User`s guide

EM1
The abbreviation for electromagnetic interference. An EM1 measurement determines
how much an undesired electromagnetic disturbance impairs the reception of a desired
electromagnetic signal.
envelope detector
A detector circuit whose output follows the envelope, but not the instantaneous variation
of its input signal. This detector is sometimes called a peak detector. In superheterodyne
spectrum analyzers, the input to the envelope detector comes from the final IF, and the
output is a video signal. When we put the spectrum analyzer in zero span, the envelope
detector demodulates the input signal, and we can observe the modulating signal as a
function of time on the display.
error message
A message displayed on the screen indicating missing or failed hardware, improper user
operation, or other conditions that require additional attention. Generally, the requested
action or operation cannot be completed until the condition is resolved.
external mixer
An independent mixer, usually having a waveguide input port, used to extend the
frequency range of those spectrum analyzers designed to use them. The analyzer provides
the local oscillator signal and mixer bias (if needed), then returns the mixing products to the
analyzer’s IF input.
FFT
The abbreviation for fast Fourier transform. It is a mathematical operation performed on a
time-domain signal to yield the individual spectral components that constitute the signal in
the frequency domain. Refer also to spectrum.
firmware
An assembly made up of hardware and instruction code that are integrated to form a
functional set which cannot be altered during normal operation. The instruction code,
permanently installed in the circuitry of the instrument, is classified as ROM (read-only
memory). The firmware determines the operating characteristics of the instrument or
equipment. Each firmware version is identified by a revision code number, or date code.
flatness
The displayed amplitude variation corresponding to the tuned frequency range of the
spectrum analyzer. Flatness of &l dB indicates that maximum and minimum values of the
analyzer’s frequency response are less than 2 dB apart.
Fourier transform
See FFT.
frequency accuracy
The uncertainty with which the frequency of a signal or spectral component is indicated,
either in an absolute sense or relative to some other signal or spectral component. Absolute
and relative frequency accuracies are specified independently.
frequency range
The range over of frequencies which the spectrum analyzer performance is specified.
The maximum frequency range of many microwave analyzers can be extended with the
application of external mixers.
Glossary-5