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Old Jun 03, 2011, 06:24 PM
No pressure
United States, TX, Carrollton
Joined Jul 2005
260 Posts
Ok, As a Noob to FPV, I have a couple questions that I think you guys may be able to answer.

Background
I have built a 1000w quad X multiwiicopter that I want to use to do low altitude (500' an below) aerial photography with. I already have several Canon Powershot cameras with CHDK that I use for AP on fixed wing aircraft. Most of the Canon Powershot cameras have a full time video out that shows you what the camera is seeing including any on screen data that you would see, including the OSD that CHDK allows.

What I am thinking I'll be able to do is feed the camera's video out into a VTX and use that to fly the Quad via FPV. Get into position and frame my shots as I want and trigger the camera. My thought is that this will give me FPV and the ability to truely see what the camera is seeing when I take pictures.

Of course, I get things dialed in on the quad before attaching fpv, and I'll test everything on the ground several time.

Does anyone see any problems with this idea?

Also, since I am only going to be flying sub 500' and rarely more that 500' any recommendations on output power needed to do this? I worry about the fact that I will likely be flying near trees and how that will affect reception. I hope to use IBcrazy's circular antennas, and I'd like to run in the 5.8Ghz range since my RC tx is 2.4 and I worry about antenna size and weight it I run 900Mhz or 1.2Ghz.

Thoughts, suggestions, concerns?

Any feedback is appreciated.
Dave Mimlitch
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Old Jun 03, 2011, 06:41 PM
Registered User
United States, MN, Orono
Joined May 2011
568 Posts
Hi
Can anbody help me?
I want to know what range my 1.3 ghz, 800mw tx with the Range Video "Double wire" antenae will give me. Also, will a 3s 500mah battery give me enough power for this system? (Using HQ550 camera)
Thank you
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Old Jun 03, 2011, 07:16 PM
Specializing in RC since 1972
Temple, GA, USA
Joined Jun 2009
3,135 Posts
Quote:
Originally Posted by IBCrazy View Post
The BoB drops out at 9V which can be disasterous if flying on a single battery. Throttle up and the video disappears when the battery is weak. However the Sunsky is good for 7.5V. I prefer the Sunsky eventhough the output power is really 600mw (not 800) and the BoB is actually 900mW (not 700).

All personal preference, though.

-Alex
Indeed...

I've never had a drop out on my BOB Fox-700; separate pack for FPV or piggybacked off the flight battery and it is not an issue if you use a separate pack for FPV. I tend to design my power systems (read: prop it down) so they can be run at WOT continuously. Lately I use a separate pack too.

Cliff
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Old Jun 03, 2011, 07:55 PM
Specializing in RC since 1972
Temple, GA, USA
Joined Jun 2009
3,135 Posts
Quote:
Originally Posted by dmimlitch View Post
Ok, As a Noob to FPV, I have a couple questions that I think you guys may be able to answer.

Background
I have built a 1000w quad X multiwiicopter that I want to use to do low altitude (500' an below) aerial photography with. I already have several Canon Powershot cameras with CHDK that I use for AP on fixed wing aircraft. Most of the Canon Powershot cameras have a full time video out that shows you what the camera is seeing including any on screen data that you would see, including the OSD that CHDK allows.

What I am thinking I'll be able to do is feed the camera's video out into a VTX and use that to fly the Quad via FPV. Get into position and frame my shots as I want and trigger the camera. My thought is that this will give me FPV and the ability to truely see what the camera is seeing when I take pictures.

Of course, I get things dialed in on the quad before attaching fpv, and I'll test everything on the ground several time.

Does anyone see any problems with this idea?

Also, since I am only going to be flying sub 500' and rarely more that 500' any recommendations on output power needed to do this? I worry about the fact that I will likely be flying near trees and how that will affect reception. I hope to use IBcrazy's circular antennas, and I'd like to run in the 5.8Ghz range since my RC tx is 2.4 and I worry about antenna size and weight it I run 900Mhz or 1.2Ghz.

Thoughts, suggestions, concerns?

