ACPR Test Results using Spectrum Analyzer
Mkr 836 MHz
35.42 dBm
REF 42.8 dBm
AT 30 dB
RBW = 1.0 MHz
RBW = 300 kHz
RBW = 30 kHz
Center 836 MHz
Span 5.000 MHz
SWP 2.00 sec
VBW 100 kHz
Figure 19. Example ACPR measurement using Spectrum Analyzer.
The meaning of 16 dB
smaller value. For example, if the
main channel power is measured
as 28 dBm in a 1.23 MHz band-
width, its power spectral density
is 28 dBm/1.23 MHz, which can
be normalized to 11.87 dBm/
30 kHz. The equation used to
Since the ACPR in an IS95
The accurate ACPR measurement
using Spectrum Analyzer needs
to consider the normalization
factor that is dependent on the
Resolution Bandwidth, RBW,
settings. The above figure (mea-
surement shown at 836 MHz for
general example) shows a com-
parison of the different ACPR
measurement results as a func-
tion of various RBW values. As
the RBW is reduced, less power is
captured during the measure-
ment and consequently the
system is specified in a 1.23 MHz
bandwidth, a channel power that
is measured using a different
RBW, can be normalized to
reflect the channel power as if it
was measured in a 1.23 MHz
calculate the normalization factor bandwidth. The difference in
of power spectral density is:
channel power measured in
30 kHz bandwidth and the
channel power measured in a
1.23 MHz bandwidth is 16 dB.
Normalization Factor =
10log[Normalization BW/Current BW
(Spectrum Analyzer RBW)]
= 10log[1.23X106/30X103]
= 16.13 dB
channel power is recorded as a
16
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