Mohr CT100B Series

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7. TDR Measurement Theory

Figure 7.12. Impedance Smith chart relationships.

CT100B TDR Cable Analyzers Operator’s Manual 109

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Copyright Notice3
Manual Updates5
Warranty7
Contacting MOHR9
Table of Contents11
Contents12
List of Figures15
General Information19
Product Description19
Power Requirements19
Options and Accessories19
Unpacking and Initial Inspection20
Repacking for Shipment20
Safety Summary21
Terms in the Manual21
Terms on the CT100B21
Danger21
Warning21
Caution21
Symbols in the Manual22
Symbols on the CT100B22
Static Charge22
Fuses23
AC Power Source23
Grounding the CT100B24
Danger Arising from Loss of Ground24
Explosive Atmospheres24
Do Not Remove Covers or Panels25
Connecting Cables to the Test Port25
Battery Replacement and Disposal25
Getting Started27
Handling27
Powering the CT100B27
Caring for the Battery28
Charging and Power Status28
Batteries and Long-Term Storage28
Low Battery28
Labels29
Nameplate29
Discharge Warning Label29
License Codes29
Example Nameplate Label Found on Back of a CT100B29
Preparing to Use the CT100B30
Front Panel Controls and Connectors30
Diagram of the CT100B Front Panel30
Rear Panel Connectors and Switches31
Keyboard Alternate Controls32
Diagram of the Rear Panel of the CT100B/CT100HF32
Menu Selections and Function Buttons33
M-FUNC Button33
SCAN Button and Menu33
Keyboard Controls for Front Panel Buttons and Knobs33
SCAN Button and Menu34
Math Menu35
SELECT Button37
AUTOFIT/HELP Button and Menu37
CURSOR Button38
FILE Button and Menu38
The Reset Options Menu38
Blue" MENU Button and Top-Level Menu39
The Two Versions of the Main Menu40
MENU Button and Menus40
Setting up the CT100B49
Navigating Dialog Boxes49
Display Features50
Setting Date and Time51
Screenshot Showing Typical Features of the CT100B51
Temperature Correction52
Cable Length Settings52
Sample Resolution52
A Small Fault in a Long Cable53
Measurement Settings54
Horizontal Units54
Vertical Units54
Relative Reflection Coefficient (RRC) Method55
Operating Instructions57
Connecting to the Cable or Device-Under-Test (DUT)57
Common Types of TDR Cable Faults58
A Scan of an SMA Connector59
Change Velocity of Propagation (Vp)60
Fine Vp Control60
Find an Unknown Velocity of Propagation (Vp)60
Screenshot Showing AUTOFIT Result61
Final Vp of the Cable62
Cable Type Library63
Load a Cable Type's Vp63
Custom Cable Types63
Smooth Settings63
Distance-To-Fault64
Measure Distance-To-Fault (DTF)64
Smoothed Vs. Unsmoothed Traces at very Small Vertical Scales64
AUTOFIT Cable. the Cable Termination Is a Short65
Vertical Scale Used to Emphasize Cable Fault65
Relative Distance and DTF Measurements66
The Set/Clear Zero Offset Button on the Display Menu68
The Zero Offset Menu68
Multi-Segment Cable DTF Measurements69
Multi-Segment Cable Segment with Vp of 0.40070
Multi-Segment Cable Segment with Vp of 0.85070
Scan a Cable71
Working with Traces72
Select a Trace72
Scan Progress Display with Cancel Button72
Selecting the Live Trace73
Selecting a Scanned Trace73
Annotate a Trace74
Selecting a Difference Trace74
The Annotations Selection in the Scan Menu75
The Annotations Menu75
Use Set Start Point to Annotate a Specific Point on a Trace76
Use Set Start Point and Set End Point to Annotate a Range of Points on a Trace76
Store a Trace78
Using the On-Screen Keyboard79
Load a Trace (Cable Records)80
The Save Trace Default Dialog Box80
Transfer and Delete Traces81
Loading a Trace81
User Configurations82
Save Configurations83
Load Configurations83
Mask Testing83
A Trace that Passes the Mask Test84