Any feedback is appreciated.
Dave Mimlitch
Does the video freeze at any time? Like just after taking a picture? Flash recharge? Be really careful to avoid OSD menus if they disable the video while in the menu. Even a whole second without video could get you in trouble if you were close to an obstacle. A hovering heli tends to drift.

Near trees is fine, on the other side of trees is a no-no. You will probably be OK for one tree, but at some point a small forest will block the video signal completely. The same goes for 2.4g RC equipment, but NOT for 72mhz RC equipment. You can fly behind trees all day long with 72mhz.

Many AP people use two cameras that are aligned to frame the same image, of course zoom or pan and tilt are obstacles.

On a similar note, there is a Swiss company senseFly that does automated aerial mapping. Watch the video. Maybe they have a heli version. It ain't cheap though. Here is a similar video by Pix4UAV showing off their mapping software with images from a senseFly.

Here is a senseFly running optiPilot which uses vision for autonomous collision avoidance.

Sorry, I just had to show you these links.

Cliff
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Old Jun 03, 2011, 08:39 PM
No pressure
United States, TX, Carrollton
Joined Jul 2005
260 Posts
Cliff

The screen on the camera blanks for almost three seconds, but the video out never does. I can see no change in the display when taking pictures.

The system I am trying to build looks more like this one, but not as exspensive or high tech. http://www.engadget.com/2011/06/03/m...inds-peace-wi/
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Old Jun 04, 2011, 12:25 AM
Engineer for Christ
IBCrazy's Avatar
Amherst, VA
Joined Jun 2006
10,542 Posts
Quote:
Originally Posted by FPV_Habu_Flyer View Post
Hi
Can anbody help me?
I want to know what range my 1.3 ghz, 800mw tx with the Range Video "Double wire" antenae will give me. Also, will a 3s 500mah battery give me enough power for this system? (Using HQ550 camera)
Thank you
Please read the first post. "what range can I get" is not answerable without a lot more information. We need photos, geographic location, surroundings, pilot skill, nearby HAM radio towers, your specific frequency, ect.

-Alex
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Old Jun 04, 2011, 11:21 AM
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Joined May 2011
405 Posts
VTx freq

Hi there!

Can you please advise what VTx frequency is best to fly with FRSky for FOX-800 1,3 and 900?
(No restrictions here - I can use any!)

Many thanks.
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Old Jun 04, 2011, 12:56 PM
Registered User
Joined Jan 2009
104 Posts
I got a very dumb question.
Bought a Yagi antenna on 2.4 to get the video signal, and need to install it on the antenna tracker.
I was wondering, if the TX antenna is (as usual) mounted vertically on the plane, I should install the Yagi the same way, and not, so to speak, parallel to the ground, because the tx antenna will be transmitting vertically polarised, and the receiving antenna would be horizontally polarised if it's "flat" or as I tried to describe, parallel to the ground... Right?
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Old Jun 04, 2011, 07:47 PM
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gmflyer's Avatar
United States, OH, Columbus
Joined May 2009
109 Posts
DX6i Antenna Question - Alex and Cliff - can you weigh in?

Hello - this is my first post here in this forum - and I've read all pages here and in the surrounding FPV antenna build threads. WOW. This has really opened up a new arena in RC for me to think about- I want to do it! Alex, I'm really grateful and amazed by your antenna refinements and new breakthroughs. And Alex and Cliff - for the extent of your sharing in an understandable way.

So, I hope this isn't a "don't ask that question", question. But I love the advice about starting off simply enough - and I live in the city and would like to get a solid mile of FPV without driving too many miles outside of town - and feel solid about it. And, being a minimalist at the moment, would like to keep to one radio - my dx6i.

I don't know if anyone has really explored DIY development of this as compared to your recent breakthroughs:
Here's my $64,000 question - isn't there a creative solution to having a better range for my dx6i - by removing the stock antenna and putting on a carefully matched Diy Omni or otherwise - I mean a break-through DIY matching antenna?. [I dropped my radio and broke my antenna a year ago or so, and it was just a wire inside the cheap plastic antenna casing. Yes, a very carefully measured out length and type of wire I understand, but still...(I read up in the forums and easily replaced it with an E-flite part)]

If it was workable, for example, I'd love to stick a carefully matched cloverleaf (or otherwise) on my RC Tx.

