HP Cable Box 8591C manual Noise marker

noise marker

A marker whose readout represents the noise level in a 1 Hz noise power bandwidth. When the noise marker is selected, the sample display detection mode is activated, the values of a number of consecutive trace points about the marker (the number depends on the type of analyzer) are averaged, and this average value is normalized to an equivalent value

in a 1 Hz noise power bandwidth. The normalization process accounts for detection and bandwidth plus the effect of the log amplifier when we select the log-display mode.

noise sidebands

Modulation sidebands that indicate the short-term instability of the local oscillator (primarily the first local oscillator) system of an analyzer. The

modulating signal is noise, in the local oscillator circuit itself or in the local oscillator stabilizing circuit, and the sidebands comprise a noise spectrum. The mixing process transfers any local oscillator instability to the mixing products, so the noise sidebands appear on any spectral component displayed on the analyzer far enough above the broadband noise floor. Because the sidebands are noise, their level relative to a spectral component is a function of resolution bandwidth. Noise sidebands are typically specified in terms of dBc/Hz (amplitude in a 1 Hz bandwidth relative to the carrier) at a given offset from the carrier, the carrier being a spectral component viewed on the display.

nonvolatile memory

Memory data that is retained in the absence of an ac power source. This memory is typically retained with a battery. Refer also to battery-backed RAM.

occupied bandwidth

A measure of the frequency bandwidth occupied by the carrier of a transmitter. It is usually the bandwidth that includes 99% of the total mean carrier power, and is equivalent to “99% power bandwidth”. It is measured by determining the lower and upper frequency limits; where 0.5% of the total mean carrier power is below the lower frequency limit and 0.5 % is above the upper frequency limit. Occasionally percentages other than 99% are specified.

Glossary 18