Department of Electrical & Computer Engineering OSCILLOSCOPE GUIDE. Tektronix TDS2000 Series

Transcription

1 OSCILLOSCOPE Department of Electrical & Computer Engineering GUIDE Tektronix TDS2000 Series

2 Contents 1 INTRODUCTION OSCILLOSCOPE OVERVIEW INSTRUMENT FRONT PANEL... 3 Power Switch... 3 USB Drive Port... 3 Save Button... 3 Multipurpose Knob... 3 LCD Screen... 4 Menu Option Buttons... 4 VERTICAL Controls... 5 HORIZONTAL Controls... 7 TRIGGER Controls... 8 Setup and Control Buttons... 9 Input Connectors PASSIVE PROBES SIMPLIFIED MEASUREMENT PROCEDURE SAVING WAVEFORMS TO A USB DRIVE SAVING WAVEFORMS TO A COMPUTER APPENDIX 1 SPECIFICATIONS APPENDIX 2 REFERENCES

3 1 Introduction This guide provides basic instructions for operating the Tektronix TDS2000 Series Digital Phosphor Oscilloscopes. These are some features of various models 1 in the product line: 50 to 200 MHz bandwidth Up to 2 GS/s sample rate 2 or 4 channels Full color LCD with graphical user interface USB I/O for data transfer and control Built-in automated measurements 2 Oscilloscope Overview Copyright Tektronix, Inc. An oscilloscope is an instrument that measures a voltage signal and displays a graph of how the signal varies over time. The vertical axis of the graph is the voltage, while the horizontal axis is time. Important signal characteristics can be extracted from the graph, such as the shape and amplitude of the signal, the frequency or period of a repetitive waveform, and the amount of noise or distortion. A probe is used to connect the circuit being tested to the inputs of the oscilloscope. Each input, or channel, can independently measure a signal. In a digital oscilloscope, an analog-to-digital converter samples the input voltage signal and converts the analog values to digital form. The sampling is performed repeatedly as part of the time sweep. The scope processes the incoming data and displays it on the built-in monitor screen as a continuously updated graph of voltage versus time. Important specifications of a digital oscilloscope include: Bandwidth Specifies the highest signal frequency that can be accurately measured Sample rate Determines how often the input signal can be sampled (samples per second) Number of channels Determines how many independent signals can be measured simultaneously The front panel of a typical digital oscilloscope has these control sections: Vertical Adjusts the vertical (voltage) scaling and positioning of the waveform Horizontal Controls the horizontal (time) scaling and positioning of the waveform Trigger Provides a way to stabilize the display of repetitive signals on the screen Acquisition Controls how the input signal is acquired or sampled 1 The TDS2014C model has a 100 MHz bandwidth, 2 GS/s sampling rate, and four analog input channels. 2

4 3 Instrument Front Panel Power switch (on top of chassis) Save/Print button Option buttons Multipurpose knob Various setup & control buttons TRIGGER controls HORIZONTAL controls VERTICAL controls LCD screen USB drive port Probe input connectors Figure 1: Tektronix TDS2000C series front panel - Copyright Tektronix, Inc. Power Switch The switch located on top of the oscilloscope s chassis turns the instrument either on or off. Note: When the power is first applied, the oscilloscope performs a diagnostics test that lasts up to 30 seconds. When the test is done, an on-screen prompt asks if the current date or time needs to be changed. To exit this display, simply push any button or wait for it to time out. USB Drive Port This port is used to attach an external mass storage device. Screen images and waveform data can be saved to or recalled from a USB flash drive (up to 64 GB in size) that is inserted in the port. Save Button Pushing this button saves the waveform. Depending on how the button is configured, the waveform can either be stored as a file on a USB drive or sent to an attached printer. Multipurpose Knob The multipurpose knob is used to navigate the screen, select an item, or change a setting. 3

