Description
NI PXI-4461 Product Description
Detailed Parameter Table
| Parameter Name | Parameter Value |
| Product Model | PXI-4461 |
| Manufacturer | National Instruments |
| Product Category | PXI Dynamic Signal Acquisition (DSA) Module |
| Form Factor | 3U PXI |
| Slot Requirement | 1 PXI slot |
| Channels | 4 differential input channels |
| Resolution | 24 bits |
| Sampling Rate | Up to 204.8 kS/s per channel (simultaneous sampling) |
| Input Type | IEPE (Integrated Electronics Piezo-Electric) and voltage |
| Input Range (Voltage) | ±10 V, ±5 V, ±2 V, ±1 V |
| IEPE Excitation | 4 mA (software-selectable per channel) |
| Frequency Response | DC to 80 kHz (-3 dB) |
| Dynamic Range | 116 dB (typical) |
| THD + N (Total Harmonic Distortion + Noise) | -100 dB (typical at 1 kHz) |
| CMRR (Common Mode Rejection Ratio) | >100 dB (at 50 Hz/60 Hz) |
| Input Impedance | 100 kΩ (voltage mode), 10 kΩ (IEPE mode) |
| Operating Temperature | 0 °C to 55 °C |
| Storage Temperature | -40 °C to 70 °C |
| Humidity Range | 5% to 95% non-condensing |
| Dimensions | 100 mm (width) x 160 mm (depth) x 37 mm (height) |
| Weight | 310 g |
| Compliance Standards | CE, UL, CSA, FCC Part 15 Class A |
| Software Compatibility | LabVIEW, LabWindows/CVI, .NET, C/C++, NI-DAQmx, Sound and Vibration Toolkit |
NI PXI-4461
Product Introduction
The NI PXI-4461 is a high-performance 3U PXI dynamic signal acquisition module engineered for precise measurement of acoustic and vibration signals. As a key member of National Instruments’ DSA family, it combines 24-bit resolution with simultaneous sampling across 4 channels, making it ideal for applications demanding high-fidelity capture of dynamic phenomena—from audio frequency analysis to machinery vibration monitoring.
This module integrates seamlessly with PXI chassis such as the PXI-1031, leveraging the PXI bus for synchronized operation with other modules like the PXI-4351 (for expanded channel count) or PXI-4071 (for multi-domain measurements). Its built-in support for IEPE sensors (e.g., accelerometers, microphones) eliminates the need for external signal conditioning, streamlining system design. Whether deployed in automotive audio testing, industrial predictive maintenance, or acoustic research, the PXI-4461 delivers low-noise, accurate measurements even in challenging environments.
Core Advantages and Technical Highlights
High-Speed Sampling with Precision
With a maximum sampling rate of 204.8 kS/s per channel—twice that of the PXI-4351—the PXI-4461 excels at capturing high-frequency transient signals. This is critical for applications like impact testing, where short-duration events (e.g., a hammer strike on a structure) must be recorded with minimal distortion. The 24-bit resolution ensures that even faint signals, such as background noise in a concert hall, are captured with exceptional detail, supporting precise spectral analysis.
Simultaneous Channel Sampling
The PXI-4461 samples all 4 channels simultaneously, ensuring time-aligned data for phase-critical measurements. In audio engineering, for example, this capability allows precise localization of sound sources by comparing arrival times across multiple microphones. In vibration analysis, it enables accurate correlation of vibrations between different points on a rotating machine, helping identify imbalance or misalignment.
Integrated IEPE Support
The module’s software-selectable 4 mA IEPE excitation simplifies direct connection to piezoelectric sensors, eliminating the need for external signal conditioners. This reduces system complexity and cost, making it ideal for portable test setups—such as field measurements of building vibrations or vehicle noise. The excitation current is configurable per channel, allowing mixed use of IEPE and voltage-mode sensors in the same system.
Broad Frequency Response
With a frequency response from DC to 80 kHz (-3 dB), the PXI-4461 covers a wide range of dynamic signals, from low-frequency structural vibrations (e.g., bridge oscillations) to high-frequency acoustic emissions (e.g., ultrasonic leaks in pressurized systems). This versatility eliminates the need for multiple modules, making it a cost-effective solution for multi-purpose test benches.
Typical Application Scenarios
Audio Device Testing
In consumer electronics manufacturing, the PXI-4461 is used to test speakers, microphones, and audio interfaces. It measures frequency response, total harmonic distortion (THD), and signal-to-noise ratio (SNR) to ensure compliance with industry standards. For example, in headphone testing, the module captures output from a test fixture’s microphones, analyzing whether the audio meets specified loudness and clarity requirements.
