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2.4ghz metal on metal interference

Old 05-22-2011, 03:53 PM
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yukonpete
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Default 2.4ghz metal on metal interference

I was told that 2.4Ghz is not suseptable to interference from metal on metal like FM . Is this correct??

Thanks
Old 05-22-2011, 04:18 PM
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BuschBarber
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Default RE: 2.4ghz metal on metal interference


ORIGINAL: yukonpete

I was told that 2.4Ghz is not suseptable to interference from metal on metal like FM . Is this correct??

Thanks
It is very unlikely that you will see any interference from that.
Old 05-22-2011, 07:01 PM
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onewasp
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Default RE: 2.4ghz metal on metal interference

As a matter of fact the opportunity for metal to metal RFI noise on 2.4GHz is zero .
At that frequency the energy level is nil .

I was looking for a quote from Paul Beard to that effect but, while I have it filed away, I cannot put my
hands on the exact wording at this moment .

The metal to metal noise did not become a factor until we went digital in the mid sixties -late 1963 -1964 on.

The 27 MHz band was totally immune to metal to metal RFI which is why it came as a shock to us with the advent of digital Propo.
We had glitches (the real kind not the minor stuff people call glitches today) and it took about a year before that was worked out.
Initially it was thought to be the slide switches and many of us went to shorting plugs to eliminate that.
Slowly we realized the cause and that was corrected. It didn't happen overnight however and many of us hung on to our reed sets far longer than people today think.

The switch to Digital Propo was quite slow in actuality . Not the overnight sensation people today seem to think.
Reeds, in the hands of a good operator was quite competitive with the Propo sets .
The time required for a majority of fliers to have Digital Propo was about three years .

As with 2.4GHz it was a new learning process with new rules . Folks wish to label this the Mfgrs. fault but it was not .
The user had to catch up with the new positives of the system and learn to avoid the new negatives as well.
My memory is that it took roughly five years before most understood the new ground rules. Not dissimilar to the 2.4GHz learning process of today.
Old 05-22-2011, 09:33 PM
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dirtybird
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Default RE: 2.4ghz metal on metal interference

27 MHZ is not immune to metal to metal RFI nor is 2.4 GHZ.
An AM digital propro set on 27 is very susceptible. I had one.
Switching to PPM-FM helped but PCM-FM nearly cured it.
The spread spectrum system on 2.7 GHZ is nearly immune but its still there.
SS like PCM systems require the received signal to match a code. Its unlikely metal to metal RFI will match that code.
Old 05-23-2011, 06:33 AM
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onewasp
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Default RE: 2.4ghz metal on metal interference


ORIGINAL: dirtybird

27 MHZ is not immune to metal to metal RFI nor is 2.4 GHZ.
An AM digital propro set on 27 is very susceptible. I had one.
Switching to PPM-FM helped but PCM-FM nearly cured it.
The spread spectrum system on 2.7 GHZ is nearly immune but its still there.
SS like PCM systems require the received signal to match a code. Its unlikely metal to metal RFI will match that code.
___________________________________

Perhaps then you would like to discuss this with Paul Beard ?
I am quite serious.

While not verbatim it is his quote I referenced . If necessary I can paw through my files and come up with the verbatim quote.

Regarding your other remarks it may be 'possible' on bench set ups to create any number of non real world conditions . We both know of what I speak .
I am but one year younger than you. I have flown for 51 years .
In the years I spent on the tortured 27 MHZ band I never once saw, experienced or talked to anyone who had experienced metal to metal RFI .
Many of the top line Pattern ships I flew on the 27MHz band were designed with metal to metal connections on motor and both elevator and rudder.
The completely Magnificent and Majestic Taurus had both motor and elevator on metal to metal .
The elevator horn/joiner was raked 15 degrees forward for differential and was all metal .

