Tektronix has updated its range of RSA (real-time spectrum-analyser) instruments with the RSA6100A series. The instruments follow the approach of their predecessors in that they capture a complete wideband signal sample, repetitively, and perform high-speed transforms on each sample to yield a stream of spectrum-analysis "snapshots", allowing the user to track and measure dynamic spectral characteristics of an RF signal. In the 6100A models, the captured bandwidth extends to 110 MHz (with 73 dB spurious-free dynamic range), and the update rate is 48,828 spectra/sec. This translates to a 100% probability of interception of signals down to 24-μsec duration. The instrument digitises the incoming RF signal and passes it to a high-speed discrete Fourier transform engine running on what a company spokesman describes as an "FPGA farm". Further processing maps the result to a pixel buffer for the display. Pixel repetition is represented as graded colour: signal features that are stable in time and that are present in every captured spectrum are shown in "warm" colours; infrequent or transient spectral events are shown in "cooler" colours. The instrument's basic display shows amplitude against frequency, with time-varying information shown as colour differences. Further processing yields a range of alternative display formats. The 110-MHz capture bandwidth (which is the broader of two options on the instrument) allows analysis of pulse waveforms down to 50 nsec. Tektronix expects that the RSA will find application in areas such as digital communications, where, for example, users can measure pre-distortion amplifiers with a greater degree of accuracy—the 110-MHz bandwidth is over five times the 20-MHz bandwidth occupied by a 3G signal. Other fields of interest include radar development, as well as surveillance, where it is possible to monitor all signal activity in a 110-MHz "slice" of spectrum, including finding low-level signals that noise masks. I/Q signal outputs pass captured signal data on to other systems for further analysis.