplitude, high and low level, average level, overshoot and undershoot Timing: period, frequency, delay, phase, rise and fall time Note that the DPScope II also offers a set of fully automated measurements. You can access them through Measure  Measurements.

  • Page 17: Frequency Spectrum (Fft) / Fft Setup

    You can use the cursors to make measurements of frequency and relative power. Note that the sample rate box changes to frequency units (Hz and kHz). In addition to cursor measurements the DPScope II software offers fully automated spectrum measurements which you can access through Measure  Spectrum Analysis: It can automatically identify the frequency and strength of the fundamental frequency and its harmonics, and calculate total distortion and noise.

  • Page 18: Vertical

    (The scope has no way of knowing what you have the probe set to). Due to the way the DPScope II is designed, the probe used (1:1 or 1:10, respectively) influences the internal signal offset. Thus it is important to always select the true probe attenuation, i.e.

  • Page 19: Probe Coupling

    1:10 mode before contacting the circuit with the probe. Note that as also stated in the disclaimer on our website, the DPScope II is not intended for high-voltage applications and as a result we decline any responsibility for damage or injury resulting from such work with high voltages –...

  • Page 20: Scope Mode / Datalogger (Roll) Mode

    2.4.2 Scope Mode / Datalogger (Roll) Mode In scope mode the DPScope II will always acquire a full data set (800 samples per channel) and store it in its internal memory before transmitting it to the computer for display. This enables very fast sample rates (up to 50 MSamples/sec in Equivalent Time Sampling Mode) because there is no limitation from the transmission speed between scope and computer.

  • Page 21: Pretrigger Mode

    2.5.1 Auto / CH1 / CH2 The Auto / CH1 / CH2 radio buttons let you select what the DPScope II shall trigger on. A trigger is basically a condition that determines when the oscilloscope starts the data acquisition. For a repetitive signal you use this to obtain a steady picture of the signals.

  • Page 22: Rising / Falling / Both

    If set to “Auto” the DPScope II will be free running (constantly collecting data) and not wait for any special event before capturing data. This is useful when you want to look at an unknown signal, because you will always see something on the screen (the scope will not wait and not display anything just because some trigger condition is not fulfilled).

  • Page 23: Noise Reject

    DPScope II from triggering at all. In this case either turn the feature off, or increase the sample rate so the period becomes a larger fraction of the screen width.

  • Page 24: Ch1 / Ch2 (Channel Offsets)

    (greyed out). 2.6.2 Trg (Trigger Level) This slider controls the trigger threshold. If the DPScope II is set up to trigger on one of the channels (CH1 or CH2), a trigger event occurs whenever the signal crosses this threshold with the desired polarity (rising or falling edge, respectively, or both rising and falling).

  • Page 25: File Menu

    2.7 File Menu 2.7.1 Load Setup Recalls a previously saved setup (all settings like acquisition mode, vertical scales, time scale, trigger setup, etc.) from a file. 2.7.2 Save Setup As Saves the current setup (i.e. all settings like acquisition mode, vertical scales, time scale, trigger setup, etc.) to a file.

  • Page 26: Exit

    2.8 Measure Menu 2.8.1 Measurements While it is possible to make measurements on the waveforms using the cursors, the DPScope II also offers a faster and much more convenient method: Fully automated measurements. Selecting Utilities  Measurements brings up the Measurement panel. Here you can select on which channel(s) (CH1 and/or CH2) the software shall take the measurements, and also which measurements to take.
  • Page 27 Important notes:  In order for the timing measurements to work, at least one full signal period needs to be displayed on the screen.  The time measurements employ linear interpolation to improve resolution and accuracy of the results. This way the resolution of the measurements is much finer than one sample period.

  • Page 28: Spectrum Analysis

    Short description of each measurement:  Low: lowest value (minimum) on the screen.  High: highest value on the screen.  Mid: Midpoint between low and high, mid = (low + high) / 2  DC mean: average voltage level, calculated over all points on the screen ...

  • Page 29: Dmm Display

    This panel is only active when the display is set to frequency spectrum (FFT). Here the software automatically finds the fundamental frequency (the assumption being that what is displayed is a periodic signal) as well as the first 10 harmonics. It shows both the frequencies (calculated as center-of-mass of the power spectrum) and the relative amplitudes (corresponding to the area of each peak), the fundamental being the 100% reference.

  • Page 30: Generator Menu

    +/-0.5%. 2.9 Generator Menu The DPScope II offers a simple frequency generator. It’s output is available at the CAL pin on the back side of the instrument. This signal is mainly intended for probe compensation (see section below) but is also usable for other applications.

  • Page 31: Calibration Menu

    1:10 probe (and the adjustment is on the trimmer of the probe, not the one in the scope). Each such probe must be adjusted to match the DPScope II’s (or any other scope’s) input, i.e. it is usually not sufficient if you performed probe compensation on a different oscilloscope.

  • Page 33: Level Compensation

    Level compensation is part of the setup and checkout process before each DPScope II is shipped so the scope is usable right out of the box without you needing to perform this procedure.

  • Page 34: Utilities Menu

    2.11 Utilities Menu 2.11.1 Comm Setup Displays the virtual COM port the DPScope II is connected to. Since detection is automatic, the “Manual” setup feature is currently always grayed out.

  • Page 35: Help Menu

    2.12 Help Menu 2.12.1 About Here you can find version and build date of your software, the version of the scope’s firmware, and finally the serial number of your scope – please always include this information when submitting bug reports or support requests. The panel also shows the support contact info.

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