Tektronix WFM2300 How-To Manual
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Tektronix WFM2300 How-To Manual

Tektronix WFM2300 How-To Manual

Sdi eye and jitter measurements portable waveform monitor
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How-to-Guide
SDI Eye and Jitter Measurements
 
WFM2300 Portable Waveform Monitor

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Summary of Contents for Tektronix WFM2300

  • Page 1 How-to-Guide SDI Eye and Jitter Measurements   WFM2300 Portable Waveform Monitor...

  • Page 2: Table Of Contents

    Cable Stress Loop ……………………………………………….……………….. How to Configure SDI Stress Loop Amplitude …………….………………… How to Configure Eye Measurements ……………………….………………… 10 Enabling Pseudo Color Display …………………………….…………………... 12 Measuring Jitter within an SDI Signal …………………….…………………… 14 Enabling Infinite Persistence Mode …………………….……………………… 18 Conclusion ………………………………………………….……………………… 20 www.tektronix.com/wfm2300...

  • Page 3: Introduction

    Does the addition of the cable length or stress cause CRC issues or loss of the signal? The cable simulator of the WFM2300 adds 20m of Belden 1694A cable along with the ability to add an interfering signal or use the internal test signal generator with the pathological test signal to stress the signal path.

  • Page 4: How To Configure Video Session Display

    Figure 1.  If the signal attached to the WFM2300 is error free then the Status will show OK in green.  If a CRC error occurs then this will show in the Video Session display in red and a count of the number of values that have occurred during the session will be displayed.

  • Page 5: How To Configure Sdi Status Display

    The WFM2300 has been designed with a robust equalizer and receiver to allow the user to determine signal issues. Some devices may fail before the WFM2300 and so it is important to check the manufacture’s specification for cable length distance and type of cable.
  • Page 6 The user can set the threshold for the jitter meter within the configuration menu CONFIG Physical Layer Settings SMPTE XXX Thresholds Jitter Level NOTE: Physical layer measurements can only be performed on Channel A input, so ensure that Input A is selected on the front panel. www.tektronix.com/wfm2300...

  • Page 7: Cable Stress Loop

    To assist in checking the performance of a cable link the Cable Stress Loop can be used within the WFM2300. This adds a simulated 20 meter length of 1694A cable between the I/O loop and can be used in two ways.
  • Page 8 SDI signal. If the device fails to recover the signal then the stress loop can be removed and the test signal generator output of the WFM2300 can be directly connected to the link to test the device on a short run of cable. The user can then determine if the health of the link is suitable for the transmission of the SDI signal or additional measures are needed to improve the signal transmission such as changing the type of cable used or adding a re-clocking DA to the system.

  • Page 9: How To Configure Sdi Stress Loop Amplitude

     The WFM2300 is able to generate a non-stress SDI test signal like color bars (75% or 100%) that are typically use to test the transmission link. Alternatively the Pathological test signal generated by the WFM2300 is used to stress the phase lock loop or equalizer of the receiving device to provide additional stress to the transmission link.

  • Page 10: How To Configure Eye Measurements

    SMPTE standards provide specification for the launch amplitude of an SDI signal output from the device Figure 7a. The test signal generator output of the WFM2300 was directly connected to the SDI A input and direct measurements were made of the physical layer parameters in Figure 7b.
  • Page 11 CRC errors are present, as is this case of Figure 8b. − The user can also add the stress loop to the system to see if the signal is still healthy with the addition of the 20m of Belden 1694A cable. www.tektronix.com/wfm2300...

  • Page 12: Enabling Pseudo Color Display

    2. Using the arrow key or general knob navigate to Display Settings as shown in Figure 9 3. Press SEL to enter sub menu and navigate to Waveform Color 4. Press SEL to enter sub menu and select Pseudo Figure 9. Display Setting menu. www.tektronix.com/wfm2300...
  • Page 13 CRC errors occurred in this signal. However these types of effects can accumulate with other errors to lower the threshold of the signal and cause CRC errors to occur failure of the transmission of the signal. www.tektronix.com/wfm2300...

  • Page 14: Measuring Jitter Within An Sdi Signal

    7. Push and Hold the GAIN button to change the gain to x1, x2, or x5 modes. 8. If additional gain is required the VAR Gain can be enable and increased to a maximum of ten times gain if required as shown in Figure 12a www.tektronix.com/wfm2300...
  • Page 15 The Jitter1 HP Filter can be selected within the WFM2300 and various filters can be selected between 10Hz and 100kHz. While changing the filter bandwidth note the jitter value at each selection.
  • Page 16 Timing Jitter is measured above 10Hz and therefore 10Hz and Timing selections within the Jitter1 HP Filter are the same.  Alignment Jitter is measured at 1kHz for SD( Standard Definition) and at 100kHz for HD and 3G SDI signals www.tektronix.com/wfm2300...
  • Page 17 An MPEG decoder can also introduce jitter at the SDI output if the program clock reference is not within limits and causes a disturbance to the clock within the device. www.tektronix.com/wfm2300...

  • Page 18: Enabling Infinite Persistence Mode

    How-to Guide Enabling Infinite Persistence Mode The Eye and Jitter display are time varying trace displays and the infinite persistence mode of the WFM2300 can be used to determine the maximum variations within the eye or jitter displays. To enable this function perform the following operation: 1.
  • Page 19 Jitter display as the bandpass filter limits the frequency band of the resultant jitter. The jitter meter shows 0.18ns of jitter whereas the measurement of total jitter in the eye display measures 0.217ns. Figure 15. Using cursors within Infinite Persistence within Eye Display menu. www.tektronix.com/wfm2300...

  • Page 20: Conclusion

    SDI signal is getting close to the digital cliff. The Stress Loop of the WFM2300 provides a 20m Belden 1694A cable simulation that can be added to the link to ensure the addition of this simulated cable does not cause errors in the transmission link.
  • Page 21 Please visit www.tektronix.com Copyright © 2014, Tektronix. All rights reserved. Tektronix products are covered by U.S. and foreign patents, issued and pending. Information in this publication supersedes that in all previously published material. Specification and price change privileges reserved. TEKTRONIX and TEK are registered trademarks of Tektronix, Inc. All other trade names referenced are the service marks, trademarks or registered trademarks of their respective companies.

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