Chapter 7
Cable Testing Fundamentals
7-21
Return Loss Errors
Like attenuation, excessive return loss reduces signal strength at the receive end. It
also indicates a mismatched impedance at some point along the cable run. A value
of 20 dB or greater indicates a good twisted pair cable. A value of 10 dB or less is
severe, and causes a large reflection of signal back to the source.
Troubleshooting Return Loss Problems
Problem: Excessive Return Loss (Value of 10 dB or less)
Probable Causes
Open, shorted, or damaged cable.
Installed cable, cable segments, or patch cord have improper
characteristics.
Damaged or worn cable or connectors.
Poor punch-down.
Factory splice in cable.
Other Tests Affected
Test
Possible Result
Attenuation
May be high.
Capacitance and
Average Impedance
Could be affected if the impedance
mismatch is caused by cable
damage.
DC Loop Resistance
May be high if due to a poor
punch-down.
Содержание LANTEK
Страница 1: ...IDEAL INDUSTRIES LANTEK CABLE TESTERS USER S GUIDE 01 FEBUARY 2002 MANUAL PART 6510 00 5000 REV A ...
Страница 80: ...Chapter 3 Calibration Configuration and Special Operations 3 39 store up to 10 custom cables ...
Страница 116: ...Chapter 4 Autotesting 4 24 ...
Страница 124: ...Chapter 5 Analyze Testing 5 8 ...
Страница 172: ...Chapter 6 Using LANTEK REPORTER 6 48 ...
Страница 208: ...Appendix A Safety Precautions A 4 ...