Mike
OP is reporting the average s/n of the channel ..
The purpose of the various speed/time versions are purely the
minimum signal decode level
The longer the time slot the lower the s/n capability , if the s/n
is showing similar , that is
indication that the noise floor at the RX has remained constant
during the capture period, with the
proviso that app 66% of the signal has been captured ...as to the
distribution of the 66 . that has yet
to be determined
In a test on 500 I ran op 4 and 16 at the same time , with the
same carrier levels , OP16 was
predicted to give 6dB gain , Eddie , decoded the 16 reliably , where
as the 4 was only decoded
with round 6 dB increase in Tx out put ..the test also produced a
lot of local op15 false spots :(
Thanks GL
73 -G.
--------------------------------------------------
From: "Mike Dennison" <[email protected]>
Sent: Thursday, January 19, 2012 2:30 PM
To: <[email protected]>
Subject: LF: Opera speeds
I have been testing the difference between Op8 (8-second message) and
Op32 (32 second message). Thanks to the software, receiving stations
can report on both modes without having to switch.
Reports on my signals from PA0A, PA0AM, G4WGT and F6CNI (between 257
and 465km) show variable results. The slower speed never produced a
worse S/N, though sometimes it was exactly the same. Usually the
result was between 4 and 9dB improvement with the slower speed.
Intuitively, I would assume a 6dB improvement (though I am no digital
expert), but occasionally better iif QRM is present as I would expect
this to affect the faster signal more. Is this a reasonable
assumption?
Not a totally scientific test, but at least it demonstrates that it
is worth using Op32 when signals are weak.
I have now stopped Windows automatically rebooting my computer in the
middle of the night so I should be able to monitor all of tonight. A
nighttime transmit test is scheduled for the weekend.
Mike, G3XDV
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