JDS Uniphase CellAdvisor JD780A Series, Руководство пользователя

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JD780A Series Analyzers
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Using Cable and Antenna Analyzer
Performing DTF measurements
The Distance-To-Fault (DTF) measurement can be used to accurately identify fault locations in the
cell-site transmission (cable and feed line) system, indicating signal discontinuities in VSWR or return
loss over distance in meter or foot. This measurement precisely pinpoints the location of such things
as damaged or degraded antennas, connectors, amplifiers, filters, and duplexers.
Making a measurement
Procedure
1.
Make a proper cable connection as describ
ed in “Connecting a cable for reflection, DTF, 1-port
phase, and Smith Chart measurements
” on page 500.
2.
Press the MEASURE SETUP hot key.
3.
Press the Data Points soft key to change the resolution of your measurement, and then select
the data point option: 126 , 251 , 501 , 1001 , and 2001 . Changing the data point does not affect
current calibration.
NOTE
The larger number you choose, the higher resolution you get and the longer the
instrument takes to sweep and display results. Selecting the data point larger than what
you need for a measurement will result in unnecessarily long sweep time. It is
recommended that you select high resolution data points only for an instance of
measuring wide frequency bands or requiring precise measurement data.
4.
Press the DTF Settings soft key, and then do the following:
–
To select a cable from the list, complete the following steps:
a. Press the Cable List soft key, and then select Standard Cable or Custom Cable .
The cable list window appears.
b. Select a cable by using the rotary knob or the Page Up / Page Down soft keys.
c. Press the Select soft key.
d. Optional . In the standard cable list window, press the Add to Custom soft key to add
the selected cable to the custom list.
–
To define a new cable, complete the following steps:
a. Press the Prop Velocity soft key to define the cable
’s relative propagation delay.
b. Enter a value by using the numeric keys. You can also use the rotary knob.
c. Press the Enter soft key.
d. Press the Cable Loss soft key to define the cable
’s cable loss.
e. Enter a value by using the numeric keys. You can also use the rotary knob.
f. Press the Enter soft key.
NOTE
The propagation velocity affects the calucation of the distance and the cable loss does
the peak level of the discontinuity in a DTF measurement.
–
Toggle the Metrics soft key and select the unit option for the X-axis: Meter or Foot .
–
Press the Windowing soft key, and then select the video filtering option: Rectangular ,
Blackman , Nominal Side Lobe , Low Side Lobe , or Minimum Side Lobe .
5.
Optional . To turn the bias tee on, complete the following steps:
a. Toggle the Bias Tee soft key and select On .
b. Enter a value between 12 and 32 with 0.1 V step.