Is it possible to reduce the resolution of the PPM signal?

[algo]

I have a little micro heli that has pretty low resolution servos and/or its receiver is low resolution. When moving the stick on the 9x there are a bunch of places where the servos will jitter like crazy. It is my theory that this is caused by the PPM signal being right in between two of the large steps on the receiver and it starts oscillating between the two steps. If the 9x could be made to transmit in larger steps for this model then I believe it would eliminate the jitter.

I hope that makes sense. So for example I assume right now if I move the stick from one side to the other the 9x will adjust the PPM signal in increments/steps of whatever resolution the ADC can digitize. Lets say that is 1024 steps (I don't know what it actually is; I'm assuming 10 bits) but I would like to reduce that to the receiver's 128 steps (or whatever it is) so that each step is large, discreet, and more difficult to hit those magic "in-between" spots where the jitter occurs.

Or maybe I have no idea what I'm talking about. I'm just wondering if there is currently a way to reduce the stick movement resolution as it were. Thoughts?

[rperkins]

When my mcpx servo's get twitchy i take them apart and clean the contacts with an eraser, then rubbing alcohol .

[algo]

I don't think this is because of dirty servos. Well maybe but the stock TX for the heli doesn't jitter. I counted the steps, the receiver or servos are only capable of around 64 discreet steps for a full motion. Looking at the PPM timing display on the 9x it does seem like it starts to jitter when I get in between two of those 64 steps. No confirmation though because even at 64 steps the timing is very small. I wish I had a spectrum analyzer so I could look at what the stock TX was doing. Maybe I can look inside and find its PPM signal.

[MikeB]

Try this set of mixes:
CH01: +100% CH1 Switch(!SW3)
CH01: R +100% AIL Switch(SW3)

CH08: +100% CH1 Offset 5%
Ch09: +100% CH1 Offset -5%

CSW1: v1>v2 AIL CH8
CSW2: v1<v2 AIL CH9
CSW3: OR SW1 SW2

Your channel 1 (AIL) should now move in steps of 5%. Change the Offsets values of 5% to change this.

Mike.

[algo]

Try this set of mixes:

Thanks! That works for the most part! At least so far, I'll have to do extensive testing. The neutral position still has jitter, maybe I need to offset the center or something.

I want a fractional percent though, 1.5625% (or possibly tweaking around with other fractional values). Can I do that? Whole percentage amounts are huge changes. 2% gets it really close to jitter free but there are still a couple spots. Doesn't look like eepe lets me do fractional values either.

I have to read up on mixes, I haven't gotten that far in my 9x journey.

[MikeB]

If you need a fractional offset, use the sub-trim (offset) in the limits menu. This will let you have 0.1% steps for the offset. Use instead of the offset on channels 8 and 9 above.

Mike.

[algo]

If you need a fractional offset, use the sub-trim (offset) in the limits menu. This will let you have 0.1% steps for the offset. Use instead of the offset on channels 8 and 9 above.

Is there anything special I need to do to make that work? I tried setting the mix offset for CH8 and 9 to zero then set an offset in the limits menu for CH8 and 9 but it doesn't appear to do anything. I tried a value of 25% for the offset but the servo moves smooth like there is no offset.

[MikeB]

Maybe the sub-trim offsets are not included in the calculation.
Try:
CH08: +90% AIL
CH08: +10% AIL Offset 15%

The weighting on the second entry also applies to the Offset, so you get 1.5%, but 90% + 10% AIL give 100% output.

Mike.

[algo]

Thanks! That seems to work and gives me finer control.

Weird thing is that I seem to get less jitter when both CH8 and CH9 have positive offsets. Something to keep playing with I guess.

Thanks for your time!