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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>At last, someone who understands SS. Jim, I
believe that if the “chirp” is fast enough, any potential interference
will be momentary and can be processed out by the RX. It’s been a while since
I worked on these systems but I do remember how highly immune they were to any
kind of interference.</span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'> </span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b>
nsrca-discussion-bounces@lists.nsrca.org
[mailto:nsrca-discussion-bounces@lists.nsrca.org] <b><span style='font-weight:
bold'>On Behalf Of </span></b>J.Oddino<br>
<b><span style='font-weight:bold'>Sent:</span></b> Friday, February 23, 2007
1:41 PM<br>
<b><span style='font-weight:bold'>To:</span></b> NSRCA Mailing List<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [NSRCA-discussion]
SPECKTRUM Modules for Futaba and JR</span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'> </span></font></p>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>I'm having a real problem
understanding what an "unused frequency" is. First of all
nothing that transmits information transmits on one frequency as it must use a
band of frequencies. SS intentionally uses a wide band of
frequencies and the wider this band is relative to the information bandwidth
the more processing gain you get and that is good. The Direct Sequence
system "chips" the baseband information at some high rate with a
pseudo random code that should be unique to your transmitter in order to spread
the bandwidth. With different codes it should therefore be
possible to operate many RC systems simultaneously using the same band of frequencies. </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
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<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Now getting back to "unused
frequencies" , which we will interpret as unused channels about one
megahertz wide, what happens if a system (not necessarily an RC
system) that uses Frequency Hopping turns on and spreads its info over more
than one channel? Or just decides to use the same channel that you
are using? Maybe the FCC rules prohibit this but I'd hate to depend on
the government to make sure my airplane doesn't get shot down. I've got
to believe that "unused" really means that the ambient noise level is
below some acceptable value and I'd like to think we can really operate a lot
more than 40 users in an 80 MHz band.</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>It sure would be nice to get an
understandable, but more technical description of this system and its
limitations.</span></font></p>
</div>
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<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>Jim O</span></font></p>
</div>
<blockquote style='border:none;border-left:solid black 1.5pt;padding:0in 0in 0in 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>----- Original Message ----- </span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='margin-left:.5in;background:#E4E4E4'><b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial;font-weight:bold'>From:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:JonLowe@aol.com" title="JonLowe@aol.com">JonLowe@aol.com</a> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>To:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:nsrca-discussion@lists.nsrca.org"
title="nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</a> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>Sent:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Thursday,
February 22, 2007 7:26 PM</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>Subject:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> Re:
[NSRCA-discussion] SPECKTRUM Modules for Futaba and JR</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>In a message dated 2/22/2007 6:52:04
PM Central Standard Time, <a href="mailto:patterndude@tx.rr.com">patterndude@tx.rr.com</a>
writes:</span></font></p>
</div>
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margin-left:3.75pt;margin-top:5.0pt;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>What does Spectral capacity - 40
systems mean? Is this the number of tranmitters that can operate in range
of each other, or is this 40 channels or what?</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>--Lance</span></font></p>
</div>
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style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
</blockquote>
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<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>This is grossly simplified, but the
2.4 ghz band has about 80 frequencies. Each Spektrum unit picks two
unused frequencies and transmits on both. 80/2=40 transmitters that can
operate at once. It is a requirement of the FCC that things on this band
don't interfere with each other, and transmitter power is strictly regulated,
therefore anything using the band has to check before transmitting. You
have no idea which two frequencies you are on (nor do you care), as they change
each time the transmitter turns on.</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>I've flown my Dad's Arresti III with
the DX7 extensively. Absolutely solid link, with no fear of getting shot
down. I have been waiting for something like the modules so I could
use a decent transmitter for things like throttle curves, conditional mixes,
etc.</span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>I don't want to be at a field that
has 40 airplanes in the air at once!</span></font></p>
</div>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'> </span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial PTSIZE=10><span
style='font-size:10.0pt;font-family:Arial'>Jon Lowe</span></font></p>
</div>
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.5in'><font size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'><br>
<br>
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<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'>_______________________________________________<br>
NSRCA-discussion mailing list<br>
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http://lists.nsrca.org/mailman/listinfo/nsrca-discussion </span></font></p>
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<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Arial><span
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