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Difference between 2.4 module and 2.4 tx.

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David Ovenden09/06/2018 10:52:18
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jr tg2.4xp.jpgI have a JR TG2.4XP DMSS transmitter module (used in a JR 9X and 10X transmitter) That works perfectly with JR DMSS receivers. I also have a JR XG14 transmitter(also DMSS protocol) that works perfectly too with the same JR receivers. So far so good.

However, I have an Orange R8DM DMSS receiver. That binds fine with my XG14 tx. It also will bind with JR XG7, XG8, XG11 and 28X DMSS transmitters. (I know as I've tried it with them all!)

But..... I cannot bind the Orange Rx to my TG2.4XP module. It is DMSS protocol just like the transmitters listed above, but cannot bind with the orange rx. So, question for you technical bods, what is the difference between a DMSS module and a DMSS transmitter? What stops the module binding with the orange rx? Is there a way round it?

 

 

Edited By David Ovenden on 09/06/2018 10:54:11

David Ovenden09/06/2018 15:16:03
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352 forum posts
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In looking at the receiver specs I wonder if latency differences might be a cause of the problem. Receiver specs say:

Orange 8Ch 2.4GHz DMSS Compatible Receiver is designed to use with JR DMSS 2.4GHz transmitters, such as XG6,XG7,XG8 ,XG11 and XG14 under DMSS protocol mode

8ch, servo channels in R8DM, under normal status.

S.BUS output support expanding servo channels on the 8th channel of R8DM,under special status.

13mS latency under linked with XG7,and 14mS latency under linked with other transmitters.

Steve J09/06/2018 16:02:32
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1772 forum posts
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I do not believe that the specification for DMSS has ever been published or licensed to third party manufacturers, so your Orange unit is probably a reverse engineered 'almost compatible'...

Steve

Edited By Steve J on 09/06/2018 16:04:35

Peter Christy09/06/2018 19:23:48
1718 forum posts

Well the Orange DSM-X module isn't 100% compatible with genuine DSM-X receivers. On Bind'n'Fly UMX models, the throttle doesn't work, so I don't see why their DMSS stuff should be any better.

I believe someone has rewritten the firmware for the DSM-X module to make it compatible, but uploading the firmware doesn't seem simple. Maybe the same people will get round to improving the Orange DMSS receivers the same way, one day....

Basically, you get what you pay for, I'm afraid!

--

Pete

David Ovenden09/06/2018 19:38:15
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352 forum posts
17 photos

Pete, The thing is, it is a genuine JR tx module! Yes the receiver is Orange, but it works with JR DMSS transmitters. Why doesn't it work with a genuine JR tx module fitted to a JR radio. There must be a difference between the JR module and the modules fitted inside the XG txs. Or is it something else?

David Ovenden09/06/2018 19:41:44
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352 forum posts
17 photos

Steve, yes the Orange rx is an "almost compatible" but it works with the JR XG transmitters. Just not with the JR module.

Frank Skilbeck09/06/2018 21:35:31
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4601 forum posts
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Maybe the Txs and Modules do a different "handshake" with the receivers, JR have programmed their rxs to recognise both, but Orange haven't.

As there is no recognised 2.4 standard, unlike the old 35mhz ppm, it's a risk you take with reverse engineered products, if the OEM changes the standard then they will make it compatible with there own stuff but 3rd party manufacturers might not be aware that there are more than one standard.

David Ovenden10/06/2018 16:07:53
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352 forum posts
17 photos

Frank, you are probably right. No doubt when reverse engineering you look for short cuts and may not follow the manufacturers full protocol. How many people use DMSS module?

Still, it would be interesting to know if the orange rx would bind with a JR XG11MV transmitter which uses exactly the same JR tx module as I'm using.

Peter Christy10/06/2018 17:48:05
1718 forum posts

The other thing to bear in mind is that I doubt if the manufacturers take kindly to people "reverse engineering" their protocols in order to undercut their own products.

Its quite possible that JR "tweaked" their module in a way that their own receivers recognise, but others may not!

--

Pete

David Ovenden10/06/2018 19:27:27
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352 forum posts
17 photos

Just to be clear, all my receivers are genuine JR DMSS models except the one orange "copy". So my question is one of technical interest rather than penny-pinching. Was really wondering if there was a difference in the way tx modules and built-in transmitter units worked. Could it be to do with the fact that plug-in modules use PPM input whereas XG transmitters use a different "input"?

Ian Jones13/06/2018 11:06:19
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3219 forum posts
1397 photos

Not JR but on a similar vane, I use several Hitec Modules (in Futaba & Hitec module type transmitters) and one "built in" Hitec Transmitter. With these I use genuine Hitec receivers, FrSky comaptible receivers, and Ikonnik KA-6 compatible receivers; all without issues.

The issues with the JR modules/transmitters seems very strange, has anyone else experienced the same problem I wonder. Are oreange receivers cheap enough to try out a new one as a test?

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