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Old Jan 13, 2012, 01:39 AM
Registered User
Romania, Dolj, Craiova
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No, isn't this what I meant
But to get a good receiver and antenna in 1.3G seems much harder than in 5.8G.
In 1.3G, from any source and vendor literaly you don't know what you buy ! I tested 6 (six) 1.2-1.3G receivers to be able to fly more than 2km with stock antennas with only one...
5.8GHz is only one model and source, and simply works.
Plus, the noise floor... you can find places awful for 1.3GHz while 5.8GHz is clean everywhere, at least now, so the 90dB of receiver are indeed 90dB, and not 60-70dB, busted by noise floor...
Last but the most important... is soooo sweet to use small antennas
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Old Jan 13, 2012, 02:32 AM
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imdone's Avatar
United States, WA, Seattle
Joined May 2011
806 Posts
keep it simple is sooooooo true. before I stated fpving anything I got everything too! a state of the art GS divesity, switches, fans, all the goodies. Now...I got a rx velcroed to a antenna which I plug into either a 7" screen or some fatsharks. and couldnt be happier.
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Old Jan 13, 2012, 03:28 AM
NDw
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Ireland, Limerick, Kilmallock
Joined Aug 2010
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Quote:
Originally Posted by RENATOA View Post
5.8GHz is only one model and source
hk ot fpvhobby? Or is it basically the same thing?
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Old Jan 13, 2012, 03:37 AM
Houba ! Houba !!
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United Kingdom, England, Milton Keynes
Joined Sep 2003
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this should be copied and pasted in the "guide for newcomers" sticky by IBCRAZY.
don't make it a sticky. it is an advice (excellent one by the way) not a discussion.
I have been flying FPV maybe 3 years now and I cannot gather enough courage to overshoot the 2km barrier.

but I enjoy it SOOOOO much !!!!!!
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Old Jan 13, 2012, 04:48 AM
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Daemon's Avatar
Lakewood, Colorado
Joined Aug 2002
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Quote:
Originally Posted by RENATOA View Post
No, isn't this what I meant
But to get a good receiver and antenna in 1.3G seems much harder than in 5.8G.
In 1.3G, from any source and vendor literaly you don't know what you buy ! I tested 6 (six) 1.2-1.3G receivers to be able to fly more than 2km with stock antennas with only one...
Still seems a false premise since you're not going to get clean video for
2km with the 5.8Ghz stock antennas ever.
It's widely known that nobody uses stock antennas on both ends of the link
on 900Mhz or 1.2Ghz.
Dunno how you went through 6 different Rxs. We know that the cheap
12-16ch ones generally all suck. They have no decent input filtering so
catch noise from well outside the 1.2-1.3Ghz band. . The Comtech based ones
(from RV) and Lawmate Rxs are both well proven. I've used three different make/model/power
1.3Ghz Txs and they all work great with my Comtech based Rx. The antennas are
what matter most.

Quote:
5.8GHz is only one model and source, and simply works.
Works with appropriate antennas.
There are actually two different "standard" sets of 5.8Ghz frequencies
that are totally incompatible with each other. For instance this
http://www.hobbyking.com/hobbyking/s...dProduct=12176
is not compatible with the 5.8Ghz Rx built into Fatshark Aviator goggles.
And of course the 100mW and 600mW ImmersionRC 5.8Ghz Tx's are not compatible with that standalone HK Rx. Kind of annoying if you want more power, but
don't want to wear the Rx on your head.

5.8Ghz channel selectivity is great though, so very handy if you want to get a lot of
FPV pilots in the air. But that's because band pass filtering gets easier (sharper edges)
the higher the frequency.

Quote:
Plus, the noise floor... you can find places awful for 1.3GHz while 5.8GHz is clean everywhere, at least now, so the 90dB of receiver are indeed 90dB, and not 60-70dB, busted by noise floor...
In what location have you found 1.3Ghz to be noisy? I've yet to see it anywhere.
900Mhz and 2.4Ghz yes.. 1.3Ghz no.

Quote:
Last but the most important... is soooo sweet to use small antennas
That is nice, but not being able to fly behind your high gain Rx antenna more than 100ft,
or having your video signal blocked instantly when anyone walks in front of your
Rx antenna at pretty much any range...

What someone needs to do is market a tiny little standalone all-in-one 5.8Ghz antenna tracker (could use
cheap standard servos) to keep the required high gain antenna pointed at the plane. Given the frequency
separation, could probably build the telemetry module/GPS/video Tx all into
the same unit for the plane. Only eats one audio channel for telemetry. Build the video
Rx and tracker electronics into the same unit on the ground station. Then you've got
a truly plug and play FPV setup that'll let 8 people fly at once.

ian
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Old Jan 13, 2012, 05:02 AM
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thus far my best performance and reception on 5.8ghz is with stock whips, lol. tried CL and SPW and they weren't really any better, and my friend has some hugo ones and he says the same thing, bout the same as the stock immersion whips.

I do love the simplicity of 5.8. It pretty much always works, and i can fly with friends. Infact i fly 5.8ghz from inside my car. just stock whip on my predator goggles. Yeah the range is reduced, but for quad flying it's great. Stay inside, stay warm
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Old Jan 13, 2012, 07:47 AM
BEOWULF
North vancouver, B.C. Canada
Joined Apr 2008
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Quote:
Originally Posted by RENATOA View Post
is soooo sweet to use small antennas
oh ya smaller antennas create way less drag, so do smaller cameras

video quality must be better with 5.8 as well comparred to 1.2
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Old Jan 13, 2012, 08:41 AM
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United Kingdom, England, Gt Lon
Joined Nov 2007
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There some people here raving about 5.8ghz when my experiance has been the oposite, there is good things as well as bad things with 5.8ghz.

