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WO1992019982A1 - Selection de canaux operationnels - Google Patents

Selection de canaux operationnels Download PDF

Info

Publication number
WO1992019982A1
WO1992019982A1 PCT/AU1992/000201 AU9200201W WO9219982A1 WO 1992019982 A1 WO1992019982 A1 WO 1992019982A1 AU 9200201 W AU9200201 W AU 9200201W WO 9219982 A1 WO9219982 A1 WO 9219982A1
Authority
WO
WIPO (PCT)
Prior art keywords
channel
channels
signals
frequency
reliability index
Prior art date
Application number
PCT/AU1992/000201
Other languages
English (en)
Inventor
Bruce Donald Ward
George Frederick Earl
Original Assignee
THE COMMONWEALTH OF AUSTRALIA c/o THE SECRETARY, DEPARTMENT OF DEFENCE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by THE COMMONWEALTH OF AUSTRALIA c/o THE SECRETARY, DEPARTMENT OF DEFENCE filed Critical THE COMMONWEALTH OF AUSTRALIA c/o THE SECRETARY, DEPARTMENT OF DEFENCE
Publication of WO1992019982A1 publication Critical patent/WO1992019982A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/14—Spectrum sharing arrangements between different networks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/0218—Very long range radars, e.g. surface wave radar, over-the-horizon or ionospheric propagation systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/021—Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/40—Means for monitoring or calibrating
    • G01S7/4004—Means for monitoring or calibrating of parts of a radar system
    • G01S7/4017—Means for monitoring or calibrating of parts of a radar system of HF systems
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/42—Diversity systems specially adapted for radar

