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3. Operating Instructions

Alligator clip and clip lead adapters with flexible wire test leads should be used only as a last
resort. Alligator clip and clip lead adapters are not made for high frequency operation, are
severely bandwidth limiting, and introduce severe aberration and measurement uncertainty into
the TDR trace. Figure 3.5 shows a comparison test of a coaxial cable using clip lead adapters
(red, top) and a controlled-impedance adapter (black, bottom). The clip lead adapter TDR
trace is severely degraded.

MOHR is able to supply controlled-impedance adapters for almost every type of cable and
connector.

Figure 3.5.

Clip lead adapter (red, top) and controlled-impedance adapter (black,

bottom) testing of 3 ft. coaxial cable with short termination. Active cursor is at the test

port. Clip lead adapters introduce severe TDR trace distortion.

3.10.2. Change Velocity of Propagation (Vp)

Vp is expressed as a fraction of the speed of light. The current setting for Vp appears on the
lower center of the screen. Press the

M-FUNC

button until the top-center information indicator

reads “Vp”. If

Vp 6 Sig. Figs

is enabled from the

Settings

→

Meas. Settings

menu, two separate

“Vp” indicators can be chosen using the

M-FUNC

button.

Coarse Adj. Vp

allows for the

modification of the first 3 significant digits and

Fine Adj. Vp

allows for the modification of the

last 3 significant digits. See Section 5.4

Velocity of Propagation (VoP, Vp)

for a detailed

description of Vp.

Turn the

M-FUNCTION

knob and the Vp value will change accordingly. Measurements and

traces are automatically updated on the display to reflect the new Vp.

All measurements done by the CT100B are based on time, and then converted to distance for
display. An accurate Vp is necessary for accurate cable length and Distance-to-Fault
calculations. For cables of a known type, the Vp can be approximated by using the nominal Vp
for that cable type. The CT100B has a built-in library of cable types and their Vp values
(see Section 3.11.27). You can also measure the Vp by testing a known length of cable that is of
the same type as the one you want to test. The method is described in the following section.

28

CT100B TDR Cable Analyzers Operator’s Manual

Содержание CT100B Series

Страница 1: ...Operator s Manual CT100B Series TDR Cable Analyzers For Software Version 2 15 Part No CT100B M OM 008 CAGE Code 4JEE1 Revision Date 2018 12 10 ...

Страница 2: ......

Страница 3: ...ght to change product specifications or pricing at any time without notice This manual contains trademarks and material copyrighted or patented by MOHR and other third parties All marks copyrights trade secrets and patents should be considered to be the property of their respective owners and all rights are reserved Nothing contained herein shall be construed by implication estoppels or otherwise ...

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Страница 5: ... our last printing there may have been minor updates to this manual To view our most recent manual revision open the accompanying CT Viewer 2 DVD or visit us online at www mohrtm com Please click on Products CT100 Downloads Date and Time Generated 10th Dec 2018 2 21pm CT100B TDR Cable Analyzers Operator s Manual iii ...

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Страница 7: ...tion procedures that may be necessary in preparation for shipment THIS WARRANTY IS EXCLUSIVE AND IN LIEU OF ANY OTHER WARRANTIES EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE MOHR SHALL NOT BE LIABLE UNDER ANY CIRCUMSTANCES FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES INCLUDING BUT NOT LIMITED TO LABOR COSTS OR LOSS OF PROF...

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Страница 9: ...88 852 0408 Mail MOHR Test and Measurement LLC 2105 Henderson Loop Richland WA 99354 USA E mail Sales sales mohrtm com Technical Support techsupport mohrtm com Web www mohrtm com CT100B TDR Cable Analyzers Operator s Manual vii ...

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Страница 11: ...tery 10 3 1 4 Charging and Power Status 10 3 1 5 Batteries and Long Term Storage 10 3 1 6 Low Battery 10 3 1 7 Nameplate 11 3 1 8 Discharge Warning Label 11 3 2 License Codes 11 3 3 Preparing to Use the CT100B 11 3 4 Front Panel Controls and Con nectors 12 3 5 Rear Panel Connectors and Switches 13 3 6 Keyboard Alternate Controls 14 3 7 Setting up the CT100B 14 3 7 1 Setting Date and Time 14 3 7 2 ...

Страница 12: ...CT Viewer 63 4 1 Sending Saved Traces to a Com puter 63 4 1 1 Send Saved Traces with a Thumb Drive 63 4 1 2 Send Saved Traces over USB 64 4 1 3 Send Saved Traces Using Ethernet 64 4 1 4 Using Remote Control 66 4 1 5 Record and Playback Real Time TDR Trace Movies 66 5 TDR Measurement Theory 67 5 1 Time Domain Reflectometry TDR 67 5 2 Reflection Coefficients 67 5 3 Common Types of TDR Cable Faults 6...

Страница 13: ...ts List 104 D Maintenance and Service Instructions 105 D 1 Cleaning and Lubrication 105 D 2 Cleaning and Lubrication Interval 105 D 3 Battery Removal Replacement 105 D 4 Calibration and Calibration In terval 105 D 5 Install CT100B License 106 D 6 Clean Storage 106 E Vp of Common Cables 107 E 1 Cable Types 107 E 2 Dielectric Material 107 E 3 RG Standards 108 E 4 MIL C 17 Standards 108 E 5 Commercia...

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Страница 15: ...tically 37 3 19 Selecting the live trace 38 3 20 Selecting a scanned trace 38 3 21 Selecting a difference trace 39 3 22 Using the on screen keyboard 40 3 23 Loading a trace 40 3 24 A trace that passes the mask test 42 3 25 A trace that fails the mask test 42 3 26 Envelope Plot with Fill Mode 45 3 27 Envelope Plot with Probability Density display 45 3 28 Envelope Plot with Fill Mode showing the ran...

Страница 16: ...69 5 3 An open cable fault at 824 ft 69 5 4 Normal SMA female barrel interconnect measuring 52 1 ohms 70 5 5 Comparison of typical SMA and BNC coaxial cable interconnects 70 5 6 Relationship of impedance to reflection coefficient 72 5 7 Relationship of return loss to reflection coefficient 73 5 8 Relationship of voltage standing wave ratio to reflection coefficient 74 5 9 Simulated comparison of a...

