Been reading the forum for a while but never had anything to add.
So this is my 1st post hope it help the conversation.
Like a lot of you I was keen to find out as much as possible about JR's new DMSS modulation system.
And the only technical looking information I could find was on the JR brochure in Japanese available on the McGregor website among other places. http://www.macgregor.co.uk/jrpropo/dsmm.pdf
After a lot of hunting around I finally found someone prepared to translate it for me. There Japanese is infinitely better than mine they are not technical by nature and also not a native Japanese speaker and so struggled a little translating the brochure.
Here is her literal translation: -
light and fast response and superior communication security “DMSS systems”
it's been three years since the 2.4 GHz band which can be used for various devices has been used for radio control signals and surely many radio control flies have experienced it is new convenience and security at this point to 2.4 GHz is becoming standard and with their DMSJ system developed for the Japanese market JR has a track record of establishing reliability and security that and now 2.4 GHz is welcoming the year of bidirectional communication using their technology and reliability they cultivated with DSMJ JR have developed an even high efficiency communication system. Dual modulation spectrum system or “DMSS” for short with simultaneous (1) communication the second chapter of JR's 2.4 GHz begins.
Differences with DSM J systems
while DSMJ system was a modulation system for FHSS only, DMSS as indicated by how it is touted as dual modulation is a communication system which has DSSS (direct scattering (2) ) system technology in addition to the FHSS (frequency hopping) system, and on top of that has improved resilience to noise also we've revised the communication format so when you choose the type of helicopter or plane it will do the format of communication suited to each for a solid/concrete example in the case of a CCP M type helicopter under the old premedication format the ailerons elevator pitch channels were allocated to ch2,ch3 and ch6 and between ch3 and ch6 there was a gap of two channels.
With the new DMSS system when you choose the type of helicopter it changes allocation of channels so without changing the connection of the receiver it will change to a system that will send the ch2/ch3/ch6 signals at one time.
It is this new system DMSS that is able to achieve this type of high-efficiency control.
Resistance to interfering signals
Even the DSMJ system had extensible resistance to interfering signals by use of FHSS (frequency hopping) but the new DMSS system has improved the resilience to interfering signals even more due to an advantage of DSSS (direct scattering (2)) which is its noise attenuation characteristics during calibration of the signal.
Notes by me (Eddy): -
Don’t forget this broacher was for a country that never had DSM2 so it’s not mentioned.
1) I suspect this is “bidirectional communication” not “simultaneous communication”
i.e. the telemetry
2) I assume the use of the word “scattering” would possibly better translate as “sequencing”.
Unfortunately this doesn’t seem to answer my main question witch is. Is it a wide band frequency hopping system?
It’s a shame the Resistance to interfering signals section is longer and has translated slightly vaguely.
I can think of a few different ways of interpreting this.
But my optimistic reading is that it is a much wider channel (like DSSS) but that hops like FHSS.
But it looks as if I will have to wait a little while longer to find out if it the modulation technique I have been waiting for. In all probability that will be when Bruce (RC model reviews) puts one in front of a frequency analyzer.