Steve Allen wrote on 2003-12-23 19:46 UTC: > Of course no agreement can stop some entity from flying a jamming > rig for both systems over particular theatres of interest.
Robustness against U.S. "navigation warfare" was one of the main funding rationales for Galileo. The U.S. are unlikely to jam easily their own military (M-code) navigation signal. As I understood it, the original plan for Galileo was to put its own Public Regulated Signal (PRS) into the spectrum in a way such that the U.S. cannot jam it without jamming their own M-code as well. This improves robustness against adverse US DoD capabilities and also simplifies tremendously the design of receivers that can listen to both GPS and Galileo (which I expect will be all new receivers as soon as Galileo is up and running). Status of Galileo Frequency and Signal Design: http://europa.eu.int/comm/dgs/energy_transport/galileo/doc/galileo_stf_ion2002.pdf http://www.gpsworld.com/gpsworld/article/articleDetail.jsp?id=61244 Status of new GPS M-code design: http://www.mitre.org/work/tech_papers/tech_papers_00/ betz_overview/betz_overview.pdf DoD versus EU battle: http://www.globalsecurity.org/org/news/2002/020514-gps.htm >From a recent local press review: ------------------------------------------------------------------------- EU and US fail to agree on interoperability of satellite navigation systems Discussions between the European Union and the US in Washington concerning the interoperability of the EU's proposed Galileo satellite navigation system and America's existing GPS service have ended without agreement, according to reports in the New Scientist. The sticking point is said to be the standard signal that the EU would like to use for Galileo. Europe's preferred option, known as binary offset carrier (BOC) 1.5, 1.5, would give users of Galileo the most accurate information possible, but the US argues that this would interfere with the GPS system's proposed new encrypted military signal. The US intends to introduce the new signal, known as the M-code, in 2012. During a military conflict, the US would attempt to jam all civilian satellite systems so as not to allow enemies to use satellite navigation. But jamming Galileo's BOC 1.5, 1.5 signal, argue US officials, would also disrupt its own M-code. The US proposes that Galileo uses an alternative signal, such as BOC 1.1, which does not overlap the M-code signal, but the EU is concerned that this will result in a less accurate system for commercial users of Galileo. Officials from the EU and the US will meet later in February to try to resolve the issue. For further information on Galileo, please consult the following web address: http://europa.eu.int/comm/dgs/energy_transport/galileo/index_en.htm ------------------------------------------------------------------------- The use of the word "interoperability" for the feature that the operator of one system can jam the other one without affecting its own has a neat Orwellian ring to it. >From what I hear behind the scenes, plans for Galileo are now to make the transmitter and receiver designs highly flexible, such that code rates, spreading sequences, BOC offsets, and perhaps even carrier center frequencies can be reprogrammed smoothly on-the-fly while the system is in operation, to be able to adapt to adverse actions and the current political climate. Apart from moving the center frequency around significantly (which clearly affects the design of the RF hardware very much on each end), most of the remaining DSP and PLL parameters can today quite easily be made reconfigurable in software at little extra cost. We may consider our deliberations on leap second rather abstract and academic here, but outside the ivory tower, the reliable distribution of nanosecond-accuracy timing signals has meanwhile become not only a military concern, but also the topic of a serious turf fight between the Pentagon and the EU Commission. Is seems the Temporal Cold War has begun ... Markus -- Markus Kuhn, Computer Lab, Univ of Cambridge, GB http://www.cl.cam.ac.uk/~mgk25/ | __oo_O..O_oo__