118 Chapter2
Making Measurements
Example 9: Adjacent Channel Power Measurement
This correction to x1 through x4 will help the spectrum analyzer
results agree with measuring receiver results, because a
measuring receiver is specified to have a −6 dB response at the
channel edges.
The ACP leakage ratio displayed as MAX ACP is for either the lower or
upper adjacent channel, whichever has the higher power. In other
words, MAX ACP is the least negative of the dB numbers displayed as
LOW and UP.
Stepping Through a Burst Signal ACP Measurement
In this example, we will be making a measurement on a PDC (personal
digital cellular) mobile transmitter. You will need to provide a signal to
the spectrum analyzer either by connecting a radio directly, or by
coupling a signal from the radio via an antenna. The MKK method is
one of the standards used for PDC radios, the two bandwidth method
(specified in the RCR-27 document) is another. We will use the two
bandwidth method in this example.
Signal transmission formats are measured using different standards
and parameter settings. Table shows the relationship between some of
the formats and their measurement requirements.
CAUTION The maximum input to the spectrum analyzer should not exceed +30
dBm (1 W) with greater than or equal to 10 dB attenuation.
Table 2-5
Format Specifi-
cation
Meas Method Channel
Spacing
Channel
Bandwidth
# Alt
Chnls
Burst
Period
Burst
Width
Weighting
Mobile Base
NADC IS-54 Gated Analog 30 kHz 33 kHz 2 20 ms 6.43 ms
√COS
*
PDC RCR-27B
2 BW
‡
Analog 50 kHz 21 kHz 1 20 ms 6.52 ms
OFF
†
PDC MKK Peak Analog 50 kHz 21 kHz 1 20 ms 6.52 ms
OFF
†
PHS
RCR-28
**
Peak Peak 300 kHz 192 kHz
2
§
5 ms 625 µs
OFF
†
Analog FM/25
kHz
Analog Analog 25 kHz 16 kHz 0 n/a n/a
OFF
†
Analog FM/12.5
kHz
Analog Analog 12.5 kHz 8.5 kHz 0 n/a n/a
OFF
†
*
When making NADC measurements, use root-raised-cosine frequency weighting with T=41 µs and α=0.35. T=42 µs is
specified for NADC measurements, but 41 µs is used due to number rounding limitations of the spectrum analyzer.
†
The weighting function is turned off, therefore T and α are not applicable.
‡
The 2BW method is described in the following section about PDC measurements.
§
The 8560 E-Series and EC-Series documentation refers to the channels that are offset by 300 kHz,600 kHz, and 900 kHz
as the adjacent channels, first alternate channels and second alternate channels. The RCR-28 standard does not have a
name for the channels at 300 kHz offset, and it calls the 600 kHz and 900 kHz offsets the adjacent channels and the first
alternate channels, respectively.
**
The RCR-28 standard is discussed further in the following section about PHS measurements.
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