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Thursday, March 8, 2012

JR Propo XG8 DMSS Overview

For few monthes, JR propo is now proposing its own and proprietary 2.4 ghz system. After releasing the XG7, JR introduced second half of 2011 the XG8, a totally new 8 channels radio, and followed soon by the XG11 already presented end of 2011, and more recently at the Nuremberg toy fair in February 2012.

For this new radio, like for the 11X/DSX11, JR Propo really broke the mould and came with a very modern and innovative transmitter shape. From my knowlegde, JR gave the chance to a young designer to propose something really new. The radio looks like it is inspired by the movie "Transformers" and gives to the radio a very strong visual identity.

The XG8 is not only a nice looking radio, but is very ergonomic too: the grip is the best I've ever held. In addition with its 770g, it is very light. The position of the stick doing a opened angle with the case is ideal as a thumbs radio. It's light, It's grippy, it balances well, it's ergonomic, in brief, I like a lot. Building quality is very nice too. Despite the case is made of plastic parts, the fit and finish is beautiful, and the case seems rigid and robust, thanks to the numerous screws to close the 2 halves of the case, providing additional stiffness. 

The XG8 brings some nice features:

  • It has in the battery compartiment a SD card slot for model data sharing, expanded storage and software updates 
  • the battery is a 2 cells LiFe battery, 1400 mAh, which provides (I have not measured yet) between 3 and 4 hours operating time. 
  • The XG8 integrates a charging circuit so you just need to plug in the 9V AC/DC adapter supplied. The charging unit will shut down automatically once it detects that the battery is fully charged. No more worries overcharging! 
  • "My List" function: The XG8 provides the capabilities to create your own dedicated menu to group the functions/mixers you access the more often. This is very convenient.
  • Glider mixing capabilities: JR was known up to now to be more specialized in the helicopter. But the latest JR radios now implement specific glider capabilities.


  •  Limit adjust 
  •  Flap rate: every flight mode 
  •  Motor system: with delay 
  •  Camber system 
  •  Brake system 
  •  Differential 
  •  Flaperon mix: with flap lever off set 


  • Dual Elevator, 
  • Dual Flap, 
  • Dual Spoiler 


  •  5 Flight modes 
  •  Dual aileron standard equipped (left:1ch/right:2ch)
I will cover more in details this part later as it is the chapter I pay attention the most !

What is DMSS ?

In the jungle of 2.4 Ghz, it becomes difficult to understand who is using what, so here is a short summary that will help you to understand:

DSSS stands for direct-sequence spread spectrum. In this method of transmission, the signal does not hop from one frequency to another but is passed through a spreading function and distributed over the entire band at once.

With FHSS, frequency-hopping spread spectrum, the frequency of the carrier is periodically modified following a specific sequence of frequencies. The amount of time spent on each hop is typically in the range of 100 ms.

JR combined the best of the two technologies into their new transmission system named DMSS (Dual Modulation Spectrum System). DMSS is a true frequency hopping based system where it hops across the entire band. In other words, DMSS is Wide band RF tansmission (like DSSS, unlike FHSS) with Frequency hoping (like FHSS, unlike DSSS). DMSS or course brings two ways communication, enabling telemetry which is a built in function in the XG8.

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