5 Apr
2006
5 Apr
'06
7:35 a.m.
Brent Hilpert wrote:
Don Y wrote:
No, I was only involved in the plotter (CPLOT-2). We had an
"all hardware" receiver that predated me. And, a CPU-based
receiver that was designed alongside the plotter (but I think
it was a white face). IIRC, we used PGD's for our displays
(I know the plotter did).
I also designed an autopilot "peripheral" (to the plotter)
that allowed you to enter geographical coordinates of
your desired destination and it would steer the boat *to*
that point (instead of just blindly keeping the boat
pointed in a certain direction) while compensating for
drift, etc. (I also learned that you should never go below
deck when in the Atlantic :< )
...
So, you have to capture the incoming coordinates, solve the
difference equations to map the hyperbolae onto a spherical
globe, compensate for the *oblateness* of that globe, do
a 2D mercator projection, scale it to the desired user's
scale and then drive X & Y motors to move the pen from
where you were (last update) to where you *are* (in a straight
line, of course) -- without running off the edge of the page,
etc.
In addition to driving the multiplexed displays, scanning the
keyboard (debouncing keys, etc.), interacting with the user, etc.
Nowadays, I could code the whole thing in a month or so.
But, it sure wouldn't fit in that hardware footprint!
(keep in mind, 2Kx8 EPROMs were $50 at the time... $250 just
to store the code!)
...
--don
It sounds like you programmed a receiver some time ago.. I don't have the
manuf./model at hand but I know of a loran receiver with blue front panel,
lots of incandescent 7-seg displays, I think it was an 8080 CPU inside - sound familiar?
Is loran off the air now or is it still hanging on? It
might be fun to connect
up an antenna and see if the above still works.
I *thought* it was decommissioned a few years ago. But, it's been
25+ years (gulp!) since I was involved with LORAN in any way
(however, it's the type of thing that, once you get exposed
to all the wacky details of how it works, it kind of sticks in
your mind :> )