PXIe-4481 High-Bandwidth Analog Input Module
Земля PXIe-4481 is a six-channel, 24-bit PXI analog input module designed for high-accuracy, high-bandwidth voltage measurements. It combines simultaneous sampling, selectable input ranges, analog antialiasing and advanced digital filtering for both frequency-domain analysis and time-domain transient acquisition.
In frequency-domain mode, the PXIe-4481 provides sample rates from 100 S/s to 1.25 MS/s per channel. When rapid transient capture is required, time-domain mode can acquire all six channels at rates up to 20 MS/s per channel.
The module is suitable for audio testing, vibration analysis, dynamic pressure measurement, high-speed transient capture and electronic signal analysis in a PXI measurement system.
Key Features of the PXIe-4481
- Six simultaneously sampled analog input channels
- 24-bit delta-sigma ADC resolution
- 100 S/s to 1.25 MS/s frequency-domain acquisition
- Up to 20 MS/s per channel in time-domain mode
- Four software-selectable voltage input ranges
- ±0.5 V, ±1 V, ±5 V and ±10 V input ranges
- Up to 115 dB dynamic range
- Alias-free bandwidth up to approximately 503.75 kHz
- 120 dBc minimum alias rejection
- Independent AC or DC coupling on every channel
- Differential or pseudodifferential input configuration
- Analog antialiasing and configurable digital filtering
- Low-latency time-domain acquisition
- Adjustable digital filter delay
- InfiniBand analog input connector
- SMB programmable function interface
- PXI Express interface
PXIe-4481 Technical Specifications
| Product Model | PXIe-4481 |
|---|---|
| Part Number | 784278-01 |
| Product Type | PXI Analog Input Module |
| Analog Input Channels | 6 simultaneously sampled channels |
| Analog Output Channels | Ничего |
| ADC Resolution | 24 bits |
| ADC Type | Delta-sigma |
| Frequency-Domain Sample Rate | 100 S/s to 1.25 MS/s per channel |
| Time-Domain Sample Rate | Up to 20 MS/s per channel |
| ADC Modulator Rate | 20 MS/s |
| Input Voltage Ranges | ±0.5 V, ±1 V, ±5 V and ±10 V peak |
| Input Configuration | Differential or pseudodifferential |
| Input Coupling | AC or DC, independently selectable per channel |
| AC-Coupled High-Pass Cutoff | Approximately 0.49 Hz at −3 dB |
| Alias-Free Bandwidth | DC to 0.403 × sample rate |
| Maximum Frequency-Domain Bandwidth | Approximately 503.75 kHz |
| Alias Rejection | 120 dBc minimum |
| Maximum Dynamic Range | Up to 115 dB |
| Powered Overvoltage Protection | Up to ±30 V peak, depending on input configuration |
| Front Connectors | 1 × InfiniBand and 1 × SMB |
| Data Transfer | DMA or programmed I/O |
| Шинный интерфейс | PXI Express |
| Operating Temperature | 0°C to 55°C |
Six Simultaneously Sampled Channels
The PXIe-4481 provides six analog input channels that acquire data simultaneously. Simultaneous sampling maintains the timing and phase relationship among channels, unlike multiplexed acquisition systems that measure channels sequentially.
This capability is important for applications such as:
- Multichannel frequency-response testing
- Phase comparison
- Structural dynamics analysis
- Acoustic arrays
- Vibration measurements
- Transient pressure testing
- Three-phase electrical measurements
- Correlated electronic signal analysis
Each channel can independently select its input range, coupling and differential or pseudodifferential configuration.
24-Bit Voltage Acquisition
The PXIe-4481 uses 24-bit delta-sigma converters to provide low-noise measurements and high dynamic range. The module is designed to capture small signal details while also supporting input signals up to ±10 V peak.
Four software-selectable voltage ranges allow the module to match different signal amplitudes:
| Selected Range | Full-Scale Peak Input | Full-Scale RMS Sine Input |
|---|---|---|
| 0.5 V | ±0.5 V peak | 0.353 V RMS |
| 1 V | ±1 V peak | 0.707 V RMS |
| 5 V | ±5 V peak | 3.53 V RMS |
| 10 V | ±10 V peak | 7.07 V RMS |
Selecting the smallest range that accommodates the expected signal generally provides better measurement resolution. A wider range should be selected when the input contains large transients or an uncertain peak amplitude.