From reading and musing - I get that on the RC radio side it can't have overhead dropouts - so CP antennas may be out of the question.

I also see that, even if I extended my range with a better antenna - if it existed or could be thought up - that the Spektrum TX/RX systems still would not warn me when out of range - like the 72mhz radios you frontiersmen have been using.

I may be a month or too out from buying anything (budgetary reasons etc).
And I've had great non-FPV experiences with this radio for all around park flying.

Just wondering if anything solid could be done on the DIY side- I think a lot of us would be aided that are, for now, closer-in flyers, etc.

Thanks in advance,

Greg
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Old Jun 04, 2011, 08:21 PM
Clueless, but trying
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United States, WA, Enumclaw
Joined Nov 2001
752 Posts
Greg,
Just my two cents (only because I am no-where near as knowledgable as many on this thread), keep an eye out on the classifieds for a solid 72 radio/receiver. 72 is older technology, but very solid and proven.

You can find them for likely less that what it'd cost to put together an Omni antenna.

**HOWEVER** flying in town with a 72, you take the risk of interference on the channel (crystal based) that you happen to be flying on. This would be an unknown if you aren't flying at an ama field.
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Old Jun 04, 2011, 08:57 PM
Specializing in RC since 1972
Temple, GA, USA
Joined Jun 2009
3,135 Posts
Quote:
Originally Posted by RocketMouse View Post
Hi there!

Can you please advise what VTx frequency is best to fly with FRSky for FOX-800 1,3 and 900?
(No restrictions here - I can use any!)

Many thanks.
Everything else being the same (and it simply isn't) some things would make 900 a little better than the slightly different 1300:
- lower frequencies travel a little farther
- lower frequencies penetrate trees a little better
- the harmonics (1.8 and 2.7) are farther away from 2.4g

The antenna is larger for 900 though. For some things that is important:
- CP antennas
- fast airplanes
- small airplanes

900 is close to cell phone frequencies in some areas.

There just is not that much difference between 900 and 1300. There may be more difference in two batches of 900's than there are between 900 and 1300.

Please try to determine what frequencies are legal for use in your country before buying equipment. You don't want to cause problems, even if you don't get caught when you could just buy something on the right frequency to begin with. You might move to a more densely populated area.

Cliff
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Old Jun 04, 2011, 09:00 PM
Specializing in RC since 1972
Temple, GA, USA
Joined Jun 2009
3,135 Posts
Quote:
Originally Posted by fabmic View Post
I got a very dumb question.
Bought a Yagi antenna on 2.4 to get the video signal, and need to install it on the antenna tracker.
I was wondering, if the TX antenna is (as usual) mounted vertically on the plane, I should install the Yagi the same way, and not, so to speak, parallel to the ground, because the tx antenna will be transmitting vertically polarised, and the receiving antenna would be horizontally polarised if it's "flat" or as I tried to describe, parallel to the ground... Right?
The dipoles should point up and down for vertical polarization to match the vertically mounted antenna on the aircraft.

Google is your friend. "yagi polarization"

Cliff
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Old Jun 04, 2011, 09:19 PM
Specializing in RC since 1972
Temple, GA, USA
Joined Jun 2009
3,135 Posts
Quote:
Originally Posted by gmflyer View Post
Hello - this is my first post here in this forum - and I've read all pages here and in the surrounding FPV antenna build threads. WOW. This has really opened up a new arena in RC for me to think about- I want to do it! Alex, I'm really grateful and amazed by your antenna refinements and new breakthroughs. And Alex and Cliff - for the extent of your sharing in an understandable way.

So, I hope this isn't a "don't ask that question", question. But I love the advice about starting off simply enough - and I live in the city and would like to get a solid mile of FPV without driving too many miles outside of town - and feel solid about it. And, being a minimalist at the moment, would like to keep to one radio - my dx6i.

