17 Apr
2014
17 Apr
'14
1:15 a.m.
On 16/04/14 23:20, Gene Heskett wrote:
On Wednesday 16 April 2014 09:09:06 Simon Wise did
opine:
> I was shown a rather nice artwork that used high
resolution radar
> (resolutions around 1 centimetre I think) to get positions (it was made
> in a university robotics department that had such things!). The way
> those work is very interesting ... the frequencies are way to high to
> digitise, so the electronics has to be all analogue ... the 'circuitry'
> is basically plumbing ... gold lined tubes and chambers using
> resonances and such to measure delays and phase differences. At those
> frequencies the speed of light becomes a dominant consideration.
We have a gismo thats basically much simpler than all that plumbing, to use
when checking a cable for damage, called a Time Domain Reflectometer. The
pro versions using a tunnel diode switch as a pulse generator, can tell you
theres a bullethole in the line 883.6' out from where you are hooked up.
I've made homemade versions using a pulse generator and a fast oscilloscope
to measure the echo delay, punched some buttons on a good calculator and
then told the tower crew where to open it up and replace a burned up
connector bullet and/or the teflon disk holding it centered in the line.
It got the job done so I figured it was good enough for the girls I go
with. :)
not at all convinced that a fast oscilloscope, a good calculator and the
wet-ware connecting them are simpler than a bit of machined metal with gold
plating, but certainly re-using existing gadgets beats making new ones.
Simon