Definitions

  • This invention relates to radio frequency surveillance systems and in particular to a method and apparatus for monitoring the occupancy of a range of channels in an operating band and utilizing an adaptive reliability index to aid in the selection of clear channels.
  • the invention relates to a system of selecting an appropriate operating frequency to minimise the effects of interference.
  • the problem is that the high frequency band from 5 to 45 MHz can be particularly congested from both man-made and natural sources. At frequencies below about 10 MHz lightning discharges distributed around the earth generate noise which inhibits use of this region of the HF spectrum. This is particularly true at night when ionospheric conditions support propagation over long distances. By contrast the noise above 20 MHz is almost entirely galactic in origin and displays little temporal variation.
  • An HF system will normally consist of one or more antennas connected to one or more receivers.
  • the antennas may be omnidirectional or may be physically arranged to have a degree of directionality.
  • various analogue techniques can be used to form receiver beams having a defined direction and width.
  • the signals from the antennas are often subjected to some degree of analogue filtering before reaching the receiver.
  • the receiver output can be converted from analogue to digital form before undergoing further processing and analysis. Once in digital form phase weighting techniques can be used to form multiple receiver beams.
  • the invention operates in two parts. Firstly the frequency surveillance system operates in a channel occupancy mode to monitor activity across the HF spectrum and identify unoccupied channels. A database of unoccupied channels is maintained. Secondly, a clear channel method selects suitable operating channels from the database of unoccupied channels. The clear channel method uses a reliability index to aid in this selection. The background atmospheric noise level is measured in selected unoccupied channels.
  • the system scans the entire band to determine the occupancy of each channel.
  • the occupancy of channels in a frequency band has been determined by using narrow band filters and directly measuring the power received through the filter.
  • the problem with this method is that it is limited by the fidelity of the filters and it is inflexible.
  • use of a narrow band filter limits the rate at which the system can be swept across the HF band.
  • a number of sub-systems such as sounders provide information for determining the optimum operating frequency band for a given combination of ionospheric conditions. Once a frequency band has been selected however, an unoccupied channel must be chosen in which to operate. This invention is designed to aid in this choice.
  • a method of identifying suitable channels for operation in a frequency band consisting of a plurality of frequency channels comprising the steps of: accumulating analogue signals from a plurality of scans over the frequency band; transforming the signals; averaging the transformed signals of a number of the scans; scaling the averaged transformed signals to absolute signals; determining the amplitude of the absolute signal in a frequency channel; and displaying the signal amplitude against frequency on a visual display means.
  • the step of transforming the signals includes converting the analogue signals to digital signals and applying a Fourier transform to the digital signals to produce transformed signals.
  • a fast Fourier transform is used to transform the digital signals into a plurality of signals at a desired resolution across a receiver bandwidth.
  • each scan is checked for the effect of impulsive noise and effected signals are excluded.
  • the remaining signals in a number of scans are averaged.
  • the number of scans that are averaged is ten.
  • signals are checked for the effects of impulsive noise by comparing the amplitude of signals at a given frequency from a number of scans. Signals which occur in a small minority of the scans are assumed to be due to impulsive noise and are therefore removed.
  • the resulting digital signal amplitudes provide a measure of the level of occupancy in each channel across a frequency band.
  • the amplitudes are displayed graphically with frequency as the independent variable.
  • a method of selecting clear channels for operation in a frequency band consisting of a plurality of frequency channels comprising the steps of: identifying suitable channels for operation; determining a reliability index for each channel; forming a list of available channels; sorting and selecting available channels from the list of available channels based on operational requirements; evaluating the selected channels to determine the best channel in which to operate and operating on the determined channel.
  • a method of selecting clear channels in a frequency band comprising the steps of: obtaining real time channel occupancy and background noise data from a frequency surveillance system; applying a threshold to determine those channels which are occupied; determining a reliability index for each channel; forming a list of available channels; sorting and selecting available channels from the list of available channels based on operational requirements; evaluating the selected channels to determine the best channel in which to operate and operating on the determined channel.
  • the threshold can be set by an operator or may be set by an expert system.
  • reject frequency list is maintained and referred to when selecting appropriate operating frequencies.
  • the reject frequency list contains two types of frequencies. Firstly there are those frequencies which are always prohibited due to designation as intemational distress frequencies or due to constant use by other HF operators. Secondly there are those frequencies which are generally occupied a high percentage of the time or always occupied at certain times.
  • the aim of the reject frequency list is to prevent operation at frequencies which have a high probability of suffering radio frequency interference. Thus if a channel is known to be occupied at a certain time each day it will not be selected at that time, even if all other considerations identify it as the best channel.
  • a passive channel evaluation method is used to evaluate the selected channels.
  • the passive channel evaluation method utilizes an antenna and receiver to look at the selected channels at higher resolution than the frequency surveillence system and thereby may select between two channels which appear equivalent from all other considerations.
  • RJ a reliability index
  • R j [ ⁇ C j + ⁇ d- ⁇ j C j -i J C
  • c j is the occupancy factor and is either 0 for an occupied channel or 1 for an unoccupied channel
  • ⁇ is a weighting factor
  • ⁇ is a data lifetime factor
  • the reliability index will be zero for a channel which is considered to be occupied and will approach unity for a channel which has been unoccupied for an extended period, the rate of transition being determined by the weighting factor ⁇ *.
  • « is a time constant which can be set to change the time that a channel must remain unoccupied to be considered as reliable.
  • the data lifetime factor ⁇ sets the relative weight given to data collected during a recent radar operation compared to an earlier operation and will be a function of time.
  • the radar tasking system determines the optimum operating frequency for the ionospheric conditions and the desired task. Suitable channels are selected from the list determined by the clear channel method and a passive radar is used to evaluate each of the possible channels and to select the most appropriate channel.
  • a frequency surveillance apparatus consisting of a plurality of omnidirectional antennas, a plurality of directional antennas, a reference noise source for providing a signal for calibration, a radio frequency receiver input unit for selecting input from an appropriate antenna, a filter unit to reduce the effects of radio frequency interference, a receiver unit for tuning across the frequency band, an analogue to digital conversion unit and a processor unit to transform and average digitised signals.
  • the apparatus may also have a local oscillator unit which supplies a signal to the receiver for use in deramping the received signal.
  • the reference noise source provides a calibration signal of -170 dBW/Hz.
  • FIG. 1 is a schematic view of a surveillance system
  • FIG.2 is a flow chart of the method of selecting an operating channel
  • FIG.3 is an example of one output of the method.
  • FIG.4 shows a hypothetical graph of the variation of a reliability index with time.
  • the surveillance system is shown in FIG. 1 and consists of a receiver input unit which is able to select an input from any one of eight beams via a beam select unit, from either of two omnidirectional antennas, a reference noise source or a diagnostic test signal generator.
  • the receiver input unit is connected via suitable filters to a single receiver. The method only utilizes one of the omnidirectional antennas and the reference noise source for calibration.
  • the receiver has a bandwidth of 20 kHz and the output is digitised at a sampling rate of 51.2 kHz. Data is acquired over an interval of 5 ms and subjected to spectral analysis, leading to a fundamental frequency resolution of 200 Hz.
  • the gain and frequency of the receiver are under direct computer control and the entire data acquisition process is coded in such a manner that it maximises the effective rate at which data can be acquired.
  • noise signal is injected into the receiver at a known level (-170 dBW/Hz) at the beginning of each set of observations.
  • Noise signal samples are acquired over a 5 msec interval as above and a fast Fourier transform is used to transform the data to a power spectrum. To remove the effects of passband fluctuations this process is repeated a number of times and the average is taken.
  • the resultant power spectrum is an absolute calibration of the response characteristics of the receiver system and is therefore used to scale all subsequent spectral estimates.
  • FIG. 2 Signal levels are measured in all 2 kHz channels by stepping the receiver in 20 kHz steps across the spectrum with the receiver connected to an omnidirectional antenna.
  • Data is acquired for 5 msec in each 20 kHz band, converted to digital form and transformed using a fast Fourier transform to give power at 200 Hz resolution.
  • Ten adjacent 200 Hz spectral estimates are averaged to provide power estimates at 2 kHz resolution in order to reduce variance.
  • Ten scans are made across the HF spectrum from 4 to 30 MHz with all 130000 spectral estimates stored in a multiport memory. The 10 scans for each 20 kHz step are examined in order to identify any scans which have been effected by impulsive noise and these are rejected. The remaining scans are averaged in order to further reduce the variance in the estimates.
  • FIG. 3 shows a typical signal level display measured over the 11 to 12 MHz band. It is clear from the display those channels that are occupied and those that are clear.
  • a threshold is applied to the data to classify each channel as occupied or unoccupied and the appropriate occupancy factor is associated with each channel.
  • a reliability index is calculated for each channel. Channels with the highest reliability index are checked against the reject frequency list and if not rejected are chosen for operation since they are known to have been unoccupied for an extended period of time.
  • the temporal behaviour of the reliability index is shown in FIG. 4.
  • the horizontal axis 1 represents time and the vertical axis 2 represents Rj which varies between zero when the channel is occupied 3 and one.
  • the reliability index takes on a non ⁇ zero value.