Frequency-Domain Measurement Mode
Frequency-domain mode is designed for spectral measurements that require high resolution, accurate amplitude response and strong alias rejection. Sampling rates can be configured from 100 S/s to 1.25 MS/s per channel.
The alias-free passband extends from DC to approximately 0.403 times the selected sample rate. At 1.25 MS/s, the maximum alias-free bandwidth is approximately 503.75 kHz.
The PXIe-4481 combines analog antialiasing with digital filtering to provide at least 120 dBc alias rejection under the specified conditions. This helps prevent high-frequency signals from appearing incorrectly at lower frequencies in the measured spectrum.
Frequency-domain mode is suitable for:
- FFT spectrum analysis
- Harmonic and distortion measurements
- Frequency-response analysis
- Noise measurements
- Order tracking
- Dynamic signal analysis
- Audio and ultrasonic testing
- Vibration spectrum analysis
20 MS/s Time-Domain Mode
Time-domain mode provides sampling rates up to 20 MS/s per channel for capturing rapid signal changes. This mode prioritizes time resolution and low-latency transient acquisition rather than the full digital filtering available in frequency-domain mode.
Typical time-domain applications include:
- Blast and shock event capture
- High-speed pressure transients
- Impact testing
- Pyrotechnic event measurement
- Rapid switching transients
- Short-duration acoustic pulses
- Electronic waveform analysis
- High-speed structural response testing
Select frequency-domain mode when spectral accuracy and antialias filtering are the primary requirements. Select time-domain mode when the application must capture a fast event with maximum temporal resolution.
Dynamic Range and Noise Performance
The PXIe-4481 provides a maximum dynamic range of up to 115 dB under the specified input-range, sample-rate and bandwidth conditions. Dynamic range varies with the selected voltage range and sample rate.
| Voltage Range | Dynamic Range at 51.2 kS/s | Dynamic Range at 1.25 MS/s |
|---|---|---|
| 10 V | 113 dB | 98 dB |
| 5 V | 115 dB | 100 dB |
| 1 V | 112 dB | 98 dB |
| 0.5 V | 107 dB | 94 dB |
Higher sample rates increase the measured noise bandwidth and can reduce the resulting full-band dynamic range. Select a sample rate and measurement bandwidth appropriate for the signal frequencies that must be analyzed.
AC and DC Input Coupling
Each channel can be independently configured for AC or DC coupling. DC coupling preserves the complete signal, including its static component, and is suitable for direct-voltage, low-frequency and transient measurements.
AC coupling blocks the DC component and is useful when the measurement focuses on dynamic signal content. The AC-coupled input has a −3 dB cutoff frequency of approximately 0.49 Hz and a −0.1 dB cutoff near 3.2 Hz.
Use DC coupling when signal content approaching 0 Hz must be measured. Use AC coupling when a DC offset would otherwise reduce the available input range for the dynamic portion of the signal.
Differential and Pseudodifferential Inputs
The PXIe-4481 supports differential and pseudodifferential voltage configurations. Differential mode measures the voltage difference between the positive and negative input terminals and provides improved rejection of common-mode noise.
Pseudodifferential mode connects the negative input to chassis ground through a 50 Ω resistance. It can be useful for signals referenced to system ground, but grounding and common-mode voltage should be checked carefully to prevent unwanted current paths.
The PXIe-4481 does not provide isolated input channels. The source voltage, common-mode level and grounding arrangement must remain within the module’s specified limits.
Adjustable Digital Filter Delay
The module’s digital filtering introduces a predictable delay in frequency-domain acquisition. This delay is compensated to zero by default and can be adjusted through software when an application requires a particular timing relationship.
Adjustable delay is valuable when synchronizing the PXIe-4481 with other measurement modules, compensating for sensor delays or aligning channels within a larger data acquisition system.