Tell me the date you first saw a nylon quick link . I can tell you, it was after the birth of digital proportional .
Until that time we used wire bends or Du Bro quick links. Some other threaded steel links were pirated from typewriter repair locations .
At that time we made most of our own hardware as there was scant available any other way.

I will accept your points as "test bench possible" but nothing else .
At the field or in the air it didn't happen !

At your age you should well remember that . I would have said OUR ages but then I do remember .

That is why we were all caught flat-footed with the digital Propo vulnerability to metal to metal noise.
Remember now, this was many years before mufflers of any kind and the throttled RC engines we flew ALL had
metal to metal exhaust baffles . I can still see them vibrating as we did our power on pre-flights .

Park the degrees and get rational. IEEE does NOT answer all and we both know it .
Old 05-23-2011, 08:46 AM
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Dick T.
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Default RE: 2.4ghz metal on metal interference

So, who is Paul Beard and what makes his opinion any better than others?
Old 05-23-2011, 10:11 AM
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onewasp
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Default RE: 2.4ghz metal on metal interference

Dick,

Are you honestly asking that question or is this a put on ?
Old 05-23-2011, 10:35 AM
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BuschBarber
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Default RE: 2.4ghz metal on metal interference

I have no idea who Paul Beard is, either.

Is he a descendant of Black Beard? Where is the map to the Treasure?
Old 05-23-2011, 10:40 AM
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Dick T.
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Default RE: 2.4ghz metal on metal interference

Asking.

I've been in this hobby (and the hobby industry) since 1965 and never heard that name.

Often someone puts up a name well known to them they may just be a regional guru or some obscure individual known only in a specific profession. Paul Beard may be a circus clown dabbling in self promotional electronic blathering for all I know.

Basically, to many on RCU, their name is meaningless without knowing who or what they are and why their opinion is elevated above others.

Old 05-23-2011, 11:23 AM
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Default RE: 2.4ghz metal on metal interference

IEEE does NOT answer all and we both know it .
[/quote]

Normally, I don't get into these 'my dad can beat up your dad' discussions.
BUT......I don't have any hesitation when info is put out that can mislead newcomers or others that have no knowledge of anything electrical.

In this case....Wasp is soooo incorrect that I thought I would quote the only thing I agree with....and is generally well known anyway.

Dick....thanks for a great product....I've had a couple of them.
Old 05-23-2011, 11:46 AM
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BuschBarber
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Default RE: 2.4ghz metal on metal interference

I did a search for Paul Beard and RC. He has made some significant contributions.

http://www.patentgenius.com/inventor/BeardPaul.html
http://en.wikipedia.org/wiki/Spektrum_RC
http://www.fai.org/awards/recipient.asp?id=30170
Old 05-23-2011, 12:11 PM
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Default RE: 2.4ghz metal on metal interference

He's a great guy too and the DSM guru at Horizon.
Old 05-23-2011, 01:02 PM
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onewasp
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Default RE: 2.4ghz metal on metal interference


ORIGINAL: Dave Harmon

IEEE does NOT answer all and we both know it .
Normally, I don't get into these 'my dad can beat up your dad' discussions.
BUT......I don't have any hesitation when info is put out that can mislead newcomers or others that have no knowledge of anything electrical.

In this case....Wasp is soooo incorrect that I thought I would quote the only thing I agree with....and is generally well known anyway.

Dick....thanks for a great product....I've had a couple of them.
[/quote]
_____________________________________

Obviously we are coming from two different view points.
Really it doesn't matter, perhaps to EE's
But why don't you tell we where it deals with the protocols ?

All answers to all things eh.
I've underrated it.



Old 05-23-2011, 01:44 PM
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Default RE: 2.4ghz metal on metal interference

Why don't we all agree that the probability of metal-on-metal interference on 2.4 GHz is very very low.

When someone claims it is zero they lose their credibility in my opinion.
Old 05-23-2011, 02:41 PM
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onewasp
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Default RE: 2.4ghz metal on metal interference

ORIGINAL: JPMacG

Why don't we all agree that the probability of metal-on-metal interference on 2.4 GHz is very very low.

