EXFO CableSHARK P3, Руководство пользователя, Страница: 193 / 321

CableSHARK
P3
User Guide
181
Section 10 Return Loss
There are two major causes of Return Loss: discontinuities and impedance mismatches. Discontinuities and
impedance mismatches occur at connections where cable is improperly terminated, changing from one wire
gauge to another of greater or lesser diameter, or from cable splices. When a transmitted signal pulse hits
one of these discontinuities, part or all of a signal is reflected back and return loss occurs. The Return Loss
result is expressed in dB.
This option can be ordered from EXFO. A special alphanumeric software key will be sent to the purchaser
based upon each CableSHARK’s unique serial number. To determine the options currently installed in the
CableSHARK or to view the units unique serial number, go to SYSTEM SETUP and select the OPTIONS
function key (see Section 6.4). Once the key is properly entered, the user can exit to the MAIN MENU, select
CABLE TESTS, and then select RETURN LOSS from the pop-up menu. The following setup screen will
appear.
EDIT /
SELECT MAIN
MENU
Test Type:
Term Impedance:
E F
CHG
RETURN LOSS
WARNING
Note: telephone cables may have dangerous A.C. or D.C.
voltages on them, therefore caution should be taken when
connecting this test set.
!
100 OHMS
F
IGURE
10A – R
ETURN
L
OSS
T
EST
S
ETUP
M
ENU
The Return Loss Test Setup menu has the following configuration options.
TEST TYPE:
Fixed at Return Loss.