Instrument Functions
R&S
®
FSVA/FSV
315Operating Manual 1176.7510.02 ─ 09
IBW method
When measuring the channel power, the R&S FSVA/FSV integrates the linear power
which corresponds to the levels of the pixels within the selected channel. The signal
analyzer uses a resolution bandwidth which is far smaller than the channel bandwidth.
When sweeping over the channel, the channel filter is formed by the passband charac-
teristics of the resolution bandwidth (see Figure 3-11).
Figure 3-11: Approximating the channel filter by sweeping with a small resolution bandwidth
The following steps are performed:
1. The linear power of all the trace pixels within the channel is calculated.
P
i
= 10
(Li/10)
where P
i
= power of the trace pixel i
L
i
= displayed level of trace point i
2. The powers of all trace pixels within the channel are summed up and the sum is
divided by the number of trace pixels in the channel.
3. The result is multiplied by the quotient of the selected channel bandwidth and the
noise bandwidth of the resolution filter (RBW).
Since the power calculation is performed by integrating the trace within the channel
bandwidth, this method is called the IBW method (Integration Bandwidth method).
Fast ACLR
Using Fast ACLR, the R&S FSVA/FSV sets the center frequency to the different chan-
nel center frequencies consecutively and measures the power with the selected mea-
surement time (= sweep time/number of channels).
The RBW filters suitable for the selected standard and frequency offset are automati-
cally used (e.g. root raised cos with IS 136).
The RMS detector is used for obtaining correct power measurement results. Therefore
no software correction factors are required.
Measurement Repeatability
The repeatability of the results, especially in the narrow adjacent channels, strongly
depends on the measurement time for a given resolution bandwidth. A longer sweep
Measurement Functions
To Next Page
Loading...
