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<body class='hmmessage'><div dir='ltr'><font style="" color="#000000" face="Tahoma,sans-serif">Yes, we will clearly agree to disagree on this. <br id="FontBreak"></font><br><br><b><font style="font-size:16pt;" size="4">73 Doug</font><font style="font-size:16pt;" size="4"><br></font><font style="font-size:16pt;" size="4">WA3DSP</font><font style="font-size:16pt;" size="4"><br></font><font style="font-size:16pt;" size="4">http://www.crompton.com/hamradio</font></b><font style="font-size:16pt;" size="4"><br></font><br><br><div><hr id="stopSpelling">Date: Sun, 16 Nov 2014 14:16:52 -0500<br>From: kuggie@kuggie.com<br>To: arm-allstar@hamvoip.org<br>Subject: Re: [arm-allstar] Yet another USB FOB Modification<br><br>
<div class="ecxmoz-cite-prefix">On 11/16/2014 12:58 PM, Doug Crompton
wrote:<br>
</div>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
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<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif">My definition of users is individual
simplex nodes which I would suspect is the overwhelming
majority especially in the BBB world.<br>
</font></div>
</blockquote>
<br>
<br>
We'll have to agree to disagree there.....<br>
<font face="Tahoma,sans-serif"><br>
<br>
</font>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"><br>
I lost track of what we are even talking about here.</font></div>
</blockquote>
<br>
<br>
I'll get you back on track.<br>
<br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"> If it is pre/deemphasis then that
can be done in the radio or in SW.</font></div>
</blockquote>
<br>
<br>
I never said anything about pre or deemphasis. <br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"> In my opinion characteristically
distorted usbradio audio is much more of an annoying problem
than improper equalization. <br>
</font></div>
</blockquote>
<br>
<br>
By definition, systems that have double pre-emphasis or any other
equalization problem are distorted. Generalizing that ALL usbradio
installations have distorted audio is not factual. If a usbradio
system has distortion which is offensive, something is wrong with
the deployment. <br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"><br>
Most radios can be made to work with simpleusb and with
pre/deempahsis done in the radio. </font></div>
</blockquote>
<br>
<br>
Suitable audio usually isn't the problem. Getting quality logic to
the radio interface is. But, there is a new solution to that
problem.<br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif">That is using fixed level speaker
audio and mic input. It works fine. Mototorla's can do it and
so can most all commercial ham equipment.</font></div>
</blockquote>
<br>
Many commercial radios have high pass filtering on the MIC input.
This is for good reason, to eliminate voice energy that can mix with
the PL tone and cause 'talk off'. As such, these filters keep you
from effectively using the MIC input for CTCSS. In some instances,
you can crank the CTCSS audio up to overcome the losses of the
filtering, only to create problems with the dynamic range of the
clipper/limiter, creating distortion. PL distortion of even the
slightest amount will cause harmonics which 'sound' louder than they
are comparing deviation. "PL" buzz is a big problem when using MIC
audio on radios that have HPF'ing. Jamming the CTCSS into the MIC
jack creates another problem. When you modulate voice peaks which
are clipped by the limiter, the CTCSS tone gets chopped off, causing
the decoder to drop on the users end.<br>
<br>
The right way is to get to the modulator, so the CTCSS tone
injection is after the clipper/filter.<br>
<br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"> It makes no difference what type of
FM modulation is being used if you let the radio do the
pre/deemphasis.</font></div>
</blockquote>
<br>
<br>
It's evident you don't have a lot of experience with modulators in
FM radio. Some modulators are PM (phase modulated). These
modulators are present in many Motorola and GE radios don't have the
ability to modulate with the same index across the entire PL and
voice range. As such, it takes a greater amount of voltage to get
industry standard PL deviation. <br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"> Why make things more difficult at
the expense of a dB or two more flatness that most people
can't even hear.<br>
</font></div>
</blockquote>
<br>
<br>
Because not doing it correctly is bad news. Creating spurious
emissions can get you a pink slip. Besides, people know the
difference - believe me.<br>
<br>
<blockquote cite="mid:BLU172-W2471EE7DEEACA77CD3C951BA8A0@phx.gbl">
<div dir="ltr"><font style="" color="#000000" face="Tahoma,sans-serif"><br>
Our local network typically has 15 to 20 nodes connected and a
mixture of radios, many Alinco, a few Motorola, and a others.
They are all running simpleusb and all typically have good
audio. I find that most audio problems arise with the users
handhelds. Listen to any repeater and you will find audio all
over the place in quality and level. You can't correct
something that is bad to begin with. <br>
</font></div>
</blockquote>
<br>
While I agree that you can do anything with poorly designed and
aligned user radios, by maximizing the dynamic range and minimizing
the distortion introduced, the better you can tolerate it. Why make
it worse than it already is? I'll agree that it is more difficult
to deploy a system where the audio is taken from the discriminator
and feeds the modulator directly, but there is no substitute for the
amount of dynamic range and lower distortion that results. Like
anything, taking the easy way out usually works okay, but I'm not
one that is generally satisfied with it just being okay.<br>
<br>
Kevin<br>
<br>
<br>
<br>
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