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Old Jan 22, 2013, 06:30 PM
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Transmitter Question

I'm new to FPV and fairly new to the whole RC heli world, but I have a quadcopter and I'm looking for a very simple FPV system. I've found some different ones that I might be interested in getting, but have a few questions first.

First, this is kind of a general electronic question, but would it be bad to hook a 5V transmitter up to an 11.1V LIPO battery? A transmitter like this one http://www.hobbyking.com/hobbyking/s...200mW_FPV.html

Also, what are some good, fairly cheap, transmitters/receivers? What are your favorite ones to use (those of you who have messed with some)?

I have a GoPro mounted on my quad now and have been videoing some just for fun, but I'd love to test out some FPV flying (and that's why I'm trying to stay cheap since I'm just in the testing phase)
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Old Jan 22, 2013, 06:57 PM
Koo
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Lets answer couple questions.
Applying 11.1v from a 3s to a tx that uses 5v would fry it almost instantly, a bad idea. What brand of transmitter do you fly with?
Readymaderc.com and bevrc.com and in my opinion, the two best places to buy FPV gear. Rmrc is more expensive but they have great customer support. I've bought $350 worth of stuff from bev and haven't had a single problem with them. You may want to take a look at their 400mw 1.3ghz vtx/rx combo. It should be good for 1.5 miles with stock antennas and is relatively cheap. You can actually use your gopro to get live feed to the vtx as well.
I have the 800mw version of the bevrc vtx and it gave me 2 miles with the stock antennas and still works great.
If you do decide to fly with 1.3ghz which will give you the best range and penetration through objects, you also want to get a low pass filter to prevent interference to your controls.
http://www.bevrc.com/bev-low-pass-fi...1400_p257.html
http://www.bevrc.com/bev-13g-400mw_p242.html
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Old Jan 22, 2013, 08:11 PM
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If you give that TX 3S, it will turn into a puff of smoke pretty quickly (i'm talking milliseconds here, not seconds or minutes)

Additionally, if you have a 2.4ghz radio you can't use a 2.4ghz video system.

I'm not a fan of the 1.2/1.3ghz stuff personally. The only thing it has going for it is object penetration - the receivers are low enough sensitivity that a 400mW 5.8ghz system will get more range on stock dipoles

The BOSCAM stuff is surprisingly good in 5.8ghz. Their RF layouts are sensible and they haven't done the typical chinese thing of using the cheapest components possible. The only dumb thing they'vee done in my book is use RP-SMA antenna connectors.

http://www.hobbyking.com/hobbyking/s...5295&aff=19701 is not too bad, and quite cheap. It's also 3S compatible. Going from the 200mW (23dBm) to 400mW system (26dBm) is about 40% more range. If you wanted more range out of these, i'd suggest going for the 600mW simply because they get hot and you may not get adequate airflow with the 400 - the 600 has a fan onboard even though the whole thing is stupidly huge and heavy. Going to 600mW (27.7dbm or so) is only a 53% range increase over the 200mW system.

In general, I'd suggest avoiding the Immersion stuff. The Boscam has pretty much identical features, but uses superior RF modules and RF layout, so you will get a cleaner clearer picture from further away.
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Old Jan 22, 2013, 09:10 PM
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About hooking the tx up to the battery, that's what I figured, just wanted to double check just in case. So I'll need to get one that can handle 12V... I'm not sure which to go with now, though, 5.8 or 1.2/1.3... From what I can see, 5.8 is cheaper and there's more out there for those, but I'm assuming stock 1.3 will go further than stock 5.8, right? I'm not too concerned with distance right now, I'm not planning on flying it across the city or anything, just around a field and building and things like that, probably a max of 200 meters for now.
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Old Jan 22, 2013, 09:33 PM
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1.3 will go further because of its lower frequency - BUT 5.8ghz will go further because of its greater sensitivity... in freespace range calculations they come off pretty similar, even thought he 5.8ghz is a lower power system.

I've had the boscam out 3.5km (admittedly the video was getting pretty bad) on 600mW with standard dipoles and a non-optimal setup.
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Old Jan 22, 2013, 11:37 PM
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meh, disagree, as I went from 5.8 to 1.3, and range has gone up by light years.
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Old Jan 22, 2013, 11:58 PM
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Ya, one should not draw conclusions based on freespace range calculators.
Out in the real world I get 4km of *clean* video on 1.3Ghz at 600mW with omni CP antennas.
I've been out to 5km on the same, and have never flown till "video was getting pretty
bad", so have no idea what the max omni range is.

There are legitimate applications for 5.8Ghz video, and it is certainly usable
at typical multi-rotor range. Besides the small antennas, and lack of interference with
other onboard components one really nice thing about 5.8Ghz is that if you fly with other
FPV pilots, you're less likely to be grounded due to frequency collisions. Around here,
you get together 3 or more FPV pilots and chances are at least two of them are on 1.3Ghz
and will have to wait while someone else flies. With 5.8Ghz that is rarely a problem as
there are more channels available, and much less crosstalk between them.
5.8Ghz is not great if you want to fly behind obstacles though. It is blocked by
or reflected off of almost everything.

ian
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Old Jan 23, 2013, 12:15 AM
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Obviously, environment and setup will best determine your optimal frequency and the range you get from it, as will your flying style.

