Re: [mowbot] A Lurker Says, "Hello".

robin nospam at
Mon, 23 Sep 1996 21:31:06 +0100

Thomas A Maier <tmaier+ nospam at> said:
> ... The only problem is that
> most 40 KHz ultrasonic transducers have such a long "ringtime" (~1msec)
> that they are blind to anything in the first ~.5 ft (.5msec out and
> .5msec back). I expect that we're going to be closer to the ground
> than that.
Ah, but it doesn't actually matter here where the edge of the pulse
lies, just how strong the echo is. So this shouldn't be an issue.
The Polaroids are no better at short-distance rangefinding, and would
be terrible in this application because they emit a complicated chirp.

> **** ATTENTION - Soapbox Erection Zone ******
Yes, sorry, this might had the makings of a war. But I would like to
point out that I wasn't trying to advocate the HC11 particularly, just
that a microcontroller has lots going for it compared with a computer
designed for a specific purpose. I happen to know a bit about the
HC11 so it made a good counter-example.

As I said, the *first* thing we need is to define our goals; only then
can we fight the processor war with live ammunition:-)


R.M.O'Leary <robin nospam at> +44 973 310035  P.O. Box 20, Swansea SA2 8YB, U.K.