In a First, Instrument Performs Multichannel Signal and Spectrum Analysis with Cross Correlation
With the launch of its FSWX signal and spectrum analyzer, Rohde & Schwarz debuts a new internal multipath instrument architecture with cross-correlation capabilities.
In a recent live demonstration of the FSWX analyzer conducted by Rohde & Schwarz’s Darren Tipton, we’re shown a low-noise block converter receiving a satellite signal at 11 GHz that's downconverted to 1 GHz. The demonstration has the input of the low-noise block converter to port B with the output from port A. Thanks to the FSWX’s phase-coherent receivers, both signals can be captured simultaneously to perform a direct comparison of the input and output of the block converter.
In this manner, the FSWX can perform a full device characterization of the converter. Displays provide the channel response magnitude, the channel response phase, and the group delay. From these parameters, the instrument can also calculate error-vector magnitude.
The FSWX’s cross-correlation functionality enables users to remove the instrument’s own noise from the equation. The demo shows measurement very close to the thermal noise level of the analyzer. Additionally, R&S claims that the FSWX embodies the first application of cross correlation on a full spectrum analyzer. Some 20 years ago, R&S pioneered the use of an RMS trace detector, and now it has implemented a cross-correlation trace detector to accompany it.
In the demonstration, the output of the satellite block converter is a 32-APSK modulated signal. On the instrument, the yellow trace is the RMS trace that would be seen on a typical spectrum analyzer. With the addition of cross correlation, the FSWX allows users to see other effects, such as out-of-band noise coming from the DUT that would not be apparent otherwise.
