Datasheet

A GUIDE TO RF SIGNALS
6 | TEK.COM/RSA
In the past decade there has been a gradual shift toward real-time spectrum displays.
While classic spectrum displays have been around since the 1960’s, they have all
suffered from a common problem, speed. In most traditional spectrum analyzers what
is displayed on the left hand side of the display and the right hand side of the display
is not measured at the same time. The instrument sweeps across the frequency range
making measurements over time. To overcome this shortcoming spectrum analyzers
employ specific trace modes (max hold, min hold, average etc) to improve the ability of
the analyzer to measure a specific signal.
Real-time spectrum analyzers function and operate the same way traditional spectrum
analyzers. The difference with real-time analyzer is that in up to the maximum real-time
span, these analyzers do not sweep the spectrum, but rather instantaneously digitize
the whole span. The real-time span could be limited by the instantaneous bandwidth
of the instrument, and they can digitize signals extremely quickly. Real time spectrum
analyzers with that capability can produce results measured in thousands of traces
per second. This has led to an upgrade of the basic spectrum display with the Digital
Phosphor Display (DPX). In the DPX display we still have low frequency on the left and
high frequency on the right hand side of the display.
Rather than producing a single trace real time analyzers are able to keep track of how
often a signal is measured for each pixel in the display. There is a counter behind each
pixel that keeps track of how often energy is measured, and the pixel color is based on
this counter. Real-time analyzers also employ a decay function, just like what was found
on traditional CRT displays. This combination provides an extremely useful tool for
analyzing fast frequency hopping signals like Bluetooth, or for isolating tough transients
that can be virtually invisible to slow sweeping spectrum analyzers.
Note that the RSA306’s Span setting is not constrained to the real-time bandwidth.
Rather, the DPX display can be swept in steps across the instrument’s entire 6.2 GHz
frequency range. The same is true for the Spectrum Analyzer displays. In general, the
RSA306 with SignalVu-PC software has conventional spectrum analyzer controls as well
as powerful real-time capabilities.
WHAT IS A REAL-TIME DISPLAY?
Take Tektronix USB spectrum analyzers into the field for fast RF analysis and geo-location.
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