Mike ,
Power gain is close to 6 dB , so that's a times four over the
standard Opera data decode limits
Any numerically processed data mode is based solely on Guess work,
just that Guess work is translated by decision making and fuzzy
logic in to a reproduction of the original message
Modes like opera / ros / olivia etc use algorithms to compress and
extract the call , hence opera data miss decodes, 'have' a normal
call profile , but are not valid . simple rtty just produce's near
random data
In the case of Marcus's opds , your are presented with a set of
values , a little deeper , these will of been constructed from a
layer of fuzzy logic , as are the dsp decisions in opera etc , in
the case of Opera dynamic , the outputs from the data decoder and
the 'search' detector are assimilated by a another layer of decision
making logic
The command structure , then decides at what point the decoder has
failed and the results from the detector are evaluated , the dynamic
call lists are maintained , via tx web beacon and 1+1 quality check
of decoded calls
Table is held for 8 days We did have 3 days as the original cycle
time , however , as activity on 136/477 tends to follow the 7 day
week pattern , stations using pic/pi/U3 and other Tx systems , with
no web-beacon would need to be decoded by 2 stations using
op32/op8 on there first pass, to catch the second
The show go's on ;)
73-Graham
G0NBD
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From: "Mike Dennison" <[email protected]>
Sent: Saturday, January 10, 2015 11:09 AM
To: <[email protected]>; <[email protected]>
Subject: LF: Opera improving
There is a British saying "Don't throw the baby out with the
bathwater". Amongst the criticism of false decodes (which I have been
part of), we must not forget that Opera is now more sensitive - the
equivalent of doubling everybody's power - which must be good. This
has led to many more good DX decodes.
Now, in response to suggestions from users, the writers have modified
the program to flag up decodes that might be suspicious, which is
what OPDS does (but in a different way). Used with caution, this will
address most of the problems experienced with the launch version.
The controversial PDF file has also been dropped from the zip file.
Deep Search, originally developed by DF6NM, has always involved
"guesswork", and therefore needs to be viewed with caution. In short
it compares a list of known active stations (again Op and OPDS does
this differently) with what might be described as 'partial decodes'
and finds the best match. Anyone who has worked DX, operated in a
contest or used QRSS will be familiar with that technique. Indeed
that is how the human brain works all of the time - it matches what
its sees with a huge look-up table of past experiences, which is why
we see faces in clouds (a false decode). The key is to use our
experience to work out what is true and what is false.
I would suggest three more improvements:
My understanding is that callsigns in the 'look-up table' are dropped
after 8 hours. Reducing this period might help.
For those who don't like Deep Search, there should be an 'off'
switch, perhaps in the existing Deep Search menu. The 'on' swtch
might come with a "use with caution" message.
Used carefully, the new v1.5.6 should be a great improvement on the
(pre Deep Search) version 1.5.4.
Mike, G3XDV
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