Страница 17: ...eck Equipment for CT100B 87 B 2 Required Performance Check Equipment for CT100HF and CT100B with SMA Option 87 C 1 Parts List 104 E 1 Vp of Common Dielectric Materials 107 E 2 Vp of RG Standards 108 E 3 Vp of MIL C 17 Standards 108 E 4 Vp of Commercial Designations 109 E 5 Vp of Twisted Pairs 109 CT100B TDR Cable Analyzers Operator s Manual xv ...

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Страница 19: ...R Cable Analyzer a user can detect localize and characterize almost any cable fault in both the time and frequency domains Please note that with the release of the CT100B the CT100HF instrument has been updated with the CT100B hardware firmware and software improvements Any reference to the CT100B in this manual also applies to the CT100HF unless specifically stated 1 2 Power Requirements The CT10...

Страница 20: ...ation or other service contact MOHR for an RMA number Affix a label to the outside of the shipping container indicating RMA number name address phone and email of the owner name of the MOHR service representative who was contacted regarding the shipment serial number of the instrument description of the problem with the instrument and or the desired service or maintenance Optimally the original sh...

Страница 21: ...ncluded in this summary 2 1 Terms in the Manual WARNING Refers to conditions or practices that could result in personal injury or loss of life CAUTION Refers to conditions or practices that could result in dam age to this product or other products and in some cases could void the Warranty 2 2 Terms on the CT100B 2 2 1 DANGER Indicates an injury hazard immediately accessible 2 2 2 WARNING Indicates...

Страница 22: ... be made before connection is made to the CT100B BNC test port This ensures that all stored charge in the DUT is discharged during the connection to the CT100B BNC test port Sometimes it is convenient to insert a patch cable between the CT100B BNC test port and the DUT In this case it is recommended that all cable connections including the connection of the patch cable to the DUT be made before co...

Страница 23: ...this breaker must be reset manually and the instrument should be serviced by qualified personnel CAUTION If the thermal breakers trip the instrument should be evalu ated by qualified service personnel for maintenance 2 7 AC Power Source The CT100B is intended to operate only from a 120 VAC or 240 VAC RMS power source using the CE and UL approved 24 VDC external power supply adapter pn CT100 AC PS ...

Страница 24: ...to a cable or device carrying a non zero electrical potential relative to earth ground This situation carries the risk of electric shock WARNING The BNC or SMA connector shield represents a floating ground and is never safely grounded even with the use of a properly grounded AC adapter Never use the CT100B to test any cable or de vice carrying a non zero electrical potential relative to earth grou...

Страница 25: ...nd the conductor s of any cable or wiring to remove any static charge prior to connecting it either directly or indirectly through attachment to another cable to the CT100B s front panel test port connector Failure to do so can damage the instrument s sensitive sampling electronics and will void the Warranty 2 13 Battery Replacement and Disposal The CT100B contains an internal battery pack The int...

Страница 26: ......

Страница 27: ... each other or to earth ground before attaching it either directly or indirectly to the front panel BNC SMA or other test port Failure to do so could damage the sampling electronics and void the Warranty The CT100B can be stored in temperatures of between 20 C to 60 C with or without a battery installed and can be operated from 0 C to 50 C 3 1 2 Powering the CT100B The CT100B can be powered throug...

Страница 28: ...onverter or batteries In power save mode the screen goes blank and only enough power is used to monitor for user input When input is received the CT100B resumes normal operation When the shutdown timer expires the CT100B will turn off A battery indicator can be toggled on or off with the Power Display menu option in the Power menu The indicator will show the level of charge in the battery It will ...

Страница 29: ...l be included with the license code Depending on how it was purchased the instrument may be supplied with either a 30 day demonstration license or permanent license Current license information can be found by pushing the blue MENU button and navigating to Settings Info License License Info A dialog showing license date and active features will appear When the CT100B has a permanent license install...

Страница 30: ...n Function depends on menu 5 H4 function button Function depends on menu 6 MENU blue button Push to display the top level menu screen If a menu is already on the screen this button will clear the menu The previous menu will be displayed This button also activates on screen help when held down while pressing other buttons 7 VERTICAL POSITION knob Controls the vertical position of the currently sele...

Страница 31: ...reen 16 SCAN button Displays a specialized soft menu that brings up the Scan menu 17 AUTOFIT HELP orange button Opens the on screen help library along with Autofit soft menu options 18 M FUNC multifunction button The function of the M FUNCTION knob 19 is set by this button The current operation is displayed on the screen top center 19 M FUNCTION multifunction knob This knob adopts the function sel...

Страница 32: ...w keys adjust the HORIZONTAL SCALE knob 10 Shift F7 rotates the M FUNCTION knob counter clockwise 11 Shift F8 rotates the M FUNCTION knob clockwise Note Some functions may require multiple button pushes to take effect 3 7 Setting up the CT100B 3 7 1 Setting Date and Time The date time and time zone must be accurately set for saved data in the CT100B to be correctly time stamped 1 Change the date a...

Страница 33: ...he Backspace menu option With the keyboard open accept the current entry with the Hide Keyboard menu option or revert to the original entry with the Cancel menu option Both options remove the on screen keyboard from the screen With the keyboard off the screen select the OK menu option to accept all changes to the current dialog box and close the dialog box Select the Cancel menu option to close th...

Страница 34: ...p of the display screen 3 9 2 SCAN Button Menu The SCAN button displays menu selections associated with saving and managing TDR traces and cable scan records SCAN menu selections are shown in Table 3 1 Table 3 1 SCAN Button and Menu Menu Selection Purpose Action Save Rename Saves selected trace to internal storage Renames previously saved traces Show Sel Trace Only Turns all traces invisible excep...

Страница 35: ...quency cut off Hide Selected Trace Hides the selected trace Apply FFT Creates FFT trace from selected trace data View Live FFT Creates live FFT trace from live TDR trace Apply VSWR Creates VSWR voltage standing wave ratio trace from a selected complex division or S11 trace Set Base Sets base trace for complex FFT trace division Complex Division Creates complex division FFT Divides selected FFT by ...

Страница 36: ...les the Phase Correction On Off Phase Corr Start Using the active time domain cursor sets a new start point for the Phase Correction Between Cursor Off On Hold Toggle S11 Between Cursors mode Off Between Cursors Off On Between Cursors On the active section will adjust with time domain cursor movement Hold Between Cursors Hold the active section will remain regardless of cursor movement Hide Select...

