Spectrum Analyser

A spectrum analyser is a piece of equipment that is used during EMC measurements. It's primary purpose is to measure the amplitude of individual frequencies that are contained in a RF signal. This RF signal is very often an electromagnetic field that is received by an antenna.

RadiMation has divided spectrum analysers in three different classes:

• Spectrum analyser
• Scanning receiver
• Receiver

Receiver

A receiver is only measuring a single RF frequency. The receiver itself is not able to measure multiple frequencies. If more than one frequency need to be measured a PC has to change the selected frequency on the receiver, before a new measurement is performed.

Scanning receiver

A scanning receiver is a more intelligent receiver, which is able to step through a frequency range on it's own, so multiple frequencies can be measured automatically. A PC that is controlling the scanning receiver can instruct the scanning receiver to measure a certain frequency range. The scanning receiver will then return the data of the all the measured frequencies after (or during) the measurement is finished.

A scanning receiver is always measuring on all and the exact frequencies that are specified by the start-, stop- and step-frequency.

Spectrum analyser

A spectrum analyser is a measuring device that sweeps in a short time along the frequency range that should be measured. During this sweep all frequencies are measured, and a PC can retrieve a list of the measured amplitudes from the spectrum analyser. The list of measured amplitudes is often a reduced list of a specific amount of frequencies (401 points, 601 points, etc...)

Common

Most scanning receivers and spectrum analysers include a lot of functionality to make it easier for an end-user to perform certain measurements. This additional functionality can be:

• EMC Overview measurements
• Completely automated EMC measurements including peak detection and peak measurements
• telecommunication measurements

Spectrum analysers are always used during Emission tests. In some situations a spectrum analyser is also used during immunity tests, mainly to measure a RF signal.

All the device drivers for spectrum analysers maintain the following information:

• Allowed frequency range
• if the device is a receiver / scanning receiver / spectrum analyser
• Instructions on how to
  • Set start-, stop-, center-, span- and step-frequency
  • change RBW settings
  • change Reference level settings
  • change Attenuation settings
  • change VBW settings
  • change preselector settings
  • change preamplifier settings
  • change measure time settings
  • change sweep time settings
  • change detector settings

A complete list of all supported spectrum analysers by RadiMation is available on this RadiWiki site.

Links

• Wikipedia: Spectrum analyser