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Oneshoot125 vs Multishoot - Real benefit ?
#1
Heu guys, 

I ´m currently using a SP Racing F3 Revo FC and since I moved from the old Naze32 I started to use Multishoot.

I read the specs of each and looks like multishoot is the fastest one, nice right ? but how about the real world ? I mean, on a F3 I´m unable to set it to 32khz update rate, so is there any benefit on this considering this scenario?

Thanks
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#2
Pretty sure you can only run 8KHz with multishot on an F3 board. Regardless, the elite pilot at the top of his game might notice a slight difference. But us mere mortals? Not likely. The only difference I've ever noticed in the short time I've been into this hobby was the first time I tried Oneshot 125. And I don't think it was the fact that I was running faster looptime, probably more the effect of damped lite.
[-] The following 1 user Likes RENOV8R's post:
  • flabombarda
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#3
+1 Dshot because you don't have to calibrate. I am not a good enough pilot to notice the difference.
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#4
(17-Jun-2017, 05:04 AM)RENOV8R Wrote: Pretty sure you can only run 8KHz with multishot on an F3 board. Regardless, the elite pilot at the top of his game might notice a slight difference. But us mere mortals? Not likely. The only difference I've ever noticed in the short time I've been into this hobby was the first time I tried Oneshot 125. And I don't think it was the fact that I was running faster looptime, probably more the effect of damped lite.

You are right that the pid loop is limited to 8khz on a f3 board, but with multishot, f3 board and the right escs, you can run 32000khz ESC signal update frequency. This could be beneficial as the signal is analog and 32000khz is 4 times more than 8khz. This means that the average signal is more likely to be what comes out of the pid loop.

Here is an example:
Let's assume the FC is running the pid loop at 8khz.
The ESC command comming from the pid loop is, let's say 5.
Since multishot is analog, it is more likely to send not 5, but something pretty close like 4.9. when running 8khz ESC update time this value is only sent once and thus 4.9 is sent to the ESC.
Now let's look at 32000khz ESC update time. For each pid loop update, 4 ESC update signals are sent. Lets assume that the 4 signals were 4.9, 5.1, 4.95, 5.05, and the average value per pid loop cycle could potentially be closer to 5 than what 4.9 is.

But I don't know if it is noticeable.
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#5
Theoretically i'd guess multishot would make for a little bit less delay (not that this was noticeable though) ... practically, the risk of electrical noise messing with the throttle values is probably higher (also really just guessing here, i'm no electronics expert at all).

Anyway i'd recommend caps on each esc, worked fine for me. Smile
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#6
As per my understanding on the posts, looks like there is difference yes, but not something that should be a MUST HAVE. Maybe for real competitors I guess
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#7
By the way, I[ll give a try on Dshot600 to see if I see what happens, it seems to be a more modern (digital) protocol against the analogue from the others discussed here (oneshot/multishot).
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#8
One thing to keep in mind is that with faster fcs (f3, f4, f7, etc) you can run the pid-loop faster than oneshot125 can keep up with resulting in "signal-de-sync" issues etc. I don't think that is a problem with newer versions of betaflight as the gui restricts the cycle-time based on what ESC signal is chosen if I remember correctly. Oneshot125 can't run faster than 2khz, maybe 2.7khz before having trouble while multishot can do at least 32khz
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