Agilent Using Fast-Sweep Techniques to Accelerate Spur Searches - Application Note 5991-3739EN c20140625 [17 free download

File name Using Fast-Sweep Techniques to Accelerate Spur Searches - Application Note 5991-3739EN c20140625 [17

Keysight Technologies Using Fast-Sweep Techniques to Accelerate Spur Searches Application Note Introduction Measurement speed is a major issue for a wide variety of RF and microwave products, and this influences production costs in industries ranging from commercial wireless to aerospace and defense. As a result, manufacturers in these areas are looking for ways to shorten design cycles, reduce manufacturing costs and increase yield. One important opportunity for improvement is the search for spurious emissions. These tests can be especially difficult and time-consuming because measurements must be made over wide frequency ranges and with high sensitivity. Unlike measurements of har- monics, the locations of spurious signals are not accurately known beforehand and there is often no choice but to sweep across wide frequency spans using narrow resolution bandwidths. In addition, the amplitudes of spurious signals are often near the measured noise floor, creating challenges for measurement accuracy and repeatability. The most commonly used tool for such measurements is an RF/microwave spectrum or signal analyzer. In recent years, the technological evolution of these analyzers has enabled faster spurious measurements. For example, high-speed analog-to-digital con- version and digital signal processing (DSP) has supplanted analog technology with digital intermediate frequency (IF) sections and therefore digital resolution bandwidth (RBW) filters. Digital filtering can provide some special benefits for narrow-RBW, wide-span operations such as spurious measurements. For example, existing digital filters have a better shape factor and can maintain full accuracy while being swept several times faster than equiva- lent analog filters. This technique is called oversweep. The latest advances in signal processing provide remarkable improvements in sweep speeds by implementing a new type of digital RBW filter in Keysight Technologies, Inc. PXA, MXA and EXA X-Series signal analyzers.1 This new filter allows sweep speeds to be up to 50 times faster without compromising accuracy in terms of amplitude and frequency. This application note focuses on this new technology and its use for spurious measurements. 1. The fast-sweep filtering technique is available in all PXA models and in MXA and EXA models configured with options MPB, DP2 or B40. Reviewing current RF performance requirements are steadily increasing, driven by demand for greater problems and practices communications throughput and wider bandwidths within the realities of a crowded spectral environment that places tight limits o