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Old Mar 23, 2011, 04:58 PM
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Do you guys get drastically different range in city vs country?

I've done a lot of reading about FPV, but one thing I never notice much is range in the city vs in the country. I live in a highly populated area near seattle. I have 2 different FPV systems, a 900mhz 500mw, and a 5.8ghz 200mw (My radio is 2.4 ghz), and even after many many hours of troubleshooting and tinkering, I have never got either one to work very good.

My 5.8ghz has about the range of a medium sized baseball field, the 900mhz even less. I'm starting to think perhaps its all the 900mhz and 5.8 mhz cordless phones, baby monitors, nanny cams, etc. that tons of the houses around here most likely have. I haven't been able to test it in a remote area yet because I simply don't know of any flyable rural area anywhere around here. Everyplace is either densly populated, or else thick forest. No remote open areas that I can think of anywhere.

So that's why I'm asking you guys, do you experience a noticeable difference in range in a city vs in the country, or remote areas?
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Old Mar 23, 2011, 05:08 PM
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outtacontrol's Avatar
Tallahassee, FL
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I do. I'm on 900mhz 500mw and I watched my plane fly away from me for over a mile today. In the city I've lost video feed at a few hundred feet.
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Old Mar 23, 2011, 10:13 PM
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Yes. I've flown 2.5 miles on 500mW 900Mhz out in the country and could
have gone further. When I'm on my home slope overlooking the city, maybe 200 yards
before video goes to crap. I don't think it's 900Mhz baby monitors and cordless
phones though. I think it's overlap from the GSM cellular bands.

For 5.8Ghz you need a higher gain patch antenna on the receiver to
get decent range. There's less interference on 5.8Ghz than most of the other
bands.

ian
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Old Mar 24, 2011, 04:51 PM
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twinturbostang's Avatar
Germantown, MD
Joined Mar 2006
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Quote:
Originally Posted by Daemon View Post
There's less interference on 5.8Ghz than most of the other
bands.

ian
What about 1.3GHz? How crowded is it?
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Old Mar 24, 2011, 05:02 PM
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On 2.4Ghz 1W I can go 1.5-2.5 miles in the country, or less than 2000 ft in a "city". Your location is really critical.

I haven't noticed as much of a problem with 900Mhz (I've went 7.5 miles on 1W while in the city, though well past the edge of it). I've only flown 1280 a few times, but it did seem pretty clear.
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Old Mar 24, 2011, 05:09 PM
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1.3Ghz is generally pretty good in urban areas. The problem we're facing though, is that
if *everyone* uses 1.3Ghz even when some other frequency might work for them
in their area then we eventually start shooting each other down. If I could use 900Mhz
I would. If I could use 2.4Ghz I would.

ian
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Old Mar 25, 2011, 07:51 AM
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Amherst, VA
Joined Jun 2006
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It's not just the RF traffic in the city, but the numer of objects the signal can reflect off of. The more objects there are around you, the worse you will get hit with multipath interference.

Here's an experiment for you:

Find a remote location where there is any type of non-wooden structure nearby (Ie barns do not work, but brick houses and metal sheds do work). Now stand far away from the structure and fly once. For your second flight stand right in front of the structure. What happened to your video? Turned to complete garbage didn't it? That's multipathing. Stand by a metal building and it gets much worse. Or try a metal fence. Same thing.

-Alex
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Old Mar 25, 2011, 12:40 PM
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Quote:
Originally Posted by IBCrazy View Post
Here's an experiment for you:

Find a remote location where there is any type of non-wooden structure nearby (Ie barns do not work, but brick houses and metal sheds do work). Now stand far away from the structure and fly once. For your second flight stand right in front of the structure. What happened to your video? Turned to complete garbage didn't it? That's multipathing. Stand by a metal building and it gets much worse. Or try a metal fence. Same thing.

-Alex
So do you think multipathing can have a big effect even if you are not actually next to the objects like your expiriment? For example, one of the main places I fly is a baseball field. I stand in the very center of it, no obstructions, open sky. However it is completely surrounded by a chain link fence, and all sorts of houses and buildings outside there. Think that's causing multipathing, even though they are a few hundered feet away?



Thanks for all the responses guys. Wasted so much time troubleshooting equipment that I thought was faulty, but sounds like it all might work just fine if I get away from the interference. I can't wait to find some country area to try out my gear. Probably will be a long time though, I'll have to probably travel half way across the state or something to get away from the population.
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Old Mar 25, 2011, 02:08 PM
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Lakewood, Colorado
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No, multi-pathing is not nearly that big of a problem, unless you're
standing with your back to a house or building or car, or flying your plane
low around the same. I would assume by your range comparison to a "baseball field"
in your first post that you're probably flying in the park and not near buildings.
Where I've experienced the worst video noise from an urban environment,
there was no multi-pathing at all.

ian
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