Страница 37: ...ppropriate horizontal and vertical scale values to display the entire cable on the screen By default the cursors are positioned approximately to the beginning and end of the cable If Vertical Recenter is selected then only vertical scale and position are affected 3 9 5 CURSOR Button Toggles between cursors making the active cursor inactive and the inactive cursor active Pressing and holding the CU...

Страница 38: ...Use to add select or delete a mask from the mask library Print Screen Prints directly to a PCL3 compatible printer via USB 3 9 7 Blue MENU Button and Top Level Menu If no menu is displayed the blue MENU button loads the main top level menu If the top level menu is displayed it closes the menu If a submenu is displayed it displays the parent menu Top level menu selections are listed below in Table ...

Страница 39: ...current horizontal scale Fixed Allows user to set a specific value no matter the cable length setting File Load Save Calls up the FILE button menu Use it to add select or delete an entry from the cable type user configuration and or cable record libraries Connect to CT Viewer Find CT Viewer Search the local area network looking for running CT Viewer 2 programs If successful it establishes a connec...

Страница 40: ...ace Prev Segment Select the segment to the left of the currently selected segment Next Segment Select the segment to the right of the currently selected segment Reset All Vp Reset the Vp of all segments to 1 000 Restore All Vp Restore Vp of all segments to the previous values Extra Long Mode Extra Long Mode allows the CT100B to obtain traces out to 40 000 ft 12 000 m assumes Vp 0 66 Extra Long Mod...

Страница 41: ...ds centimeters RRC Classic 1502C Mode Classic Referenced to amplitude at inactive cursor 1502C Referenced to amplitude at test port Vp 3 6 Sig Figs Toggle Vp significant digits from 3 to 6 digits Vertical Correction Adjust mρ Offset Allows manual vertical measurement offset adjustments This allows advanced users to manually calibrate impedance measurements at a particular location to a known value...

Страница 42: ...etails on accessing data using web export On Normal operation 2 frames sec Fast Mode Fast refresh 7 frames sec Off Web server not active Note See Section 4 for more information on using CT Viewer 2 to acquire TDR traces See www mohrtm com for information on the CT100B Python programming library and binary programming protocol for Ethernet CT100B interface Selected csv Options Opens a dialog for ad...

Страница 43: ...Front Panel Check This item opens the front panel button and knob check screen Hit each button once and turn every knob in each direction Press the red power button to exit when finished Jitter Jitter measures signal noise jitter rise time and sampling efficiency of the trace These values are used as part of the calibration checkout for the CT100B and results of interest are explained in Appendix ...

Страница 44: ...ne Change the time zone Daylight Savings On Off Sets adjustment for daylight savings time on off Display Change Screen Profile Toggles screen background black gray white Ohms Rho Toggles display of impedance ohms and reflection coefficient millirho at cursor and between cursors VSWR Toggles display of VSWR voltage standing wave ratio at cursor Trace Labels On Off Toggles display of the trace label...

Страница 45: ...instrument internal temperatures AutoSmooth On Off When on the CT100B will automatically pick a smoothing value based on the observed noise When off the CT100B will use the user entered smoothed value 3 10 Test Preparations If you would like a detailed explanation of TDR measurement theory and applications before using the CT100B to test cables please read Section 5 TDR Measurement Theory or go to...

Страница 46: ...he screen Press the M FUNC button until the top center information indicator reads Vp If Vp 6 Sig Figs is enabled from the Settings Meas Settings menu two separate Vp indicators can be chosen using the M FUNC button Coarse Adj Vp allows for the modification of the first 3 significant digits and Fine Adj Vp allows for the modification of the last 3 significant digits See Section 5 4 Velocity of Pro...

Страница 47: ... of the cable and get a more accurate placement Figure 3 7 of the active cursor at the beginning or toe of the open fault at the end of the cable 5 Press the M FUNC button to set the M FUNCTION to Vp and Adjust Vp using the M FUNCTION knob until the CT100B distance measurement to the active cursor equals the physical measurement The final Vp value is the true Vp value of the cable Figure 3 8 Note ...

Страница 48: ...9 3 10 5 Sample Resolution The sample resolution setting establishes the number of sample points per unit time or distance in the live TDR trace In general higher sample resolution sharpens traces at larger horizontal scales by increasing the effective sampling efficiency of the TDR trace the ratio of sampled vs actual change in voltage from sample to sample For larger horizontal scales it also he...

Страница 49: ...t a sample resolution manually using M FUNCTION knob it stays fixed regardless of screen horizontal scale Useful for enhancing frequency resolution of S11 return loss and cable loss traces which may require sampling at resolutions higher than Normal mode Using fine resolution may result in the CT100B buffering The CT100B will show a green circle buffering symbol on screen until buffering is comple...

Страница 50: ...nstructions on using the cable type library 3 Press the AUTOFIT HELP AUTOFIT menu option The CT100B trace is now scaled to show the entire cable from beginning to end See Figure 3 11 4 Note the bump in the middle of the cable This is where two short test cables are connected with a BNC barrel connector Position the active cursor on the reflection caused by this cable fault Adjusting the vertical s...

Страница 51: ...is not between the cursors will not affect the relative distance measurement To measure the relative distance between two points in a cable do the following 1 Move the active cursor to the beginning of the section to be measured 2 Press the CURSOR button to switch cursors 3 Move the newly active cursor to the end of the section to be measured 4 The CT100B displays the distance measured between the...

Страница 52: ... to rise above or fall below the cable characteristic impedance 3 11 3 Multi Segment Cable DTF Measurements Cable assemblies are sometimes made up from different types of cables in series each of which may be chosen for unique characteristics such as high temperature operation or radiation resistance Such cables frequently have different velocities of propagation Vp making Distance to Fault DTF me...

Страница 53: ...al distance as calculated using known Vp for a given cable segment 4 Select Add New Segment 5 Repeat steps 3 and 4 for each cable segment 6 Use the Prev Segment and Next Segment selections to select each cable segment and use the M FUNC Vp option to set the given segment s velocity of propagation 7 The Distance to Fault measured by the cursor reflects multi segment Vp as shown in Figure 3 15 and F...

