Carrier 38TXA Guide Betriebsanweisung PDF herunterladen (Seite 78)

78 Chapter 2

S:\agilent\83217\OPT001\BOOK\CHAPTERS\tdscrip.fm

Test Descriptions

TEST_35 - TXD Closed Loop Power Control

Description

This test measures the range of the MSUT’s output power in response

to the Test Set’s power control subchannel.

This test is performed as follows:

1. A Service Option 2 (or 9 if parameter 19. RT Rate Set Selection

[0=9600 1=14400] is set to 1) call is attempted, unless a Service

Option 2 call is already connected. If the MSUT has not registered,

the call attempt may be unsuccessful and the error message “Failed

to establish a call in test <>” will be displayed. To correct this

problem, perform the CPD Registration test.

2. The forward channel power is adjusted to yield an open loop

estimate power level from the MSUT of approximately -15 dBm.

3. The Test Set’s “call drop” timer is disabled so that when “all down”

power control bits are sent to the MSUT, the call is not dropped by

the Test Set.

4. The Test Set is put in Open Loop power control mode and the actual

reverse power from the MSUT is measured. This value will serve as

the reference power level for determining the range of closed loop

power control. In this mode, the Test Set’s power control subchannel

does not adjust the MSUT’s output power based on signal strength

measurements. Instead, the Test Set’s power control subchannel

outputs a fixed pattern of up and down bits, holding the MSUT

power level at or near its open loop estimate.

5. The Test Set is programmed to send continuous “always up” power

control bits at full data rate. This series of power control bits will

increase the MSUT’s power level from its open loop estimate (-15

dBm) to its maximum transmitted output power.

6. The Test Set’s input attenuator is put in “Hold” mode, and the

attenuation is set to its maximum value (40 dB).

7. An Average Power measurement is made while the “always up”

power control bits are being sent.

8. The Closed Loop Up Range value is calculated and displayed. The

Closed Loop Up Range value is calculated by taking the difference

between the Average Power measurement taken while “up” power

control bits were being received by the MSUT, and the reference

measurement made on the MSUT’s open loop estimate from step 2.

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Carrier 38TXA Guide Betriebsanweisung Seite 78