5 LCD Screen The screen shows a graph of the signal that is measured on an input channel. The oscilloscope provides controls for making individual channels either active (waveform is displayed on the screen) or inactive (waveform is omitted). Aquisition mode Trigger status (VERTICAL) Voltage Graticle divisions Waveform Waveform Time (HORIZONTAL) Ground reference marker Menu options Vertical scale (voltage/div) Channel indicator Horizontal scale (time/div) Trigger values Each channel is color coded: CH1=yellow, CH2=blue, CH3=purple, CH4=green The main graph area is divided into a grid to aid in reading the amplitude and timing of the waveforms. Dotted grid lines represent the major divisions on each axis. The vertical axis has units of voltage, while the horizontal axis has units of time. Menu Option Buttons The TDS2000C series support an on-screen menu for accessing various oscilloscope features that are not assigned to a dedicated button. If an oscilloscope function provides menu options, they are displayed in a column on the right side of the LCD screen. The content of the menu will vary depending on the current function. To the right of the menu column are the physical option buttons, which are located on the plastic bezel that surrounds the LCD. By pressing a button, the menu option associated with the button is selected. 4

6 VERTICAL Controls The vertical section adjusts the vertical (voltage) configuration, scaling, and positioning of the waveform. Each channel has its own independent vertical controls and settings. 1, 2, 3, 4 buttons The 1 (yellow), 2 (blue), 3 (purple), 4 (green) buttons display on-screen menu options for a selected channel (CH1 thru CH4). The menu options are applied only to the currently selected channel. If a channel is not active when its button is pressed, then the channel becomes active, its measured waveform is displayed on the screen, and its menu options appear. If a channel is already active when its button is pressed, then the channel becomes inactive, and its waveform stops being displayed. The menu options are: Coupling Selects the channel s input coupling. {DC, AC, Ground} DC Allows both AC and DC signals to get through. AC Filters out any DC signals, so only the AC variation is displayed. Ground Temporarily replaces the waveform with a 0 V flat reference line. BW Limit Volts/Div Probe Invert Limits the bandwidth to filter out high frequency noise. {Off, 20 MHz} Selects the resolution of the vertical Scale knob. {Coarse, Fine} Sets the scope to match the probe s operating characteristics. {Type, Attenuation} Type Type of probe being used (either voltage or current). Attenuation Sets the attenuation factor to match the probe s factor. Press the option button repeatedly or else use the multipurpose knob. {1X, 10X, 20X, 50X, 100X, 200X, 500X, 1000X} Flips the vertical polarity of the waveform. 5

7 Math button The Math (red) button allows math operations to be performed on waveforms. The result is displayed as a separate red-colored waveform on the screen. The menu options are: Operation Selects the math operation. {+, -, x, FFT} + Adds two waveforms - Subtracts two waveforms x Multiplies two waveforms FFT Fast Fourier Transform (magnitude vs frequency) of a single waveform Sources Selects source channels. {+,-,x: CH1&CH2 or CH3&CH4 FFT: CH1 thru CH4} Position knob (vertical) This knob moves the currently selected waveform up or down on the screen. It does not affect the waveform s vertical size. When multiple channels are active, the knob is useful for providing some vertical separation among the waveforms, which are otherwise overlaid by default. Scale knob (vertical) This knob adjusts the vertical scale (size) of the currently selected waveform. The vertical voltage scale is specified in units of volts per division (V/div). Example: If the scale is 2 V/div, then each major division on the vertical axis represents a 2 V span. 6

