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HelicopterRadio - JR DMSS › 9303 digital, or analog
12-15-2008 04:29 AM  8 years agoPost 1
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rrVeteran

Omaha, Nebraska U.S.A.

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Futaba 10C claims total digital data stream, no conv. from analog to digital, thus reducing latency, how about 9303? all digital, or conversion, and does this matter anyway?
greg

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12-15-2008 09:23 AM  8 years agoPost 2
Climax

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West London, United Kingdom

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I bet the 10C still uses an analogue to digital converter (ADC) to sample the joystick pots! But then so do all makes of Tx at the moment...

I would imagine that the X9303 was also fully digital, in the same sense as the 10C. I certainly hope it's not re-sampling an internal PPM signal in the way that the Spektrum modules have to.

In regard to these modules, I doubt that they use ADCs either. As almost all descent microcontrollers have hardware facilities to digitally time pulses, this does however add latency.

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12-16-2008 12:23 AM  8 years agoPost 3
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rrVeteran

Omaha, Nebraska U.S.A.

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what do you mean, specktrum re-sampling ppm signal?
greg

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12-16-2008 07:44 AM  8 years agoPost 4
Climax

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West London, United Kingdom

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The Spektrum modules (for use with existing 72/35MHz transmitters) use the transmitter’s PPM signal, which they then decode and re-transmit in Spektrum format on 2.4GHz.

Theoretically they could decode the PCM signal, but this would raise a number of technical and possibly even legal issues as each RC manufacturer has their own proprietary PCM encoding. Thus it’s much easier to decode the PPM signal as it is pretty much standardized across all manufacturers.

Re-sampling PPM is not a big deal, whenever you buddy with someone the communication between the master and slave transmitters is done using good old fashioned PPM. The only real issue with re-sampling is that it introduces latency and in a poor implementation could sacrifice a bit of accuracy.

In the case of the 10C, the Futaba designed module can directly access the internals of the transmitter (they designed it and know how it works etc) and can thus encode and transmit their FASST signal efficiently, i.e. there is no need to re-sample a PPM signal.

I would imagine that a similar situation exists with the X9303/DSX9/PCM12 as the systems are fully integrated and the Spektrum/JR designers would have fully collaborated on the design.

I hope this make a bit more sense?

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12-17-2008 01:23 AM  8 years agoPost 5
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rrVeteran

Omaha, Nebraska U.S.A.

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yes thanks, so this only happens with ppm radio, with 204 module, correct?

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12-17-2008 08:47 AM  8 years agoPost 6
Climax

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West London, United Kingdom

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It could be a "high end" PCM capable radio, but it would need to be put into PPM mode in order for these types of module to access a signal that they can easily decode etc. etc.

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HelicopterRadio - JR DMSS › 9303 digital, or analog
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