A gadget like that differentiate between pusle out or not from the Rx. Tx ON, then pulse ON, Tx OFF then no pulse. What that is telling us is the PPM Rx have a function not so popular to the RC fans is the "mute" function. Every noticed in the old days TV tune to an empty channel will flood the speaker with white noise? as oppose to TV today only give us a blue screen and speaker mute for empty channel? A mute function do exist in our PPM Rx either intentionally by the original designer or un intentionally coloned in by some electronic artists of another vendor. By such function the noise of an empty channel is gated off from reaching the de-multiplexer, a function that turn pulse position back to channel specific signal fan out to each servo. A properly designed muting function also posses a good threshold preset plus adequate hysteresis to prevent premature muting and spurious muting in/out oscillation under low input signal condition. In a sense, muting function can be view as the "lock up" function in a PCM system. What I am trying to get at is that a good designed muting function in PPM system should be one that when interference sharp enough, all servo channel output are cut off immediately thereby holding the original servo position and by luck glide through the interference zone. On the other hand, however, a poorly implemented muting function (or scheme) can cause the spurious in/out muting under interference or at weak signals that can lead to wild servo movement. I trust IPD can represent such muting but execute the desire through our intellegen stored in code inside the Rx. The result should be better and not worse. Karlton, am I right about that? YK ----- Original Message ----- From: Scobie Puchtler or Sarah Felstiner <[EMAIL PROTECTED]> To: RCSE <[EMAIL PROTECTED]>; Richard Dolf <[EMAIL PROTECTED]> Sent: Friday, July 14, 2000 2:59 PM Subject: [RCSE] Radio reception, ideas relevant to the PCM, IPD, thing? > Just wanted to add an interesting note to the discussion on radio > performance/interference etc. All the talk over modes of transmission and > reception are a bit over my head, but I had an interesting experience flying > with my pal Richard last night that might be of interest to those generally > concerned with RC transmission/reception. > > We were flying Richard's Handlaunch and it started to ring exactly like a > cell phone. He explained to me that it had on board an alarm designed to > begin sounding whenever the TX is turned off, as an aid in finding the plane > were it to come down out of sight or in tall grass or whatever. Of course > this same alarm happily goes off any time that the TX is not in > communication with the RX, regardless of the reason, so it basically > functions as an audio glitch alarm. I found it really interesting to have. > We flew the plane, trading TX between us for maybe 30 minutes, and the thing > maybe went off briefly 3 or 4 times. The short glitches never caused much > problem. > > But it was really informative to learn when and where interruptions were > occasionally occuring. Everyone who flies at our local hill gets some > glitching, and there are various unconfirmed theories as to where and why > and which occurrences are just turbulence and not radio related etc. etc.. > Having the alarm was very clarifying. I'm not sure what it is called, but > its about 5g, and sold by Thermal Gromit Works, and perhaps others as well. > Maybe Richard will fill us all in if he reads this. As long as you are > downwind of the glider, it seems as if the sound carries pretty well, but > I'm guessing it probably wouldn't be useful for indicating glitching at > truly speck height. > > Lift, > Scobie in Seattle > > RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED] RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
