New FHSS from JR?

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Re: New FHSS from JR?

Postby RCModelReviews » Sun Nov 14, 2010 8:55 pm

I don't know where JR are going with the 11X and telemetry -- they (like Spektrum) won't talk to me -- ignoring my emails. Even my emails to the (new) local distributor didn't get a reply.

I think JR 11X users are in the same camp as Futaba 8FG users -- neither knows whether they'll be able to upgrade their radios to handle telemetry or not.

Perhaps this is just a way of ensuring that sales of radios that might not be upgradable don't stall because people might rather wait until the newer (telemetry enabled) versions are on the market.
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Re: New FHSS from JR?

Postby theaton56 » Mon Nov 15, 2010 9:31 pm

HI Bruce,

Out of curiosity who did you email at JR ? My understanding is that the current 11X will not be upgradeable to DMSS via a module. There are only 5 pins used in the module and these are allocated as +Batt, 0V, Data, +6V and Antenna out.

Therefore there are no additional data lines for the Telemetry received.

An XG11 will be a dedicated DMSS based system with integrated Telemetry and will probably put in an appearance next year. So JR will have 2 x 11 channel systems available, 1 on DSM2 and the other on DMSS. (I am led to believe that they will stop using DSMJ in favour of DMSS)

But I think we will have to wait and see what transpires as changes can be made on a whim.

:geek:
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Re: New FHSS from JR?

Postby Eddy4224 » Thu Jan 13, 2011 11:56 am

Hi
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.

Eddy
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Re: New FHSS from JR?

Postby RCModelReviews » Thu Jan 13, 2011 8:50 pm

DMSS "Dual Modulation Spread Spectrum" is a constantly agile DSSS system (just like FASST, FrSky, Hitec's AFHSS etc).

The combination of DSSS and constant hopping provides the best of both worlds and is where they get the "dual modulation" part of the acronym from.

I would expect DMSS to perform pretty similarly to the other systems (listed above) in respect to its interference capabilities.

It's interesting that the're changing the channel grouping based on the type of model -- that's interesting and good for marketing but I'm not so sure many fliers would notice the difference if they simply grouped the channels as for a CCPM setup and used that for everything. Still, it won't hurt any so why not?

With the release of DMSS by JR, DSM2 is really starting to look very old and inadequate in today's noisy 2.4GHz environment.

Unfortunately, having gone to great lengths to paint pure DSSS as better than FHSS, Spektrum will find it hard to swallow their pride and switch to a constantly agile system. Even if they offered DSMJ then their customers would be a heap better off and they could make the transmitters backwards compatible with DSM2 so as to provide existing users with a painless upgrade path.
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Re: New FHSS from JR?

Postby raptor22 » Fri Jan 14, 2011 8:16 am

RCModelReviews wrote:I don't know where JR are going with the 11X and telemetry -- they (like Spektrum) won't talk to me -- ignoring my emails. Even my emails to the (new) local distributor didn't get a reply.

I think JR 11X users are in the same camp as Futaba 8FG users -- neither knows whether they'll be able to upgrade their radios to handle telemetry or not.

Perhaps this is just a way of ensuring that sales of radios that might not be upgradable don't stall because people might rather wait until the newer (telemetry enabled) versions are on the market.


This is purely speculation on my part but Futaba has released a beta version (2.106) software update in Europe for the T8FG. This upgrades the radio to a 14channel unit (12+2).
Since they are moving the unit upmarket I would hoep that the kings of telemetry would also ensure that the 8FG remains competitive against it main rivals and will be telemetry capable via firmware upgrade. I'm told the Nurnburg tgoy Fiar is where all will be revealed so only 3 weeks to go.

JR's release of DMSS it appears is only for markets outside the US. So unless they divorce themselves from Horizon it appears the US folk will be stuck with DSM2 until Spektrum changes tack. Would you agree with this?
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Re: New FHSS from JR?

Postby RCModelReviews » Fri Jan 14, 2011 8:30 am

raptor22 wrote:JR's release of DMSS it appears is only for markets outside the US. So unless they divorce themselves from Horizon it appears the US folk will be stuck with DSM2 until Spektrum changes tack. Would you agree with this?

Absolutely -- HH/Spektrum want to squeeze every penny they can from the US customer and so they want them buying DSM/2 because even when it's a JR-branded radio, HH/Spektrum is still collecting a pretty penny in royalties, plus their markup.

If they were to distribute DMSS they'd only get the markup on JR gear, not the commission/royalties for the DSM2 technology.

It's simple economics, from HH/Spektrum's perspective.

From the US-customer's perspective however, it's a raw deal.
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Re: New FHSS from JR?

Postby raptor22 » Fri Jan 14, 2011 8:55 am

The American Dream is a raw deal indeed.

With every bit of information available indicating that a frequency hopping system is the only way to future proof RC hardware, I find it a little irresponsible that HH choses to manage the problem the in the "Deny Deny Deny" manner. Its a great pity because I think the JR radio's are actually quite good.
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Re: New FHSS from JR?

Postby khymlawrence » Tue Apr 12, 2011 4:13 am

i have the jr xg7 DMSS... and no comment from a newbie.... hahaha
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