The patent's assignee for patent number 8654003 is
News editors obtained the following quote from the background information supplied by the inventors: "Systems for interrogating and identifying an object are equipped with an antenna having a given angle aperture making it possible to interrogate in a direction (emit a directional beam) and in a controlled angle sector. These interrogator or interrogator/responder systems on account of the directivity of their antenna do not generally make it possible to carry out passive listening. Indeed, the angle sector over which they operate is limited. Moreover, the low emission rate of unsolicited responders (better known as 'squitters' (.about.1 Hz)), allied with the use of traditional interrogator/responder or IFF (Identification Friend and Foe) antennas (sum pathway .SIGMA./difference pathway .DELTA. with an aperture of .about.10.degree.) implies that, to chart the aerial situation, an IFF interrogator customarily used in the prior art must perform numerous antenna revolutions. The response of the 'squitter' will be received only when it is situated in a precise angle sector and the time for observing its response will therefore be limited (duration for which the response is observed).
"Current antenna systems (.SIGMA./.DELTA. antenna patterns necessary for the sidelobe suppression processing, RSLS for short) used by IFF interrogators are therefore completely unsuitable for the squitters' listening function which requires an omnidirectional antenna.
"Various solutions are currently known in the prior art. Various examples are given in relation to FIGS. 1, 2 and 3 which comprise in a common manner a digital core 1, a signal processing device, having notably the function of eliminating the responses of the antenna sidelobes or RSLS, for decoding the information of the signal received by the system, a reception pathway 4 corresponding to the sum pattern of the antenna, a reception pathway 5 corresponding to the difference pattern of the antenna 6 with which the responder interrogator is equipped.
"A first solution for responding to the passive listening requirement is illustrated in FIG. 1. It consists in adding a reception pathway 7 and an omnidirectional antenna 8 dedicated to the listening function, as well as a device 3 for processing and decoding the information received on this extra pathway. The addition of such an antenna and of a dedicated reception pathway gives rise to the presence of a dedicated digital processing pathway. These additions engender problems of complexity of installation, costs (consumption of the FPGA digital processing devices, etc.)
"A second solution illustrated in FIG. 2 relies on the addition of a switching device 9 making it possible to use an omnidirectional antenna 10 on the sum reception pathway of the antenna customarily used. Such a device gives rise to the addition of an omnidirectional antenna and an increase in the complexity of the radiofrequency function and of installing the assembly.
"A third solution known to the Applicant is illustrated in FIG. 3. It consists in adding an extra processing chain 11 on the pathway of the sum pattern or .DELTA.. In the example of FIG. 3, the addition is done on the difference reception pathway or .DELTA.. This leads to an increase in the complexity (with 2 decoding pathways) of the extra processing module on the pathway as well as limitations related to the 'blind' zone on the axis of the antenna .DELTA.."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventors' summary information for this patent: "The system according to the invention relies on a new approach which to consists in creating an omnidirectional pseudo-antenna on the basis of a directional antenna (having a given aperture a for the given antenna pattern) and of an appropriate processing chain making it possible to use the system in a first interrogator mode or in a second passive listening mode. In the case where the system is an IFF system, by using the radiation patterns of the .SIGMA. and .DELTA. antennas of IFF interrogators (radiation pattern of the .DELTA. antenna overlapping that of the .SIGMA. antenna outside of the main lobe of the antenna .SIGMA.) and by means of a processing performed in the interrogator, the invention makes it possible to obtain an effective listening station (360.degree. listening instead of the .about.8.degree. of aperture of a standard system).
"The object of the invention relates to a system making it possible to operate in an interrogator mode and/or in a passive listening mode characterized in that it comprises in combination at least the following elements: an antenna having a given aperture sector .alpha., a control means making it possible to toggle the system into a first interrogator operating mode using a first given angle sector or into a second passive listening operating mode using a second angle sector of greater value than the first, means making it possible to add together the signals received on the sum pathway and on the difference pathway of the antenna in the case of the passive listening operating mode.
"The system and the method according to the invention offer notably the following advantages: of transforming at lesser cost a Mode S IFF interrogator into an ADS-B listening station without any modification of the installation (addition of omni antenna, RF switching, reception pathway) or hardware modification of the interrogator, of carrying out the new function with a simple FPGA modification (addition of 2 buses and injection of the resulting signal into the normal processing chain), of adding configurable processings making it possible to adjust (time domain and amplitude) the pathways, of decreasing the acquisition time of passive response devices or 'squitters' of an interrogator devoid of any omnidirectional antenna for example, from a few tens of seconds to a few seconds.
"It also relates to a method for allowing a device provided with at least one antenna having a given sector to be made to operate in interrogator mode and/or in passive listening mode characterized in that it comprises at least the following steps:
"select the interrogator mode or the passive listening mode,
"if the mode selected is the interrogator mode, then transmit the signals received on the sum pathway of the antenna and on the difference pathway to a processing chain suitable for processing the signals received, if the mode selected is the passive listening mode, then transmit the signals received on the sum pathway of the antenna and on the difference pathway to an adder."
For additional information on this patent, see: Soula, Stephane; Provost, Claude. Omnidirectional Pseudo-Antenna for Interrogator Or System Allowing the Interrogation Response And/Or Passive Listening Functions. U.S. Patent Number 8654003, filed
Keywords for this news article include: Thales, Electronics, Omnidirectional Antenna.
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