I don't know if anyone has really explored DIY development of this as compared to your recent breakthroughs:
Here's my $64,000 question - isn't there a creative solution to having a better range for my dx6i - by removing the stock antenna and putting on a carefully matched Diy Omni or otherwise - I mean a break-through DIY matching antenna?. [I dropped my radio and broke my antenna a year ago or so, and it was just a wire inside the cheap plastic antenna casing. Yes, a very carefully measured out length and type of wire I understand, but still...(I read up in the forums and easily replaced it with an E-flite part)]

If it was workable, for example, I'd love to stick a carefully matched cloverleaf (or otherwise) on my RC Tx.

From reading and musing - I get that on the RC radio side it can't have overhead dropouts - so CP antennas may be out of the question.

I also see that, even if I extended my range with a better antenna - if it existed or could be thought up - that the Spektrum TX/RX systems still would not warn me when out of range - like the 72mhz radios you frontiersmen have been using.

I may be a month or too out from buying anything (budgetary reasons etc).
And I've had great non-FPV experiences with this radio for all around park flying.

Just wondering if anything solid could be done on the DIY side- I think a lot of us would be aided that are, for now, closer-in flyers, etc.

Thanks in advance,

Greg
For folks in the USA, it is not actually legal to change antennas on a transmitter without a license, and you would need CP antennas on both tx and rx. That being said, it is not too morally reprehensible an act to slide sloooooowly through a stop sign when it is obvious that there are no other cars around...

There is a "dropout overhead" (called a null) on any antenna type for the same reason that a hairy 8 ball must have at least one cowlick.

I have honestly wondered why there is not more talk of CP's on 2.4g RC for FPV. Probably because you would need a coax from the receiver to where you mounted the antenna (a short coax is best) and most of the more expensive RC rx's have two antennas... You need a CP on the tx too.

Someone correct me if I am wrong, but I recall that the DX6i is a "park flyer" which would make it suited only to close in FPV flight. FPV begs you to fly it farther out.

Cliff
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Old Jun 04, 2011, 10:16 PM
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gmflyer's Avatar
United States, OH, Columbus
Joined May 2009
109 Posts
Quote:
Originally Posted by Orcoz View Post
Greg,
Just my two cents (only because I am no-where near as knowledgable as many on this thread), keep an eye out on the classifieds for a solid 72 radio/receiver. 72 is older technology, but very solid and proven.

You can find them for likely less that what it'd cost to put together an Omni antenna.

**HOWEVER** flying in town with a 72, you take the risk of interference on the channel (crystal based) that you happen to be flying on. This would be an unknown if you aren't flying at an ama field.
Thanks, Orcoz - that's good advice and probably where i'll head if there's not another alternative - and yes, sigh, I have ENJOYED the "glitch free with no frequency checking" aspect of flying for the last 2 years on 2.4 in the city.

Greg
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Old Jun 04, 2011, 10:26 PM
Registered User
gmflyer's Avatar
United States, OH, Columbus
Joined May 2009
109 Posts
Quote:
Originally Posted by theothercliff View Post
For folks in the USA, it is not actually legal to change antennas on a transmitter without a license, and you would need CP antennas on both tx and rx. That being said, it is not too morally reprehensible an act to slide sloooooowly through a stop sign when it is obvious that there are no other cars around...

There is a "dropout overhead" (called a null) on any antenna type for the same reason that a hairy 8 ball must have at least one cowlick.

I have honestly wondered why there is not more talk of CP's on 2.4g RC for FPV. Probably because you would need a coax from the receiver to where you mounted the antenna (a short coax is best) and most of the more expensive RC rx's have two antennas... You need a CP on the tx too.

Someone correct me if I am wrong, but I recall that the DX6i is a "park flyer" which would make it suited only to close in FPV flight. FPV begs you to fly it farther out.

Cliff
Aha! a legal thing! Thanks Cliff - LOL on the stop sign. But you answered the mystery, I think, of why, when my antenna broke, and I naturally thought - "I'll check the forums to see who's modded an antenna for both better structural integrity and hopefully longer range" - and found nothing but a post or two on heat-shrink-tubing it back together, etc.

The Dx6i may be enough to get me started - really in-close - until I find/budget a better radio solution dedicated to FPV amongst the ones you've laid out in the thread.

Still pondering and laughing,

Greg
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