The NI 5791R is an RF transceiver with continuous frequency coverage from 200 MHz to 4.4 GHz, with 100 MHz of instantaneous bandwidth on both TX and RX. It features a single-stage, direct conversion architecture, providing high bandwidth in the small form factor of an NI FlexRIO adapter module. The onboard synthesizer (local oscillator or LO) sets the center frequency for acquisition and generation, and can be exported to other modules for multiple-input, multiple-output (MIMO) synchronization. The LO can also be imported from an external connector, enabling synchronization of up to eight NI 5791R modules at up to 2.8 GHz without external amplification. For higher frequencies or a greater number of devices, an external LO distribution amplifier may be used.
The baseband analog-to-digital converters (ADCs) on the NI 5791R are 14-bit, clocked at 130 MS/s, to provide a sufficient excess rate for 100 MHz bandwidth after any digital signal processor (DSP) resampling and frequency shifting. Similarly, the digital-to-analog converter (DAC) has a 16-bit resolution and the data rate is 130 MS/s, which simplifies algorithm design. In a DSP on the DAC hardware, the data is subsequently interpolated four times to 520 MS/s before generation, which reduces out-of-band images. Direct access to raw ADC and DAC data on the NI FlexRIO FPGA module provides the ultimate flexibility in digital signal processing, data storage and streaming, and custom algorithm design for software defined radio (SDR), signal intelligence (SIGINT), streaming to and from disk, MIMO, beamforming, and other high-performance embedded RF applications. Additionally, the NI FlexRIO FPGA module and the PXI platform provide a means for ADC and DAC data synchronization, which is necessary for channel expansion. Twelve bidirectional digital I/O lines routed from the FPGA to a connector on the adapter module enable digital device under test (DUT) control and simple digital protocols. Though the NI 5791R is compatible with all NI FlexRIO FPGA modules, National Instruments recommends the NI PXIe-7966R to fit all of the provided LabVIEW FPGA software for RF configuration and DSP correction, in addition to any user code and IP. Examples for the NI 5791R are configured and compiled for only the NI PXIe-7966R and NI PXIe-7965R FPGA modules.
RF performance on the NI 5791R is also exceptional, given its size. RX dynamic range is greater than 105 dB, with a noise figure less than 8 dB at 2 GHz. The LO phase noise is better than 94 dBc/Hz at 2.4 GHz and a 10 kHz offset, and the loopback EVM is less than 1.5 percent. All specifications are typical, and some require FPGA-based correction algorithms, which are provided in the form of example code.