Страница 54: ...ns to identify subtle changes in cable or connector performance See Figure 3 17 and Figure 3 18 Scans may also be referred to as traces in this manual Figure 3 17 Scan progress display with Cancel button Saved scans can appear on the screen in addition to the live trace Pressing the SELECT button switches between traces Vertical position and scale are adjusted for individual traces Changing these ...

Страница 55: ...ion Select Cancel to abort the scan 3 11 6 Select a Trace The CT100B always shows one trace on the screen in bold This is the selected trace If it is a live trace the VERTICAL POSITION and VERTICAL SCALE knobs can be used on the selected trace leaving other traces on the screen unchanged If the selected trace is not a live trace you can also use the Save Rename and Hide Selected Trace options on t...

Страница 56: ...ppears Press the Show Keyboard menu option to display the on screen keyboard or use a USB keyboard 6 When using the on screen keyboard use the M FUNCTION knob to highlight characters See Figure 3 22 Review Section 3 7 2 for more information on using the Keyboard menu Press the Select Highlighted option to enter the highlighted letter into the name 7 Press the OK option from the menu when finished ...

Страница 57: ...the M FUNCTION knob to highlight the trace you wish to load 4 Press the Select menu option to load the trace The stored trace now appears on the screen It can be selected and manipulated the same as any scanned trace See Figure 3 23 in which the loaded trace red top has been translated slightly upward using the VERTICAL POSITION knob in order to improve visualization Some stored traces such as FFT...

Страница 58: ...uctions Figure 3 22 Using the on screen keyboard Choose Hide Keyboard when finished Then choose OK to save the trace with the name you entered Figure 3 23 Loading a trace 40 CT100B TDR Cable Analyzers Operator s Manual ...

Страница 59: ...aces for transfer using the Toggle Selected option or select them all with the Mark All option 4 Press the Export USB menu option A message should appear after a short time confirming that the traces were transferred 3 11 9 1 2 Export Trace to CSV The active trace can be exported to a csv file on an attached thumb drive To do this 1 Select the desired trace to export using the SELECT button 2 Pres...

Страница 60: ...e Figure 3 24 and Figure 3 25 for examples of traces passing and failing a mask test Figure 3 24 A trace that passes the mask test Figure 3 25 A trace that fails the mask test To create a Mask use the following procedure 1 Create a cable scan or load a scan from memory that will be used to generate a mask 2 Select File Masks menu 3 With the desired cable scan selected select Create Mask from Trace...

Страница 61: ...process 1 Press the FILE button The File menu appears 2 Press the Masks option to enter into the Masks menu 3 Press the Masks option again to enter into the mask storage dialog 4 Use the M FUNCTION knob to highlight the mask you wish to load 5 Press the Select menu option to load the mask The stored mask will now appear on screen after a brief loading time 3 11 10 3 Exporting Importing a Mask Mask...

Страница 62: ...termittent faults To create an Envelope Plot use the following procedure 1 Position the TDR trace such that the area of interest is located on the screen at a satisfactory horizontal and vertical scale Resolution from previous measurement will be preserved 2 Select MENU Measurement menu 3 Select Envelope Plot submenu 4 Select Envelope Plot Off to turn Envelope Plot mode on 5 Use the Fill Mode On O...

Страница 63: ...race can allow the operator to identify subtle changes in cable or connector performance It is recommended that for any important cable and connector assembly the as manufactured or known good configuration of the assembly be scanned and archived on the CT100B and or a host PC running CT Viewer 2 Later these archived traces can be used to create difference traces from current data to highlight cha...

Страница 64: ...nu A new trace is created that displays the difference between the base trace and the selected trace See Figure 3 29 which shows 3 43 ohm excess impedance due to a slightly loosened BNC barrel adapter The bottom bold trace is created by subtracting the top live trace from the middle scanned trace and adjusting the vertical scale to emphasize trace detail Figure 3 29 Difference trace Live base trac...

Страница 65: ...tive trace yellow bottom 3 11 14 Second and Higher Order Derivative Traces The 1st Derivative function can be applied to First Derivative traces to create second and higher order derivatives 3 11 15 Vertical Reference Vert Ref Calibration Use the vertical reference Vert Ref system to increase the accuracy of vertical measurements including impedance reflection coefficient and return loss The Vert ...

Страница 66: ...ing for resistive loss dribble up in cables This allows the operator to measure impedance more accurately through long and or lossy cables Under the Measurement menu there is an item to set ohms per unit length and another item to toggle the correction on and off The calculations of this feature assume a linear serial resistance to an attached cable and no other loss The procedure for performing r...

Страница 67: ...length correction until the measured impedance reads the correct value Figure 3 31 Resistive cable loss correction before Note that the trace slowly rises Figure 3 32 Resistive cable loss correction after Note that the trace is nearly horizontal 3 11 17 Return Loss S11 Traces This feature uses precision open short and 50 ohm load OSL calibration standard measurements to correct for systematic erro...

Страница 68: ...n or alternatively press Use Selected to use the currently selected trace as the open calibration standard For the best results when using type SMA terminators use a calibrated 3 5 in lbs 0 4 Nm torque wrench pn CT100 TL TORX7 to tighten the test standards as well as the DUT 8 Follow the same process as instructed to scan or use the selected trace for the short and 50 ohm load calibration standard...

Страница 69: ...to change the settings to those set above The S11 trace will update using the new settings 3 11 18 2 Return Loss S11 Post Filter The Post Filter can reduce excess noise in the S11 trace To enable or disable the setting do the following 1 Create an S11 return loss plot using the procedure as described on page 49 2 Select the S11 Options menu then Post Filter Options 3 Toggle Use this filter to appl...

Страница 70: ...eature on The S11 trace may change to reflect just the features in the highlighted time domain cursor interval 5 Pressing the Between Cursors On menu option again will change it to Between Cursors Hold which will keep the time domain region fixed while moving the time domain cursors Otherwise you may select the S11 trace to make frequency domain measurements using the cursors without changing the ...

Страница 71: ... S11 trace will update although it might not look visually different depending on the settings 3 11 18 6 Return Loss S11 Other S11 Options Additional miscellaneous options can be found under SCAN Math SParam Normalize Tools S11 Options Other S11 Options and then toggle the options desired OSL Bases Visible If not checked the Open Short and Load traces will be hidden after the S11 trace is created ...

