NI RF Signal Analyzers

NI RF signal analyzers measure the frequency content, power, and modulation quality of radio-frequency signals. Used in automated production testing, RF component characterization, radar verification, and spectrum monitoring, these instruments help engineers investigate unwanted emissions and evaluate transmitter performance. National Instruments combines modular PXI or PXI Express hardware with software-defined analysis, allowing RF measurements to operate alongside other instruments within an automated test platform. Vector analysis retains both amplitude and phase information in in-phase and quadrature data, enabling demodulation and measurements such as error vector magnitude when suitable analysis software and hardware are available.

NI’s 566x analyzer family spans several generations of measurement capability. The PXI-5660 and PXI-5661 cover 9 kHz to 2.7 GHz with 20 MHz acquisition bandwidth. PXI-5660 ordering options include 778284-01 with 32 MB memory and 778284-02 with 64 MB. The PXI-5661, including part number 779782-03, uses onboard digital downconversion to reduce waveform data transferred to the host during supported acquisitions.

For higher-frequency measurements, the PXIe-5663 extends coverage to 6.6 GHz. Its 780415-01 and 780415-02 configurations provide 64 MB and 256 MB memory, respectively. The PXIe-5665 offers versions reaching 3.6 GHz or 14 GHz, with up to 50 MHz instantaneous bandwidth. These differences matter when selecting replacement hardware: matching the analyzer family alone does not establish matching frequency coverage, memory, or acquisition capabilities.

The PXIe-5668, also identified as PXIe-5668R in ordering descriptions, addresses wider-bandwidth applications. Options include 14 GHz and 26.5 GHz frequency coverage. Part number 783124-03 identifies a 26.5 GHz, 2 GB configuration with 320/765 MHz bandwidth capability. On this configuration, instantaneous bandwidth reaches 320 MHz below 3.6 GHz and up to 765 MHz in the higher-frequency band with the appropriate filter settings. Lower-bandwidth versions should not be assumed equivalent.

Many NI RF signal analyzers are complete instrument combinations rather than single modules. For example, the PXI-5661 pairs a PXI-5600 RF downconverter with a PXI-5142 intermediate-frequency digitizer. A compatible chassis, controller, interconnecting cables, and software are also required. Purchasing only a downconverter or digitizer does not provide the complete analyzer functionality described by the system model.

Selection should consider carrier frequency, occupied signal bandwidth, noise floor, phase noise, dynamic range, and capture memory. Frequency range describes where the analyzer can tune; instantaneous bandwidth describes how much spectrum it captures at once. Appropriate attenuation and signal conditioning help avoid overload when measuring strong signals or weak emissions near larger carriers.

NI-RFSA provides acquisition control for supported analyzers, while compatible RFmx packages add measurement functions. The PXI-5660 follows a separate legacy software path. Check operating-system, driver, and application compatibility before changing hardware. For established test systems, contact Apex Waves with the complete model, ordering number, module configuration, and calibration requirements to discuss replacement options.