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Fundamentals
of Digital PhosphorTM Technology
in Real-Time Spectrum Analyzers
Fundamentals of Digital PhosphorTM Technology in Real-Time Spectrum Analyzers
Primer
Table of Contents
Digital PhosphorTM Technology in Real-Time Spectrum Analyzers:
a Revolutionary Tool for Signal Discovery----------------------------------------------------------------------------------------------------------4
Digital Phosphor Display ----------------------------------------------------------------------------------------------------------------------------4 - 9
Application: Finding low-level signals beneath
a stronger signal ----------------------------------------------------------------------------------------------------------------------------------4 - 6
The DPX Display Engine ----------------------------------------------------------------------------------------------------------------------------6 - 7
Persistence ------------------------------------------------------------------------------------------------------------------------------------------8
Statistical Line Traces ------------------------------------------------------------------------------------------------------------------------------9
Super-Fast Spectral Updates ------------------------------------------------------------------------------------------------------------------------9 - 12
The DPX Transform Engine--------------------------------------------------------------------------------------------------------------------------10
Application: Guaranteed detection of
short, infrequent signals --------------------------------------------------------------------------------------------------------------------------10 - 11
Probability of Intercept ------------------------------------------------------------------------------------------------------------------------------11 - 12
Discover DPX------------------------------------------------------------------------------------------------------------------------------------------12
Getting the Most out of the DPX Spectrum Display ----------------------------------------------------------------------------------------------13 - 15
Adjustments for the Bitmap Display --------------------------------------------------------------------------------------------------------------13 - 14
Persistence ------------------------------------------------------------------------------------------------------------------------------------------13
Intensity --------------------------------------------------------------------------------------------------------------------------------------------13
Color Palettes --------------------------------------------------------------------------------------------------------------------------------------13
Color Scale ------------------------------------------------------------------------------------------------------------------------------------------14
Interaction with other RTSA Functions------------------------------------------------------------------------------------------------------------14 - 15
RBW ------------------------------------------------------------------------------------------------------------------------------------------------14
Span ------------------------------------------------------------------------------------------------------------------------------------------------15
Markers----------------------------------------------------------------------------------------------------------------------------------------------15
Frequency Mask Trigger ----------------------------------------------------------------------------------------------------------------------------15
Analysis Time----------------------------------------------------------------------------------------------------------------------------------------15
Power Level Triggering ----------------------------------------------------------------------------------------------------------------------------15
www.tektronix.com/rsa 3
Fundamentals of Digital PhosphorTM Technology in Real-Time Spectrum Analyzers
Primer
Digital PhosphorTM Technology in However, the combination of phosphor coatings and vector
Real-Time Spectrum Analyzers: a drawing in CRTs provided several valuable benefits.
Revolutionary Tool for Signal Discovery Persistence: Phosphor continues to glow even after the
Detection is the first step in characterizing, diagnosing, electron beam has passed by. Generally, the fluorescence
understanding and resolving any problem relating to time- fades quickly enough that viewers don't perceive it lingering,
variant signals. As more channels crowd into available but even a small amount of persistence will allow the human
bandwidth, new applications utilize wireless transmission, eye to detect events that would otherwise be too short
and RF systems become digital-based, engineers need to see.
better tools to help them find and interpret complex Proportionality: The slower the electron beam passes
behaviors and interactions. through a point on the phosphor-coated screen, the brighter
Tektronix' patented Digital Phosphor technology, standard in the resulting light. Brightness of a spot also increases as the
our next-generation RSA6100A Series Real-Time Spectrum beam hits it more frequently. Users intuitively know how to
Analyzers (RTSAs), reveals signal details that are completely interpret this z-axis information: a bright section of the trace
missed by conventional spectrum analyzers and vector indicates a frequent event or slow beam motion, and a dim
signal analyzers. The full-motion DPXTM Spectrum's live RF trace results from infrequent events or fast-moving beams.
display shows signals never seen before, giving users In the DPX display, both color and brightness provide z-axis
instant insight and greatly accelerating discovery emphasis.
and diagnosis. Persistence and proportionality do not come naturally to
This primer describes the DPXTM Spectrum display and how instruments with LCDs (or even raster CRTs) and a digital
it addresses situations involving brief, intermittent, complex signal path. Tektronix developed Digital Phosphor
and/or coincident signals. Also covered are the methods for technology so the analog benefits of a vector CRT could
achieving its key performance specifications: be achieved, and even improved upon, in our industry-
leading digital oscilloscopes and now in our real-time