Agilent Technologies N1911A Bedienungsanleitung PDF herunterladen (Seite 7)

7

Output Power

Transmit power level is an important

IEEE 802.16 conformance speciﬁ ca-

tion. This is deﬁ ned as the time-aver-

aged power during the useful period

of a UL or DL subframe burst. Peak-to-

average power can also be obtained

during this period of time. In order to

make accurate and stable measure-

ments, it is important to be able to

consistently capture the desired com-

plete subframe within the ﬁ xed time

span. This can be achieved via apply-

ing proper time-triggering mechanisms

such as trigger level, holdoff and delay

of P-Series power meter.

Agilent P-Series power meter’s trig-

ger level is typically set at auto-level.

Trigger holdoff ensures that acquisi-

tion will not occur until the holdoff

time has passed AND a valid trigger

is found. This is very useful for burst

signals that have amplitude variations

because these variations can cause

false triggering.

Figure 6 WiMAX burst power proﬁ le (without constant duty cycle)

Figure 7 CCDF plot

CCDF

The Complementary Cumulative

Distribution Function (CCDF) is a plot

of probability versus Peak-to-Average

Ratio (PAR) and it characterizes the

power statistics of a signal. CCDF is

one of the measurements for WiMAX

power ampliﬁ er design that is particu-

larly challenging because the ampli-

ﬁ er must be capable of handling high

PAR signal exhibits while constantly

maintain good adjacent channel leak-

age performance.

The CCDF plot is primarily used in the

wireless communications market for

evaluating multi-carrier power ampli-

ﬁ er performance. It provides a mea-

sure on the percentage of time where

the PAR is at or exceeds a speciﬁ c

power level, Y axis represents the

percentage of time the signal power

is at or exceeds the power speciﬁ ed

by the X axis.

Trigger delay allows measurements

to be made on different signals. For

instance, by just changing the delay

setting, P-Series power meter is able

to make power measurements of

the next subframe burst on the next

measurement.

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