Страница 72: ...h the cursors see Figure 3 37 4 Perform SParam calibration as described in Section 3 11 17 The time windowed trace will have substantially reduced noise due to exclusion of the secondary reflections 3 11 20 Smith Charts The Smith chart is a useful graphical tool for plotting reflection coefficients and complex impedance values and can be used to simplify impedance matching For a very brief introdu...

Страница 73: ...t cursor to the left of the secondary reflections red circle occurring after the open or short at the end of cable under test blue arrow so that they are excluded Figures 3 38 3 41 show Smith chart representations of an open short resistive 50 ohm load and a reactive 200 ohm load Figure 3 38 Smith chart representation of open fault red arrow CT100B TDR Cable Analyzers Operator s Manual 55 ...

Страница 74: ...ect a particular cable fault will have on signals with differing rise times The following procedure creates a normalized TDR trace 1 Create an S11 return loss plot using the procedure as described on page 49 2 From the SParam Normalize Tools menu select Apply Normalization 3 Select Normalize Pulse Rise Time and use the M FUNCTION knob to select a suitable rise time for the cable system as applicab...

Страница 75: ... shows reduced aberrations and more accurate relative reflection coefficient and impedance after the fault compared with the live TDR trace Figure 3 42 Normalized trace blue bottom showing short fault in a 50 ohm cable 3 11 22 Vertical Units The CT100B is able to change vertical units of the live TDR trace so that it is displayed in units of reflection coefficient millirho impedance ohms or voltag...

Страница 76: ...ities these reflected waves will constructively or destructively interfere along the length of the TDR trace leading to impedance measurement errors The CT100B Layer Peeling feature iteratively extracts the underlying reflection coefficients as described in Section 5 14 For a more detailed description of layer peeling see Section 5 14 To create a layer peeling trace use the following procedure 1 P...

Страница 77: ...SITION knob to set the boundaries for the FFT with a cursor at either end 3 Press the SCAN button and then select Math FFT Tools 4 Select Apply FFT The CT100B will now take a high resolution scan of the live trace between the cursors and then convert the scan into an FFT plot FFT traces can be stored reloaded and transferred to CT Viewer 2 just like normal scanned traces 3 11 25 Web Export The CT1...

Страница 78: ...27 1 Load a Cable Type s Vp To load a cable type follow this procedure 1 Press the FILE button The File menu appears 2 Select Reference Cable Types or Custom Cable Types from the menu An interface appears that allows you to scroll through the cable types with the M FUNCTION knob 3 Highlight the desired cable type and press Select Vp is now set to the value for that cable type 3 11 27 2 Custom Cabl...

Страница 79: ... that change The relative reflection coefficient is displayed on screen with a prefix of mρ To view the relative reflection coefficient values go to MENU Settings Display and make sure Rho is toggled on By default the value is displayed in Classic mode displaying the true reflection coefficient relative to the signal at the input of the reflection The CT100B can also measure in 1502C mode which di...

Страница 80: ... displayed 3 Scroll through saved configurations with the M FUNCTION knob 4 Press Select to load the highlighted configuration All settings saved in that configuration are automatically restored Measurements and traces are updated to reflect the new Vp cursor position and other applicable settings 3 11 30 Take a Screenshot To save a screenshot first insert a USB drive into the CT100B Then hold dow...

Страница 81: ...aved Traces to a Computer When a scanned trace is saved to the CT100B it can be sent to a computer that has CT Viewer 2 installed 4 1 1 Send Saved Traces with a Thumb Drive 1 Insert a USB drive into a USB port on the front of the CT100B Wait until the USB drive icon appears on screen 2 Press the FILE button to bring up the File menu 3 Choose the Cable Scan Records menu option A window listing all ...

Страница 82: ...ved Traces Using Ethernet 4 1 3 1 Setup Ethernet In order to send traces over Ethernet to a computer both the computer and the CT100B need to be setup for the network Depending on the how your network is configured the default settings for the CT100B may work If not have your network administrator setup the network settings for the CT100B and the computer The CT100B network settings are located at...

Страница 83: ...n keyboard or a USB keyboard to enter values In PC Name enter a user friendly name for the computer 3 In PC Address enter either a network name or an IP address for the computer 4 Do not change the default port number 5 Press OK to save the server entry then press Select to connect If the connection is successful a message will appear in CT Viewer 2 4 1 3 4 Connecting After the First Time 1 Naviga...

Страница 84: ...e Control has been established a new live trace will appear in CT Viewer 2 This trace will be identical to the trace on the CT100B screen It can be moved around or scaled just like any other trace in CT Viewer 2 Normally the CT100B screen goes blank during remote control To turn on the CT100B screen at the same time as Remote Control select Remote Control Assistant Mode in CT Viewer 2 4 1 5 Record...

Страница 85: ... and or 3 Partial or complete interruption in one or both of the signal conductors Cable faults are important because they degrade signal quality Short or open faults completely disrupt signal transmission In many ways such hard faults are helpful because they are easy to diagnose However more subtle partial or soft faults cause portions of the signal energy to be reflected and or delayed contribu...

Страница 86: ...ay frequency domain complex reflection coefficient values in the context of S11 return loss and cable loss plots such as those produced with Vector Network Analyzer VNA and Frequency Domain Reflectometer FDR equipment This is discussed further on page 76 5 3 Common Types of TDR Cable Faults Open faults appear as a pulse upward in the TDR trace Figure 5 1 because the fault reflects all of the incid...

Страница 87: ... connectors will show up as an impedance discontinuity simulating a small fault Depending on the type and quality of the connectors the expected impedance variation will differ as shown in Figure 5 4 and Figure 5 5 for SMA and BNC type connections Connector damage and corrosion can change the impedance profile of a connector over time typically increasing the excess impedance of the connector Peri...

Страница 88: ...aracteristic signal propagation velocity This velocity of propagation Vp VoP or VP sometimes also called the velocity factor VF or wave propagation speed is the measure of the velocity of an electrical signal within a cable expressed as a fraction of the speed of light in a vacuum With the CT100B Vp can be set between 0 250000 and 1 000000 Nominal Vp values for most types of cable can be found in ...

