Single and Multi-Record Acquisition Modes
For technical reasons, a certain acquisition memory “overhead” is required for each waveform, reducing the
available memory by a small amount.
The effective maximum memory available for acquisition depends on several
parameters, such as the acquisition mode (single / multi-record), sampling rate, record
size, number of records, trigger delay, etc.... This maximum is determined by the driver
for each specific configuration. The AQMD3_ATTR_MAX_SAMPLES_PER_
CHANNEL attribute in IVI-C or IAqMD3Acquisition.MaxSamplesPerChannel
property in IVI.NET can be used to retrieve the maximum number of samples per
channel that can be acquired for a specific configuration. When using the Soft Front
Panel, the Max Samples per channel parameter is given on the Acquisition panel.
Single and Multi-Record Acquisition Modes
ADC cards acquire waveforms in association with triggers. Each waveform is made of a series of measured
voltage values (sample points) that are made by the ADC at a uniform clock rate.
To maximize sampling rates and utilize memory as efficiently as possible the ADC cards include both single
and multi-record modes. For both of these modes the data of all of the active channels is acquired
synchronously; all of the ADC's are acquiring data at the same time, to within a small fraction of the
maximum sampling rate.
The single acquisition mode is the normal operation of most ADC card products. In this mode an
acquisition consists of a waveform recorded with a single trigger. The user selects the sampling rate and
acquisition memory size and sets the number of records to 1 (default value). For details about the trigger
sources, see .
The ADC cards also feature a multi-record acquisition mode. This mode allows the capture and storage of
consecutive “single” waveforms. Multi-record acquisition mode is useful as it can optimize the ADC card's
sampling rate and memory requirements for applications where only portions of the signal being analyzed are
important. The mode is extremely useful in almost all impulse-response type applications (RADAR, SONAR,
LIDAR, Time-of-Flight, Ultrasonics, Medical and Biomedical Research, etc.).
In multi-record acquisition mode the acquisition memory is divided into a pre-selected number of records.
Waveforms are stored in successive memory records as they arrive. Each waveform requires its own
individual trigger.
10 U5309A User's Manual