8 HORIZONTAL Controls The horizontal section adjusts the horizontal (time) scaling and positioning of the waveform. All channels share the same horizontal settings. Horiz button The button displays on-screen menu options for viewing a waveform across the entire acquisition period, or just a windowed section of it. The menu options are: Main Displays the original, complete waveform. Window Zone Sets the position of the window within the waveform. Use the horizontal Position knob to move the window s left (start) and right (stop) markers to frame the zone boundaries. Window Displays only the part of the waveform that is within the defined window zone. The contents of the window are zoomed out to the full width of the screen. Position knob (horizontal) This knob moves all waveforms left or right on the screen. It does not affect the horizontal time scale. Set to Zero button If waveforms have been horizontally shifted, this sets their position back to the zero reference point. Scale knob (horizontal) This knob adjusts the horizontal scale of all waveforms. The horizontal time scale is specified in units of time per division (e.g., ms/div). Example: If the scale is 5 ms/div, then each major division on the horizontal axis represents 5 ms. 7

9 TRIGGER Controls To show a stable image of a repeating waveform on the screen, the oscilloscope needs to acquire the signal at the same point on the waveform during each sweep. This is done by setting a threshold voltage value that, when the measured signal crosses the threshold, causes the oscilloscope to initiate an acquisition sweep. This threshold is called the trigger level. The trigger source can be either the input signal itself or an external trigger signal. Note: If the measured input signal never crosses the threshold because the level was set too high or too low, the displayed waveform will be unstable and jitter erratically on the screen. Trig View button As long as this button is pushed, a horizontal dashed line that represents the current trigger level is superimposed on the trigger source s waveform. Force Trig button Manually initiates acquisition regardless of an adequate trigger signal. Set to 50% button Automatically sets the trigger level to the midpoint between the trigger source s minimum and maximum voltage values. Level knob Manually adjusts the trigger level. An arrow marker on the right edge of the screen shows the level relative to the waveform. Trig Menu button This is used to configure the trigger parameters. The menu options are: Type Source Slope Mode Selects the type of trigger to detect. {Edge, Video, Pulse} Edge Triggers on the rising/falling edge of a signal that crosses the trigger level. Pulse Used when the trigger is a very fast pulse that the Edge mode would miss. Selects the trigger signal source. {CH1, CH2, CH3, CH4, Ext, Ext/5, AC Line} CH1 CH4 Uses one of the measurement channels as the trigger source. Ext An external trigger input is used as the source. Determines whether to trigger on the rising or falling edge of a signal. {Rising, Falling} Determines acquisition method if a valid trigger signal is not available. {Auto, Normal} Coupling Sets which components of the trigger signal are passed on to the trigger circuit. {DC, Noise Reject, HF Reject, LF Reject, AC} 8

10 Setup and Control Buttons Buttons in this area provide additional control over waveform acquisition, measurement, and display. AUTOSET button Automatically adjusts the VERTICAL, HORIZONTAL, and TRIGGER controls to acquire a usable display. The controls may need further manual adjustment for best results. Single button Enables a single sweep acquisition of a signal, after which the acquisition stops. Run/Stop button Allows the user to start and stop a continuous waveform acquisition. Help button This accesses the oscilloscope s built-in help system. {Show Topic, Index, Help on Help, Back, Exit} Default Setup button Sets the oscilloscope back to its initial startup settings. Acquire button This sets up the acquisition parameters. Menu options are: Sample Default mode for acquiring most waveforms. Peak Detect Used for detecting glitches and reducing the chance of aliasing. Average Used for reducing random or uncorrelated noise in the signal display. Averages (X) Sets the number of averages to use if the Average option is active. {4, 16, 62, 128} 9