When someone claims it is zero they lose their credibility in my opinion.
_________________________________

That I can buy .

Little in this world is without qualification .
I just keep forgetting that IEEE is a "Political-Religion" .


Old 05-24-2011, 05:40 AM
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MX240
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Default RE: 2.4ghz metal on metal interference

WOW, you have to be kidding me that there was no interference on the old 27 band from metal to metal contact.
As someone that grew up flying rudder only in the late fifties I have soldered two metal parts together with a little wire loops to stop the interference between the two parts.

(The completely Magnificent and Majestic Taurus had both motor and elevator on metal to metal .
The elevator horn/joiner was raked 15 degrees forward for differential and was all metal .)
YES AND I EVEN HAVE SOLDERED THESE TWO PARTS TOGETHER ON THIS VERY PLANE WITH A WIRE LOOP!
Old 05-24-2011, 06:28 AM
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Default RE: 2.4ghz metal on metal interference

ORIGINAL: MX240

WOW, you have to be kidding me that there was no interference on the old 27 band from metal to metal contact.
As someone that grew up flying rudder only in the late fifties I have soldered two metal parts together with a little wire loops to stop the interference between the two parts.

(The completely Magnificent and Majestic Taurus had both motor and elevator on metal to metal .
The elevator horn/joiner was raked 15 degrees forward for differential and was all metal .)
YES AND I EVEN HAVE SOLDERED THESE TWO PARTS TOGETHER ON THIS VERY PLANE WITH A WIRE LOOP!
________________________________________

The OP's question concerned 2.4GHz and I believe that has been answered.

I threw in the 27MHz days for perspective only.

Should you care to start another thread regarding the 27MHz band I will be happy to join you there.
It will, by its very nature, be a bunch of 'old timers'. That's not all bad come to think about it .
Old 05-24-2011, 06:36 AM
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Default RE: 2.4ghz metal on metal interference

Biggest problem there, especiallly in the South was bubba with his giant 4x4 and 20k watt linear on his Childrens Band radio
Old 05-24-2011, 07:09 AM
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Rodney
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Default RE: 2.4ghz metal on metal interference

Dirty bird is correct. You can have metal to metal interference on all bands, 27, 50, 72, 75 MHz and on 2.4GHz. It is less likely to happen on 2.4 but does happen. I have personally witnessed the effect. As an EE, I have done a lot of work on most aspects of electronics and any time you can create a difference in potential between two objects and let it discharge between them, you generate a pulse of energy over a wide range of frequencies. If the charge is large enough, you will be able to cause interference over a large range of frequencies.
Old 05-24-2011, 07:24 AM
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onewasp
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Default RE: 2.4ghz metal on metal interference

ORIGINAL: BarracudaHockey

Biggest problem there, especiallly in the South was bubba with his giant 4x4 and 20k watt linear on his Childrens Band radio
__________________________________

Wasn't just the South unfortunately.
The North had the same problems .
It did have one positive however, when you were hit (we often had a monitor on at the field to ID the sources )
you knew you weren't getting it back .

Well do I remember doing the polarity dance .
I don't remember any positive results but try we did.

In 1960 we had some Super Regens whose front ends were as wide open as the Big Sky country.
Needless to say that didn't help things at all .
Old 05-24-2011, 11:28 AM
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Bax
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Default RE: 2.4ghz metal on metal interference

The "Good Old Days".....

Ahhhh, yes.  A scene of someone running across the field, towards an airplane in the air, with transmitter held high above the head yelling, "I ain't got it!"

...someone having difficulties with their transmitter, and then holding it by the antenna and tapping the entire unit on the ground (this was a transmitter that was box about 12" x 12" x 5" or so).

....remembering the "B" battery.

...putting a counting box on the transmitter so you didn't have to remember the count for left, right, up, or down.

...touching a screwdriver to the engine and seeing the servos jump.

