Tektronix CMD 80, User Manual

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CDMA: Manual Test (Signaling)
CMD 80 Digital Radiocommunication Tester User Manual
3–17
Open Loop Time Response. Press this softkey to test the open-loop power control
of the mobile station in response to an increase or decrease in base station total
power. The default increase or decrease for this test is 20 dB. Figure 3–11 shows
the response to this test.
Figure 3–11: Open loop time response display
The tester performs an initial test when it opens this menu; you can perform
additional measurements by pressing the STEP UP and STEP DOWN softkeys.
You can change the step size and direction by pressing the CONFIG front-panel
key. The minimum increase or decrease is 1 dB.
NOTE
. The measurement display indicates all step changes with a positive slope.
During the open-loop test, the closed-loop power is controlled to prevent
unwanted interaction; this is achieved by alternately sending up and down power
control bits to the mobile station.
Defective mobiles can produce power spikes at certain power steps during the
OLTR test, which can result in a digitizer overflow in the tester. Digitizer
overflow is reported as “OVL” instead of “– – –” in the INITIAL MS POWER
display. Displaying “– – –” indicates that no measurement has been made.
When this overflow condition occurs neither the front panel display nor the
GPIB results data buffer are updated. They retain and display (or return) the
values of the most recent successful measurement. If the INITIAL MS POWER
display shows “OVL”, ignore the displayed results.