How hard is to build a processor?
in [Embedded]
|
Prev: LCD interfaces
Next: warentest berufsunfähigkeitsversicherung, berufsunfähigkeitsversicherungen vergleich, privathaftpflicht versicherung, volksfürsorge, kündigung berufsunfähigkeitsversicherung,
From: -jg on 9 Mar 2010 16:17 On Mar 10, 6:20 am, D Yuniskis <not.going.to...(a)seen.com> wrote: > Jasen Betts wrote: > > Given lattitude and longitude (or equivalent) and sufficiently good > > instruments, and the right data and skills, yes. > > So, a *device* that watched these things could deduce date/time (?) > How much more would it have to do to deduce location (or, at least, > latitude)? Probably just watch for a longer period of time? The fish-hook here is in the careful wording of "and sufficiently good instruments, and the right data and skills, yes" So a smarter question, could be what is practical ? - and using what measurement systems ? I found this revealing page, which has real datapoints, and a practical location (ie less than ideal) http://www.austintek.com/astro/analemma/analemma.html Most revealing are the nice dots-on-the-door http://www.austintek.com/astro/analemma/images/4215.door_from_inside_rotate..jpg and the red arcs, are snapshots of the actual path, ~4wks - note they include a dot on alternating sides of the analemma, as the 12 arcs interlace. This site below shows the analemma actually moves yr-yr, so that's more data to track ;) http://myweb.tiscali.co.uk/moonkmft/Articles/EquationOfTime.html -jg
From: D Yuniskis on 9 Mar 2010 16:38 Hi Walter, Walter Banks wrote: > I saw a sundial on a beach near Kobe Japan that had elaborate > error correcting instructions that was probably good to a second > after ten minutes of calculations. There were a lot of factors involved > it accounted for earths orbital period I always thought a cool hack would be a motorized sundial. (i.e., the motorization being a cleverly hidden aspect) E.g., with nice, evenly spaced markings -- and a motor to rotate the whole assembly such that the shadow fell "where it should" (on this nicely marked indicator). It;s the sort of thing that would elicit comment *only* from someone who *knew* it was "quite impossible" to work as it *suggests* it works... (obviously, I like things that mess with people's heads :> )
From: Paul Keinanen on 9 Mar 2010 23:00 On Tue, 09 Mar 2010 10:20:08 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Jasen Betts wrote: >>> So (thinking in terms of a *truly* unique hack), if you *watched* >>> the motion over the course of a particular day (e.g., 'yesterday'), >>> could you *uniquely* determine that day? >> >> Given lattitude and longitude (or equivalent) and sufficiently good >> instruments, and the right data and skills, yes. > >So, a *device* that watched these things could deduce date/time (?) >How much more would it have to do to deduce location (or, at least, >latitude)? Probably just watch for a longer period of time? By observing when the sum passes the meridian, one cloud free week in the spring and one in the autumn should give a quite good resolution for the latitude, provided that some internal time reference is capable of measuring the number of days between the measuring periods with at least +/-12 hour accuracy. During one week long period the sun moves south and on he other it moves north. Of course, there is the north/south hemisphere ambiguity, but with additional sensors to the left and right of the meridian line should help solve this ambiguity. After all, in order to detect meridian passing you would have to align the device towards true north. A camera with at least 150 degree field of view pointing directly upwards towards zenith, should be able to detect the orientation, latitude, date and local solar time within a year of observations.
From: Joe Pfeiffer on 10 Mar 2010 00:29 Paul Keinanen <keinanen(a)sci.fi> writes: > On Tue, 09 Mar 2010 10:20:08 -0700, D Yuniskis > <not.going.to.be(a)seen.com> wrote: > >>Jasen Betts wrote: >>>> So (thinking in terms of a *truly* unique hack), if you *watched* >>>> the motion over the course of a particular day (e.g., 'yesterday'), >>>> could you *uniquely* determine that day? >>> >>> Given lattitude and longitude (or equivalent) and sufficiently good >>> instruments, and the right data and skills, yes. >> >>So, a *device* that watched these things could deduce date/time (?) >>How much more would it have to do to deduce location (or, at least, >>latitude)? Probably just watch for a longer period of time? > > By observing when the sum passes the meridian, one cloud free week in > the spring and one in the autumn should give a quite good resolution > for the latitude, provided that some internal time reference is > capable of measuring the number of days between the measuring periods > with at least +/-12 hour accuracy. During one week long period the sun > moves south and on he other it moves north. > > Of course, there is the north/south hemisphere ambiguity, but with > additional sensors to the left and right of the meridian line should > help solve this ambiguity. After all, in order to detect meridian > passing you would have to align the device towards true north. > > A camera with at least 150 degree field of view pointing directly > upwards towards zenith, should be able to detect the orientation, > latitude, date and local solar time within a year of observations. > The hardware for this is in the current issue of Circuit Cellar. Different programming needed.... -- As we enjoy great advantages from the inventions of others, we should be glad of an opportunity to serve others by any invention of ours; and this we should do freely and generously. (Benjamin Franklin)
From: Jasen Betts on 10 Mar 2010 05:57
On 2010-03-09, D Yuniskis <not.going.to.be(a)seen.com> wrote: > Jasen Betts wrote: >>> So (thinking in terms of a *truly* unique hack), if you *watched* >>> the motion over the course of a particular day (e.g., 'yesterday'), >>> could you *uniquely* determine that day? >> >> Given lattitude and longitude (or equivalent) and sufficiently good >> instruments, and the right data and skills, yes. > > So, a *device* that watched these things could deduce date/time (?) > How much more would it have to do to deduce location (or, at least, > latitude)? Probably just watch for a longer period of time? 6 months would be sufficient, probably shorter periods too. the earths's axial wobble, and orbital precession, are probably going to make it impossible do it in less than a week. OTOH if you can see the stars and planets at night that would help a lot... --- news://freenews.netfront.net/ - complaints: news(a)netfront.net --- |