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  1. #1

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    Experience of JR DMSS

    JR new style modulation DMSS.Dose anyone have experienced this new Radio?Thanks for your sharing!

  2. #2
    Zor's Avatar
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    RE: Experience of JR DMSS


    ORIGINAL: CPS

    JR new style modulation DMSS.Dose anyone have experienced this new Radio?Thanks for your sharing!
    No one has responded in three days.

    Please post again and state the new radio model you are concerned with.

    DMSS is not a radio. It is a mehod of using the spread spectrum technology in the 2.4 Ghz band.

    Zor

    Edited to correct two keyboard errors.(spelling).

  3. #3
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    RE: Experience of JR DMSS

    Its a "hopper"

    DMSS started as an Japan only deal. DMS2 can not be used in Japan, so JR came up with DMSS to replace their DMSJ. Yes I said DMSJ [:@]

    I think JR is going sell it else where (not in US yet), but I think DMSS will replace DMS2 in the US someday.

    I know this doesn't help you at all, sorry.
    Maybe I should just take rubbing alcohol with me to the field and rub the props down before starting any of my planes!

  4. #4

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    RE: Experience of JR DMSS

    There is only one set that uses DMSS and that is the XG7. It is only available in the Far East at the moment as it is not yet on general release.

  5. #5
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    RE: Experience of JR DMSS


    ORIGINAL: scooterinvegas

    Its a "hopper"

    DMSS started as an Japan only deal. DMS2 can not be used in Japan, so JR came up with DMSS to replace their DMSJ. Yes I said DMSJ [:@]

    I think JR is going sell it else where (not in US yet), but I think DMSS will replace DMS2 in the US someday.

    I know this doesn't help you at all, sorry.
    Hello scout,

    I hope some day soon I will understand better the differences between DMS, DMS2, DMSJ and DMSS.

    It is not easy to find this kind of information.

    Do you happen to know ? Could you help ?

    Zor

    Edited to replace the typing "jope" by the word "hope".(first line).

  6. #6

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    RE: Experience of JR DMSS

    Okay.... in the beginning there was DSM as seen in the DX6. (Alright, the purists will mention the modules for car systems that Spektrum designed when they where an independent company...)

    But this is a very quick noddy guide and I won't go into any technical detail.

    I believe that the DSM system only transmitted on a single channel in the 2.4 GHz RF spectrum. (DSM2 selects 2 clear channels and stays on those 2 channels.)

    Then came DSM2 which is used all Spektrums systems and all the current JR systems (less the XG7). A vast improvement but the Japanese authorities did not accept DSM2 as being valid for their home market and treated it as a 10mW based system. Fine for cars and short distances but not really viable for aircraft.

    Spektrum and JR worked together to make the current DSM2 module into a frequency hopping system and came out with DSMJ (the J indicated Japanese home market).

    The agreement that prevented JR from continuing development on their own system seems to have expired and JR have developed and released their DMSS system which is a FHSS or DSSS depending on what receiver is in use (or so I am led to believe) DMSS stands for Dual Modulation Spread Spectrum. This is only available as an XG7 currently but there are plans for an XG11 and probably an XG8, XG9 and who knows.. an XG10 or XG12 ??

    There are a lot of other systems out there but they all seem to have opted for FHSS based systems instead of DSSS systems.


  7. #7
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    RE: Experience of JR DMSS


    ORIGINAL: slarty

    >
    >.

    But this is a very quick noddy guide and I won't go into any technical detail.

    >
    >
    Thanks starty,

    A brief technical aspect is what I am looking for so we (the readers) can have a good mental picture of the various aspects.

    Seasojn's Greetings.

    Zor


  8. #8

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    RE: Experience of JR DMSS

    JR is like Apple , you just understand the system and you have another one available , I have bough a 11X with DSMX at the beginning of this year ... it is already obsolet with that DMSS ... it sucks

  9. #9
    Moderator BarracudaHockey's Avatar
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    RE: Experience of JR DMSS

    Why is it obsolete? Is it not doing something you expect of it? Its firmware is updateable and its fully supported by JR, I don't understand your statement.
    Andy - Helicopter Forum Moderator
    AMA 77227 Leader Member- Contest Director
    www.JaxRC.com

  10. #10
    Zor's Avatar
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    RE: Experience of JR DMSS

    Hello gentlemen,

    I am glad to see this topic brought back alive from 2010.

