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Interference heads-up: receiver techniques for detecting and characterizing RFI [radio-frequency interference] / P. Ward in GPS world, vol 19 n° 6 (June 2008)

Public [article]  inGPS world > vol 19 n° 6 (June 2008) . - pp 64 - 73 Titre : Interference heads-up: receiver techniques for detecting and characterizing RFI [radio-frequency interference] Type de document : Article/Communication Auteurs : P. Ward, Auteur Année de publication : 2008 Article en page(s) : pp 64 - 73 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal [Termes IGN] brouillage [Termes IGN] interférence [Termes IGN] rapport signal sur bruit [Termes IGN] récepteur GNSS Résumé : (Editeur) As we all know, GPS signals are weak. At a receiver's antenna, in the open air, their strength is about-160 dBW or 1 x 10~l6watts. Compare this to a cell-phone signal, which might be 60 dBW or 1 x 10~6 watts, 10 billion times stronger! While code correlation in the receiver lifts the GPS signals above the background noise floor, the signals are still relatively fragile, and building walls and other obstructions can significantly attenuate the received signal power so that they cannot be tracked by a conventional receiver. It is the ratio of the signal power to the noise power per unit band-width that determines the trackability of | the signal. Accordingly, if the receiver's noise floor should increase sufficiently, even in an outdoor environment, the signals may also become untrackable. This can happen when the receiver is subjected to intentional or unintentional radio-frequency interference (RFI) by transmitter operating on or near GPS frequencies. If the interference is strong enough, it can jam the receiver. Although intentional jamming is typically of concern only to military GPS users, unintentional jamming can occur anywhere and any- time and can affect large numbers of users within the range of the jamming transmitter. The jamming incident in San Diego harbor in January 2007, for example, affected all GPS users within a range of about 15 kilometers including a medical services paging network. Such jamming renders a GPS receiver inoperable. But how do users know that their receivers are being jammed and not suffering some other type of malfunction? Clearly it would be advantageous for users to receive a heads-up when jamming signals are present and, if possible, for the receiver to take corrective action automatically. In this month's column, we look at some simple techniques, which can be easily incorporated into the design of a GNSS receiver, to detect, characterize, and actually mitigate RFI. Such receiver enhancements will benefit civilian and military users alike. Copyright Questex Media Group Inc Numéro de notice : A2008-165 Affiliation des auteurs : non IGN Thématique : IMAGERIE/POSITIONNEMENT Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29160 [article]

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