Pros:
Larger bandwidth means better video quality
Smaller antenna size = easier to mount and less drag, less weight and smaller ground station
Antenna availability is decent
5.8ghz is not expensive as it once was

Cons:
Its literally a LOS frequency so penetration is poor, ok if you have a plane but not if you have a cf heli
It is more affected by multipathing than lower frequencies
Commercially available also means more people and businesses will be using it although not as much as 2.4ghz at the moment

For my platform and location 5.8ghz is NOT good as I get interferance around my area and as I fly helis and multicopters they are mostly made out of CF so I get a lot of static at times. I now use 1.3ghz and I love the penetration I get out of it, antenna availability isnt a problem, just get antennas from IBcrazy. I also like the fact that I know the public and businesses wont be using it in commercial products. I personally see little difference in video quality between the two in my googles so its not really applicable in my opinion.

At the end of the day it depends a lot on what your flying and where your flying and what gear your using to get the best out of the frequencies your using.
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Old Jan 13, 2012, 09:52 AM
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Amherst, VA
Joined Jun 2006
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5.8GHz antenna availability is fair at best. You basically have me and Hugo as commercial builders and a handful of DIYers out there who sell them as well. Of course, Hugo and I are the developers and the rest are copying the designs (usually mine) with little or no knowledge of how it works, so quality is questionable. Hugo and I are struggling to come up with better 5.8GHz directional antennas. The filtration on the RX side is so poor that you can even pick up 2.4GHz video with a 5.8GHz RX! Then add the fact that every antenna Hugo and I make is wideband, and this only adds to the problem.

What 5.8GHz really needs is better RX quality. If we can get a good RX with better filtration, 5.8GHz will absolutely rock.

-Alex
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Old Jan 13, 2012, 09:56 AM
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One thing that puzzles me is why I am the only person flying 6 meter (50MHz) control and 2.4GHz video. Unless you are flying around a bunch of houses, Wifi really isn't a problem. I find 2.4Ghz has the best video quality and is very reliable. its flying around people on 2.4GHz control that is the problem.

And for control, 50MHz is empty. It's completely devoid of anything except a few extremely low power baby monitors. Nobody has it, it punches through everything, and it's not much more expensive than 72MHz.

-Alex
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Old Jan 13, 2012, 11:15 AM
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Lakewood, Colorado
Joined Aug 2002
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Reason none of the FPVers in Colorado, use 2.4Ghz video, is that we all
fly with various other pilots (FPV and otherwise) who use R/C control, and that
just thrashes the video. Lawmate channel 8 is an option, but then it's not 2.4Ghz band at all.

If the filtration on 5.8Ghz Rx's is so bad, I wonder why my buddies can fly on
adjacent 5.8Ghz channels with zero interference from each other. I use the 100mW
5.8Ghz Tx as a ground station relay to my wireless Fatshark goggles, and I've set it up
on a fellow FPVer's 5.8Ghz groundstation about 3 inches from his video Rx antenna, without issue.

ian
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Old Jan 13, 2012, 12:06 PM
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Birmingham, Alabama
Joined Jun 2002
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ive never used 5.8, but i always have to wonder about the talked about "higher quality" from the "extra bandwidth" on 5.8ghz. what extra bandwidth? we're working with ancient video here.
standard NTSC is 640*480 29.97fps interlaced (59.94 field/second). an uncompressed bitrate of 9.21 MB/s on the video. that's only what? 4.something mhz?
and THAT is assuming the cheap ass chinese junk we all use isn't using a worse bit & colorspace than standard. which... probably is...


idk.... someone break out a dslr and do a side by side with equipment from the same OEM. i wanna see it.
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Old Jan 13, 2012, 12:25 PM
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United States, UT, Ogden
Joined Nov 2011
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Quote:
Originally Posted by IBCrazy View Post
One thing that puzzles me is why I am the only person flying 6 meter (50MHz) control and 2.4GHz video. Unless you are flying around a bunch of houses, Wifi really isn't a problem. I find 2.4Ghz has the best video quality and is very reliable. its flying around people on 2.4GHz control that is the problem.

And for control, 50MHz is empty. It's completely devoid of anything except a few extremely low power baby monitors. Nobody has it, it punches through everything, and it's not much more expensive than 72MHz.

-Alex
What puzzles ME is why all the video signals are stuck in the high / crappy frequencies (1.2ghz, 2.4ghz, and 5.8ghz). Why not run the video through 433mhz, 144mhz, or even 50mhz?
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Old Jan 13, 2012, 12:28 PM
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Lakewood, Colorado
Joined Aug 2002
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The video channels we use are roughly all the same theoretical bandwidth (about 6Mhz
including audio subcarrier or 4.x without), but 5.8Ghz gear makes better use of it, probably due to
better selectivity (sharper cutoffs at higher frequencies). When you see it in person,
it's hard to deny that the image quality looks a lot better. That is, when it's not
cutting out due to multi-pathing or blockage or flying behind or to the side of the high
gain Rx antena.
Most DVRs don't fully capture the difference in quality because they're bitrate limited
themselves.

Note that true analog NTSC is really 525 scanlines, 486 of which are visible
and has no pre-defined horizontal resolution. 640x480 or 720x480 don't appear until
we enter the digital realm. There can be a lot more than 640 pixels worth of
information on a given analog scan line.

ian
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Old Jan 13, 2012, 12:29 PM
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Amherst, VA
Joined Jun 2006
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Bandwidth. 433 was selected for control (although I prefer 50MHz, honestly). 433 is a legal ATV band. However the equipment is expensive and hard to find. Lower bands cannot carry that much data as their bandwidth is significantly smaller.


-Alex
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