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Old Jun 23, 2015, 12:51 PM
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Manufacturers aren't testing their radios in the field or some metal building. They're testing them in a small room immune to outside interference...so it's expected the results will be ideal.

2.4 GHz is the worst possible frequency they could have chosen. It's used by every bluetooth device, wireless router, microwave transmitters and repeaters, microwave ovens. I don't care how many times the frequencies hop from one place to the other, it's prone to significant interference. It behaves much differently than 50, 53, 72 and 75 MHz. Plus it's broadcasting at a severely reduced output compared to what we used to have.

I'm designing an RC lawnmower. I wouldn't dare use 2.4 GHz on such a device because I can't get a clean signal from one side of the house to the other. I can't even get decent wireless access in my basement through 3/4" of Teak and 3/4" of ply subfloor.
So you have experience in the telecom and wireless industry?
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Old Jun 23, 2015, 01:05 PM
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Originally Posted by seeingeyegod View Post
So you have experience in the telecom and wireless industry?
Yes. I spent some time working for South Western Bell Mobile Systems in the late 90's. I'm well aware of how high frequencies react with surrounding objects. They tend to reflect off of them, rather than penetrating completely.
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Old Jun 23, 2015, 08:38 PM
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Yes. I spent some time working for South Western Bell Mobile Systems in the late 90's. I'm well aware of how high frequencies react with surrounding objects. They tend to reflect off of them, rather than penetrating completely.
Yes, and we regularly fly our RC planes with walls and panes of glass between us and the plane.
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Old Jun 23, 2015, 08:55 PM
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Yes, and we regularly fly our RC planes with walls and panes of glass between us and the plane.
You're not understanding where I was going with my previous statement. They use ideal conditions to test their products in. The specifications in the manual and data sheets for the radio are based in those environments. If they were to use real world environments (carbon fiber fuselages, flying fields surrounded with fences and trees, whatever, etc) you'd see the differences in how the radio behaves.

I was going to have a camera on a gimbal broadcasting video on the lawnmower so I could see things. As soon as it goes out of sight and around the side of the house, the signal is lost. The distance is only 60 feet....please tell me why 2.4 GHz is so amazing. I've tested multiple products from multiple vendors. The results are roughly the same.
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Old Jun 24, 2015, 01:53 PM
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I thought 2.4ghz for video broadcast was considered to be very weak, and that everyone who wants any real range uses ham radio freq? Also again, 2.4ghz for RC is not designed to go through barriers because we never want to be out of LOS. Frequency hopping 2.4 has been proven over many years now to be very effective and safe for RC in real world usage, and it doesn't work the same as wifi anyway so comparing crappy wifi data throughput to 2.4ghz RC systems is kind of apples to oranges. I know a lot of FPV enthusiasts use 72mhz for radio control if they are doing 2.4 for RC though, to avoid interference between the two.
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Old Jun 24, 2015, 02:09 PM
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Originally Posted by godfrey View Post
Manufacturers aren't testing their radios in the field or some metal building. They're testing them in a small room immune to outside interference
They may well be doing sensitivty measuerments, in controlled indoor conditions, so they can put fiqures in the manual, that makes sense.

To suggest they are not testing radios actually work for real, as in controlling RC models outside "in the field" is plain daft.
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Old Jun 24, 2015, 02:30 PM
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Originally Posted by godfrey View Post
As soon as it goes out of sight and around the side of the house, the signal is lost. The distance is only 60 feet....please tell me why 2.4 GHz is so amazing. I've tested multiple products from multiple vendors. The results are roughly the same.
We normally fly planes such that they are above the horizon and the TX has a direct view, a clear line of sight (LOS) to the RX on a plane.

The distance differance between normal RC conditions (good LOS) and an obstructed not direct view can be circa 1000:1

Whats 1000 x 60ft ?
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Old Jun 30, 2015, 04:35 PM
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2.4 Ghz Spectrum Analyzer

Quote:
Originally Posted by godfrey View Post
Manufacturers aren't testing their radios in the field or some metal building. They're testing them in a small room immune to outside interference...so it's expected the results will be ideal.

