HP Cable Box 8591C manual Meas Uncal

LO

The abbreviation for local oscillator. The local oscillator output in a superheterodyne system is mixed with the received signal to produce a sum or difference equal to the intermediate frequency (IF) of the receiver. Refer also to IF.

LO feedthrough

The response that occurs on an analyzer’s display when the first local oscillator frequency is equal to the first IF. The LO feedthrough is a 0 Hz marker with no error, so it can be used to improve the frequency accuracy of analyzers with nonsynthesized LO systems.

log display

The display mode in which vertical deflection is a logarithmic function of the input-signal voltage. Log display is also referred to as logarithmic mode. The display calibration is set by selecting the value of the top graticule line (reference level), and scale factor in volts per division. On Hewlett-Packard analyzers, the bottom graticule line represents zero volts for scale factors of 10 dB/division or more. The bottom division, therefore, is not calibrated for those analyzers. Analyzers with microprocessors allow reference level and marker values to be indicated in dBm, dBmV, dB/IV, volts, and occasionally in watts. Nonmicroprocessor-based analyzers usually offer only one kind of unit, typically dBm.

marker

A visual indicator we can place anywhere along the displayed trace. A marker readout indicates the absolute value of the trace frequency and amplitude at the marked point. The amplitude value is displayed with the currently selected units. Refer also to delta marker and noise marker.

maximum input level

The maximum signal power that may be safely applied to the input of an analyzer. Typically 1 W (-30 dBm) for Hewlett-Packard analyzers.

MEAS UNCAL

Annotation indicating an uncalibrated measurement condition exists. It appears when instrument settings affect accuracy of measurement results to the extent that they no longer meet specifications.

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