5-8
IM 703155-01E
Low-pass Filter
You can select a low-pass filter for removing unneeded frequency components that are
generated when waveforms are output. If you select Through, the signal is output
without passing through the filter.
6 MHz
,
30 MHz
,
100 MHz
, or
Through
Noise
You can add AWGN (Additive White Gaussian Noise) to the output waveform. Because
the AWGN is added as a digital signal before the D/A converter (DAC, see the block
diagram in section 2.2) stage, it is also applied to the signal output from the digital output
terminal.
ON
Adds the noise of the specified level.
OFF
Does not add noise.
Noise Level
The specified noise level is assumed to be constant at frequencies less than or equal
to the specified internal clock signal. If an external clock signal is selected (see
section 5.2), the noise level is set by assuming a clock frequency of 300 MHz.
*
The actual noise level gradually rolls off as the frequency is increased from a low
frequency toward the clock frequency according to the (sin x)/x function. It is a valley at
the clock frequency.
Selectable range: –130 to –80 dBm/Hz (in 1 dBm/Hz steps)
However, the minimum value setting is –130 + 10
×
log
10
(300/fs). Here, fs is the
clock frequency in MHz.
Default value: –100 dBm/Hz
Note
•
If a sequence list containing multiple elements is loaded, the RMS value is the value
corresponding to the maximum element value in the list.
•
If the setting exceeds the output range (3 Vp-p) of the output waveform, the peak values in
the Wave View list are displayed in red. In this case, the waveform may not be output with
the correct amplitude.
•
If the noise level is set smaller than the minimum valid setting even if the level is within the
selectable range of the noise level, the noise level value in the Wave View list is displayed in
red.
•
Depending on the amplitude of the added noise level, the maximum input value of the D/A
converter (DAC) in the output waveform circuit may be exceeded. If this happens, a message
“DAC data over range” is displayed in the status display bar at the top section of the screen.
If this occurs frequently, the error from the Gaussian distribution becomes large.
•
There is no correlation between the noise signals added to I and Q.
5.4 Setting the Gain, Phase, IQ Gain Ratio, Quadrature Offset, Voltage Offset, Low-pass Filter, and Noise
