9Xii / 9303 with spektrum module.Advice pls.

[diduhearthat]

My understanding of radio specs and workinds are poor.
I would like to move to the 2.4G system so for financial reasons so it would have to be the Spektrum module route.And once done i will not be moving back and forth with 35mhz with module.
I have looked at posts about the module system but i do not fully understand how much of the full benifits you get compared to the X9303.
I know you lose model match and some sort of fail safe BUT in actual performance is it as good as the full system.I have heard latency mentioned and resoltion,1024 and 2048 but i am lost on this.
I have read that you lose speed or resolution due to back log of data being decoded in the ppm side of radio?
Also i have seen a video where the Spektrum module for futaba was used and the ccpm sysyem was horrid.Would this be the same with the JR.
I know the signal part,lockouts,interferance etc is great it is just the speed or resolution or latency side i am not sure of OR understand.

[Pinecone]

The Spektrum module will add some latency, but since most people fly helis with PCM, there may be a net gain (lower patency) since PCM translation takes extra time.

The native X9303 has higher resolution, but if you already have been flying a 9303/9xII you have been fine with 1024 resoltuion. The number refers to the number of steps that the stick motion is translated into. A resolution of 2 would be a light switch, on or off. A resolution of 1024 means that the from full low stick to full high stick is translated into 1024 different positions.

The Spektrum module route is fine. At least I think so, as I have a module sitting waiting for the time to make the conversion of the Rxes in the models. :)

[growler]

I'm also extremely interested in upgrading my current 9xii with the module. either the XPS or Spekrum one.

Is there anyone else out there that can offer any more advice on this subject? Has nobody else done the upgrade yet?

Any advice would be great. Thanks.

[Pinecone]

I am flying the Spektrum module in a 9303.

You should see similar or less latency than the 9303 in PCM mode. PPM has less latency, but the module has to translate to the coding use by Spektrum. An X9303 would probably be a bit faster since it doesn't have to do the double translation. BTW CCPM on Futaba is slow (high latency) due to their CCPM translation, nothing to do with Spektrum. And unless they recode the CCPM translation, their 2.4 systems will still be slow.
el match or servo sync. Because the moudle is only getting the PPM pulse stream and power from the radio. It has no idea what model memory is selected.

Spektrum (and all 2.4 systems) are digital. The 1024 and 2048 are measure of how many steps the stick travel is translated into. The more steps, the smaller stick movement that can be transmitted to the model. Realize that some PCM system are currently running at 512 step resoultion, and maybe even LESS (I think I have heard of 256 resolution). Can you really move your stick less than 1/500 of the range?

There is no data back log. Latency means that you move a stick, the Tx reads that position and translates it into a PPM signal, which is sent to the module which translates it to a digital code, which is then transmitted. Each piece of data generated by the Tx is sent, it is just that there is a slight delay before being sent. But pretty much the same thing happens with PCM, so it has higher latency than PPM already.

So yes, a module will increase latency over PPM in the same Tx, BUT, most systems have more latency in PCM, so you will be in the same range or even faster than the same Tx in PCM mode.

Bottom line is, it works, and it works fine. Not quite as good as a full on direct implementation, but for well less than half the price of a new X9303 you can be flying 2.4 with a module.

[growler]

Thanks Pinecone for all the great info.

What about the XPS system. looks pretty impressive. Any advice?

[Pinecone]

Technically I think the XPS is super. The thing that stops me is the lack of reasonably priced Rxes. Jim Drew states that he is after the high end market, and doesn't really care about the people who have a bunch of less expensive aircraft. He had one batch of 6 channel Rxes, and no more, at least last time I checked. So you are stuck with 8 ch at $100 each.

Also missed deadlines. The whole system came out around telemetry, but no telemetry yet.

If I buy a turbine, I might do XPS, but for my flying SPektrum works fine and at $40 each for Rxes, it is mroe than good enough. :)

[Finn Erik]

Excuse my ignorance, but what is servosync?

[kamtsa]

Excuse my ignorance, but what is servosync?

This is a trademark of Spektrum. I think it means that the 50Hz pulses that are sent to the servos arrive to all the servos at the same time (as opposed to staggered pulses every few milliseconds), causing them to move together. I presume that this is also calls for the TX sticks and switched to be sampled at about the same time on the TX side.

Kam

[Finn Erik]

Ah, I see. For more presice control of the swashplate.

Thanks.

[Pinecone]

It also reorders the commands in the data stream so that they are sent right in a row, so 2 - 3 and 6 are sent together rather than having 4 and 5 in between.

[Dré]

Pinnecone,


It looks like you know were you talking about, so I have a question for you.

I like to upgrade mine 9XII with a spectrum module, because it gives me a save way to fly mine heli.
But what kind of features will I loose when I do this? or will all stay the same?


Thanks for your replay.


Greets


Dré

[Pinecone]

You will lose the setable fail safe (assuming you are using PCM) and only get fail safe on throttle. All other radio features work.

Versus getting a native 2.4 radio, like the X9303 or DSM9x, you lose Model Match and Servo Sync.

Model match binds each Rx to a specific model memory, so you can't try to fly a heli with a plank memory selected.

Servo Sync reorders how the channel is sent so all three cyclic servos get tehir new data at the same time. Reduces interactions.

Both native and module work fine.

[Dré]

Thanks Pinecone,


I went for it, and it works great.(only the antenna insert is crape)


Just feel a bit more safe, going out flying without the change some switch on his Radio, and you take a nose dive.


Greets


Dré