<div>Years ago, I made some similar measurements on my 7UAP radio (published in the K-Factor) and noted similar step size for the trim. I modified my aileron and elevator trims to reduce the trim step size, by adding resistors to each end of the pot. Of course, this reduces the overall trim range, but I got the step size close to 1 step (1/1024) per notch of the trim lever.</div> <div> </div> <div>Bob R.</div> <div><BR><BR><B><I>Ed Alt <ed_alt@hotmail.com></I></B> wrote:</div> <BLOCKQUOTE class=replbq style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid"> <META content="MSHTML 6.00.5730.11" name=GENERATOR> <STYLE></STYLE> <DIV>Hi Jim:</DIV> <DIV>I thought JR SPCM was about a 44 ms frame rate for a complete interlaced pair of frames transmit. Futaba PCM 1024 is 23 or 24 ms for a full data frame if I'm not mistaken. No idea about Airtronics though.</DIV> <DIV> </DIV> <DIV>Too bad about the trim resolution
being so wide on the DX7, but I would assume and hope that as long as you go back and re-adjust things through some servo centering option, you ought to be able to re-center the trims and avoid that sloppiness?</DIV> <DIV> </DIV> <DIV>Ed</DIV> <BLOCKQUOTE style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <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> <div> <HR> <div></div>_______________________________________________<BR>NSRCA-discussion mailing list<BR>NSRCA-discussion@lists.nsrca.org<BR>http://lists.nsrca.org/mailman/listinfo/nsrca-discussion</BLOCKQUOTE>_______________________________________________<BR>NSRCA-discussion mailing
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