Ok,That's fine,
But everyone neads to learn that GPS can only do 1 thing: Tell you
*where you are*.GPS does not tell you how to get somewhere else.
That's a function of the mapping software on the reciever. And it can be out-of-date, or just wrong.
I say again: you cannot abdicate responsibilty for your route to a GPS device. YOU need to look at it's proposed route and veify that it's reasonable.
With all due respect I have been using a Satnav now for many years. My last two cars and my current car all have it built in. I am well familiar with their foibles. However, getting lost in a totally strange city and having only a limited command of the language left the best option to be the satnav.
None of the satnavs I have used to date have had an easy quick way of showing the route selected prior to departure apart from which it sure as shit isn't going to show me, or tell me, the route is via dirt tracks. I.M.E.they have no topographical detail
The idea of comparing the satnav track with a map when trying to negotiate through a strange city is hilarious.
I.M.E. they are pretty useless at telling one in a meaningful way where one is, the screens are too small and the resolution too poor. An iPhone is superior, assuming one is getting a good signal.
I always have a good Michelin map of the area I will be in. Unfortunately it would be extremely difficult to carry city maps when touring extensively on the continents and anyway there are out of date as soon as they are printed.
I generally only depend on the satnav for the last leg of the journey. City to city is easy. Its finding one's way from or to a particular address in a strange environment is what a satnav is best at ,I.M.H.O..
By the by could you explain how a R.Y.A.day skipper course would have helped my find my way around Ourense, or even how it would help in day to day use of a satnav in a car ? Oh of course, it would help one calculate and apply corrections for variations caused by tide and wind etc.
Right.
Real useful.
Paul Mc Cann
I was driving up the A11 a couple of weeks back. I'd been following a minibus-taxi, going 1 or 2 MPH faster, and had nearly caught up. We both pulled out to pass someone, then he pulled back into the left lane, and I stayed in the right to pass him. I then spotted a tractor ahead. A bit of time-and-distance and I reckoned I'd be next to the taxi just as he got to the tractor - so I slowed down a few MPH to give him room to pass it, which he did.
At this moment the guy who'd been about to pass me on the left at 20MPH faster saw the tractor.
He definitely had ABS :)
Andy
No. Not terribly good in tunnels.
OTOH the technology for an optical mouse seems quite cheap - surely it could be scaled up? And it's pretty dark under a car...
However this might put the cost of the car up by 5 squid and we couldn't have that.
GPS accuracy at car speeds is so good you won't be able to detect the error. Most cars I've checked seem to be 8% over - 3MPH is pretty good. They aren't allowed to be under. I had a car a few years back with a trip computer - that read pretty much bang on, even though the speedo lied. Average speed readout was pretty handy for roadworks!
Andy
Given the choice of buying a load of already out of date maps or following the satnav I will follow the satnav and look at the road signs on the way.
Dark doesn't help, they use a camera and need a LED to provide light. There may not work on all road surfaces, especially when wet.
True if you either vastly over-inflate a tyre or the opposite. But why would anyone (other than you) do so? But in either case, any such error is tiny as regards the speedo reading. But of course you could try driving with flat tyres to prove it yourself.
Why would you need a satnav to work for long without being plugged into the car electrics?
Less confusing for all if you accelerate a few mph in that situation, so you're ahead of the taxi and they can see you're out of the way before you all get to the tractor.
With steel belt radials, can you change the diameter (or should I say circumference) to any degree by under/over inflating?
You can distort the tread somewhat, but the effect on the speedo reading would be negligible. As is the difference between a new and worn out tyre.
Twas during my first (and for that matter, only) "proper job" at GEC Sensors "Electro Optical Surveillance Group" in Basildon.
A bunch of us got involved with it somewhat tangentially, as as a part of a course for new grads they ran. They got groups of us to form virtual "companies" to go through all the engineering stages of developing a product and then marketing it.
They happened to pick this Doppler speed sensor (it was in fact a real product they sold) as the product they wanted built and sold. Since there was not enough time to actually develop it for real, most teams created a fictional product to "develop" with semblances to reality as best they could. We took the alternative approach of having a quiet word with the engineering team that actually developed it for real and lifted copies of the design docs, circuit diagrams, and even CAD drawings for the box etc. We then reverse engineered the basic functionality, and then set about enhancing its spec (just in case any of the other teams had the same idea) and working out all sorts of new clever tricks the software could perform on "our" version.
Finally fed that all back to them over a course of a set of presentations to groups of management who were posing as our potential customers.
(I seem to recall we also worried them at one point by sending out rather too convincing marketing info on our enhanced product to the various managers involved - only we neglected to tell them that it was all part of the exercise!) So various departments were frantically trying to find out who their new competitor was with a better specced product at a lower price! ;-)
Interesting idea - it possibly could. Might have difficulty on reflective road surfaces though.
The level of processing that goes on in a completely optical laser/led mouse is actually quite impressive. They basically do a small reference patch version of "correlation auto tracking" - i.e. recording the scene as seen by a camera at various intervals, and then attempting to match where a section of the previous image has moved to in the next image.
(the same basic idea used in military infra red head up displays for cueing targets, and for laser target designation (and by young randy engineers in a lab to auto track the totty walking about wearing thin summer dresses (translucent to IR!) ;-)
My TomTom is usually pretty good, but there is the occasional section of road that causes it grief. This one, with its elongated roundabout that spans either side of the overpass, in particular:
That seems to be a standard TT feature - you can browse the proposed route as a series of instructions or by map. You can then go and add "vias" or places to avoid and have it recalculate the route (or failing that - just ignore the bits you don't like when actually driving it, and let it re-route on the fly)
Well indeed - if you are talking about in "real time". Obviously if planning one in advance, then you could compare.
You can normally zoom in and out, and get a fairly good feel for where you are on mine...
Quite handy for reminding you which junctions to turn off major roads as well...
It only takes a few mm on the radius to make some measurable difference. The over reading effect of soft tyres is more pronounced than the under read effect of over inflated ones though IME
My Jap spec car which I had chipped to covert from km to miles seems a little closer to reality than some - although it still over reads by a bit - probably about 1 mph at 30, 4 ish at 70.
The tread difference is probably more significant...
Say you have 17" wheels with 225/50s on them. That is 17 * 25.4 + 2 *
225 * 0.5 = 657 mm diameter. Hence rolling radius will be a nominal 2064 mm. At 35 m/sec that equates to 1017 RPM. If you now lose 4mm of tread (i.e. 8mm off the diameter), the wheel RPM will rise to 1030. So a change of a bit over 1%You will probably get a bigger hit changing from driver only, to four passengers and luggage.
Well, its much more useful than say 1 hour... you can plan a two hour journey and know that it will have the juice to go there and back on a charge without needing to plug it into the cigarette lighter socket.
Obviously its not as attractive on a push bike!
Times like that you could do with one of those scrolly message boards in the back of the car... ;-)
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