Radio frequency sweep
Encyclopedia
Radio frequency sweep or "Frequency sweep" or "RF sweep" refer to scanning a radio frequency band for detecting signals being transmitted there. This is implemented using a radio receiver having a tunable receiving frequency. As the frequency of the receiver is changed to scan (sweep) a desired frequency band, a display indicates the power of the signals received at each frequency.
is a standard instrument used for RF sweep. It includes an electronically tunable receiver and a display. The display presents measured power (y axis) vs frequency (x axis).
The power spectrum display is a two-dimensional display of measured power vs. frequency. The power may be either in linear units, or logarithmic units (dBm). Usually the logarithmic display is more useful, because it presents a larger dynamic range with better detail at each value. An RF sweep relates to a receiver which changes its frequency of operation continuously from a minimum frequency to a maximum (or from maximum to minimum). Usually the sweep is performed at a fixed, controllable rate, for example 5 MHz/sec.
Some systems use frequency hopping, switching from one frequency of operation to another. One method of CDMA uses frequency hopping. Usually frequency hopping is performed in a random or pseudo-random pattern.
, to ensure that users only transmit according to their licenses. The FCC for example controls and monitors the use of the spectrum in U.S.A. In testing of new electronic devices, a frequency sweep may be done to measure the performance of electronic components or systems. For example, RF oscillators are measured for phase noise, harmonics and spurious signals; computers for consumer sale are tested
to avoid radio frequency interference with radio systems. Portable sweep equipment may be used to detect some types of covert listening device
(bugs).
Methods and tools
A spectrum analyzerSpectrum analyzer
A spectrum analyzer measures the magnitude of an input signal versus frequency within the full frequency range of the instrument. The primary use is to measure the power of the spectrum of known and unknown signals...
is a standard instrument used for RF sweep. It includes an electronically tunable receiver and a display. The display presents measured power (y axis) vs frequency (x axis).
The power spectrum display is a two-dimensional display of measured power vs. frequency. The power may be either in linear units, or logarithmic units (dBm). Usually the logarithmic display is more useful, because it presents a larger dynamic range with better detail at each value. An RF sweep relates to a receiver which changes its frequency of operation continuously from a minimum frequency to a maximum (or from maximum to minimum). Usually the sweep is performed at a fixed, controllable rate, for example 5 MHz/sec.
Some systems use frequency hopping, switching from one frequency of operation to another. One method of CDMA uses frequency hopping. Usually frequency hopping is performed in a random or pseudo-random pattern.
Applications
Frequency sweeps may be used by regulatory agencies to monitor the radio spectrumRadio spectrum
Radio spectrum refers to the part of the electromagnetic spectrum corresponding to radio frequencies – that is, frequencies lower than around 300 GHz ....
, to ensure that users only transmit according to their licenses. The FCC for example controls and monitors the use of the spectrum in U.S.A. In testing of new electronic devices, a frequency sweep may be done to measure the performance of electronic components or systems. For example, RF oscillators are measured for phase noise, harmonics and spurious signals; computers for consumer sale are tested
Product certification
Product certification or product qualification is the process of verifying that a certain product has passed performance tests and quality assurance tests or qualification requirements stipulated in contracts, regulations, or specifications...
to avoid radio frequency interference with radio systems. Portable sweep equipment may be used to detect some types of covert listening device
Covert listening device
A covert listening device, more commonly known as a bug or a wire, is usually a combination of a miniature radio transmitter with a microphone. The use of bugs, called bugging, is a common technique in surveillance, espionage and in police investigations.A bug does not have to be a device...
(bugs).
See also
- Spectrum managementSpectrum managementSpectrum management is the process of regulating the use of radio frequencies to promote efficient use and gain a net social benefit.The term radio spectrum typically refers to the full frequency range from 3 kHz to 300 GHz that may be used for wireless communication...
- Measuring receiverMeasuring ReceiverIn telecommunication, a measuring receiver or measurement receiver is a calibrated laboratory-grade radio receiver designed to measure the characteristics of radio signals. The parameters of such receivers can usually be adjusted over a much wider range of values than is the case with other radio...
- Technical surveillance counter-measuresTechnical Surveillance Counter-MeasuresTSCM is the original United States Federal government abbreviation denoting the process of bug-sweeping or electronic countersurveillance...