A Trace that Fails the Mask Test84
Storing a Mask85
Loading a Mask85
Saving and Loading a Mask as Part of a Configuration85
Exporting/Importing a Mask85
Deleting a Mask86
Envelope Plot (Transient/Intermittent Fault Detection)86
Envelope Plot with Fill Mode87
Envelope Plot with Frequency Density Display88
Improving Measurements89
Vertical Reference (Vert. Ref.) Calibration89
Cable Resistive Loss Correction90
Take a Screenshot91
Resistive Cable Loss Correction, before91
Resistive Cable Loss Correction, after91
Web Server92
Remote Control93
The Live Control Display on the CT100B Web Page93
Math Functions95
Difference (Subtraction) Traces95
First Derivative (Slope) Traces96
Difference Trace96
Second and Higher Order Derivative Traces97
Fast Fourier Transform (FFT) Traces97
First Derivative Trace97
Return Loss (S ) Traces98
FFT Trace98
Return Loss (S ) Options99
Return Loss100
Pre-Filter100
Post-Filter100
Phase Correction100
Return Loss Plot100
Cursors101
Return Loss102
Calibration Standards102
Between Cursors with Tightened Connector102
Between Cursors with Loosened Connector102
Other Return Loss103
Options103
Improving S-Parameter Measurements103
Normalized TDR Traces104
Using a Phase Stable Cable to Improve S-Parameter Measurements104
Layer-Peeling (Dynamic Deconvolution) Traces105
Smith Charts106
Example Layer-Peeling Trace106
Smith Chart Representation of Open Fault107
Smith Chart Representation of Short Fault107
Smith Chart Representation of a 50 Ohm Resistive Load108
Smith Chart of Reactive 200 Ohm Load108
CT Viewer109
Transferring Saved Traces to a Computer109
Send Saved Traces with a Thumb Drive109
Send Saved Traces over USB110
Send Saved Traces Using Ethernet110
Options under the Connect to CT Viewer Menu111
Using Remote Control112
Record and Playback Real-Time TDR Trace Movies112
TDR Measurement Theory113
Time-Domain Reflectometry (TDR)113
Reflection Coefficients113
Common Types of TDR Cable Faults114
An Open Cable Fault Shows an Upward Step Edge at the Location of the Fault114
A Short Cable Fault Shows a Downward Step Edge at the Location of the Fault115
An Open Cable Fault at 824 Ft115
Normal SMA Female Barrel Interconnect Measuring 52.1 Ohms116
Velocity of Propagation (Vop, Vp)117
Distance-To-Fault (DTF) and Cable Length117
Impedance117
Return Loss119
Vswr120
Rise Time and Spatial Resolution121
Timebase/Cursor/Horizontal Resolution122
Frequency-Domain Measurements123
Scattering Parameters123
Return Loss (S )124
Insertion Loss (S )124
Cable Loss (S )124
Comparison of S124
Normalized TDR Traces125
Layer Peeling/Dynamic Deconvolution125
Smith Charts126
Specifications129
Electrical Specifications129
Environmental Specifications131
Mechanical Specifications131
Certifications and Compliances131
Operator Performance Checks133
General Information133
Required Equipment133
Required Performance Check Equipment for CT100B133
Getting Ready134
Operator Performance Checks134
Options and Accessories139
Options139
Accessories139
Standard BNC Accessories - CT100B (BNC)139
Standard SMA Accessories140
Optional Accessories140
P of Common Cables141
Cable Types141
Dielectric Material141
RG Standards142
MIL-C-17 Standards142
Commercial Designations143
Twisted Pair143
Maintenance and Service Instructions145
Cleaning and Lubrication145
Cleaning and Lubrication Interval145
Battery Removal/Replacement145
Calibration and Calibration Interval146
Install CT100B License146
Clean Storage146
Operator Troubleshooting147
General Information147
Power on Test147
Functional Block Diagram and Troubleshooting Flowcharts147
Parts List158
Glossary159
Index165

Mohr CT100B Series - Page 127

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