User`s guide

112 Agilent N5161A/62A/81A/82A/83A MXG Signal Generators User’s Guide
Optimizing Performance
Using Unleveled Operating Modes
Figure 5-24 Calculating the Output Power Error for a Single Waveform Sample Point
Figure 5-25 Calculating the RMS Voltage of the Waveform
The RMS and MANUAL references are the most powerful selections. The user provides the reference
level. The IQ signal can be bursted (radar) or have different RMS levels (Wireless Signals). Once the
RMS/MANUAL reference level is set, the power search runs independent of the current Vrms value of
the waveform.
The RMS and MANUAL references, with a reference level of 1.0 Vrms are equivalent to a calculated
rms value of 1 and can be measured using SINE_TEST_WFM.
The FIXED, RMS, and MANUAL references use a DAC to apply the reference voltage and do not
require the IQ signal to be present.
NOTE The MXG reference voltage is designed to operate between 0.1 Vrms to 1 Vrms nominally, but
it can overrange to 1.414 Vrms. (The RMS can overrange to 1.414, if the constant values are
loaded manually and all “1”s are entered for the I and Q values.) See also “Saving a
Waveform’s Settings & Parameters” on page 151.
CAUTION The minimum reference level that results in a successful power search is dependent on
RF Frequency, RF Amplitude, and Temperature. An MXG power search using a reference
level of 0.1 Vrms for 0 dBm at 1 GHz may fail.
20 10 V1()V2()⁄()log×=
Where:
V1 is the actual waveform RMS voltage
V2 is the entered RMS voltage
The Output Power Error
Note: If the RMS voltage value entered is lower than the actual RMS voltage, the output power will be higher than desired.
If the RMS voltage value entered is higher than the actual RMS voltage, the output power will be lower than desired.
The MXG can calculate the RMS value automatically.if more than two
contiguous IQ data points are zero, the MXG calculation ignores those
zero points. Also, because the RMS calculation, that is done by the signal
generator, is slow and may not be appropriate for your application, it is
recommended that the user calculate and enter in their measured RMS
value for the waveform file.
RMS value for the waveform =
SCPI Commands:
[:SOURce]:RADio:ARB:HEADER:RMS <"file_name">,<val>|UNSPecified
[:SOURce]:RADio:ARB:HEADER:RMS? <"file_name">
For a programming example of determining the RMS voltage of a waveform, refer to the Programming Guide and to the
Documentation CD that came with this instrument.