Charles,
I have tried that method ... ditto setting L and searching for best C. It
works but is no better than the one I am using now which is to begin with
both L and C at 0 and then search for the best C for every L as L increases
from 0 to max. The searching is done in large steps (coarse granularity, to
use Waynes term) so it doesn't take very long to cover the range. When a
best solution is found the steps are then decreased in size while searching
a limited range around that solution. Typical solutions take from 5 to 10
seconds and I know it could be much quicker using a more clever algorithm.
I am happy with what I have because once a solution is found and stored the
tuner tunes from memory anyway, switching in milliseconds.
I keep pursuing this because of the challenge, the same reason I do
crosswords and computer games.
Don K7FJ
Why not take an approach normal to the manual tuner. That is capacitance
to
mid scale and adjust L to best. Then adjust C up or down from midscale
for
min. ? Doing this with a possible repeat for missing the L value by +/- 1
has always yielded me good fast manual results on my old mfj tuners and
doesn't require a tremendous number of iterations or complex programming.
best regards,
Charles
wb5izd
A reiterative multilevel slope-sensing algorithm using decreasing
granularity* is the answer. I have been slowely creeping up on a
satisfactory solution and, depending on distractions, hope to have a
fairly
fast autotuner in a week or so. Suggestions from the list have been very
helpful.
* my term ... don't try to look it up! ;)
Don K7FJ
On Sep 15, 2005, at 11:22 AM, Craig Rairdin wrote:
In this particular case, if you were to iterate over all possible
combinations of L and C it's only necessary to store the best result so
far
and compare the current result to the best result. If the current
result
is
better, it becomes the new best. Now you have no sorting at all and
your
time is order N instead of order N^2.
The problem with the exhaustive search is there are 2^17 = 131,072
combinations to try. (256 cap and inductor values, plus reversing the
whole L network)
It takes a few ms for each relay to physically switch. If you can try
100
combinations a second (10 ms), that's still about 20 minutes to try them
all. Even with 1 ms switching time, you're still looking at 2 minutes to
find a match.
A tough problem.
Bill Coleman, AA4LR, PP-ASEL Mail: [EMAIL PROTECTED]
Quote: "Not within a thousand years will man ever fly!"
-- Wilbur Wright, 1901
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