2.2 Real-time averaging mode (AVG option)
Acqiris SA240P User's Manual 25
Self trigger mode
See Trigger output (page 59).
Self trigger
In self-trigger mode an autonomous trigger signal is generated internally in the ADC card and output
through the front panel TRG OUT connector. This trigger signal consists of programmable periodic
pulses that are synchronous to the sample clock.
The self-trigger mode serves two purposes:
– Reducing trigger jitter by synchronizing the input signal to the sample clock
– Minimizing the synchronous noise, which consistently improve SNR through averaging of
successive measurements.
To use the Self-Trigger mode, the Trigger ActiveSource must be set to SelfTrigger.
Parameters
ActiveSource (IAqMD3Trigger.ActiveSource property): Specifies the trigger source.
There are three trigger sources: internal, external and self-trigger. If the Self-Trigger mode is
selected the Self-Trigger parameters should be set and the TRG OUT output should be enabled.
Frequency (IAqMD3TriggerSourceSelfTriggerSquareWave Interface): Specifies the
frequency of the Self-Trigger square wave signal. The units are Hertz.
DutyCycle (IAqMD3TriggerSourceSelfTriggerSquareWave Interface): Configures
the duty cycle of the Self-Trigger square wave signal. Units are percentage of the period.
Slope (IAqMD3TriggerSourceSelfTriggerSquareWave Interface): Specifies whether
a rising or a falling edge of the generated waveform triggers the acquisition card.
Out-AveragerAwg (ControlIOs interface): Self-Trigger signal is propagated through the
TRG OUT.
Baseline stabilization and digital offset
See section Other Signal Processing Features (page 44).
Multi-purpose inputs and outputs (IO 1, 2, 3)
The multi-purpose inputs and outputs (IO 1, 2, 3) in the front panel may be used to control the
accumulation or read the ADC card status:
Parameters (ControlIO interface)
In-AccumulationEnable: ADC card input (IO 1). This signal controls the execution of the
averaging sequence. If a pulse occurs, then the next accumulation sequence will be executed.
Otherwise, no accumulation is performed and the card is waiting for either a pulse on IO 1 or a stop.
Out-AnalyzerArmed: ADC card input (IO 3). Indicates that the acquisition is ongoing.
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