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<DIV>I just browsed some FAQ's on Futaba's site and they had a response about
frame rate for PCMG3. They state that it is 17.6mS. I had seen
someone's scope trace for PCM 1024 and they had that at around 23 ms. I
guess they have improved their PCM coding algorithm with the introduction of the
14Z and 12Z? </DIV>
<DIV> </DIV>
<DIV>Ed</DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mailto:joddino@socal.rr.com
href="mailto:joddino@socal.rr.com">J.Oddino</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=mailto:nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Sunday, December 17, 2006 5:52
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [NSRCA-discussion] 2.4 Ghz</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>I flew the Dx7 on Thursday and it felt pretty
good. It was in a Dog House Extreme with marginal servos but still had a
very nice feel. I took it way up and out so we could barely see it and
had no problems.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Today I ran a few tests. Following are some
results and my comments:</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>1) The update rate, that is, the rate at which
the servos get new information was about 45 Hz or every 22 milleseconds.
This is a little slower than most modern day systems.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>2) The resolution less the servo, that is, the
minimum change in the pulse width to the servo, was 1.0 microsecond.
This is better than any system I have measured. When I connected one
of my elevators with a good JR digital servo it was extremely accurate and
neutralized perfectly as far as I could see. This was confirmed by
measuring the pulse width on a scope scaled to one microsecond per cm.
This also says the mechanics of the transmitter gimbal are not creating an
error in commanding neutral.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>3) The change in pulse width per click of the
digital trim was 3 to 4 microseconds which is not good. The basic system
is a 1024, 1024 steps from lock to lock, but you can only trim it as if
it were a 256. To me it is setting the trim that requires the
best resolution. We could fly with a 256 system as long as we could trim
to 1 in 1024. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>4) An interesting thing was the dither on the
pulse width of .4 to .8 microseconds. I assume this was done on purpose
because there should be no pulse jitter in a digital system. I'm
wondering if this can contribute to the good feel when flying. Any
opinions out there?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This system looks like a very good value and the
big boys better get a spread spectrum system out if they want to sell systems
in this price range.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Jim O</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<P>
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