NI Digitizers

NI digitizers convert analog waveforms into sampled data for automated measurements, transient capture, and signal analysis. Rather than relying on a dedicated front-panel display, engineers acquire and process signals through software. National Instruments offers conventional oscilloscope-style digitizers alongside FPGA-based acquisition hardware, covering different priorities in bandwidth, resolution, channel density, and processing flexibility. Applications include aerospace test, communications development, semiconductor characterization, scientific research, and precision audio analysis.

The NI 51xx family includes established PCI, PXI, and PXI Express instruments. The PXI-5122 provides two channels, 14-bit resolution, 100 MS/s sampling, and 100 MHz analog bandwidth. Its ordering numbers distinguish memory configurations: 778756-01 provides 8 MB per channel, while 778756-04 provides 512 MB per channel. The PXI-5124 offers two channels with 12-bit resolution, 200 MS/s sampling, and 150 MHz bandwidth, providing a different balance between amplitude resolution and acquisition speed.

For applications emphasizing dynamic range, the NI 59xx family includes the PXI-5922 flexible-resolution digitizer. It delivers 24-bit resolution at sample rates up to 500 kS/s, or 16-bit resolution at 15 MS/s. These are alternative operating points, not simultaneous maximum specifications. Part numbers 779153-01, 779153-02, and 779153-03 identify configurations with 8, 32, and 256 MB of memory per channel, respectively.

Faster waveform capture is available through the PXIe-5162, which combines 10-bit resolution with up to 1.5 GHz bandwidth. Its maximum real-time rate depends on enabled channels: 5 GS/s on one, 2.5 GS/s on two, or 1.25 GS/s on four. The PXIe-517x family emphasizes channel density and reconfiguration. For example, the PXIe-5171, part number 783692-01, provides eight simultaneously sampled channels at 250 MS/s, 14-bit resolution, and a programmable Kintex-7 FPGA.

FlexRIO digitizers extend this approach for custom acquisition and onboard processing. The PXIe-5764 offers four simultaneously sampled channels at 1 GS/s, 16-bit resolution, and 400 MHz analog bandwidth. Available variants differ in input coupling and FPGA resources. Unlike conventional NI-SCOPE-controlled instruments, this model uses the FlexRIO driver and supports custom signal processing through LabVIEW FPGA.

Supported NI-SCOPE digitizers integrate acquisition, triggering, and waveform measurements into LabVIEW or other supported programming environments. Compatible instruments can use NI-TClk to coordinate captures across modules. Deep onboard memory supports longer records, while streaming performance depends on the complete data path, including the module, chassis, controller, and storage system. These capabilities help scale repeatable automated measurements.

Selecting a digitizer requires more than comparing headline sampling rates. Check analog bandwidth, input impedance, voltage range, noise performance, trigger requirements, record length, and sustained transfer capacity. Confirm chassis compatibility and the supported combination of operating system, driver, and development software. For existing test systems, matching the complete ordering number helps preserve the required configuration. Contact Apex Waves to discuss replacement digitizers, available hardware, and calibration requirements.