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Old Dec 13, 2012, 11:18 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
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JR DMSS protocol

I learned something interesting today. It seems that the Chinese companies are quick to knock off receivers. First DSM, then DSM2, then Hitec AFHSS, and now the new DMSS protocol. I did some research and read about how amazing the DMSS protocol was by using a wide band spread spectrum signal hopping over the band. It turns out that it's the same format we have been using all along. The only thing odd I found was the frequency range was just 1/2 the band (2405MHz to 2450MHz). I will do some investigating, but it could likely be that the Nano could be programmed to work with DMSS systems.
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Old Dec 14, 2012, 06:17 AM
SailPlane'r
wernersville, Pa
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Or your tx modules programmed to talk to other receivers?
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Old Dec 14, 2012, 08:24 AM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
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It's possible to program our system to work with any other 802.15.4 system. First was us, then JETI, and now apparently JR. I knew our system was the best for noise rejection and speed.
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Old Dec 16, 2012, 04:23 PM
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DMSS is Japan only, DSMx should use a larger portion of the band.
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Old Dec 16, 2012, 04:39 PM
Xtreme Power Systems
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No, that is not true. DSMJ is the system used in Japan. DMSS is JR's new (non-spectrum, not DSMJ compatible) system that was released. Look at JR's new XG6, XG8, XG11, etc. These are all being sold in the U.S.

DMSS apparently uses 10 frequencies (2405MHz to 2450MHz) of the ISM band, using 802.15.4. I know their receivers use the CC2520 Zigbee RF chip. So, they are basically using a reduced frequency version of what the XtremeLink system is. I will have one of their complete systems with telemetry here this week to confirm. I suspect that the telemetry channel is likely above 2450MHz and that is why they don't use more than 10 frequencies. Our telemetry data is transmitted on the current hopping channel, so we can use 12 frequencies in the U.S. and 16 frequencies outside of the U.S. JR's brags in their DMSS ads about 'wide band DSSS' transmissions hopping over the band, which got me curious since that is what I have believed would be the most robust system possible, and why I chose it for XtremeLink. I found info on their receiver using a Zigbee compatble RF chip, and it makes sense. JETI also uses the same system we do.

Edit: the 10 frequencies is for France setting... they use the same frequencies as we do otherwise.
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Old Dec 16, 2012, 06:20 PM
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Yes, I had that confused with DSMJ
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Old Dec 17, 2012, 11:58 AM
Radio? Screwdriver!
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Quote:
Originally Posted by JimDrew View Post
I learned something interesting today. It seems that the Chinese companies are quick to knock off receivers. First DSM, then DSM2, then Hitec AFHSS, and now the new DMSS protocol.
The Hitec A-FHSS compatible receivers are not knock off's. Also how do you know that the Chinese developed it?

Quote:
Originally Posted by JimDrew View Post
The only thing odd I found was the frequency range was just 1/2 the band (2405MHz to 2450MHz).
Likely done so that they wouldn't have required a separate version for the French market. Futaba do this too for their S-FHSS protocol. However that 2.4GHz band restriction was finally lifted in France earlier this year.

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Originally Posted by JimDrew View Post
I will do some investigating, but it could likely be that the Nano could be programmed to work with DMSS systems.
On the same reasoning above, these DMSS Nanos will be knock-offs.

Si.
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Old Dec 17, 2012, 02:14 PM
Xtreme Power Systems
Lake Havasu, AZ
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The Hitec A-FHSS compatible receivers are not knock off's. Also how do you know that the Chinese developed it?
Because a Chinese company we met with at the 2010 Nuremberg toy fair offered these to us last year. You were not the first to discover that they forgot to burn the fuse links in their micros.


Quote:
Likely done so that they wouldn't have required a separate version for the French market. Futaba do this too for their S-FHSS protocol. However that 2.4GHz band restriction was finally lifted in France earlier this year.
Except power output would have to also be limited, and that is not the case.
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Old Dec 17, 2012, 02:28 PM
SailPlane'r
wernersville, Pa
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So, now that we know that you can do it.

Are you planning to add that ability to your TX modules?

Quote:
Originally Posted by JimDrew View Post
No, that is not true. DSMJ is the system used in Japan. DMSS is JR's new (non-spectrum, not DSMJ compatible) system that was released. Look at JR's new XG6, XG8, XG11, etc. These are all being sold in the U.S.