    I am one that would like to understand better what is going on with the DMS systems.

    I happen to be one of the rare fellows who likes to understand how things work (function).
    Most people are satisfied as long as it works for their purpose. They do not feel any need to know any more. When I tried to find information I found it next to impossible.

    I imagine that has not chnaged as developers of systems are very secretive as they are competing in the market.

    Frequency hopping, as I imagine it, is a constant change in emitted frequency in time.
    I do not know at what rate the changes are taking place or if there is a pattern in the switching of frequency.
    I do not know how the receiver gets to know where in the band to listen to for the next frequency shift.
    Perhaps the receivers are just wide frequency responding (poor selectivity).

    I also do not understand "Dual Modulation". Does it mean that at one moment a specific modulation type is used and then it is switched to a different type of modulation ? What types are used? I do not know.

    It all has to end up in the proper signals that servos need at their signal line input and it appears that all servos need the same signal which is a variable time DC pulse. The rate of these pulses can vary but we are still limited to the ability of any servo to produce the resolution of the control surfaces.

    We cannot get better resolution than the servos are capable of resolving no matter what the feeding rate to them is. Advertising higher resolution like 2048 does not change the ability of the servos to deliver. That is just a marketing gimmick as far as I understand.

    Any comments posted would be nice to read.

    Zor


  11. #11
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    RE: Experience of JR DMSS


    ORIGINAL: BarracudaHockey

    Why is it obsolete? Is it not doing something you expect of it? Its firmware is updateable and its fully supported by JR, I don't understand your statement.
    JR will swap a DSMX to DMSS?


    Even If so, why do it ?
    Libby is still watching you

  12. #12

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    RE: Experience of JR DMSS


    ORIGINAL: rmh


    ORIGINAL: BarracudaHockey

    Why is it obsolete? Is it not doing something you expect of it? Its firmware is updateable and its fully supported by JR, I don't understand your statement.
    JR will swap a DSMX to DMSS?


    Even If so, why do it ?
    I don't think he means a DSMX to DMSS upgrade. I think he means that the 11X is not obsolete. There is still support for it and it is still compatible with all DSM2/DSMX Rx's.
    Rich
    byronf16@gmail.com

  13. #13
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    RE: Experience of JR DMSS

    2.4 - the less some know about it the more prone they are to believe there is some "superior' protocol.

    This has gotten to be like gasoline
    some actually belive there are superior brands of gasoline ,here in th e US
    Note - gasoline supplies are often traded -
    Libby is still watching you

  14. #14

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    RE: Experience of JR DMSS

    ORIGINAL: Zor

    We cannot get better resolution than the servos are capable of resolving no matter what the feeding rate to them is. Advertising higher resolution like 2048 does not change the ability of the servos to deliver. That is just a marketing gimmick as far as I understand.

    Any comments posted would be nice to read.
    A few notes:

    1) You're right, you cannot get better resolution than the servos can deliver. However, there are detectable differences between resolutions even with poor servos. For instance, compare the same servo with PCM-512, PCM-1024, and a 2048 system like Spektrum (use a high-end rx and tx to see it). You will see a difference.

    2) It's not just a marketing gimmick. High quality servos will show that even more. If you choose to fly crappy servos, then you won't get resolution and your aircraft will fly accordingly.

    It's not just the signal to the servo, it's the math leading up to it too.

    Andy


    Andy Kunz - AMA 46063
    Spektrum Development Team

  15. #15

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    RE: Experience of JR DMSS

    amazing. Andy says a difference in resolution is detectable when using a 2048 resolution PLectrum radio, but before they had it the resolution was indetectable to even the best pilots. LOL. And we're supposed to believe anything you say because its the gospel truth...Heck, What next Andy, Frequency hoppng is needed for connection security and DSM2 was never good enough? I'm sure it will come when you think the market has forgotten.

