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Romania, Dolj, Craiova
Joined Sep 2007
12,358 Posts
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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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Latest blog entry: JRSky - birth of a dream radio
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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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Latest blog entry: Airframes
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Quote:
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:
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:
900Mhz and 2.4Ghz yes.. 1.3Ghz no. Quote:
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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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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Latest blog entry: Project Covert Ops: Long range ground...
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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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Latest blog entry: Project Covert Ops: Long range ground...
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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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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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Latest blog entry: Project Covert Ops: Long range ground...
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