Re: How do you measure SPEED on skates?

On Mon, 01 Dec 2003 02:49:37 GMT, FNGuy <[EMAIL PROTECTED]>
wrote:

>> Several devices use GPS for measuring speed and distance. Timex has
>> such a device; I believe that Garmin came out with a
>> speed-and-distance-only device this year.
>
>Others in this thread have pointed out the problematic performance of the 
>Garmin and similar units.

There were clearly some mis-reads with the generalized Garmin GPS
unit. I haven't heard of such things happening with the Timex box. And
I would guess that the speed-and-distance-only Garmin box would also
work within a few percentage points of correct. That doesn't fit my
definition of "problematic".

>> As you said in the first message of this thread, you could have a
>> widget that kicked out ultrasonic pulses and measured speed/distance
>> based on the doppler shift of the echoes. That has been done; someone
>> made a widget around 1988 for skiers. I just saw the description in
>> Outside magazine; I never saw any production units.
>
>I seem to remember some hobbyist magazine that did the same thing with the 
>sonar unit from the old Polaroid SX-70 cameras.

I don't know if you're in the US -- Outside isn't a hobbyist magazine.
It was clearly a professional unit, not a kit. But it had the fatal
flaw that the only way to know your instantaneous speed was to look
down at the device. Unfortunately, that's the wrong place for your
attention to be when at maximum speed.

>>... After all, the existence
>> of a patent doesn't imply the existence of a market for the device.
>
>That's why I said "LOL!!"  There's nothing there that's really new--just 
>where it's applied.

...or applied poorly. About 5 years ago, some spammer tried to foist
off hand brakes for inlines on this very newsgroup.

>  Late model motor vehicles have rotation-rate sensing 
>going on all over--crankshaft, brake rotors, etc... (I don't get why so 
>many still have a mechanical speedo cable though...?)

Just like evolution in nature, evolution in engineering design often
stops when something works well enough.

There was recently an article in the Wall Street Journal about a
gentleman who patented a far better mechanism for opening and closing
power windows. His device has about half the number of moving parts of
the current designs and is far less prone to failure. But, IIRC, his
device will only get about 20% of the market -- for now.

--phil