Typical PXIe-4481 Applications
- High-bandwidth voltage measurement
- Dynamic signal acquisition
- Frequency-domain analysis
- Time-domain transient capture
- Blast and pressure event testing
- Audio and ultrasonic measurements
- Structural vibration testing
- Automotive NVH analysis
- Aerospace acoustic and vibration testing
- Electronic signal-chain validation
- Power electronics waveform acquisition
- Мониторинг состояния оборудования
- Research and laboratory automation
- High-speed synchronized data acquisition
Synchronization and Triggering
The PXIe-4481 supports PXI Express timing and triggering resources for coordinating acquisition with other PXI instruments. The front-panel SMB programmable function interface can be used for supported external timing and trigger signals.
Multiple modules can be synchronized when more than six channels are required. A common timebase should be used when maintaining intermodule phase relationships is important.
For high-accuracy multichannel measurements, allow the modules to complete the recommended warm-up period and use consistent ranges, coupling settings and timing configurations.
Software and Driver Support
The PXIe-4481 uses the NI-DAQmx driver for input configuration, timing, triggering, filtering and data acquisition. It can be programmed through supported versions of LabVIEW, LabWindows/CVI, C/C++, .NET and Python.
FlexLogger can be used for interactive measurement configuration, data logging, triggering and alarms. The LabVIEW Sound and Vibration Toolkit provides additional frequency, octave, order, transient and vibration analysis functions.
NI DIAdem supports offline data processing, visualization and automated report generation. Confirm software, driver and operating-system compatibility before installing the module in an existing PXI system.
PXIe-4481 Connectivity
The six analog input channels are accessed through a front-panel InfiniBand connector. An appropriate breakout cable, terminal block or application-specific interface is required to connect individual signals.
The module also includes an SMB programmable function interface for supported triggering and timing. Cables and connection accessories may need to be ordered separately.
PXIe-4481 Chassis Compatibility
The PXIe-4481 is a PXI Express module and requires a compatible PXI Express peripheral or hybrid slot. It cannot be installed in a traditional PXI-only peripheral slot.
Before purchasing, verify the chassis slot type, controller, NI-DAQmx compatibility, cooling and available PCI Express bandwidth. High-speed acquisition across six channels can produce substantial data throughput, especially in time-domain mode.
PXIe-4481 Troubleshooting
The Input Waveform Is Clipped
Select a wider input range and confirm that the signal does not exceed the configured full-scale value. Consider transient peaks in addition to the normal steady-state amplitude.
The Measurement Contains Excessive Noise
Select the smallest range that does not clip the signal and avoid using a sample rate much higher than required. Use differential wiring, shielded cables and proper grounding.
Low-Frequency Signals Are Attenuated
Check whether AC coupling is enabled. Select DC coupling when the measurement must include static or very low-frequency signal content.
Unexpected Frequencies Appear in the Spectrum
Verify that frequency-domain mode is selected and that the signal of interest remains within the alias-free bandwidth. Increase the sample rate or reduce unwanted out-of-band interference if necessary.
The Module Cannot Sustain 20 MS/s Streaming
Check the PXI Express backplane, controller, system memory and storage write speed. Six channels operating at 20 MS/s generate a large amount of data.
Phase Measurements Differ Across Modules
Synchronize all modules to a common timebase and configure equivalent sampling and filtering settings. Account for intermodule clock skew when calculating phase accuracy.
The Module Is Not Detected
Confirm that the PXIe-4481 is installed in a compatible PXI Express or hybrid slot. Check the PXI controller, NI-DAQmx installation and device recognition in NI Measurement & Automation Explorer.
PXIe-4481 Compared with Similar Analog Input Modules
| Модель | Input Channels | Maximum Standard Sample Rate | Maximum Time-Domain Rate | Primary Capability |
|---|---|---|---|---|
| PXIe-4464 | 4 | 204.8 kS/s | Not applicable | Sound and vibration input with IEPE conditioning |
| PXIe-4468 | 2 | 250 kS/s | Not applicable | Two inputs, two outputs and IEPE conditioning |
| PXIe-4480 | 6 | 1,25 МСм/с | 20 MS/s | Voltage, charge, IEPE, voltage excitation and TEDS |
| PXIe-4481 | 6 | 1,25 МСм/с | 20 MS/s | High-bandwidth voltage acquisition |
The PXIe-4481 and PXIe-4480 provide similar voltage acquisition, frequency-domain filtering and time-domain sampling capabilities. The primary difference is signal conditioning: the PXIe-4480 adds charge measurement, IEPE excitation, sensor voltage excitation and TEDS support.
