Grounding ESC to motor frame test

[miragewsu]

Originally Posted by HeliBurns

Looks like that Maxim link demonstrates that there are IF's in a DSSS....

Well true, but I'm sure its all done on-chip multiplying the signal by a sine wave. I would think it would be tough to "jam" an on-chip function.

[HeliBurns]

Where would the LO sine wave generator be located?

[miragewsu]

Well, for my design.. We made a sine look up table in memory. Say, 40 values of sin from 0 to 2pi. Now, at corresponding time intervals according to the frequency we wish to generate, we pulled the appropriate value of the sin function and multiplied the incoming signal by that value. This is the first step of our demodulation process. We actually multiplied by both sin and cos since we had a QAM signal space which is 2d. Then you feed into the correlator to get the bits you sent.

Spektrum's system is a lot more complicated, but I would assume a similar approach is used.

[spork]

Originally Posted by HeliBurns

Kevin, I don't use wikipedia for a technical source....

A recent study showed Wikipedia to be as reliable a source as the Encyclopedia Brittanica.

http://www.news.com/2100-1038_3-5997332.html


Frankly I wouldn't take either one as the final word. But they're both excellent resources to learn a heck of a lot about a subject in a hurry. As with any source it's then up to the user to verify the facts.

[ClayK]

Originally Posted by Pinecone

Brownout is low battery power.

But you can also have other things that cause loss of signal.

Back a few pages I (post 129) did a list.

One thing for everyone to remember, if the Rx has quick connect and the Rx loses power, it reconnects quickly.

If the Rx loses the signal and starts hunting, it has to scan the 80 channels to find the Tx. If the Tx is power cycled, it may come back on the same channels or it may not, depends on the RF environment.

If the Rx cold boots from a ESD spark, it will probably NOT remember the last channels used even with quick connect, so it will have to scan for the Tx.

Anytime the Rx starts scanning the time to link will depend on how far up into the channels the Tx has picked. Say the Rx starts scanning 1 - 80. If the Tx is on 1 and 2, the link will be very quick. If the Tx is on 70 and 71, then it will take longer for the Rx to find it.

If there is a lot of noise, and the Rx loses the signal the noise may cause it to have to scan for the Tx again.

Lots of things that can happen.

I'm curious, if the issue is apparent with Spektrum receivers only, wouldn't that lead one to conclude that the issue is with the RX and not the model?

It seemed to me that this logic flow was applied to the G3 RX's from Futaba, as an example...

[spork]

Originally Posted by ClayK

I'm curious, if the issue is apparent with Spektrum receivers only, wouldn't that lead one to conclude that the issue is with the RX and not the model?

It quite possibly involves both. If the RX has less immunity to noise, low voltage, etc. these problems could arise. For most, it's probably easier to try and attack these problems of their model/setup until Spektrum makes their RX bulletproof.

[cudaboy_71]

Originally Posted by ClayK

I'm curious, if the issue is apparent with Spektrum receivers only, wouldn't that lead one to conclude that the issue is with the RX and not the model?

It seemed to me that this logic flow was applied to the G3 RX's from Futaba, as an example...

it is also a personal fact that i am running spektrum on 5 other models at the moment, and the 500 is the ONLY one with an issue. none of the others have even hinted at a glitch, much less shut down completely in 2 out of 3 flights.

i'm tending to like fogger's thinking about the larger belt in the relatively smaller boom theory. but, i'm gonna be running ALL of the suggested fixes before i go up again.

[ClayK]

Originally Posted by spork

It quite possibly involves both. If the RX has less immunity to noise, low voltage, etc. these problems could arise. For most, it's probably easier to try and attack these problems of their model/setup until Spektrum makes their RX bulletproof.

I completely agree that there is a low immunity to noise. What I find odd is the application of logic.....

If a G3 lockouts, "It's the receivers, they are bad!" mentality.
When a Spektrum brownouts/whatever, "It's the model or bad electronics setup".