2.4 GHz is the worst possible frequency they could have chosen. It's used by every bluetooth device, wireless router, microwave transmitters and repeaters, microwave ovens. I don't care how many times the frequencies hop from one place to the other, it's prone to significant interference. It behaves much differently than 50, 53, 72 and 75 MHz. Plus it's broadcasting at a severely reduced output compared to what we used to have.

I'm designing an RC lawnmower. I wouldn't dare use 2.4 GHz on such a device because I can't get a clean signal from one side of the house to the other. I can't even get decent wireless access in my basement through 3/4" of Teak and 3/4" of ply subfloor.
Spektrum has a video where they turn on 100 Spektrum radios all at the same time, then fly another model on 2.4 Ghz right over the pile of 100 transmitters.

They were not flying some little back yard flier, they were flying $$$$ helis' and other high powered models.

Spectrum DSMX 100 Transmitters
DSMX (10 min 6 sec)



Just go to any very large model fun fly, and you'll see lots of Spekies. A dozen of my club members traveled to Joe Nall at their last fly-in. The above video mentions Joe Nall. Don't think anyone at Joe Nall and many other places would risk a $$$$ model with a radio system and frequency that isn't reliable. All members were flying with Spektrum radios. And solid receiver battery supplies like primary/backup 2300 Mah A123 packs. And with that huge flyin with who knows how many models were flying, had absolutely no problems with interference or similar.

As for 2.4 Ghz, it's well known that this frequency is line of sight. If you can't see your model, you can't depend on getting a good signal. Just about any name brand 2.4 Ghz radio system now is far more reliable than anything we had in 72 Mhz. Again, 2.4 Ghz has to have solid receiver battery or BEC power. If not, you won't have a reliable system.

Take a look:
http://www.wattflyer.com/forums/showthread.php?t=72719
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Old Jun 30, 2015, 04:53 PM
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Quote:
Originally Posted by srnet View Post
We normally fly planes such that they are above the horizon and the TX has a direct view, a clear line of sight (LOS) to the RX on a plane.

The distance differance between normal RC conditions (good LOS) and an obstructed not direct view can be circa 1000:1

Whats 1000 x 60ft ?
There are more than a few folks that conducted direct line of sight full range checks with the 2.4 Ghz radios. Their results show that these radios work up to two miles distant, and more.
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Old Jun 30, 2015, 05:40 PM
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Quote:
Originally Posted by vollrathd View Post
All members were flying with Spektrum radios. And solid receiver battery supplies like primary/backup 2300 Mah A123 packs. And with that huge flyin with who knows how many models were flying, had absolutely no problems with interference or similar.

i think the reason that people with high end radio systems have few problems is that they put in a lot more effort into all the other parts of the system like power that they will see very few problems so they believe its their expensive radio rather than all the prep work. chances are they could have flown on a 20 hkt6a flysky 2.4 system and it would have flown just as well.
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Old Jul 01, 2015, 09:19 AM
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Originally Posted by geofrancis View Post
i think the reason that people with high end radio systems have few problems is that they put in a lot more effort into all the other parts of the system like power that they will see very few problems so they believe its their expensive radio rather than all the prep work. chances are they could have flown on a 20 hkt6a flysky 2.4 system and it would have flown just as well.
Very good points!

As for me what's worked well for a model is to put 1/3 of the $$$$ in the model, 1/3 into the radio, 1/3 into the power system. More or less anyhow.

Don't make much sense to buy a $1000 radio when all you fly is $100 models. Or buy a $99 radio when you're flying giant scale models.

At any rate, just about any name brand radio works very well now days.
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Old Jul 14, 2015, 02:01 PM
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I have this loose wire in my brain that puts out the most horrible interference you could imagine...
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