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Old 06-21-2003, 01:20 PM   #1
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PPM, PCM, HRS, Advance HSR

I'm start to wondering, Do those really can feel the difference? Does PPM have disavantage than Futaba's HRS or KoPropo's Advance HSR? Airtronics still use PPM.
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Old 06-22-2003, 09:06 AM   #2
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I think high response is actually the same as ppm but the signal frequency ( not the carrier frequency which is controlled by your crystal) is higher.

With an analogue servo this makes very little difference but with the new digital servos they are controlled by very rapidly turning power to the motor on and off. With a high response system then the power can be turned on and off more rapidly resulting in faster servo speed and higher torque.

It is a very small difference though and if you have a good radio already it is not worth upgrading.
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Old 06-22-2003, 11:28 AM   #3
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I have Futaba 3PK. If the result only little difference, I'm thinking about changing my 3PK to Airtronics M8 back light Novak switch. No need crystal anymore. I can switch all 30 ch. what ever I want. BTW, can I use Futaba digital servo with M8?
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Old 06-22-2003, 02:28 PM   #4
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PCM isn't intended for use on electric cars, it is intended for nitro cars because of the battery and interference fail safe features available. If you ever goto a big electric race, you will never see any of the pro's using PCM because it is a little bit slower than PPM or something of that sort, I don't know the exact details.

HRS is a great thing, however unless you're a professional driver who has been racing for 10+ years, I highly doubt you will be able to tell the difference between HRS and PPM while on the track. I use HRS, but I turn the steering speed on my 3PK down to 40%. HRS is very precise and very fast, a beginner or weekend warrior definetly will not be able to use all of HRS' capabilities, I know I can't.

I'm going to be switching back to PPM for my electric cars and i'm going to be switching all of my gas and nitro cars to PCM.
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Old 06-22-2003, 06:36 PM   #5
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Originally posted by Accord
If you ever goto a big electric race, you will never see any of the pro's using PCM because it is a little bit slower than PPM or something of that sort, I don't know the exact details.

The main reason you don't see many pros using PCM on electrics is because it is very rare to have an electric runaway at WOT (wide open throttle) like a nitro can. The other reason is that the pros don't want a fail-safe device shutting down their car for a little interference that they could drive through. The pros are out to win races not play it safe.

The Futaba PCM receiver receives the signals at the same rate as regular PPM (FM) it just that the signal is pulse coded which is very similar to digital. There is another PPM system out there that is a bit slower but not noticably and that's dual conversion where the signal is processed twice at the Rx to reject interference.
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Old 04-27-2004, 10:37 PM   #6
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I just bought a KO 4232 with Advanced HSR...

I know regular servos run at a 50Hz frame rate...
What frame rate does an HSR or Advanced HSR servo run at ???
Any idea?

The Airtronics 98758z is really popular with helo guys. That thing can run at 300Hz and work with their auto-stabilization gyros. THat's pretty awesome.

I am very interested in the frame rate because I am using these servos for a high precision robotics project.
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