Chapter 2 121
Making Measurements
Example 9: Adjacent Channel Power Measurement
The user may want to add +7.25 dB to the (negative) ACP ratios
measured, to compensate for the difference between the standard and
the Agilent Technologies interpretation of its intent. The 8560 E-Series
and EC-Series implementation is consistent with that used in the
Agilent 85720A JDC/TDMA Measurement Personality.
PHS Measurements of Mobiles According to the
RCR-28 Standard
The following information is applicable as of September 1993. The
RCR-28 standard does not specify a ratio for adjacent channel power,
but rather an absolute power. The standard specifies that the power be
computed as follows:
where:
P
adjS
is the (absolute) adjacent channel power according to
the definition of standard RCR-28.
P
adj
is the power measured in the adjacent channel using
the peak method.
P
main
is the power measured in the main channel, within the
channel bandwidth, using the peak method.
P
xmit
is the total power measured in the transmitted burst.
That is the average power measured in a wide
bandwidth, while the burst is "on."
Because the transmitter is specified to have at least 99% of its power
within a 288 kHz bandwidth, P
main
, being measured in a 192 kHz
bandwidth, must be accurately measured.
To find P
adjS
according to the standard, we can make the following
measurements and computations:
where:
ACP
adj
is the ACP ratio in the adjacent channel (or alternate
channel). This result should be in decimal form,
converted from decibels by the equation:
where ACPdB is the ACP ratio in decibels (it is
always negative).
P
adjS
P
adj
P
main
--------------
P
xmit
×=
P
adjS
ACP
adj
P
wide
P
center
-----------------
× P
carr
×=
ACP
adj
10
0.1 ACP
dB
×
=
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