National Instruments PXI-2557 (778572-57)

National Instruments PXI-2557 PXI RF Multiplexer Switch Module

The National Instruments PXI-2557 (Part Number: 778572-57) is a PXI RF Multiplexer Switch Module. The higher channel count of the PXI-2557 makes it perfect for test frameworks that require the switching of an expansive number of video RF signals, including switching several video tuners under test to a single channel on the RF analyzer.

Each switch causes some lessening and power loss on the signal routed. Insertion Loss is a measure of this lessening and power loss. An insertion loss graph for a switch module is analogous to a 3 dB graph (Bode plot) for a lowpass channel. To pick the best switch for a specific RF application, it is critical to know the insertion loss of the switch at the recurrence of the signal being routed.

The NI PXI-2557 Multiplexer Switch Module includes VSWR, which is the ratio of reflected to transmitted waves. At higher frequencies, signals take the form and shape of a wave when going through a transmission line. In RF applications, this happens when a signal is made to propagate between parts with unmatched impedances. Such mismatches happen in switch modules due to slight varieties in impedances of the connectors on the module, PCB traces, and the actual relay itself. Since VSWR is a measure of the energy of the reflected wave, it additionally adds to the measure of energy loss in the transmission line. VSWR is particularly imperative in RF applications where signal reflections can harm the source.