The two are the same issue yet the response is diametric. I suppose that's where my beef is..... I flew G3 receivers for 2+ years on 9 different models without any issues. I've always held that there are additional issues (bearings, static, general RF, placement, etc) that is the root cause. I find it odd that since it's Spektrum, the end result/opinion has a different impact.

[Finless]

Well the G3 argument was that someone had a model running fine on FM PCM for a long time and when they went to 2048 and G3 they got lock outs. Thus it became known that the G3 was more susceptible to issues than plain old 1024 PCM. But agreed even though it IS more susceptible the issues were the model and how the user implemented.

I believe the 500 does have some issues related to more BEC noise and static than other helis and thus users need to be aware of this and do what they can to make sure it doesn't happen.

Just like the G3 issues that came up, I too ran them even on models like the Lepton where Hirobo said NOT to use them, and I never had a problem with G3 RXs!

I flew the crap out of my 500 yesterday TOTALLY STOCK mind you and here is another weekend with no issues.

I have NOT grounded my ESC or did anything about static. but I do have my remote RX in a place that I believe might be the best location.....

I am thinking that having the remote RX where the antennas are parallel to the CF frame (like Cuda has them) could be an issue.

Bob

[tkbr0wn]

Bob,

Is your remote antenna still in the same location that you had it in on the build videos?

[fogger]

A guy from my lhs had his PCM reciever in his 500 lockout this weekend. He had no grounding present. He will test the grounding on his machine. So, it is not just a problem with spektrum. I think everyone here would agree that the radio mfr's could do a better job of "hardening" the electronics.

-Fog

[Mr.Gobler]

Originally Posted by fogger

A guy from my lhs had his PCM reciever in his 500 lockout this weekend. He had no grounding present. He will test the grounding on his machine. So, it is not just a problem with spektrum. I think everyone here would agree that the radio mfr's could do a better job of "hardening" the electronics.

-Fog

I hope this is true, i have a DX7, and about to purchase a Trex 500, maybe i should wait, or research another brand.....

[HeliBurns]

fogger, I agree with you completely.....

While "hardening" is kind of a vague term with respect to specifics, one can understand exactly what you mean......

Having personally disassembled, and I don't mean any disrepect, an AR7000 main RX(not the satellite RX), I was very much unimpressed by the design of their RX PCB's......but then again, whatever works.....

While some think that we are just consumer customers, the demands of reliability as we except, puts us in a different category and we might expect issues as these to have been addressed.........with all the insight that we have seen on all these threads on this specific subject, it almost seems as if we have done almost everything possible for a cure/cures.....

On the other hand, (tongue in cheek), we just had to have the Trex 500 ASAP, and we just had to have the DSSS systems ASAP, etc.............. gotta have it now......

[HeliBurns]

Spork, I don't use Encyclopedia Brittanica for a technical resource, either....

Superficial "knowledge" is only good for BS sessions....

Haste makes waste...

[Super D]

Fogger! Are you talking about mike?

[fogger]

yup. Any word on his progress? (who's this btw ? )

[bmlasater]

fwiw..

Been flying a friends' SJM 500...really LONG carbon boom...Really long belt, no grounding, and the clear gelcoat prevents conduction from t/r assy to boom mount...NO issues with spektrum...No spray, no straps, belts or pins...Align recently released a noise filter..what freqs, and why?...This is, as they say, a puzzlement...

John.

[cudaboy_71]

someone already mentioned (sorry, i cant remember who and i'm not reading 200+ posts ) that it may have something to do with the ratio of belt width to boom diameter.

for example, on the 450 the boom is small, but the belt is narrow, too. on the 600, the belt is considerably wider---but, so is the boom. on the 500, the belt is more the size of the 600, but the boom is smaller diameter like the 450...hence a greater 'van de graff' effect.

that may or may not be the case. but, it sounds good, and i'm sticking with it barring some revalation.