11 AutoRange button This sets up automatic scaling of a waveform when it is displayed on the screen. Menu options are: Autoranging Determines if the acquired waveform is scaled to fit the screen. {On, Off} Vertical and Horizontal Autoranges both the vertical and horizontal scales. Vertical Only Autoranges just the vertical (voltage) scale. Horizontal Only Autoranges just the horizontal (time) scale. Undo Autoranging Undos the last autorange. Cursor button This is used to superimpose a pair of movable vertical or horizontal bars on the screen to mark key points on waveforms for measurement. The oscilloscope provides readouts of the cursors absolute location values at the marked points, as well as relative deltas. Menu options include: Type Source Cursor1 Cursor2 Sets the type of cursor to show (horizontal bars for amplitude, vertical bars for time). {Off, Amplitude, Time} Selects which channel s waveform the cursors will bound. {CH1, CH2, CH3, CH4, MATH, } If selected, use the multipurpose knob to move cursor bar 1 (vertically when Type=Amplitude or horizontally when Type=Time). If selected, use the multipurpose knob to move cursor bar 2 (vertically when Type=Amplitude or horizontally when Type=Time). When activated, Cursor 1 and Cursor 2 display continuously updated readouts of their current values (Amplitude mode: V, Time mode: t, V). The center slot in the menu list shows a continuous readout of the difference between the two cursors bars (Amplitude mode: V, Time mode: t, 1/ t, V). Display button The button is used to configure advanced display modes. Menu options are: Type Controls how the waveform s points are displayed. {Vectors, Dots} Persistence Sets the length of time each sample point remains displayed. {Off, 1 sec, 2 sec, 5 sec, Infinite} Format Determines the type of data displayed on each display axis. {YT, XY} YT XY Vertical axis is voltage and horizontal axis is time (default mode). CH1 determines the X coordinate (horizontal), while CH1 determines the Y coordinate (vertical). 10

12 Measure button This controls access to the oscilloscope s built-in automated measurements, such as calculating the amplitude or frequency of a cyclic signal. The menu slots on the right side of the screen can show up to five measurements simultaneously. Each slot is labeled with the channel number, measurement type, and updated measured value. By selecting a slot, these menu options appear to configure the measurement for that slot: Source Determines which channel will be measured. {CH1, CH2, CH3, CH4, Math} Type Type of measurement to be performed. {None, Freq, Period, Mean, Pk-Pk, Cyc RMS, RMS, Min, Max, Cursor RMS, Rise Time, Fall Time, Pos Width, Neg Width, Duty Cyc, Phase, Delay} None Freq Period Mean Pk-Pk Cyc RMS RMS Turns off automated measurement for the source channel Frequency of the waveform Period (time) of the waveform s first complete cycle Arithmetic mean amplitude over the entire record Absolute difference between the maximum and minimum peaks of the entire waveform True RMS (root mean square) of the waveform s first complete cycle True RMS for all 2500 samples from one frame of the waveform data Cursor RMS True RMS of the waveform data from the selected starting to ending points Min Minimum value of the entire 2500 point waveform record Max Maximum value of the entire 2500 point waveform record Rise Time Time between 10% and 90% of the first rising edge of the waveform Fall Time Time between 90% and 10% of the first falling edge of the waveform Pos Width Time between first rising edge and next falling edge at waveform 50% level Neg Width Time between first falling edge and next rising edge at waveform 50% level Duty Cyc Ratio of positive pulse duration to the whole cycle Phase Phase angle difference from two different channels, using the rising edge of the first signal compared to the rising edge of the second signal Delay Time difference from two different channels using the rising edge of the first signal compared to the rising edge of the second signal Ref button This button recalls a waveform that was previously saved to the onboard reference memory and displays it on the screen. It can then be compared to a waveform that is currently being measured. Menu options include: Ref A Ref B Ref C Ref D Recall reference waveform A. {Off, On} Recall reference waveform B. {Off, On} Recall reference waveform C. {Off, On} Recall reference waveform D. {Off, On} 11

