any help chaps
by the way its an aftermarket sat-nav not built in
speedo or sat-nav
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speedo or sat-nav
which is the most accurate the speedo or the sat-nav??? while i know about the speedo under-reading by 4mph at 30 i dont know how accurate the sat-nav is does anyone know if they are bang on or not(just so i know cos i never checked the speedo on me van an there's a LOT of cameras where i deliver) i would hate to think the sat-nav was accurate and get another 3 points
any help chaps
by the way its an aftermarket sat-nav not built in
any help chaps
by the way its an aftermarket sat-nav not built in
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nick
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depends, most sat nav RECIEVERS are accurate toabout 0.04 MPH (if i remeber correctly) - but then you may have a delay in processing time (i.e how long the computer takes to get the info from the sat nav, convert it, and display it on the screen) - so you could look at a lag of up to 0.5 to 1sec.. again, it may not seem a lot, but that time delay could be your reaction time to break for a camera (not that you'd be going fast anyways! 
)..
Speedos are generally out by no more than a few mph. thats why speedcameras dont go off at bang on 30 (or 40 50 etc.)
Generallym your allowed a small "compensation" figure for inaccurate speedos, roughly 10% of your speed, plus 2mph, so a 30mph camera should go off untill 35 (10% 30 = 3 + 2)..
Remeber tho, ur speedo is calibrated when it leaves the factory for the wheels on the car at the time. SO bigger or smaller wheels screws it up a bit..
Nick
)..Speedos are generally out by no more than a few mph. thats why speedcameras dont go off at bang on 30 (or 40 50 etc.)
Generallym your allowed a small "compensation" figure for inaccurate speedos, roughly 10% of your speed, plus 2mph, so a 30mph camera should go off untill 35 (10% 30 = 3 + 2)..
Remeber tho, ur speedo is calibrated when it leaves the factory for the wheels on the car at the time. SO bigger or smaller wheels screws it up a bit..
Nick
Thanks,
Nick
Nick
DaiRees wrote:I got the "premium" standard fit system in mine, 10 speakers, changer, JBL amp. I'm quite happy with it for listening to the radio / CDs or my "teach yourself Welsh" stuff on the way to work
Speedo isn't as accurate, but it gives a truer reading. Weird? Let me explain.
As you drive you are travelling across the outside surface of a sphere, so your speedo is measuring your actual speed along the surface of a curve, somewhat akin to an aircrafts airspeed in nots being the measurement of the crafts sopeed in relation to the air. Most modern electroic speedos are designed to read a bit high for licence proteting purposes (and to prevent the makers geting sued as we all lose our licences), but once you subtract the extra 3 mph (or whatever) are actually pretty accurate.
Sat nav, on the other hand, is not measuring your speed along the curved surcae, but is measuring your speed along 2 points in 3d space, which are constantly recalculated as you travel. the difference is something like 4 or 5 metres a mile, so it's not a big difference, but allowing for the built in error the speedo in your car is measuring a truer reflection of the ground your vehicle has covered in relation to the time elapsed.
As you drive you are travelling across the outside surface of a sphere, so your speedo is measuring your actual speed along the surface of a curve, somewhat akin to an aircrafts airspeed in nots being the measurement of the crafts sopeed in relation to the air. Most modern electroic speedos are designed to read a bit high for licence proteting purposes (and to prevent the makers geting sued as we all lose our licences), but once you subtract the extra 3 mph (or whatever) are actually pretty accurate.
Sat nav, on the other hand, is not measuring your speed along the curved surcae, but is measuring your speed along 2 points in 3d space, which are constantly recalculated as you travel. the difference is something like 4 or 5 metres a mile, so it's not a big difference, but allowing for the built in error the speedo in your car is measuring a truer reflection of the ground your vehicle has covered in relation to the time elapsed.