S2's publication titled "20 GHz Instantaneous Bandwidth RF Spectrum Analyzer Measurements with High Sensitivity and Spur Free Dynamic Range" was recently presented at the GOMAC 2014 conference. The following describes the papers findings:
The paradigm of operations for radio frequency (RF) monitoring is rapidly moving towards “wideband sense and react”, given the proliferation of transmitters for radar and communication systems operating over more of the electromagnetic spectrum (EMS). A significant challenge for present and future military and commercial systems is to analyze signals over a wide bandwidth, out to 120 GHz, in real time without any scanning in frequency, and without any prior knowledge of the signals, carrier frequency, or modulation format. For spectrum monitoring (SM), a receiver system must have a high spur free dynamic range (SFDR), so that the small signals of interest (SOI) are not mistaken for the false signals – spurs – that are generated by large signals, such as other SOIs, co-site interference, or jammers. The system should have fast update rates for tracking signals with fast pulse repletion frequency (PRF), with changing PRFs and wide bandwidth to handle frequency hops, and low latency to cue other systems or countermeasures. Such a system should also have high RF sensitivity. Typical high sensitivity measurement systems “choke down” the bandwidth to get a lower noise floor, which can approach the thermal noise floor limit of -174 dBm/Hz, less the noise figure (NF) of the system. Typical narrow band measurement techniques use superheterodyne detection at a fixed frequency and resolution bandwidth (RBW). For wideband coverage the local oscillator (LO) tunes across the desired bandwidth dwelling on each frequency sequentially [1]. Modern digital spectrum analyzers use digitizers and Fast Fourier Transform (FFT) processing to enable higher instantaneous bandwidth measurements limited by mainly the digitizer performance [2]. In comparison, our spectral sensing system remains fully open to the entire bandwidth of interest, presently over 20 GHz and readily extendable to >100 GHz, operates with high sensitivity, high SFDR and generates 400,000,000 unique frequency measurements per second.