HP 8590 E-Series User Manual page 347

read-only memory
ROM (read-only memory) that is encoded into the analyzer's firmware. The data can be
accessed (read) only; it cannot be altered by the user.
reference level
The calibrated vertical position on the display used as a reference for amplitude
measurement in which the amplitude of one signal is compared with the amplitude of
another regardless of the absolute amplitude of either.
relative amplitude accuracy
The uncertainty of an amplitude measurement in which the amplitude of one signal is
compared with the amplitude of another, regardless of the absolute amplitude of either.
Distortion measurements are relative measurements. Contributors to uncertainty include
frequency response and display fidelity and changes of input attenuation, IF gain, scale
factor, and resolution bandwidth.
relative-marker mode
The active marker is positioned relative to the position of the reference marker. Marker
readout shows amplitude, frequency, or time differences between the two markers.
residual FM
The inherent short-term frequency instability of an oscillator in the absence of any other
modulation. In the case of spectrum analyzers, we usually expand the definition to include
the case where the local oscillator is swept. Residual FM is usually specified in peak-to-peak
values, because they are most easily measured on the display, if they are visible at all.
residual responses
These are discrete responses seen on a spectrum analyzer display although no input signal is
applied.
resolution
Refer to frequency resolution.
resolution bandwidth
The ability of a spectrum analyzer to display adjacent responses discretely (hertz, hertz
decibel down). This term is used to identify the width of the resolution bandwidth filter
of a spectrum analyzer at some level below the minimum insertion-loss point (maximum
deflection point on the display). The 3 dB resolution bandwidth is specified; for others, it is
the 6 dB resolution bandwidth.
rosenfell
For digital displays, this is the display detection mode in which the value displayed at each
point on a trace is based upon whether or not the video signal both rose and fell during the
frequency or time interval represented by the point. If the video signal only rose or only
fell, the maximum value is displayed. If the video signal both rose and fell, the maximum
value during the interval is displayed by odd-numbered points, and the minimum value by
even-numbered points. To prevent the loss of a signal occurring during an even-numbered
interval, the maximum value of the signal during this interval is preserved. At the next
(odd-numbered) interval, the value displayed is the greater value carried over, or the
maximum, that occurs during the current interval.
sample
The instantaneous value of an incoming signal. On digital displays, each displayed point of
the signal indicates the instantaneous value of the signal for that part of the frequency span
or time interval represented by the point.
Glossary-13