Freespace is good for "in a perfect world.. you would expect to see:" type comparisons, so they are good to say that both pieces of equipment should preform similarly but your environment will change the outcome.

I fly in open farmland, with clear line of sight for dozens of kilometres in all directions. In the suburbs I can expect a 30% range reduction flying at parks with the same setup due to trees and buildings.

Out at the farm, I have a friend flying on 1.2, one on 2.4 and one on 5.8. Interestingly, the guy on 2.4 complains the most. I can't fly down into valleys as easily as the guy on 1.2 due to the ground getting in the way and the huge amount of metal laden rock. He however can't fly as high or far as me. I'm using a 9dbi circular pol helical on a not-yet-released 5.8ghz receiver, he's flying higher wattage on a 14dbi circular pol patch with a tracking antenna.

For me, 5.8ghz is the best option.. it's not for everyone (otherwise other frequencies wouldnt exist right?). I dont like everyone saying that 1.2/1.3/0.9ghz always beats out the 5.8ghz on range - it doesnt. In certain circumstances it most certainly does. Just like in certain circumstances 5.8ghz is better.
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Old Jan 23, 2013, 12:37 AM
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If your buddy with the 14dB 1.3Ghz gear is having range issues anywhere inside of 20km,
then he's done something wrong with his setup.
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Old Jan 23, 2013, 12:42 AM
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Nothing wrong with his setup

He left most of his planes at home, he only bought 6 of them, a car and 2 helis last time we went out. I believe he's using the lawmate 1.2ghz systems. About half of them use the stock whip antennas as he cant see a difference between the CP and LP antennas with his setup.
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Old Jan 23, 2013, 12:47 AM
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Quote:
Originally Posted by Ascended View Post
Obviously, environment and setup will best determine your optimal frequency and the range you get from it, as will your flying style.

Freespace is good for "in a perfect world.. you would expect to see:" type comparisons, so they are good to say that both pieces of equipment should preform similarly but your environment will change the outcome.

I fly in open farmland, with clear line of sight for dozens of kilometres in all directions. In the suburbs I can expect a 30% range reduction flying at parks with the same setup due to trees and buildings.

Out at the farm, I have a friend flying on 1.2, one on 2.4 and one on 5.8. Interestingly, the guy on 2.4 complains the most. I can't fly down into valleys as easily as the guy on 1.2 due to the ground getting in the way and the huge amount of metal laden rock. He however can't fly as high or far as me. I'm using a 9dbi circular pol helical on a not-yet-released 5.8ghz receiver, he's flying higher wattage on a 14dbi circular pol patch with a tracking antenna.

For me, 5.8ghz is the best option.. it's not for everyone (otherwise other frequencies wouldnt exist right?). I dont like everyone saying that 1.2/1.3/0.9ghz always beats out the 5.8ghz on range - it doesnt. In certain circumstances it most certainly does. Just like in certain circumstances 5.8ghz is better.
In my area 5.8 beats the pants off of 2.4 and 900, that is, until i get behind a few trees But i absolutely love the 5.8 for my multi, can't beat that tiny antenna. With a 200mw tx on omnis i get 1.5km easily, which is plenty for me.

having said that, i've ordered blue beams for my 900 and i'll see how that works out, at least i'll have a fair comparison then. linear on 900 in my area just doesn't work
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Old Jan 23, 2013, 01:03 AM
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Quote:
Originally Posted by Ascended View Post
Nothing wrong with his setup

He left most of his planes at home, he only bought 6 of them, a car and 2 helis last time we went out. I believe he's using the lawmate 1.2ghz systems. About half of them use the stock whip antennas as he cant see a difference between the CP and LP antennas with his setup.
I stand by my assertion. I can get 10km of relatively clean video with a homemade Vee and
an 8dB patch on 600mW 1.3Ghz in a near urban environment surrounded by
high powered broadcast antennas with the supposedly low sensitivity Racewood Rx. By the
numbers 14dB Rx ant will double that range, and should be nowhere close to it's maximum.
If he's having issues inside that range, he's doing something wrong. If he's mixing linear
and CP antennas and seeing no difference between that and CP to CP, he's doing something wrong.
Or are you flying out well past 20km with your 5.8Ghz gear on 9dB Helical?

ian
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Old Jan 23, 2013, 01:56 AM
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Lets just say 10km is no issue for either of us.
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Old Jan 23, 2013, 02:01 AM
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And still missing the point, on purpose I suspect. His video should be solid out over 20km.
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Old Jan 23, 2013, 02:13 AM
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Not on purpose Daemon, I've never said his video isn't solid out over 20km I'm just not willing to say if we're flying that far out or not on here.

I believe the racewood system is better than the lawmate systems, I hear a lot of good things about the Racewood system from clients.

All i'm saying is, In my experience, with my flying style, I can match or exceed a lower frequency setup with my aircraft and receiver. YMMV.

5.8ghz has always had a reputation of not being able to fly far, and has had for the past 5yrs or more on here. I'm trying to highlight the fact that you can fly far on 5.8ghz, if you have the right setup.
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