Страница 89: ...he speed of light c and the measured round trip time t to the fault according to D V p c t 2 The product is divided by 2 because the CT100B measures the time for the pulse to travel to and from the point of interest 5 6 Impedance As mentioned previously TDR instruments measure reflection coefficient essentially but must calculate impedance according to Z t ZS Γ t 1 Γ t 1 Where Z t is the impedance...

Страница 90: ...tion of energy in the reflected signal the lower the numerical return loss value so that an open or a short that returns 100 of the signal has a return loss of 0 dB A very low loss cable will have a large return loss in dB Likewise a 50 ohm cable terminated with a perfect 50 ohm load will have very large return loss in dB This relationship is shown in Figure 5 7 Return loss measured directly from ...

Страница 91: ...ion coefficient Γ according to VSWR 1 Γ 1 Γ VSWR measures the ratio of the maximum over time amplitude of the nodes and anti nodes of the standing wave off of a reflection If there s no reflection e g 50 ohm termination VSWR will be 1 If all energy is reflected e g short or open fault VSWR goes to infinity This relationship is shown in Figure 5 8 VSWR is a unitless scalar value The CT100B displays...

Страница 92: ...ccepted rule of thumb is that the limiting spatial resolution of a TDR instrument is approximately 1 2 of the system rise time 10 90 This is the time required for the step signal reflected from an open or short termination to transition from 10 to 90 of the final step amplitude The estimated spatial resolution R is calculated by the following equation R 1 2 c Vp tr where c is the speed of light an...

Страница 93: ... along the TDR trace In order to faithfully depict the TDR profile of a connector or cable fault the cursor resolution should be at least 5 to 10 times higher than the spatial resolution For the example just shown in Figure 5 9 it is unlikely that the cursor resolution for the slower rise time instrument would be adequate to reliably depict the fault in the first case Cursor resolution also comes ...

Страница 94: ...sive networks like cables splitters attenuators and combiners can be considered reciprocal networks such that S11 S22 and S21 S12 One port measurements can be used to characterize the return loss S11 S22 and insertion loss S21 S12 of a variety of 2 port passive networks such as cables This will be discussed in the Cable Loss S21 section on page 77 You can measure S parameters directly in the frequ...

Страница 95: ...ion loss measurements require a 2 port instrument however the cable loss measurement described below uses the reciprocity feature of passive networks to determine insertion loss from cables and other suitable 2 port networks using a 1 port test instrument 5 11 4 Cable Loss S21 Cable insertion loss in dB is additive per unit length Assuming that port 2 of a 2 port DUT e g a coaxial cable is termina...

Страница 96: ... models the TDR pulser sampler system as a two port error network and subtracts systematic pulser sampler errors from the S11 matrix Convolution of the S11 matrix with an idealized Gaussian step or other idealized excitation signal allows the CT100B to create and display a normalized TDR trace The normalized TDR trace has lower aberration and improved impedance accuracy compared with the original ...

Страница 97: ...edance values Zx at different physical distances The diagram shows that for each time step forward in the TDR trace there are increasingly complex contributions from forward and backward reflections as they interact with each new impedance boundary For instance the test signal moving forward from the Z0 Z1 impedance boundary is reduced by the energy reflected by the Z0 Z1 boundary Likewise the Z1 ...

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Страница 99: ... 2 Standard BNC Accessories CT100B BNC BNC 50 ohm 36 in Reference Cable CT100 AC W536 SMA 50 ohm Terminator CT100 AC ER50 S Connector SMA female to BNC male CT100 AC ISFBM BNC Female to Female Adapter CT100 AC IBFF BNC Male to Male Adapter CT100 AC IBMM BNC Shorting Cap CT100 AC IBS 24 VDC External Charger Power Supply CT100 AC PS Operator s Manual Printed CT100B M OM xxx CT Viewer 2 Quick User Gu...

Страница 100: ...lican CT100 AC CH MIL STD 1553B TRB Adapter Kit CT100 AK TRB OSL S Parameter Calibration Kit SMA CT100 AK CALSMA 3 5 ft lbs 0 4 Nm Torque Wrench CT100 TL TORX7 Phase Stable Cable 3 ft SMA M M CT100 AC PSCSMSM36 Phase Stable Cable 3 ft SMA M F CT100 AC PSCSMSF36 25 ft 300 50 ohm test cable CT100 AC W5300 Small Form Factor Keyboard CT100 AC KBD Clear Screen Protector Pack CT100 AC SPC BNC Adapter Ki...

Страница 101: ... 50 00 0 04 12 50 0 02 kHz Averaged values change for short medium and long cable length settings respectively Vertical scale 0 5 mρ div Vertical accuracy 3 full scale 1 of measurement typ Vertical position Any trace point is movable to the center of the screen Sampling efficiency CT100B 50 to 90 into 50Ω Sampling efficiency CT100HF 45 to 90 into 50Ω Noise 5 mρ peak to peak Input susceptibility 1 ...

Страница 102: ...OHR approved power supply 500 VDC isolation from test port Battery pack 12 NiMH AA cells fused at 2 5 A Pack may wear out over time Battery operation time 6 hours Power save options may extend operating time 18V full charge down to 12V battery low 35 duty cycle Battery charge time 2 5 hours from fully discharged state Overcharge protection Charging discontinues once full charge is attained Dischar...

Страница 103: ...de of Federal Regulations 47 Part 15 Subpart B Class A Limits A 4 3 EMC CT100B and CT100HF comply with MIL PRF 28800F MIL STD 461F RE102 CE102 and IEC61000 A 4 4 Shock and Vibration CT100B and CT100HF comply with MIL PRF 28800F class 3 A 4 5 Temperature and Humidity CT100B and CT100HF comply with MIL PRF 28800F class 3 A 4 6 Explosive Atmosphere CT100B and CT100HF comply with MIL STD 810 G 511 5 P...

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Страница 105: ...o each published specification Throughout this procedure any references made to the CT100B should be considered applicable to the CT100HF and CT100S NOTE Operator Performance Checks should not be considered CT100B calibration NOTE If a CT100B fails any Operator Performance Check it should be serviced by a qualified repair facility B 2 Required Equipment Table B 1 Required Performance Check Equipme...