Predictive Maintenance
Industrial facilities deploy the PXI-4461 to monitor rotating equipment such as motors, pumps, and compressors. By sampling vibration data at high rates, it detects early warning signs of failure—such as bearing defects or gear wear—through analysis of frequency harmonics. When paired with a PXI controller, it can log data over time and trigger alerts when abnormal patterns emerge, reducing unplanned downtime.
Acoustic Research
In academic and industrial research, the PXI-4461 supports studies of sound propagation, noise control, and environmental acoustics. For example, researchers measuring aircraft noise can use the module with an array of microphones to map sound pressure levels across a test area, analyzing how noise propagates and identifying mitigation strategies. The module’s high dynamic range ensures accurate measurements even in noisy environments like airports.
NI PXI-4461
Related Model Recommendations
NI PXI-1031: A 5-slot PXI chassis that houses the PXI-4461 and other modules, providing a compact platform for dynamic signal acquisition systems. Its backplane enables synchronization with controllers and other instruments.
NI PXI-4351: An 8-channel DSA module that, when paired with the PXI-4461, expands system channel count for large-scale testing (e.g., monitoring vibrations across an entire production line).
NI PXI-8106: A PXI controller with an Intel Core i7 processor, which processes high-speed data from the PXI-4461 in real time. It runs LabVIEW-based analysis tools to compute FFTs, octave band analyses, and order tracking.
NI Sound and Vibration Toolkit: Software that enhances the PXI-4461 with pre-built functions for acoustic analysis, including sound pressure level (SPL) calculations, frequency weighting (A/C/Z), and toneburst generation.
NI BNC-2140: A terminal block that provides BNC connectors for easy connection of IEPE sensors and voltage signals to the PXI-4461. It includes LED indicators for excitation status, simplifying system validation.
Installation, Commissioning, and Maintenance
Installation Steps
Module Insertion: Power off the PXI chassis (e.g., PXI-1031). Insert the PXI-4461 into an available peripheral slot, ensuring it is fully seated in the backplane. Secure the module with front-panel screws to prevent movement during operation.
Sensor Connection: Use the BNC-2140 terminal block to connect IEPE sensors or voltage sources to the module. For IEPE sensors, enable 4 mA excitation via software. Use shielded cables for low-level signals (e.g., microphone outputs) to minimize electromagnetic interference.
Software Setup: Install NI-DAQmx drivers and the Sound and Vibration Toolkit on the PXI controller. Launch NI Measurement & Automation Explorer (MAX) to verify module detection and configure channel settings (input range, excitation, coupling).
Commissioning
Calibration Verification: Inject a calibrated 1 kHz sine wave (e.g., 1 Vrms) into each channel and verify measurements match the input within specified tolerances. Use a frequency generator to test response across the module’s 0–80 kHz range.
Synchronization Check: Connect a common signal to all 4 channels and confirm time stamps are aligned using NI-DAQmx tools. This ensures phase relationships are preserved for multi-channel analysis.
IEPE Functionality Test: Connect an IEPE accelerometer to one channel, apply a known vibration (e.g., using a calibrator), and verify the module accurately captures amplitude and frequency.
Maintenance Tips
Annual Calibration: Use NI’s accredited calibration services to maintain measurement accuracy, critical for compliance with standards like ISO 9001 or automotive ISO 16750.
Connector Care: Clean BNC connectors with isopropyl alcohol quarterly to prevent corrosion, which can introduce noise. Inspect cables for damage, replacing any with frayed shielding.
Environmental Control: Operate the module within its specified temperature (0 °C to 55 °C) and humidity ranges. Avoid mounting near heat sources or high-vibration equipment.
Software Updates: Regularly update NI-DAQmx drivers to access performance improvements and new features. NI’s website provides compatibility information for different software versions.
Service and Guarantee Commitment
The NI PXI-4461 comes with a 2-year standard warranty covering defects in materials and workmanship. National Instruments’ global technical support team offers 24/7 assistance for installation, troubleshooting, and software integration via phone, email, and online resources.
NI provides NIST-traceable calibration services to ensure the module meets published specifications. Extended warranty and calibration plans are available for customers requiring long-term support. Engineered for reliability, the PXI-4461 delivers consistent performance in demanding dynamic signal acquisition applications, backed by NI’s commitment to quality and customer success.