13 Save/Recall button This controls settings for saving and recalling screen images, waveform data, and setups. Menu options 2 are: Action Determines which save or recall function is active. {Save All, Save Image, Save Setup, Save Waveform, Recall Setup, Recall Waveform} Save All Save Image Save Setup Configures the Save/Print button. PRINT Button Determines what the Save/Print button will do. {Saves All To Files, Saves Images To File, Prints} Select Folder Selects the directory on the USB drive for saving files. {Change Folder, New Folder} Saves the screen image. File Format Selects the format for saving screen images. {JPEG, PCX, RLE, TIFF, BMP, EPSIMAGE} Select Folder Selects the directory on the USB drive for saving files. {Change Folder, New Folder} Save Initiates saving the current screen image to a file. Saves the current oscilloscope settings to a file named TEKnnnn.SET on a USB flash drive or to non-volatile setup memory. { } Save Waveform Saves the current waveform in CSV text format to a file named TEKnnnn.CSV on a USB drive or to reference memory. Save To Source To Save Selects the format for saving screen images. {Ref, File} Selects the directory on the USB drive for saving files. {CH1, CH2, CH3, CH4, Math} Selects the directory on the USB drive for saving files. {RefA, RefB, RefC, RefD} Initiates saving the current waveform. Recall Setup Recalls previously saved oscilloscope settings either from a USB drive or from non-volatile setup memory. { } Recall Waveform Recalls a previously saved waveform either from a USB drive or from reference memory. { } 2 The lesser-used functions will not be described in depth. Refer to the Tektronix reference manual for details. 12

14 Utility button This button gives access to system utility functions. Menu options 3 include: Limit Test Sets up limit testing of waveforms compared to a template. { } Data logging Sets up logging of data over a long time span. {...} System Status Displays the current setup configuration of the oscilloscope. {Horizontal, Vertical CH1 CH2, Vertical CH3 CH4, Trigger, Misc} Options Do Self Cal File Utilities Language Configures miscellaneous system options. {Read USB Port, Printer Setup, GPIB Setup, Set Date and Time, Error Log} Rear USB Port Printer setup GPIB Setup Sets the type of device connected to the rear USB port. {Autodetect, Printer, Computer} Configures the Save/Print button. {PRINT Button, Ink Saver, Layout, File Format} PRINT Button Determines what the Save/Print button will do. {Saves All To Files, Saves Image To File, Prints} Ink Saver Layout Determines if saved screen images will have a dark or light background color. {Off, On} Sets the orientation when saving screen images. {Portrait, Landscape} File Format Sets the file type when saving screen images. {JPEG, PCX, RLE, TIFF, BMP, EPSIMAGE} Sets the address of the oscilloscope for GPIB data connection. {Address} Set Date and Time Sets the oscilloscope s internal clock. { } Error Log Displays a list of errors logged. { } Performs a self-calibration routine, which can take several minutes to complete. {OK, Cancel} If a FAT32-formatted USB flash drive is inserted in the oscilloscope s front USB port, this option gives access to basic file and directory operations on the drive. {Change Folder, New Folder, Delete, Rename, Format} Sets the language used for prompts and help menus. {English, French, German, Italian, Spanish, Portuguese, Japanese, Korean, Chinese} 3 The lesser-used functions will not be described in depth. Refer to the Tektronix reference manual for details. 13

15 Input Connectors External probes are attached to the input connectors on the front panel of the oscilloscope. 1, 2, 3, 4 connector Each channel has a dedicated female BNC connector. The input resistance is 1 MΩ and the input capacitance is 20 pf. Warning The maximum allowed input voltage is 300 V. Do not exceed this limit! Ext Trig connector This female BNC connector is utilized when an external signal is required to trigger the waveform acquisition. For example, a trigger signal can be either a single pulse or a periodic pulse train. 14

16 4 Passive Probes A typical passive probe consists of a cable with a male BNC connector on one end and a retractable hook tip (or a pointed tip) with ground clip on the other. The BNC side attaches to one of the oscilloscope s inputs, while the probe tip is attached to a measurement point in the test circuit. The probe tip is where the voltage signal enters the probe and is then carried through the cable to the center pin of the BNC connector. The ground clip provides the ground reference from the test circuit to the outer shield of the BNC connector. Retractable Hook Tip Adapter Probe Clip-on Ground Lead This end attaches to the oscilloscope input Cable Adjustment Tool Figure 2: General purpose voltage probe with accessories Copyright Tektronix, Inc. Circuit Being Measured Tip Probe R probe 9 MΩ Cable Oscilloscope Input C probe C cable R in 1 MΩ C in 20 pf GND A 10X probe uses a 9 MΩ series resistor to increase the total input resistance seen by the measured device to 10 MΩ. All cables have some amount of shunt capacitance. TDS2000 series scopes have a fixed input resistance of 1 MΩ. Figure 3: Simplified circuit model of a 10X probe connected to an oscilloscope s input channel (For a 1X probe, R probe and C probe are omitted and replaced by a direct wire path.) 15

