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Old Nov 03, 2012, 08:26 AM
AndyKunz's Avatar
Illinois
Joined Sep 2001
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Different regions have different frequencies assigned to cell links, Rich.

Here in the US our frequencies don't interfere. Other countries use the same freqs in opposite directions. Others do things way different bands.

And then there are the satellite phones.

2.4gHz is great because it's far more uniform around the globe.

Andy
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Old Nov 03, 2012, 08:34 AM
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United States, NY, Rochester
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Quote:
Originally Posted by AndyKunz View Post
Different regions have different frequencies assigned to cell links, Rich.

Here in the US our frequencies don't interfere. Other countries use the same freqs in opposite directions. Others do things way different bands.

And then there are the satellite phones.

2.4gHz is great because it's far more uniform around the globe.

Andy
I guessed as much. Thanks!
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Old Nov 03, 2012, 05:10 PM
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Originally Posted by PaulChurchley View Post
Surely we should have mobile phones on when we are flying as they can cause interference. Here in the UK the recommendation is not to have them switched on at all, not just in Flight Mode, when in or near the pits and definitely not at the flightline.

Just a thought...
Mobile phones causing interference? That sounds very puzzling considering Spektrum makes an STi module for a mobile phone... Are there any confirmed cases of a phone causing interference?
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Old Nov 03, 2012, 05:29 PM
AndyKunz's Avatar
Illinois
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Think "outside the US" and it becomes possible with the different frequencies they use.

Andy
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Old Nov 03, 2012, 05:39 PM
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Canada, ON, Rockland
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When using the iPhone to fly the ARdrone, Parrots recommends you put the phone in airplane mode.

You can do the same when using the STi device.
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Old Nov 03, 2012, 11:40 PM
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Originally Posted by AndyKunz View Post
Think "outside the US" and it becomes possible with the different frequencies they use.

Andy
There are way bigger problems on 2.4GHz than cellphones. This is also a primary band for point to point data services, TV ENG operations, and things I'm not even sure about (yet). The top pic is a sweep from 2.4 to 2.5GHz with my DX8 and the Hex with a TM1000, all separated by about 30' between us. The 3 pedestals is the DX8, but mixed in with this is the building WiFi; Note the noise floor @ aprox. -65db... Thats HIGH, and is caused by the WiFi at least 10 WiFi POPs running on the floor (and there are 5 floors identically wired).

The lower picture was taken on the 104th floor at Sears/ Willis tower plugged into the South antenna of a TV ENG receive antenna. This is the same screen scan setup.. Notice how much lower the noise floor is in one of the noisiest areas in the country off this antenna, but look at the junk operating in the same space as my DX8. Whatever it is, it's loud enough that we cannot run 2GHz TV links with 10W transmitters into +20db directional antennas on both ends. This interference, including that from us RC folks was mentioned during a meeting with the National Association of Broadcasters recently while discussing what services are being shared in this band. I captured screen shots at 2.4GHz at Sears & Hancock towers in Chicago, and 3 mtn.tops in So. Cal, and the results are essentially the same, although Chicago was considerably more congested being in the center of town.

The good news is that 2.4GHz drops off fairly fast, and data links are usually on highly directional antennas. Thank goodness DSM(X) is as robust as it is, because there is competition out there for this space.At least most of the bad stuff is in the metro areas, but in my book cell activity is way down the list of worries.

DX8 & TM1000

SEARS Tower South Antenna/ LNA Off
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Old Nov 04, 2012, 02:13 AM
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Jeff you are opening a huge can of worms.Im no RF expert by any means and I let my ham license kind of expire some years ago but Im trying to get back up to speed a little more.One thing I learned/relearned is I cant use analog logic in a digital world.The way we use RF is completely different than in the past.At least from what I was used to 20 years ago.I have a couple spectrum analyzers and just because a band is being used doesnt mean it cant be shared.Ive found some pretty harsh environments and the system still works.Ive seen places where an analyzer will show reasonable RF all across the 2.4 band.Some may call it "saturated". All frequencies are being used.There is still room to get an RC system to connect and be usable.Even DSM2 which many claim to be obsolete in the ever harsher 2.4 environment we all try to share.True enough there are situations where it could be at a distinct disadvantage but IMO they are still very rare.Alot of the claims of inherent problems and conflicts IMO are based on misconceptions of how the bandwidth is being used especially the amount of time it is used(when and where).
Huge can of worms.

As long as all the users stay within the laws/rules/guidelines theres still plenty of room for everyone to play well together.There is potential for conflicts but for the most part its not a "sky is falling" scenario.
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Old Nov 04, 2012, 02:37 AM
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Belgium
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Originally Posted by AndyKunz View Post
UMX telemetry only shows holds and fades. It does not report voltage or RPM or anything else. The next update for all radios will display it.

Andy
Thanks Andy,

Finally updated (from 2.3beta) and glad so far!
My Carbon Cubs basic telemetry is working ;-)
Thanks for helping.

Best regards,
Tom.
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Old Nov 04, 2012, 03:01 AM
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Malaysia, Perak, Taiping
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I'm doing right thing...ooooh i feel very very old when dealing with computer tech
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Old Nov 04, 2012, 04:43 AM
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Central California
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where to look the PDF this morning i meet my friend he also facing same problem like me when change swash type to 3 servo 120 at monitor ail and ele not zero when change back to 1 servo normal monitor ail and ele zero...i need to learn more
Your swash servos will only be zero at midstick.

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I'm doing right thing...ooooh i feel very very old when dealing with computer tech
Watch these videos.

http://www.helifreak.com/showthread.php?t=354008
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Old Nov 04, 2012, 12:08 PM
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Real-time RF Interference

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Old Nov 04, 2012, 12:28 PM
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I'm not opening it, I'm just pointing out what I see and how congested this band can be in the right area. It's still WAY WAY better that a single carrier device that can get completely creamed, THIS at least system has redundancy.

With the TV guys, the shoe is also on the other foot. We install ENG receive sites at the top of buildings, mtns., and local hills, some of those exactly where the glider guys fly. So not only is it possible that the pilots radio can get into the receiver, but also the glider flying by the antenna at 100mph with it's telemetry. We don't have the luxury of frequency hoppers, ours is a 6MHz carrier, and if a hole is punched anywhere in that carrier, away goes pix. BTW, the point of those pix was to make the case that the TV guys cannot co-exist on 2.4GHz (ENG Ch.8) with any of those data services, and are now, at least in the Chicago mkt, working to move elsewhere in the band. That's a good thing for everyone.

Back to the thread..

PS: I have also heard rumors of excessive holds at Apollo Field in So. Cal, so I might take the analyzer out and let it run for the afternoon some day.
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Old Nov 04, 2012, 02:20 PM
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Greece, Attica, Spata
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Hello , will spectrum release an update for the DX8 for glider menu?
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Old Nov 04, 2012, 02:34 PM
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Old Nov 04, 2012, 02:38 PM
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Originally Posted by SCVJeff View Post
PS: I have also heard rumors of excessive holds at Apollo Field in So. Cal, so I might take the analyzer out and let it run for the afternoon some day.
That would be really cool to see. Please post the results. What memories... Apollo Field in the Sepulveda Basin was my very first club back in '82 or '83. I wouldn't be surprised if there were excessive holds. That place was always bad ( or at least worse than any other club I've ever flown with) for radio interference, from AM all the way up through narrow band FM/PCM. I can't imagine the amount of RF noise there these days. Plus, Van Nuys airport was right there, too. Do the FAA cars with the yellow twirly lights still come out almost every weekend and yell at people when Tower thinks they're flying over 400ft like they did back then?
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