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Signal Processing (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

Méthode de sélection de canaux appropriés pour exploitation dans une bande de fréquence donnée, comprenant des étapes consistant à obtenir une occupation de canal en temps réel d'un système de surveillance de fréquences, appliquer un seuil pour déterminer les canaux occupés, définir un indice de fiabilité pour chaque canal, établir une liste de canaux disponibles, trier et choisir des canaux disponibles à partir de la liste des canaux disponibles sur la base des impératifs d'exploitation, évaluer les canaux sélectionnés afin de déterminer le meilleur canal à utiliser et, enfin utiliser le canal déterminé. L'indice de fiabilité est défini par la formule Rj = [νCj + Δ(1-ν)Cj-1]Cj, dans laquelle Cj est un facteur d'occupation ayant soit la valeur 0 pour un canal occupé, soit la valeur 1 pour un canal inoccupé, l'≡ est un facteur de pondération et Δ est un facteur de durée de vie de donnée.
PCT/AU1992/000201 1991-05-02 1992-05-01 Selection de canaux operationnels WO1992019982A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AUPK5955 1991-05-02
AUPK5952 1991-05-02
AUPK595591 1991-05-02
AUPK595291 1991-05-02

Publications (1)

Publication Number Publication Date
WO1992019982A1 true WO1992019982A1 (fr) 1992-11-12

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996033560A1 (fr) * 1995-04-21 1996-10-24 Italtel S.P.A. Procede et systeme permettant de determiner le parametre pscn en partant du parametre mfn dans un systeme de telephone sans fil dect
WO1997022223A1 (fr) * 1995-12-11 1997-06-19 Telefonaktiebolaget Lm Ericsson (Publ) Programme de balayage de canaux pour systemes et procedes de mesure d'intensite de signaux
WO2000060373A1 (fr) * 1999-03-24 2000-10-12 Raytheon Company Circuit d'echantillonnage de donnees polyvalent
WO2004107792A3 (fr) * 2003-05-28 2005-05-06 Lyrtech Inc Station de base mobile flexible
WO2009130361A1 (fr) * 2008-04-23 2009-10-29 Elektrobit Wireless Communications Oy Surveillance de canaux
CN102227098A (zh) * 2011-06-21 2011-10-26 山东大学 一种多模mimo-scfde自适应传输系统频域承载点选取方法
US8107955B2 (en) 2008-07-18 2012-01-31 Research In Motion Limited Apparatus and method for performing network scanning using black-list network information
US8249591B2 (en) 2009-01-21 2012-08-21 Research In Motion Limited Method and device for obtaining candidate information
US8311576B2 (en) 2009-01-30 2012-11-13 Research In Motion Limited Method and apparatus for network scanning based on neighbor information
EP2139275A3 (fr) * 2008-06-25 2014-01-15 Honeywell International Inc. Système et procédé pour prévenir déterministiquement et dynamiquement l'interférence du fonctionnement d'un équipement radio de sauvegarde des personnes
US8639394B2 (en) 2008-12-01 2014-01-28 Lockheed Martin Corporation Dynamic optical countermeasures for ground level threats to an aircraft
US9008594B2 (en) 2010-11-30 2015-04-14 Thales Method and system of adaptive communication in the HF band
US9103628B1 (en) 2013-03-14 2015-08-11 Lockheed Martin Corporation System, method, and computer program product for hostile fire strike indication
US9146251B2 (en) 2013-03-14 2015-09-29 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9196041B2 (en) 2013-03-14 2015-11-24 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9632168B2 (en) 2012-06-19 2017-04-25 Lockheed Martin Corporation Visual disruption system, method, and computer program product
US9714815B2 (en) 2012-06-19 2017-07-25 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof

