Bind a different rx of the same type in DSMX to the same rx.

I hate getting jammed
http://youtu.be/FcArnepkhv0?t=13s

Here's a couple other possibilities that could cause serious interference to 2.4 RC flyers, and they are both caused by fellow RC flyers. Well RC flyers doing FPV flying.

1/ a subset of us FPV flyers actually broadcast out video on 2.4 GHz. They use anywhere from 10mW to 1500mW power, and it is wide band and definitely not coded digitally nor spread spectrum. Just swamps the RCers. I have tried this myself with a 100mW 2.4 video transmitter on a plane with Spektrum radio setup - both the video and the RC link had problems, though the video suffered more than the RC link. And it was possible to get them to work tenuously - turn the video on first, then turn on the RC system and the Spektrum radio would figure out its way around the video signal leaving both working somewhat OK. Now I don't use 2.4 for video at all.

2/ A lot more of us FPV flyers use 1280MHz to broadcast our video signal to our ground station (eg video goggles). That would seem OK, but it isn't. There are significant harmonic signals also sent on approximately 2.4GHz, which is the first harmonic double of 1280, given the wide bandwidth needed for analog video. The more conscientious FPVers will use a low-pass filter to attenuate the harmonics because we're nice, and also even some of use use 2.4 to fly with (I use 2.4GHz and 433MHz for RC control).

just throwing this out there for discussion. I hate to see fellow Flyers getting 'jammed'

Originally Posted by jasmine2501

Yes, but they should be relatively equal in terms of time spent on each frequency, from one TX to the other. I am still not clear on what Spek means by "Smart" hopping or "adaptive" or whatever they call it... but I'm pretty sure it's not adapting to anything happening at the receiver.

That is - if there's 30 channels, I would expect that ALL transmitters spend 1/30th of their time equally on each of those channels, regardless of differences in the pattern. Like, how many different ways can you write the numbers from 1 to 30 in different order, while only using each number once... 30-factorial? I don't know, but it's a lot.... and they all use each channel one time in the pattern. So, I don't think there should be any difference between one transmitter and the next.

The use 23 out 78 channels, the have 49 spreading codes* avaible, the use variety hop pattern. DSMX is code and frequency agile and use unequal hop spacing.

*CYWUSB6935

Forty-nine spreading codes selected for optimal performance (Gold codes) are supported across 78 1-MHz channels yielding a theoretical spectral capacity of 3822 channels.

Originally Posted by jasmine2501

FASST uses two channels at the same time, while hopping, and spreading with DSS. Keep in mind that whenever you increase complexity, you decrease reliability (unless you do something to compensate for the increased complexity, and your compensation method represents another increase in complexity).

This might help... he shows the signals in frequency domain. (Note Hedy Lamarr in the preview slide)

http://www.youtube.com/watch?v=wrDRhGizof0

I found this very informative - thanks for posting!
Scott

23 out 78 give 3.45013035e+19 possible combinations.

I can't do that on my fingers - so I will accept that stepping on someones frequency and killing it is jus a pipe dream-
I still adamantly believe thta 99%of the failures attributed to rx lockout are simply screw ups on the part of the user.
I spent a few years doing Beta testing on new gas engines for an importer - very informative .
Those that "got it" never had a moments trouble -those who had a better idea on how to setup engines were constantly burning em up. or shaking things to pieces or wrecking ignitions - on n on.
This radio stuff is the same thing all over again - in Spades.

Originally Posted by BCSaltchucker

Here's a couple other possibilities that could cause serious interference to 2.4 RC flyers, and they are both caused by fellow RC flyers. Well RC flyers doing FPV flying.

<snip>

just throwing this out there for discussion. I hate to see fellow Flyers getting 'jammed'

Thank you.

I use a 50mW 5.8g system myself, and it works just fine. Until I fly behind a tree or something I have a friend who uses 1280 or 5.8 depending on what he's doing, and the filters definitely help.

Andy

I'm going to tell a story about someone that was blasting Spektrum on the internet.He said that his receiver lost bind. Horizon sent him another one. It wouldn't bind either. horizon told him to send in the radio to have it checked and he was mad.

I'm a dealer and sell all the brands and I think I have a good working knowledge of how all the systems work.

I sent him a PM to call me so I could help. I went thru the binding process step by step and sure enough no bind. The following is our conversation to find what the problem was.

ME what battery are you using?
HIM A 4.8 750ma.
Me when was the last time you flew?
HIM two weeks ago and everything worked.
ME How many flights?
HIM 5 flights
ME Can you check the voltage?
HIM how do you do that?
ME When did you charge the battery last?
HIM Do I have too?
ME Charge the battery over night and try the bind again in the morning and call me.

