The Hellenic Navy (HN) (Greek: Πολεμικό Ναυτικό, Polemikó Naftikó, abbreviated ΠΝ) is the naval force of Greece, part of the Greek Armed Forces. The modern Greek navy has its roots in the naval forces of various Aegean Islands, which fought in the Greek War of Independence. During the periods of monarchy (1833–1924 and 1936–1973) it was known as the Royal Navy (Βασιλικόν Ναυτικόν, Vasilikón Naftikón, abbreviated ΒΝ).The total displacement of all the navy's vessels is approximately 150,000 tons.The motto of the Hellenic Navy is "Μέγα το της Θαλάσσης Κράτος" from Thucydides' account of Pericles' oration on the eve of the Peloponnesian War. This has been roughly translated as "Great is the country that controls the sea". The Hellenic Navy's emblem consists of an anchor in front of a crossed Christian cross and trident, with the cross symbolizing Greek Orthodoxy, and the trident symbolizing Poseidon, the god of the sea in Greek mythology. Pericles' words are written across the top of the emblem. "The navy, as it represents a necessary weapon for Greece, should only be created for war and aim to victory."...............The Hellenic Merchant Marine refers to the Merchant Marine of Greece, engaged in commerce and transportation of goods and services universally. It consists of the merchant vessels owned by Greek civilians, flying either the Greek flag or a flag of convenience. Greece is a maritime nation by tradition, as shipping is arguably the oldest form of occupation of the Greeks and a key element of Greek economic activity since the ancient times. Nowadays, Greece has the largest merchant fleet in the world, which is the second largest contributor to the national economy after tourism and forms the backbone of world shipping. The Greek fleet flies a variety of flags, however some Greek shipowners gradually return to Greece following the changes to the legislative framework governing their operations and the improvement of infrastructure.Blogger Tips and Tricks
This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς....This is a bilingual blog in English and / or Greek and you can translate any post to any language by pressing on the appropriate flag....Note that there is provided below a scrolling text with the 30 recent posts...Αυτό είναι ένα δίγλωσσο blog στα Αγγλικά η/και στα Ελληνικά και μπορείτε να μεταφράσετε οποιοδήποτε ποστ σε οποιαδήποτε γλώσσα κάνοντας κλικ στη σχετική σημαία. Σημειωτέον ότι παρακάτω παρέχεται και ένα κινούμενο κείμενο με τα 30 πρόσφατα ποστς.........

Thursday, April 10, 2014

'Russian GPS' failure.[ 3958 ]

Map illustrates 'Russian GPS' failure

Glonass receiver A GLONASS receiver (red dot) on England's east coast gave position fixes in the North Sea (blue triangles)
The General Lighthouse Authorities of the UK and Ireland have issued a map illustrating the effects of last week's failure in "Russia's GPS" system.
Satellites of the GLONASS network experienced a half-day outage when bad data was uploaded to spacecraft.
The GLA map shows a GLONASS receiver at Harwich giving corrupted position fixes that were off by more than 50km.
The Authorities say the 2 April event is a timely reminder that alternatives to satellite navigation are essential.
The GLA themselves are supporting a system in the UK and Ireland called eLoran, which transmits long-range position, navigation and timing signals from a ground-based radio network.
Its primary use is for ships and others in the maritime sector, but there is a feeling also that eLoran could provide a robust back-up for GPS, GLONASS, and Galileo when it arrives.
Galileo is the European sat-nav system, which is in the process of roll-out.
A Royal Academy of Engineering (RAEng) report in 2011 found that the UK was becoming dangerously over-reliant on what are termed Global Navigation Satellite Systems (GNSS).
Use of space-borne positioning and timing data is now widespread, in everything from freight movement to synchronisation of computer networks.
The academy found that too few of these applications were able to lean on alternatives should the primary sat-nav signals go down.
Receivers needed to be capable of switching seamlessly between a variety of data sources, the RAEng expert panel argued.
"GLONASS is used by quite a lot of people, actually; the iPhone-5 can pick up its signals," explained Prof David Last, a consultant engineer and past president of the Royal Institute of Navigation.
"What we saw last week was many people being affected by the GLONASS failure even with receivers that were also picking up GPS.
"The lesson that comes out of this is not just that satellite-navigation systems are vulnerable, but that you don't get a protection by simply plugging in a second satellite-navigation system.
"You need something that is different and doesn't share common modes of failure," he told BBC News.

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