GW Instek GRF-1300A - Manual (Page 85)

RF Communication and Signals Experiments
In accordance with the definition of ACPR (Figure 7-2), we know
that ACPR =10 log (P
adj
/P
carrier
).
When using a spectrum analyzer to measure ACPR, first you
need to select the appropriate settings for the span and the
resolution bandwidth (RBW). The span needs to be greater than
the measurement bandwidth. The RBW should be equal to
approximately 1% of the measurement bandwidth. Because the
sweep time of the spectrum analyzer is inversely proportional to
the square of the RBW, the RBW settings should be considered.
The RBW should not more than 4% of the measured channel
bandwidth. Otherwise, the RBW will too wide and will obscure
the original spectrum of channel. The RBW settings on the GSP-
730 have a number of set ranges, therefore it fine to set the RBW
to Auto mode.
2. OCBW-measurement
OCBW measurement is for measuring the bandwidth that the
channel occupies for a specified amount of power. This is used to
measure the occupied bandwidth as a percentage of the channel
power for a specified amount of power. Commonly used
parameters for the measurements are: channel bandwidth,
channel spacing and OCBW %.
Experiment
contents 1. Measure the ACPR from the FM signal produced by the GRF-
1300A.
2. Measure the OCBW from the FM signal produced by the GRF-
1300A.
1. Turn on the GRF-1300A and GSP-730.
2. Set up the GRF-1300A as follows:
Experiment
steps
• Set the GRF to the power-on default state.
• Use the RF wire to connect the baseband output to the FM
in port on the RF synthesizer/FM module.
• Connect the output terminal on the RF/FM module to the
input terminal on the spectrum analyzer with the RF cable.
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