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<DIV><FONT size=2 face=Arial>All,</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Many thanks to Jeremy and helpers for getting the
new SVN in place .</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>There are a couple of new features both in Doug's,
W5WC, PowerSDR(TM) and KISS Konsole that I'd like to highlight. Both of
these are thanks to Warren who took on the challenge of modifying dttSP for us
and Doug who added the GUI support for PowerSDR whilst George undertook the
tasks for KK.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The first is an new speech processor. This is
a processing technique suggested by Peter, G3PLX, and is the software
equivalent of an RF speech clipper. It's by far the best speech processor I've
ever used, a view shared by the beta testers. Whilst the processor has a
range of 0-20dB if you are going to use above about 10dB then I suggest getting
some reports from a local station before letting loose on the bands. The
setting does vary between different voices so be sure to
experiment.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The second feature is one that I've been wanting
for many years and that is a really effective AGC system. Warren has fully
implemented some ideas I had back in the SDR1000 days and they work really well.
</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The AGC </FONT><FONT size=2 face=Arial>attack,
decay and hang settings have all be optimised and the noise pulse removal is
exceptional.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>One new feature is the addition of Hang AGC.
For those not familiar with this concept it works as follows. For a strong
SSB signal its nice to have an AGC setting with a long decay so that there is no
band noise between pauses in speech. Since the AGC decay is exponential
the delay, before the receiver regains full sensitivity, for a very strong
signal this can be many seconds. With Hang AGC a strong signal can be
allowed to trigger a large AGC gain reduction but when the signal is
removed the AGC will maintain the gain reduction for a pre-determined period (
usually a second or two) and then very quickly return to full gain. In
this way the AGC decay time constant does not alter with signal levels.
It's very effective when working in a net where signal levels can vary
greatly.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>One issue is how do you set the level at which the
Hang is activated? Doug has implemented a simple visual guide in the form
of a horizontal line that appears on the bandscope ( user selectable to be
across the width of the screen or just with the receiver bandwidth). When
Hang AGC is available (for Slow, Long and Custom AGC settings) you can move this
line up and down the screen with your mouse by placing your cursor in a small
square at the left hand side of the line. If the peak of the signal in the
passband crosses the line then Hang AGC is activated. To deactivate
Hang simply push the line above the signal towards to top of the
screen. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>The line has an 'H' next to it for easy
identification. This feature can be turned off using the Setup
form.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>In addition there is a similar horizontal line to
set the AGC 'knee' or threshold. This line shows the signal level at which
the AGC will start to activate. Just like the Hang threshold you can set it by
moving the line with your mouse or by using the AGC-T slider. I suggest
setting the knee about 10dB above the average band noise. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Finally when Fixed AGC gain is selected a
horizontal line is displayed that indicates the level of gain being
applied.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>There could well be some final optimisation to do
regarding the AGC dynamics so please report your findings and suggestions via
the reflector. </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>73 Phil....VK6APH </FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
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