    DMSS, all reports from pals who have bought it are loving it. One pal swiched from a DX7 to the XG8 and says the connection has been glitch free. He lost quite a few planes on that DX7. He also has a 8FG but being locked into JR he decided to move with DMSS instead.

  16. #16
    Moderator BarracudaHockey's Avatar
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    RE: Experience of JR DMSS

    You can tell the difference between 1024 and 2048. But to tell the difference you need very high performance equipment (fast servos, zero slop linkages) on something like a helicopter, and you have to be a damn good pilot.
    Andy - Helicopter Forum Moderator
    AMA 77227 Leader Member- Contest Director
    www.JaxRC.com

  17. #17
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    RE: Experience of JR DMSS

    No - listen to the words from the land of the lost -
    Plus - pals are loving it -
    In the order of detectible difference- worst to best situation-
    PCM 512- 1024 2048- anlogue then 2.4 systems with latest 1024/2048 rx.
    Anybody elses tests show a different order of responses?
    A good 1024 setup- on 2.4 is in practice hard to beat - The 2048 IS on test better but in a blindfold test -hard to detect. All the 2.4 stuf is very close -those I have seen.
    Libby is still watching you

  18. #18
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    RE: Experience of JR DMSS

    For some of ussome attraction to the hobby is the understanding of "what is going on" with our activities.

    We read a lot for example about "digital" and many become convinced that digital is much superior being more accurate and more reliable.

    How many RC fliers (pilots) have looked into the functioning of their rigs (transmitters, receivers, servos, Electronic Speed Controls and other various items they spend money on to use).

    The digital manipulation of electronic signals is a convenience for mathematical handling but it is still entirely dependent on analog inputs to the digital manipulation.

    ADC and DAC converters are fine devices but potentiometers are devices that will handle digital signals but do so in an analog way.

    When a pilot handles the sticks on his transmitter, all he is doing is moving the rotation of a contact in a potentiometer and not onlyare the potentiometers an analog device but what is picked up by the variable contact in the potentiometer is actually a regulated DC potential. There is nothing digital at that point of generating such resolution as 512, 1048 or 2048.

    Quite obviously the capability of moving our control surfaces on our models with lots of resolution which means that we can reliably move the surfaces in very tiny angles of rotation is affected by many contributing factors.

    Slop (mechanical looseness) in the servos to control surfaces has to be absolutely absent.
    Look at a system claiming 2048 resolution. That signal resolution still ends up invariable width pulses (pulses timing duration) at the servo signal wire and those variable width pulsestiming is an analog variation.

    The servos know they have reached the commanded position using another analog device (a potentiometer) monitoring the servo output shaft position.

    So ___are we using digital commands to our model airplanes ?
    Do we have great advantages of using claimed 1024 resolution as being twice as accurate as 512 ?
    Which specific servos can resolve 2048 variations of pulses durations that last from one to two miliseconds at the signal wire of the servos ?

    Look at the arm on a servo and use some radius (1/2" or 1" or any radius) where the linkage is connected and calculate the linear motion of that linkage with a 120 degrees of servo rotation (limit to limit) .
    That will show you for sure how much slop could be tolerated.

    Put a sensitive motion gauge on the servo arm (like I have done) and see the smallest reliable rotary motion the servo will provide and compare to the calculated value for 2048 resolution. That is a real fun experiment.

    OK ___who cares ? Perhaps you are a reader but not interested.

    Thanks for reading up to here and enjoy your day.

    Zor

    Edited to change "an" to "and" somewhere in the text.
    End


  19. #19
    Zor's Avatar
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    RE: Experience of JR DMSS






    ORIGINAL: Zor



    We cannot get better resolution than the servos are capable of resolving no matter what the feeding rate to them is. Advertising higher resolution like 2048 does not change the ability of the servos to deliver. That is just a marketing gimmick as far as I understand.



    Any comments posted would be nice to read.