17 These are some important characteristics of a probe: Bandwidth This is the highest frequency signal that the probe can accurately pass through to the oscilloscope for measurement. A common metric is the frequency at which the measured signal amplitude has decreased by 3 db from the original value. Attenuation The attenuation factor determines how much the probe reduces the amplitude of the input signal before it enters the oscilloscope. Typical probes are either 1X (no attenuation at all) or 10X (amplitude is divided by 10). Some probes support manual switching between 1X and 10X modes. Attenuation also affects the total input resistance that is seen by the circuit being tested. Note: The attenuation factor setting in the vertical section of the oscilloscope should be changed to match the attenuation factor of the probe. The displayed V/div value will be incorrect if the factors do not match. Loading Effect As seen in the schematic diagram, the probe and oscilloscope are attached in parallel with the test circuit. As a consequence, the measured voltage is influenced not only by the circuit s intrinsic characteristics, but also by the components of the probe and oscilloscope. In particular, the effective input resistance and capacitance of the combined probe and oscilloscope system affects the accuracy and fidelity of the voltage measurement. Table 1: Typical characteristics of common probes Probe Description Attenuation Ratio Total Input Resistance Total Input Capacitance 10X probe 10:1 10 MΩ 1 to 25 pf 1X probe 1:1 1 MΩ 100 to 200 pf Best Used For Low-to-high amplitude DC-to-high frequency Very low-to-medium amplitude DC-to-low frequency For most measurements, the 10X probe is utilized because its high effective input resistance lessens the load effect on the test circuit, and its low input capacitance allows higher frequencies to be measured. On the other hand, the large attenuation factor makes measurements of very low amplitude signals less accurate. If the voltage level of the input signal is tiny, then a 1X probe may be a better choice because there is no attenuation through the probe. However, the 1 MΩ input resistance imposes a larger loading effect and the high input capacitance limits the frequency range. 16

18 Probe Compensation Some probes have a built-in compensation network that can be adjusted to better match a probe s unique operating characteristics to the oscilloscope s inputs. Use the following procedure to compensate a probe: 1. Connect the probe to the desired input channel on the oscilloscope. 2. On the front panel of the oscilloscope, attach the probe s tip to the Probe Comp terminal and the probe s ground lead to the chassis ground terminal. On the TDS2000 series, the terminals are located by the Channel 1 input connector. PROBE COMP generates a 5 volt square wave at 1 khz. 3. Push the AUTOSET button to acquire the test signal. 4. Use the probe s adjustment tool to make the square wave have a flat top. Over compensated Under compensated Properly compensated Figure 4: Effects of probe compensation on a square wave 17

19 5 Simplified Measurement Procedure 1. Before making any connections, verify that the test circuit will not produce voltage or current levels that could damage the oscilloscope. 2. Turn on the oscilloscope. The instrument is more accurate if allowed to warm up for a while. 3. Choose probes that are appropriate for the measurement. Each channel requires a separate probe. 4. For each channel that will be used: a. Attach the probe s BNC connector to an input connector on the oscilloscope. b. If necessary, configure the coupling and attenuation factor for the channel. c. If the probe has a built-in compensation network, then compensate the probe. (Perform compensation whenever a probe is connected to the oscilloscope for the first time.) d. Connect the probe to the test circuit. If you will be working with static-sensitive parts, then wear a grounding strap before making the connections. i. Attach the ground clip of the probe to a ground point in the circuit. ii. Attach the probe tip to the voltage measurement point in the circuit. 5. If the test circuit is not turned on yet, then apply power to the circuit. 6. Adjust the oscilloscope s controls to achieve a stable display of the waveform. (The Autoset button can be used to get a reasonable initial display.) 7. Voltage measurements are done by counting the number of graticle divisions that a waveform spans in the vertical direction. Timing measurements are performed similarly in the horizontal direction. (The Measure button can be used to automate common signal measurements.) 18