The next day he calls to tell me after the charge everything was working again. Told me no one had told him about charging the batteries.

He never went back to his thread and told people why the radio lost bind. No more posts.

Just another example of how Spektrum "looses bind" without the truth being told. Dennis

No surprise to me -
A a 4.8 v 750 ma pack -even fully charged is typically far smaller than all but the most tiny servos can use.
I got into a little discussion with a guy on using th 2000ma ENELOOPS as rx packs - he said -they sell em as rx packs and they work.
In testing them using Horizon ampmeter set on 2 amps - -each pack of four I tested (I have a bunch of latest ENELOOP) dropped instantly from 5.5 v to 3.8 aprox-that is a 1.7 volt drop!
As long as users persist in using cells with little ability to resist voltage depression- the problem with "rx failure" will just keep on going.
I don't expect the problem to go away-

Originally Posted by Dadstoysbg

I'm going to tell a story about someone that was blasting Spektrum on the internet.He said that his receiver lost bind. Horizon sent him another one. It wouldn't bind either. horizon told him to send in the radio to have it checked and he was mad.

I'm a dealer and sell all the brands and I think I have a good working knowledge of how all the systems work.

I sent him a PM to call me so I could help. I went thru the binding process step by step and sure enough no bind. The following is our conversation to find what the problem was.

ME what battery are you using?
HIM A 4.8 750ma.
Me when was the last time you flew?
HIM two weeks ago and everything worked.
ME How many flights?
HIM 5 flights
ME Can you check the voltage?
HIM how do you do that?
ME When did you charge the battery last?
HIM Do I have too?
ME Charge the battery over night and try the bind again in the morning and call me.

The next day he calls to tell me after the charge everything was working again. Told me no one had told him about charging the batteries.

He never went back to his thread and told people why the radio lost bind. No more posts.

Just another example of how Spektrum "looses bind" without the truth being told. Dennis

sling blade (0 min 4 sec)

Originally Posted by BCSaltchucker

2/ A lot more of us FPV flyers use 1280MHz to broadcast our video signal to our ground station (eg video goggles). That would seem OK, but it isn't. There are significant harmonic signals also sent on approximately 2.4GHz, which is the first harmonic double of 1280, given the wide bandwidth needed for analog video. The more conscientious FPVers will use a low-pass filter to attenuate the harmonics because we're nice, and also even some of use use 2.4 to fly with (I use 2.4GHz and 433MHz for RC control).'

Two times 1280 is 2560. Doesn't the 2.4GHz band go from 2350 to 2550?

Originally Posted by jasmine2501

Two times 1280 is 2560. Doesn't the 2.4GHz band go from 2350 to 2550?

yebbut we use up a good 40mHz bandwidth

but to tell you the truth I have flown many times with my 1280 video running and no lowpass filter, while other folks fly Spektrum all around me and no issues detected. This is coming from that rare instance within the wider FPV comunity, not my personal experience. Of courseI have heeded the warning and keep the lowpass filter on there nowadays.

Originally Posted by jasmine2501

Two times 1280 is 2560. Doesn't the 2.4GHz band go from 2350 to 2550?

If only it were that simple! There are areas off to each side that are affected too. It looks more like a bell curve.

A channel isn't a single frequency, it's a continuous band of frequencies between two points. Instead of 1280 think 1260 to 1300 (for the 40MHz he mentioned). Then you double both of them - 2520 and 2600. Then you add on the crap to each side, and it's suddenly very easy to see how they overlap a little.

If you could look at a spectrum analyzer you would see a bell curve that is highest in the 2520-2600 range but still extends outwards some.

Andy

Originally Posted by richard hanson

I got into a little discussion with a guy on using th 2000ma ENELOOPS as rx packs - he said -they sell em as rx packs and they work.
In testing them using Horizon ampmeter set on 2 amps - -each pack of four I tested (I have a bunch of latest ENELOOP) dropped instantly from 5.5 v to 3.8 aprox-that is a 1.7 volt drop!
As long as users persist in using cells with little ability to resist voltage depression- the problem with "rx failure" will just keep on going.
I don't expect the problem to go away-

That is both surprising and worrying - I use Eneloops regularly as RX packs on my slope models, and many of my friends use them on 6 digi servo F3X ships (indeed I just bought a pack for my Acacia 2). Are these the new 3rd generation Eneloops, or the 2Gs (which everyone I know swears by)?