News and New Products

DSP-based instruments radically alter swept-spectrum analysis

By Dan Strassberg, Contributing Technical Editor -- EDN, 5/26/2009

Tektronix has announced enhancements to its RSA6000 Series of DSP-based real-time spectrum analyzers. With the aid of new hardware and software, the enhanced instruments use advanced triggering technology and real-time signal analysis to deliver unique diagnostic capabilities that speed analysis in resolving performance problems in systems for spectrum management, radar, electronic warfare, and radio communications at frequencies to 14 GHz. The enhanced units’ fast measurements and short test times thus help system engineers to control project costs.

An increased need to combine digital computing with traditional RF technologies has presented spectrum-analyzer users with new challenges, such as broadband transients, DSP errors, and runt pulses. The use of analyzers with only narrowband filters, which impose slow spectrum-update rates, makes troubleshooting of these signals increasingly complex and time-consuming. Allowed transmissions can be difficult to separate from elusive transients, with which they often overlap in time and frequency. Such interferers and hostile signals can also cause intermittent failures, which are unacceptable in high-reliability applications. The enhanced instruments’ advanced time-, amplitude-, and DPX-triggering functions and swept-DPX (digital-phosphor-technology) capability, enable faster discovery and capture of these intermittent and rapidly changing signals.

The enhanced spectrum analyzers’ improved broad-sweep capability enables rapid detection of signals of interest. The DPX engine collects hundreds of thousands of spectra per second over a 110-MHz bandwidth. By enabling the instrument to sweep across its full input-frequency range of as much as 14 GHz and capture tens or hundreds of spectra in no more time than a conventional spectrum analyzer needs to capture just one spectrum, this enhancement greatly reduces the possibility of missing time-interleaved or transient signals during broadband searches. The analyzers now capture 292,000 spectra/sec—six times as many spectra per second as the manufacturer’s previous generation of DPX-equipped spectrum analyzers. With this feature, you can be confident of detecting transients as brief as 10.3 μsec, which conventional spectrum analyzers miss. This enhancement is particularly important to those who work with such systems as software-defined radio and radar.

The DPX trigger also enables the instruments to trigger on signals within signals. You invoke this capability by pointing at the signal on the spectrum display and selecting the “trigger-on-this” feature. You can also time-qualify any trigger. The enhanced instruments’ unique time- and amplitude-qualified triggers reduce troubleshooting time in such applications as radar and spectrum management. Suggested US prices for the enhanced RSA6000 Series instruments begin at $77,900. For those who own earlier instruments in the series, a user-installable hardware/software upgrade kit costs $12,900.