20 6 Saving Waveforms to a USB Drive Pressing the Save/Print button on the front panel of the oscilloscope can quickly save a measured waveform to an attached USB drive. Depending on how the button is configured, it can store the data in the following formats: Screen image A screen image is an exact copy of what is currently being shown on the LCD screen, including the annotations around the perimeter of the graph and the menu options. Be sure to adjust everything to your liking before saving. A captured screen image can be pasted directly into reports. CSV file A CSV file is just a text file with the data stored in Comma Separated Values format: o o o o o Column 1: Defines labels for selected measurement setup parameters Column 2: Holds actual values of the parameters at the time of the screen capture Column 3: Empty Column 4: Holds the time axis (horizontal) values Column 5: Holds the voltage axis (vertical) values The file can be imported into applications like Excel or MATLAB for further analysis. Option 1: Configuring the Save/Print Button to save only screen images 1. Press: Utility button Options Printer Setup 2. Select PRINT Button multiple times until Saves Image To File appears. 3. Select File Format multiple times until the desired image type (e.g., JPEG) appears. OPTIONAL: 4. Select Ink Saver and choose On to invert the saved image s background from its normal black to white, or choose Off to keep the background black. 5. Select Layout and choose either Portrait or Landscape orientation. Option 2: Configuring the Save/Print Button to save both screen images and CSV data 1. Press: Utility button Options Printer Setup 2. Press: PRINT Button multiple times until Saves All to Files is selected. 3. Select the desired File Format, Ink Saver, and Layout settings (see previous section). 19

21 Using the Save/Print Button to save waveforms 1. Insert a formatted USB drive into the oscilloscope s front USB port. 2. Adjust the oscilloscope to get a good waveform displayed on the screen. 3. Press the Save/Print button to save the waveform to the USB drive. Note: After a few seconds, a clock icon will appear on the screen. It will then take several more seconds before the data is finally saved and the normal menu options reappear. Warning: Wait until the clock disappears before removing the USB drive. If the Save/Print button is configured to save only screen images A file named TEKnnnn.xxx is created on the USB drive each time the Save/Print button is pressed. nnnn is a number from 0000 to It starts at 0000 and is automatically incremented. xxx is the extension of the image format, e.g., JPG. If the Save/Print button is configured to save both screen images and CSV data A directory named ALLnnnn is created on the USB drive each time the Save/Print button is pressed. nnnn is a number from 0000 to It starts at 0000 and is automatically incremented. These files are stored within the ALLxxxx directory: FnnnnCHm.CSV (m is the channel number) This is the CSV file containing the raw measured data. Each active channel is stored in its own file. FnnnnTEK.xxx (xxx is the extension of the image format, e.g., JPG) This is the actual screen image file. FnnnnTEK.SET This contains some additional oscilloscope settings. 20