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Cited By (33)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996033560A1 (fr) * 1995-04-21 1996-10-24 Italtel S.P.A. Procede et systeme permettant de determiner le parametre pscn en partant du parametre mfn dans un systeme de telephone sans fil dect
WO1997022223A1 (fr) * 1995-12-11 1997-06-19 Telefonaktiebolaget Lm Ericsson (Publ) Programme de balayage de canaux pour systemes et procedes de mesure d'intensite de signaux
US5822686A (en) * 1995-12-11 1998-10-13 Telefonaktiebolaget Lm Ericsson Channel scanning scheme for signal strength measurement systems and methods
WO2000060373A1 (fr) * 1999-03-24 2000-10-12 Raytheon Company Circuit d'echantillonnage de donnees polyvalent
WO2004107792A3 (fr) * 2003-05-28 2005-05-06 Lyrtech Inc Station de base mobile flexible
US8219031B2 (en) 2008-04-23 2012-07-10 Elektrobit Wireless Communications Oy Monitoring channels
WO2009130361A1 (fr) * 2008-04-23 2009-10-29 Elektrobit Wireless Communications Oy Surveillance de canaux
EP2139275A3 (fr) * 2008-06-25 2014-01-15 Honeywell International Inc. Système et procédé pour prévenir déterministiquement et dynamiquement l'interférence du fonctionnement d'un équipement radio de sauvegarde des personnes
US8725144B2 (en) 2008-07-18 2014-05-13 Blackberry Limited Apparatus and method for performing network scanning using black-list network information
US8107955B2 (en) 2008-07-18 2012-01-31 Research In Motion Limited Apparatus and method for performing network scanning using black-list network information
US8639394B2 (en) 2008-12-01 2014-01-28 Lockheed Martin Corporation Dynamic optical countermeasures for ground level threats to an aircraft
US8249591B2 (en) 2009-01-21 2012-08-21 Research In Motion Limited Method and device for obtaining candidate information
US8600381B2 (en) 2009-01-21 2013-12-03 Blackberry Limited Method and device for obtaining candidate information
US9060317B2 (en) 2009-01-21 2015-06-16 Blackberry Limited Method and device for obtaining candidate information
US8311576B2 (en) 2009-01-30 2012-11-13 Research In Motion Limited Method and apparatus for network scanning based on neighbor information
US8560008B2 (en) 2009-01-30 2013-10-15 Blackberry Limited Method and apparatus for network scanning based on neighbor information
US9008594B2 (en) 2010-11-30 2015-04-14 Thales Method and system of adaptive communication in the HF band
CN102227098B (zh) * 2011-06-21 2014-02-26 山东大学 一种多模mimo-scfde自适应传输系统频域承载点选取方法
CN102227098A (zh) * 2011-06-21 2011-10-26 山东大学 一种多模mimo-scfde自适应传输系统频域承载点选取方法
US9719757B2 (en) 2012-06-19 2017-08-01 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof
US9714815B2 (en) 2012-06-19 2017-07-25 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof
US10156429B2 (en) 2012-06-19 2018-12-18 Lockheed Martin Corporation Visual disruption network, and system, method, and computer program product thereof
US10151567B2 (en) 2012-06-19 2018-12-11 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof
US10082369B2 (en) 2012-06-19 2018-09-25 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof
US9632168B2 (en) 2012-06-19 2017-04-25 Lockheed Martin Corporation Visual disruption system, method, and computer program product
US9719758B2 (en) 2012-06-19 2017-08-01 Lockheed Martin Corporation Visual disruption network and system, method, and computer program product thereof
US9569849B2 (en) 2013-03-14 2017-02-14 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9103628B1 (en) 2013-03-14 2015-08-11 Lockheed Martin Corporation System, method, and computer program product for hostile fire strike indication
US9658108B2 (en) 2013-03-14 2017-05-23 Lockheed Martin Corporation System, method, and computer program product for hostile fire strike indication
US9830695B2 (en) 2013-03-14 2017-11-28 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9146251B2 (en) 2013-03-14 2015-09-29 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9360370B2 (en) 2013-03-14 2016-06-07 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire
US9196041B2 (en) 2013-03-14 2015-11-24 Lockheed Martin Corporation System, method, and computer program product for indicating hostile fire

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