Then just add some metal-to-metal noise and your AM system let you know it...especially when the engine was running.
Old 05-24-2011, 11:57 AM
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Default RE: 2.4ghz metal on metal interference

Bax,

Ahhhh,

Do NOT forget the sign of a good weekend at the field .

Going home with enough BIG pieces so that you could make it back for the next week end .

I'm afraid my sympathy level for today's "The Radio did me in" pilots is more than a little
lacking in real heart felt consolation .
They simply have no idea how great things really are !

Edit addition:
Tripping lightly over the years, or is that eons, I just remembered the constant maintenance of the
reed systems .
I was the one who showed up with all the screws in place on my Tx back. Simple meaning,
I had done all my tuning at home on the bench . While also cleaning the reed bank with a brand new dollar bill .

Most of our guys took the screws for the back cover off the Tx the day they got it and left it that way as it was much easier to
rip the cover off and tune that recalcitrant pot .
Then, ..... after getting everything tuned to absolute perfection you had to "fuss" (being polite) with it some more as you tuned for a solid simul setting .

That was all a piece of cake that could be accomplished in just a couple of hours.

The REAL challenge was getting the relays to work !!
I don't think I ever got the last one set any earlier than about 2:00AM .
If you have never 'played' with relay settings it is impossible to describe !
The language simply hasn't the words .

One thing certain, we had the flying bug BIG time as one ship was the equivalent of 90 days in the basement.
Those who did that and then risked it all at the flying field were simply a different breed .

Comparing it to today is impossible unless you were one of them .

With the world's best reed equipment we figured it would take three airplanes to complete a full season .
Seldom were we wrong.

Still, yes they were the good old days . I'll argue that point till the cows come home.
I enjoyed every minute of it.
Old 05-24-2011, 01:03 PM
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Default RE: 2.4ghz metal on metal interference

I admit I'm a little behind you guys because I started out with an old EK Logictrol Digital Propo. I learned to fly R/C on that thing (lost a couple too) and man I was hooked. Yep, I still flew my control line stuff but not near as often as before the Shiny New Bright RED EK. Yes, those were the good ole days. Not too many years later I picked up a Gold Case Futaba with exponential trims and off we went. I built a Flightline Models Scooter II when I had that Futaba and that baby is still flying today. I even still have the old OS 40 FSR that I ran on it and take it out once in a while for a few flights. That plane is roughly 26 years old and still going strong. Now for some interference stuff here is a picture of all the things you shouldn't do but it flies like a dream and has never suffered a single glitch in control. It has a Spektrum AR7000 and a gasoline converted SuperTigre 51 running a CH CDI. The throttle pushrod is metal and the ignition and receiver packs are nested on top of each other. If you notice the CDI case and AR7000 are sitting right next to each other. From my point of view, especially looking at this plane, 2.4 is dang near bullet proof short of an EMP device going off nearby. I just had to agitate a little but in truth I haven't dumped one due to radio problems since the 72mHz FM stuff came out. It's all been either dumb thumbs or plain ole stupidity like forgetting to refuel or charge the batteries before taking off.

As mentioned above, I keep hearing the same "I got hit" or "The radio glitched" and funny thing is some folks just never seem to have any problems. "Scratching Head" I wonder why that is. Any clues?
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Old 05-26-2011, 06:24 PM
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dirtybird
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Default RE: 2.4ghz metal on metal interference

I remember when flying my new C&G reed system I had several unexplained glitches. I tried everything but they persisted. I finally took the receiver apart and guess what? I found a big black spider in there tramping around on the reeds! I had a bug in my equipment
Old 05-27-2011, 06:43 AM
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Default RE: 2.4ghz metal on metal interference


ORIGINAL: dirtybird

I remember when flying my new C&G reed system I had several unexplained glitches. I tried everything but they persisted. I finally took the receiver apart and guess what? I found a big black spider in there tramping around on the reeds! I had a bug in my equipment
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