    A few notes:



    1) You're right, you cannot get better resolution than the servos can deliver. However, there are detectable differences between resolutions even with poor servos. For instance, compare the same servo with PCM-512, PCM-1024, and a 2048 system like Spektrum (use a high-end rx and tx to see it). You will see a difference.



    2) It's not just a marketing gimmick. High quality servos will show that even more. If you choose to fly crappy servos, then you won't get resolution and your aircraft will fly accordingly.



    It's not just the signal to the servo, it's the math leading up to it too.



    Andy
    Hi Andy,

    1) I will see a difference if I can measure it in terms of linkage movements making 2048 incremental motions.

    It cannot be confirmed by flying a model. No one is able to judge a servo motion which is 1/2048 (one over 2048) of its limit to limit rotation by looking at a model in flight.

    Making a statment is one thing but proving it is another thing.



    2) The math leading up to it is what the advertising is using as a selling argument but the end results have to prove it such that the buyer can realize his money was well spent.

    If you can name a servo capable of 2048 or even only 1024 individual rotation I would like to repeat measurment as I did in the past and post picturesAGAIN of the results.

    If I have a linkage connected to a servo at 0.500" radius the cicumference is 3.141593 inches.
    A full servo rotation of plus and minus 60 degrees (120 deg total) is 1.047198" on the circumference.
    That would be divided in 2048 small arcs. Each small arc having a length of 0.000511".
    That is cutting a length of one inch in one thousand parts and again cutting each of these parts in half.
    I mention it this way for anyone not familiar with the normal decimal nomenclature.

    Now a 1024 resolution system would double this for each servo increment. It would now be 0.001023"
    The best I could have with two DS821 (I used two servos to make the measurements) was 0.0030".
    That is a resolution of just about 1024 / 3 = 341.33 ___quite far from 2048.

    Please let me know of a servo (brand or manufacturer and type or model) that can move a no slop linkage in small steps of 0.000511".

    I am also curious what this represents in terms of time variation of the pulses on the signal wire of the servo.
    If I use as limits 1.1 milisecond to 1.9 miliseconds I have 0.80 milisecond. Dividing that timing in 2048 parts I get 0.8 / 2048 = 0.000391 miliseconds or 0.391 microsecond of variation in the pulse timing.

    I want to see a potentiometer in the transmitter that will faithfully change the DC voltage so that the ADC converters will digitize the change that in turn will be converted back by DAC to produce this kind of pulse width variation to the servo wires.

    Feel free to show where my knowledge or reasoning is wrong.
    I am posting it so that you can show where I am not understanding properly.

    I think it is too easy for a pilot to be convinced that he sees what he anticipates.
    A well known characteristic of the human mind.

    Thanks for your feedback.
    NOTE: I am not trying to prove anyone wrong; I am only trying to understand the reality of the facts.

    Zor


  20. #20

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    RE: Experience of JR DMSS

    NOTE: I am not trying to prove anyone wrong; I am only trying to understand the reality of the facts.
    I think you're just being yourself and posting to match your reputation

    This thread is about "Experience of JR DMSS" - please stop trying to hijack it. Remember this thread: http://www.rcuniverse.com/forum/m_11...anchor/tm.htm# - there are others like it.

    Adios!

    Andy
    Andy Kunz - AMA 46063
    Spektrum Development Team

  21. #21
    Zor's Avatar
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    RE: Experience of JR DMSS


    ORIGINAL: AndyKunz

    NOTE: I am not trying to prove anyone wrong; I am only trying to understand the reality of the facts.
    AndyKunz
    I think you're just being yourself and posting to match your reputation
    Of course I am being myself just like you are being yourself as seen in your reply.
    I do not accept statements, much less in advetisements, if they do not make sense to me or if I cannot intelligently figure them out.

    AndyKunz
    This thread is about "Experience of JR DMSS" - please stop trying to hijack it.
    You are saying "please stop trying to hijack it" because you you have not found any faults in my reasoning.
    You have not and likely cannot show a servo that can resolve 2048 individual rotary motions.
    So what is the point of having 2048 mathematical resolution (easy to do in digital manipulations) if it ends up with barely a few hundreds.

