Es Datarack. Datatrak is a medium-area LF automatic vehicle location (AVL) system operating in the UK, Benelux countries, Germany and Austria. It is operated by Securicor Information Systems in the UK and by Siemens-Datatrak in mainland Europe. It was originally developed to fulfil a need for the monitoring of Securicor's own parcel and security vehicles, however it is now marketed to a number of other customers. The system is a conventional hyperbolic positioning system where a number of stations making up a chain transmit in sequence on a common pair of frequencies in the band 130 to 170 kHz. The receiver calculates it's position and communicates this back to the control centre (Swindon in the UK) by means of a UHF radio system that provides similar coverage to the LF network. The system is enhanced by the provision of Event Activated Tracking (EAT) or 'Trak Bak' as Securicor call the product. This allows a stolen vehicle to be tracked and aprehended. Also, the UHF component may monitor various inputs from the vehicle, providing a telemetry function. There are apparently 14 sites in the UK but their location is unknown. The sequential transmissions are clearly audible at around 145 kHz in the UK, the interesting thing about them is that they 'warble' as if FSK modulated at around 20bps. Using Manchester coding, the transmission would still be usable for positioning as long as the phase were averaged over many symbols. Buscando en listas los vas a encontrar de donde son, si los encuentro lo envio. 73's Claudio
--- El jue 18-jun-09, juan jose <[email protected]> escribió: De: juan jose <[email protected]> Asunto: [ondalarga] sabeis que es esto? [2 Attachments] A: [email protected] Fecha: jueves, 18 junio, 2009, 7:23 am [Attachment(s) from juan jose included below] hola, escuchando por la onda larga me e encontrado con esto, sabeis que es?es en 133,78 y 147,04 khz saludos ____________________________________________________________________________________ ¡Obtén la mejor experiencia en la web! Descarga gratis el nuevo Internet Explorer 8. http://downloads.yahoo.com/ieak8/?l=e1