Страница 106: ...formance Checks B 4 1 Jitter Noise Rise Time and Sampling Efficiency Checks 1 Connect a 50 ohm terminator to the CT100B front panel cable connector 2 Select the MENU Settings Diagnostics menu item to enter the Diagnostics submenu 3 Select Jitter After a moment a results window appears with a list of measurements The value for Jitter used in the specification for a CT100B is Jitter P2P The value fo...

Страница 107: ...r The average pulse width should be between 1 000 2 000 µsec for Short 5 000 6 000 µsec for Medium and 20 00 21 00 µsec for Long 6 Repeat pulse width check for Medium and Long settings B 4 5 Pulse Repetition Period Check 1 Pulse repetition rate measurement should be taken with a device that can accurately measure frequency pulse width period and amplitude 2 Set the device input impedance to 50 ohm...

Страница 108: ...nter clockwise 2 Use the VERTICAL POSITION knob to move the live trace completely above the horizontal midline of the screen 3 Use the VERTICAL POSITION knob to move the live trace completely below the horizontal midline of the screen A CT100B must succeed at both operations to pass the Vertical Position Check B 4 11 Distance Cursor Resolution Check Distance cursor resolution is a value determined...

Страница 109: ... 2 Position a cursor on the trace well beyond the end of the cable The vertical impedance measurement should read 1 5k ohms 3 Position a cursor on the trace well before the leading edge of the pulse The vertical impedance measurement should read 1 ohm B 4 16 Resolution Check Position a cursor at a point of the trace where the vertical impedance measurement is greater than 1 ohm and less than 1500 ...

Страница 110: ...d 61 m div or 200 ft div 4 Turn the HORIZONTAL SCALE knob clockwise Horizontal scale should decrease below 0 01 m div or 0 03 ft div B 4 19 Horizontal Range Check See the cursor readout range instructions on page 90 Horizontal range and cursor readout range are always equal B 4 20 Horizontal Position Check This test is passed implicitly when the Cursor Readout Range and Horizontal Range checks are...

Страница 111: ...if it exhibits signs of thermal overload such as emitting heat or smoke or if it smells of burning plastic C 2 Power On Test Verify that the back switch is in the ON position Press the red front button to turn the instrument on If the instrument does not show anything on the screen within 20 seconds turn the back switch to the OFF position unplug all USB and Ethernet devices and attempt to turn it...

Страница 112: ...r CT100 AC PS DC Power Digicomp A2A1 Analog Board A1 Front Panel Assembly CT290B Ethernet W2W6C1 Client USB W2W6C3 Serial Port Serial Port W2W3C1 Video Cable W2W7C1 USB Host W2W3C2 Data Interface W2W1C1 Test Port W1W9C1 Analog Signal 5V Digital Analog Power W1W5C1 Ethernet Client USB DC Power Temperature Host USB Buttons Knobs User Input 94 CT100B TDR Cable Analyzers Operator s Manual ...

Страница 113: ...trace appear on the device Perform TDR Trace Verification Procedure C 3 7 Perform Analog Diagnostics C 3 6 PASS Perform USB Client and Ethernet Verification C 3 8 PASS Perform File IO Verification C 3 10 Device isin working order PASS Perform Startup Diagnostics C 3 4 Return to MOHR for factory Diagnosisand Repair FAIL FAIL FAIL FAIL FAIL NO PASS YES FAIL PASS Perform Real Time Clock Verification ...

Страница 114: ... supply comeon YES Finished DC Power supply Diagnostics NO Verify the power supply is firmly plugged in to the AC cord and outlet Does the light on the power supply comeon YES NO Test outlet with working device or outlet tester Does the AC outlet work NO Change to a working AC wall outlet Yes Replacepower supply CT100 AC PS 96 CT100B TDR Cable Analyzers Operator s Manual ...

Страница 115: ...nging for 1 minute Start NO Did the MOHR splash screen appear NO YES Did a progress bar appear NO YES Is the progress bar frozen or reporting an error YES Is the device locking up after the progress bar is finished YES FAILED NO PASSED YES NO CT100B TDR Cable Analyzers Operator s Manual 97 ...

Страница 116: ...el Check menu item Start Front Control Diagnostics Does The front panel diagnostics screen appear NO Turn each knob left and right and press each button except the red one Do all of the button and knob icons turn grey NO Press the red power button YES Did the front panel diagnostics screen disappear NO Passed YES FAILED NO 98 CT100B TDR Cable Analyzers Operator s Manual ...

Страница 117: ...alid license file by following the instructions in Appendix C of the manual and restart the device NO Did a message appear stating that a critical license file is missing from the device NO Press the Autofit Help Button to bring up the Autofit Help menu and select Autofit Did the trace appear on the screen NO YES PASSED FAILED YES CT100B TDR Cable Analyzers Operator s Manual 99 ...

Страница 118: ...ications NO YES Start TDR Pulse Diagnostics Attach a 50 ohm test cable of known length and set Vp to match the pulse velocity of the cable Measure the length of the cable for Short Medium and Long Cable Length Settings Do distance measurements meet specification PASS TDR Trace Verification Passed Enable temperature display This can be found under the Main Menuà SettingsàDisplay Do temperatures upd...

Страница 119: ... to known working PC with CT Viewer 2 installed Does the PC recognize the device YES NO Connect known working Ethernet cable that is connected to a network to the device Watch Ethernet lights on back Do Ethernet lights blink PASSED YES NO FAILED CT100B TDR Cable Analyzers Operator s Manual 101 ...

Страница 120: ...on Start Navigate to Main Menu Settings Info Time Change the date and time and select OK Turn power off then restart the device Does the devicedisplay the new time Reset Correct Date and Time YES PASSED NO FAILED 102 CT100B TDR Cable Analyzers Operator s Manual ...

Страница 121: ...traces Export the traces using a USB drive or CT Viewer and then delete the traces on the device YES Attempt to save the scanned trace again Did the trace fail to save due to insufficient space YES YES Hide the saved trace and attempt to reload the saved trace See section 3 11 8 for instructions on loading a saved trace NO NO Did the trace load correctly NO YES PASSED Verify that only the live TDR...