22 7 Saving Waveforms to a Computer Although the TDS2000 series of oscilloscopes can save data to a USB drive, it also supports data transfer to a computer over a USB cable. Tektronix makes software called OpenChoice Desktop that runs on a Windows-based computer to control the oscilloscope and initiate screen image and/or data capture. Starting OpenChoice Desktop 1. Verify that OpenChoice Desktop has been installed on the computer, along with the TekVISA driver. 2. Connect one end of a standard A/B USB cable to the USB port on back of the oscilloscope and the other end to an available USB port on the computer Turn on the oscilloscope and let it fully initialize before running OpenChoice Desktop. 4. Run the OpenChoice Desktop software. The application window (Figure 6) presents an interface with tabs on top, command buttons on the left, and the screen image/data area on the right. The default tab is Screen Capture. Figure 6: OpenChoice Desktop startup window Figure 5: Pop-up for selecting instrument The upper left area of the window should display the name of the connected instrument that will generate the screen image or waveform data. Note: If the desired instrument name (e.g., TDS 2014C) is not shown, then follow this procedure: 1. In the main application window, click the [Select Instrument] button. 2. When the Select Instrument pop-up dialog (Figure 5) appears, look for an entry that starts with USB0::. Select that item and click the OK button. 4 The computer communicates with the oscilloscope using the USBTMC-GPIB protocol and SCPI commands. 21

23 Using OpenChoice Desktop to get a screen image 1. Click the Screen Capture tab. 2. Click the [Get Screen] button to initiate the screen image transfer to the computer. 3. Click [Save As] to save the screen image as a file (jpg, png, bmp, or tif) on the computer s local drive. Figure 7: Screen image capture Using OpenChoice Desktop to get waveform data 1. Click the Waveform Data Capture tab. 2. Click the [Select Channels] button. 3. When the Select Channels pop-up dialog (Figure 8) appears, select the channels you want and click the dialog box s Get Data button to initiate the data transfer to the computer. Note: To capture another waveform, click the [Get Data] button on the main application window. 4. Click [Save As] to save the waveform as a file (CSV or tab-delimited text) on the computer s drive. Figure 9: Waveform data capture Figure 8: Pop-up for selecting channels 22

24 Appendix 1 Specifications Table 2: Manufacturer s instrument specifications Model TDS2014C Bandwidth 100 MHz Channels 4 Sample rate on each channel 2 GS/s VERTICAL SYSTEM Record length 2.5K points Vertical resolution 8 bits Vertical sensitivity 2 mv to 5 V/div DC vertical accuracy ±3% Maximum input voltage 300 VRMS CAT II; derated at 20 db/decade above 100 khz to 13 Vp-pAC at 3 MHz Position range 2 mv to 200 mv/div +2 V; >200 mv to 5 V/div +50 V Bandwidth limit 20 MHz Input impedance 1 MΩ in parallel with 20 pf Input coupling AC, DC, GND HORIZONTAL SYSTEM Time base accuracy 50 ppm TRIGGER SYSTEM Trigger modes Auto, Normal, Single Sequence Trigger types Edge (rising/falling), Video, Pulse width Trigger source CH1, Ch2, CH3, CH4, Ext, Ext/5, AC line ACQUISITION SYSTEM Acquisition modes Peak detect, Sample, Average, Single sequence, Roll mode WAVEFORM MEASUREMENTS Period, Frequency, +Width, -Width, Rise Time, Fall Time, Automatic measurements Max, Min, Peak-to-Peak, Mean, RMS, Cycle RMS, Cursor RMS, Duty Cycle, Phase, Delay Cursors Types: Amplitude and time Measurements: T, 1/ T, V WAVEFORM MATH Operators Add, Subtract, Multiply, FFT Sources CH1-CH2, CH2-CH1, CH3-CH4, CH4-CH3, CH1+CH2,CH3+CH4, CH1 CH2, CH3 CH4 FFT Windows: Hanning, Flat Top, Rectangular 2048 sample points Autoset menu Single-button, automatic setup of all channels for vertical, horizontal, and trigger systems 23

25 Appendix 2 References [1] Tektronix TDS2000C Series Data Sheet, Tektronix, Inc. [2] TDS2000C and TDS1000C-EDU Series Digital Storage Oscilloscope User Manual, Tektronix, Inc. [3] XYZs of Oscilloscopes - Primer, Tektronix, Inc. [4] ABCs of Probes - Primer, Tektronix, Inc. 24