Agilent Technologies Agilent 33500 Series Operating And Service Manual page 292

SUM Subsystem Introduction
The SUM subsystem adds a modulation source signal to a channel's primary signal. This allows you to generate a two-
tone signal on one channel, or to add noise to a primary signal. The SUM function uses the
used by the modulation subsystems.
Only one modulation or SUM function may be active on a channel at a time, so you cannot add noise to an FM signal
using only one channel. For this operation, use COMBine:FEED, which combines both channels of a two-channel instru-
ment into one channel output connector.
When signals are SUMmed:
Their peak amplitude may not exceed the instrument's output rating.
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No other internal or external modulation is possible on that channel.
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You can synchronize the phase between the primary signal and the SUM signal by sending
ASe:SYNChronize after setting the functions for the primary signal and the SUM signal. Otherwise, the phase between
the two signals is arbitrary.
Example
To create a SUM waveform:
1. Configure carrier waveform: Use FUNCtion, FREQuency, VOLTage, and
waveform's function, frequency, amplitude, and offset.
2. Select the summing source: The instrument accepts an internal or external modulation source (EXT, Channel
1, or Channel 2). Select the modulation source with SUM:SOURce. For an external modulation source, skip steps 3
and 4.
3. Configure the summing waveform: Use FUNCtion, FREQuency, VOLTage, and
configure the summing waveform.
4. Set the amplitude percentage to sum:SUM:AMPLitude.
5. Enable SUM Modulation: SUM:STATe:ON.
6. If using the other channel of a two-channel instrument, synchronize the channels:
NChronize.
The following code illustrates the procedure described above.
SOURce1:FUNCtion RAMP
SOURce1:FREQuency +2000.0
SOURce1:VOLTage +1.0
SOURce1:VOLTage:OFFS +0.0
SOURce1:FUNCtion:RAMP:SYMMetry +50.0
SOURce2:FUNCtion SQU
SOURce2:FREQuency +4000.0
SOURce2:VOLTage +1.0
SOURce2:VOLTage:OFFS +0.0;
SOURce1:SUM:AMPLitude +50.0
SOURce1:SUM:SOURce CH2
SOURce1:SUM:STATe 1
SOURce1:PHASe:SYNC
Agilent 33500 Series Operating and Service Guide
SUM Subsystem Introduction
same secondary sources
SOURce[1|2]:PH-
VOLTage:OFFSet to specify the carrier
VOLTage:OFFSet
PHASe:SY-
as
commands to
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