Страница 122: ...bly Analog Digicomp Assembly CT208B Analog Digicomp Assembly 1 A1 1 Analog Board Assembly 2 A2A1 1 Digicomp Board 3 A2A3 1 microSD Card 4 A2A4 1 Clock Battery 5 W2W1C1 1 Digicomp to Analog Board FFC 6 W2W3C1 1 Serial Port Cable Assembly Front 7 W2W3C2 1 USB Host Cable Back Panel Assembly CT209B Power board back bezel battery cables and fan 1 CT100 AC B2700 1 Battery set NiMH with thermistors 2700 ...

Страница 123: ...s from both ends of the instrument nearest the handle mounts 7 Carefully remove the rear housing CT291 from the front panel CT290B using the handle for gripping The housing may be tight and the rubber feet may momentarily catch while they slide past the metal frame 8 The battery pack should now be exposed at the lower rear of the instrument 9 Unclip the 3 pin battery connector by pressing on the r...

Страница 124: ...lash drive the CT100B will reject the file Make sure the intended license file is the only MOHR license file on the drive 1 Copy the file to an empty USB flash drive Do not change the file name 2 Power on the CT100B device and let it boot completely 3 Attach the USB flash drive to a front USB port on the CT100B 4 Push the blue button Main menu button to bring up the Main menu 5 Using the soft menu...

Страница 125: ...e and condition whether it is flat or coiled on a roll and other variables The most accurate way to test a cable is to determine the Vp of the cable using the CT100B and a known length of the cable you wish to test See Section 3 10 3 for more information on determining the Vp of a cable E 2 Dielectric Material Table E 1 Vp of Common Dielectric Materials Type Probable Vp Jelly filled 0 64 Polyethyl...

Страница 126: ... RG 214 50 0 66 RG 218 50 0 66 RG 223 50 0 66 RG 316 U 50 0 66 RG 393 50 0 66 E 4 MIL C 17 Standards Table E 3 Vp of MIL C 17 Standards Designation Z0 ohms Vp M17 2 RG6 RG 6 U 75 0 66 M17 163 00001 RG 8 U 50 0 66 M17 6 RG11 RG 11 U 75 0 66 M17 155 00001 RG 58 U 50 0 66 M17 29 59 RG 59 U 75 0 66 M17 173 00001 RG 174 U 50 0 84 M17 169 00001 RG 178 U 50 0 69 M17 094 RG179 RG 179 U 75 0 67 M17 172 000...

Страница 127: ...79 H500 50 0 82 LMR 200 50 0 83 HDF 200 50 0 83 CFD 200 50 0 83 LMR 400 50 0 85 HDF 400 50 0 85 CFD 400 50 0 85 LMR 600 50 0 87 LMR 900 50 0 87 LMR 1200 50 0 88 LMR 1700 50 0 89 E 6 Twisted Pair Table E 5 Vp of Twisted Pairs Designation Z0 ohms Vp CAT5 100 0 71 CAT6 100 0 71 CT100B TDR Cable Analyzers Operator s Manual 109 ...

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Страница 129: ...d cable two signal wires carrying differential signals of opposite polarity are both separated from ground by an equal impedance Cable Attenuation A quantity describing the energy in a signal that is absorbed reflected or otherwise lost during propagation through a cable Higher frequencies are typically the most susceptible to attenuation Cable attenuation can distort some TDR measurements Attenua...

Страница 130: ...FT algorithm the term is used in this manual to describe both the algorithm and its outputs An FFT Trace is a frequency domain trace created by running the FFT algorithm on a TDR trace Impedance The ratio of voltage to electrical current in a cable or circuit Impedance is a frequency dependent value that is influenced both by resistive and reactive components Impedance is expressed in terms of ohm...

Страница 131: ... a variable measured multiple times Precision and accuracy are both important factors in determining the reliability of a given measurement Precision may also be used to describe the number of digits or the unit of the least significant digit with which a particular quantity is expressed Reactance The imaginary component of electrical impedance Reactance describes the opposition of a conductor to ...

Страница 132: ...ar electronic device See Scattering Parameters S21 A scattering parameter that measures complex transmission loss from port 1 to port 2 on a linear electronic device See Scattering Parameters Sampling Efficiency The CT100B makes measurements through a process known as sequential sampling In sequential sampling a succession of incident pulses followed by discrete samples progressively builds up a g...

Страница 133: ... RF and digital communications systems Trace A displayed or stored signal When displayed a trace appears as a line across the screen A trace may be a direct TDR measurement as with the live trace or derived trace such as a difference trace or an S11 trace A trace is sometimes referred to as a waveform A scanned or saved trace may be called a scan A trace is a visual representation of the waveform ...

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Страница 135: ...6 38 SELECT 13 19 V1 13 V2 13 V3 13 V4 13 cable fault common types 68 distance to fault 32 cable loss S21 77 cable resistance correction 48 cable scans 36 cable type 60 change units 60 charging the battery 10 compound cables 34 configurations 61 load 62 save 62 connectors 24 VDC power adapater plug 13 BNC connector 13 client USB 13 rear panel 13 RJ 45 Ethernet port 13 USB port 13 controls front pa...

Страница 136: ...equency domain S21 77 inspection 2 intermittent fault detection 44 jitter 83 specification 83 keyboard 14 15 keyboard shortcuts 14 knob HORIZONTAL POSITION 12 HORIZONTAL SCALE 12 M FUNCTION 13 VERTICAL POSITION 12 VERTICAL SCALE 12 layer peeling create trace 58 theory 79 license code 11 106 live trace data 59 loading a trace 39 loss of ground 6 low battery 10 maintenance calibration interval 105 m...

Страница 137: ...oxes 15 second derivative 47 secondary reflections 54 selecting a trace 37 setup 14 date and time 14 Smith chart creating 54 theory 78 soft keyboard see keyboard specifications 83 85 static charge damage to BNC connector 13 grounding the BNC connector 6 storage temperature 9 storing a trace 38 switches power 13 TDR 1 67 temperature correction 32 operating 9 storage 9 temperature correction 32 ther...

Страница 138: ...107 load a cable type s Vp 60 load and save custom cable types 60 multisegment cable 34 theory 70 Vert Ref calibration 47 vertical reference 47 vertical units 57 vibration 9 voltage standing wave ratio VSWR 73 create VSWR trace 17 toggle VSWR at cursor 26 water hazards 9 water spray 9 watertight 9 web export 59 web server 59 WiFi 50 120 CT100B TDR Cable Analyzers Operator s Manual ...

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