    AndyKunz
    Remember this thread: http://www.rcuniverse.com/forum/m_11...anchor/tm.htm# - there are others like it.
    Yes I remember this thread in which a fellow had an antenna that had broken some distance away from the PC board and some fellows suggesting to him to solder a new wire on the PC board when all he had to do is avoid the risk of damaging that board. All he had to do from my suggestion was to solder a wire at the end of the remaining wire and make it the recommmended length.

    AndyKunz
    Adios!

    Andy
    Adios! ____ ___trying an easy way out ?

    Let us leave the readersmake their own judgments.
    I am only trying to understand the facts and have no reasons to make claims that I cannot explain.

    Zor

  22. #22

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    RE: Experience of JR DMSS


    ORIGINAL: Zor


    ORIGINAL: AndyKunz

    NOTE: I am not trying to prove anyone wrong; I am only trying to understand the reality of the facts.
    AndyKunz
    I think you're just being yourself and posting to match your reputation
    Of course I am being myself just like you are being yourself as seen in your reply.
    I do not accept statements, much less in advetisements, if they do not make sense to me or if I cannot intelligently figure them out.

    AndyKunz
    This thread is about ''Experience of JR DMSS'' - please stop trying to hijack it.
    You are saying ''please stop trying to hijack it'' because you you have not found any faults in my reasoning.
    You have not and likely cannot show a servo that can resolve 2048 individual rotary motions.
    So what is the point of having 2048 mathematical resolution (easy to do in digital manipulations) if it ends up with barely a few hundreds.

    AndyKunz
    Remember this thread: http://www.rcuniverse.com/forum/m_11...anchor/tm.htm# - there are others like it.
    Yes I remember this thread in which a fellow had an antenna that had broken some distance away from the PC board and some fellows suggesting to him to solder a new wire on the PC board when all he had to do is avoid the risk of damaging that board. All he had to do from my suggestion was to solder a wire at the end of the remaining wire and make it the recommmended length.

    AndyKunz
    Adios!

    Andy
    Adios! _Β*_Β*_Β*_Β*[img][/img]Β* [img][/img]Β*_Β*_Β*_Β*trying an easy way out ?

    Let us leave the readersΒ*make their own judgments.
    I am only trying to understand the facts and have no reasons to make claims that I cannot explain.

    Zor
    Zor - I see that you have once again emerged from Zorasic Park to crank up the BS Machine.

    You have the right to remain Silent!

    You MO is the same as always, to spray out a plethora of technical terms, to sound like an authority, and then cry foul when your lack of understanding is exposed.
    Rich
    byronf16@gmail.com

  23. #23

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    RE: Experience of JR DMSS

    speaking as a reader of this thread - which was asking if anyone had experience with DMSS -

    It seems as if it has wandered into a technical diatribe on the pros and cons of high resolution - which has NOTHING to do with DMSS per se.

    So - while this reader does enjoy technical discussions, let's not sidetrack the original poster's thread..

    And - no, I haven't used a DMSS radio. Been tempted, but not tempted enough to get out the checkbook.

    Out of all the places we could be, this is one of them.

  24. #24

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    RE: Experience of JR DMSS

    You will find nothing different in the software of the dsmx or the dmss Jr radios. You will not see or feel any difference in the two radios. What you will find is that if you already are using Spektrum's system, all your receivers will have to be replaced. The new JR DMSS is their own protocol on 2.4 so they can market world wide.
    If I had waited just four months more I could have had the Spektrum 18 in stead of the JR 11x for not much more. Dennis
    I just needed to add this. The plane doesn't care what protocol the plane is using to fly. If your happy then the plane is happy and your using the best radio.
    DadstoysRC. I fly what I sell
    CD Vette City Big Bird

  25. #25

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    RE: Experience of JR DMSS


    ORIGINAL: fizzwater2

    speaking as a reader of this thread - which was asking if anyone had experience with DMSS -

    It seems as if it has wandered into a technical diatribe on the pros and cons of high resolution - which has NOTHING to do with DMSS per se.

    Ditto.... anyone used a 11xg?

    Thx,
    Steve


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