Choose the PXIe-4481 when the application requires direct voltage acquisition without integrated sensor excitation. Choose the PXIe-4480 when charge-output, IEPE or voltage-excited sensors must connect directly to the module.
Recommended Related Products
- PXIe-4480 Sound and Vibration Module – Adds IEPE, charge measurement, voltage excitation and TEDS sensor support.
- PXIe-4468 Sound and Vibration Module – Combines two 250 kS/s analog inputs with two precision analog outputs.
- PXIe-4464 Sound and Vibration Module – Provides four 24-bit input channels with integrated IEPE conditioning.
- PXIe-4499 Sound and Vibration Module – A higher-channel-count option for acoustic arrays and large vibration measurement systems.
- PXIe-5172 Reconfigurable Oscilloscope – An alternative for applications requiring higher sampling rates and wider oscilloscope bandwidth.
How to Select the Correct PXI Analog Input Module
Choose the PXIe-4481 when the application requires six synchronized voltage channels, 24-bit frequency-domain acquisition, bandwidth up to approximately 500 kHz or time-domain transient capture at up to 20 MS/s.
Before ordering, confirm the following:
- Required channel count
- Frequency-domain or time-domain operation
- Required sampling rate and bandwidth
- Maximum expected input voltage
- AC- or DC-coupled measurement requirements
- Differential or pseudodifferential wiring
- Need for IEPE, charge or voltage excitation
- InfiniBand breakout cable or terminal accessory
- PXI Express chassis bandwidth
- Controller and storage streaming performance
- NI-DAQmx and application-software compatibility
Why Choose the PXIe-4481?
The PXIe-4481 combines six synchronized 24-bit voltage inputs with two measurement modes optimized for different test requirements. Frequency-domain mode provides accurate spectral measurements and strong alias rejection, while time-domain mode captures rapid events at up to 20 MS/s per channel.
Its four input ranges, flexible coupling and PXI Express synchronization make it suitable for high-performance systems that need more bandwidth than conventional sound and vibration acquisition modules.
Frequently Asked Questions
What is the PXIe-4481?
The PXIe-4481 is a six-channel, 24-bit PXI Express analog input module designed for high-bandwidth frequency-domain and time-domain voltage measurements.
What is the PXIe-4481 part number?
The standard NI part number is 784278-01.
What is the maximum frequency-domain sample rate?
Frequency-domain mode supports sampling rates up to 1.25 MS/s per channel.
Can the PXIe-4481 sample at 20 MS/s?
Yes. It can acquire all six channels at up to 20 MS/s per channel in time-domain mode.
How many analog input channels does it provide?
The PXIe-4481 provides six simultaneously sampled analog input channels.
What input voltage ranges are available?
The module provides ±0.5 V, ±1 V, ±5 V and ±10 V peak input ranges.
Does the PXIe-4481 support AC and DC coupling?
Yes. AC or DC coupling can be selected independently for each input channel.
Does it provide isolated inputs?
No. Its inputs are not isolated. Signal common-mode voltage and grounding must remain within the module’s specifications.
Does the PXIe-4481 support IEPE or charge sensors?
No. Select the PXIe-4480 when integrated IEPE excitation, charge measurement, voltage excitation or TEDS support is required.
Does the PXIe-4481 have analog outputs?
No. It is an analog input module. Select the PXIe-4468 if the application also requires dynamic analog signal generation.
What connector does it use?
The analog input channels use an InfiniBand connector. An SMB programmable function interface is also provided for supported trigger and timing signals.
Which driver controls the PXIe-4481?
The module uses NI-DAQmx and can be operated with supported versions of FlexLogger, LabVIEW and other compatible development environments.
Request a Quote for the PXIe-4481
Contact us for current availability, lead time and project pricing for the PXIe-4481 24-Bit High-Bandwidth Analog Input Module, part number 784278-01.
We can also help verify compatible PXI Express chassis, controllers, InfiniBand cables, terminal accessories and related analog input modules for your measurement system.