DMSS apparently uses 10 frequencies (2405MHz to 2450MHz) of the ISM band, using 802.15.4. I know their receivers use the CC2520 Zigbee RF chip. So, they are basically using a reduced frequency version of what the XtremeLink system is. I will have one of their complete systems with telemetry here this week to confirm. I suspect that the telemetry channel is likely above 2450MHz and that is why they don't use more than 10 frequencies. Our telemetry data is transmitted on the current hopping channel, so we can use 12 frequencies in the U.S. and 16 frequencies outside of the U.S. JR's brags in their DMSS ads about 'wide band DSSS' transmissions hopping over the band, which got me curious since that is what I have believed would be the most robust system possible, and why I chose it for XtremeLink. I found info on their receiver using a Zigbee compatble RF chip, and it makes sense. JETI also uses the same system we do.
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Old Dec 17, 2012, 02:59 PM
Radio? Screwdriver!
United Kingdom, England, Bristol
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Quote:
Originally Posted by JimDrew View Post
Because a Chinese company we met with at the 2010 Nuremberg toy fair offered these to us last year. You were not the first to discover that they forgot to burn the fuse links in their micros.
Erm, I'm guessing you didn't read through the first post. Either way, I'm a bit insulted that you are implying I simply copied the firmware. My firmware is completely my own - this is most obvious in the fact that there is both 8 channel and 5 channel versions - that output PPM/RSSI, that none of the Hitec receivers do. Thus the Chinese outfit that offered you them would be selling clones, thus breaking copyright law and bring up a whole lot of other problems. Where as my version obv doesn't have that problem...

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Except power output would have to also be limited, and that is not the case.
In the lower band (2400 to 2450MHz) France had the same output power as the rest of Europe - i.e. 100mW. The upper band 2450->2480, if used outdoors, was limited to 10mW.

However this is all academic, as this restriction was removed earlier this year.

Si.
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Old Dec 17, 2012, 06:03 PM
Xtreme Power Systems
Lake Havasu, AZ
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Originally Posted by cluft View Post
So, now that we know that you can do it.

Are you planning to add that ability to your TX modules?
No, the Hitec/FrSky/Hott systems use the narrow band transmission TI CC2x00 series chipset. This is not compatible with our data format.
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Old Dec 17, 2012, 06:22 PM
Xtreme Power Systems
Lake Havasu, AZ
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Originally Posted by SimonChambers View Post
Erm, I'm guessing you didn't read through the first post. Either way, I'm a bit insulted that you are implying I simply copied the firmware. My firmware is completely my own - this is most obvious in the fact that there is both 8 channel and 5 channel versions - that output PPM/RSSI, that none of the Hitec receivers do. Thus the Chinese outfit that offered you them would be selling clones, thus breaking copyright law and bring up a whole lot of other problems. Where as my version obv doesn't have that problem...
No need to be insulted! I didn't suggest that you copied the original code. I merely pointed out that there were others that knew the chips were not locked. Obviously I could not copy their code for our module replacement, but I could definitely confirm (as could you) that my assumptions about how it worked were correct.


Quote:
Originally Posted by SimonChambers View Post
In the lower band (2400 to 2450MHz) France had the same output power as the rest of Europe - i.e. 100mW. The upper band 2450->2480, if used outdoors, was limited to 10mW.

However this is all academic, as this restriction was removed earlier this year.

Si.
Actually, the indoor power was different from the rest of Europe. But as you say, the restrictions have been lifted to match EN300-328.
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Old Dec 17, 2012, 07:01 PM
SailPlane'r
wernersville, Pa
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Quote:
Originally Posted by JimDrew View Post
No, the Hitec/FrSky/Hott systems use the narrow band transmission TI CC2x00 series chipset. This is not compatible with our data format.

I found two nanos hiding in a parts box and an XPS tx module is on its way to fit my hitec a9 so I'm good to go in the spring.

I just thought it would be cool to watch some jaws drop when I powered on my A9/XPS system to controll a plane with a JR receiver

"Oh well"
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Old Dec 18, 2012, 01:16 PM
Xtreme Power Systems
Lake Havasu, AZ
Joined Jun 2005
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Well, it's confirmed. JR now uses the same over-air protocol that we use. Nice to see them getting away from Spektrum technology, realizing we had the best design from the beginning, and going with it. They do use fewer frequencies than we do though, making it a less robust system than ours.
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Old Dec 18, 2012, 03:18 PM
SailPlane'r
wernersville, Pa
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Originally Posted by JimDrew View Post
Well, it's confirmed. JR now uses the same over-air protocol that we use. Nice to see them getting away from Spektrum technology, realizing we had the best design from the beginning, and going with it. They do use fewer frequencies than we do though, making it a less robust system than ours.
Ok, one more thought:

Does your system have more frequencies because it uses the entire band or it uses tighter frequency spacing

Also, I kinda remember that you got an increase in range by going to freq. hopping.
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