doc.fixit Posted April 9, 2014 Share Posted April 9, 2014 blimey that's deep. Link to comment Share on other sites More sharing options...
Albert Tatlock Posted April 9, 2014 Share Posted April 9, 2014 Dig your cossy and snorkel out, and let's get you out there immediately! On flat ground (2D) you generally need 3 receivers (or one mobile receiver moving to 3 separate points, as in Radio Direction finding vans etc.) to work out accurately where a transmitter is located. Finding this signal is the equivalent of finding someone on the ground transmitting in potentially mountainous terrain when the radio direction finding equipment is in the air (there is length, breadth and depth - hence 3D). It is further complicated as the transmit frequency appears to change slightly, so you cannot judge accurate distance between 3 or 4 consecutive pings happening every 1 second (this is because transmissions go through several water layers affected by temp differences, and affect the received frequency, and thus the perceived distance) which also brings in an unreliable 4th Dimension (time) and so distance inferred between pings is not accurate. Light and radio waves in free space travel at a fixed speed (light speed), but it is not the same for water, especially deep water with several layers, and just like radio signals can bounce off the ionosphere (change in air layer) to transmit, underwater radio signals do the same at changes in the water layers. In other words 2 ships could be 1 mile away from the transmitter, with the transmitter sat exactly between them, and both would say it was in completely different places because of what they receive. 5 ships all 1 mile away would get different readings too. There will no doubt be someone collating and modelling the results, also measuring the temperature layers by other means, so that they can produce a much more accurate model and thus analyse the water effects at the time of the readings and take them into account in the model and adjust the readings they have picked up accordingly. Link to comment Share on other sites More sharing options...
Monkey boy Posted April 9, 2014 Share Posted April 9, 2014 It amazes me how many people still use feet. I have absolutely no idea why. Link to comment Share on other sites More sharing options...
mojomonkey Posted April 9, 2014 Share Posted April 9, 2014 It amazes me how many people still use feet. I have absolutely no idea why. Without them I would fall over. Link to comment Share on other sites More sharing options...
doc.fixit Posted April 9, 2014 Share Posted April 9, 2014 most people I know use both imperial and metric including me.............................I've even heard folk in the merchants ask for 4mtrs of 2x2 (inches) Link to comment Share on other sites More sharing options...
Lisenchuk Posted April 9, 2014 Share Posted April 9, 2014 I often use imperial and metric on the same project. Sometimes the metric provides better workable divisions,sometimes imperial. Went to school at a time when both systems were taught concurrently. Link to comment Share on other sites More sharing options...
Chinahand Posted April 9, 2014 Share Posted April 9, 2014 Just to add, Mojomonkey's graphic can be found here in bigger and clearer form. Link to comment Share on other sites More sharing options...
Albert Tatlock Posted April 9, 2014 Share Posted April 9, 2014 Mine's 12 inches. But I would never admit to having a 30.48 cm one - sounds like bragging. How would you describe your ruler? Link to comment Share on other sites More sharing options...
Lisenchuk Posted April 9, 2014 Share Posted April 9, 2014 2mm thick. Link to comment Share on other sites More sharing options...
Albert Tatlock Posted April 10, 2014 Share Posted April 10, 2014 From BBC: Missing Malaysia plane: Search area narrows Link to comment Share on other sites More sharing options...
Domino Posted April 10, 2014 Share Posted April 10, 2014 Oh well ... pings ain't what they used to be. Link to comment Share on other sites More sharing options...
Lonan3 Posted April 10, 2014 Share Posted April 10, 2014 2mm thick. mm? They're the little things on the other side of the rule, aren't they? Link to comment Share on other sites More sharing options...
quilp Posted May 1, 2014 Share Posted May 1, 2014 Why has this thread gone off the radar? Took me ages to find it.... Link to comment Share on other sites More sharing options...
Lonan3 Posted May 1, 2014 Share Posted May 1, 2014 The search has been handed over to the Scots - there's a full drinks trolley and it's finders keepers! Link to comment Share on other sites More sharing options...
Nom de plume Posted May 13, 2014 Author Share Posted May 13, 2014 ... and gone. Forever. Link to comment Share on other sites More sharing options...
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