Re: [Paparazzi-devel] nav.h missing? SOLVED

[Chris]

Hi David.
Unfortunately those antennas have low efficiency, low gain and high SWR.
A better alternative is a log periodic or a Vivaldi antenna but in any 
case in order to use a multiband antenna a duplexer is needed with high 
isolation which usually involves cavities which leads to heavy and bulky 
constructions especially in 900-1200 Mhz bands.
I have tried this road when one antenna is used for both telemetry and 
video (2.4 ghz and 5.8 ghz)
with good results but such duplexers are hard and expensive to find.
A better (airborne) multiband antenna might be a crossed dual band yagi 
(a yagi with one boom and elements that look like a cross)
So far my own make single band yagis are performing really well both for 
rf and low drag.
Chris


On 05/31/2014 12:23 AM, David Conger wrote:
> Hey Chris,
> Maybe my ignorance shining through but what about multi-frequency
> antennas? Here's one someone once suggested to me:
> http://www.digikey.com/product-detail/en/FXP14.07.0100A/931-1056-ND/2332683
> I wish someone Paparazzi would try one of these out and report their
> experience. Soon I will have some time to try the ones out I have.
> DigiKey has one with u.fl connector that connects right to the XBee
> (with u.fl).
> -David
>
> On Fri, May 30, 2014 at 2:06 PM, Chris <address@hidden> wrote:
> > Well it is too expensive as you said so i am looking also for a cheap
> > solution.
> > I expect to fly at least 100km away with a 10dbd yagi on the airplane
> > something i have done
> > but with a fuel cooled 10w analogue video transmitter (believe it or not)
> > something i don't now think as a good idea :-D
> > A 5w video tx coupled with 2 steerable yagis on the wing tips is more than
> > enough because of power consumption and interference on other systems.
> > I have used nearly all bands but the best band for airborne video seems to
> > be the 2.3-2.4 ghz band
> > Experimenting is necessary to find new things.
> > Chris
> >
> >
> > On 05/30/2014 11:28 PM, Eduardo lavratti wrote:
> >
> > wow ... 4w is much power.
> > Please, when you have idea on how much long you can fly using this solution
> > ... tell me.
> >
> > Today i can fly more than 4km using 600mw 5.8ghz fatshark clone transmitter
> > with good video signal.
> >
> > i like this digital video system but its too expansive.
> > http://www.nghobbies.com/cart/index.php?main_page=index&cPath=1_147
> >
> > ________________________________
> > Date: Fri, 30 May 2014 22:29:08 +0300
> > From: address@hidden
> > To: address@hidden
> > Subject: Re: [Paparazzi-devel] nav.h missing? SOLVED
> >
> > So far it looks that the receiver has the same or better sensitivity with
> > it's analog counterpart.
> > The real testing will be done in a few weeks over the sea.
> > In ground testing with and without obstacles  i lost video at about the same
> > or slightly more distance than the analog tx of comparable power which is
> > very promising.
> > Fhss also works well as seen on a spectrum analyser, the moving scene video
> > quality is very nice and latency is small enough at ~150-200 ms.
> > I wouldn't fly fpv with it but ~200 ms are not bad for watching around.
> > I have also noticed some dropped frames but i need to do some more testing.
> > The strong point of this system is that you can use a common power
> > bidirectional wifi amplifier
> > to increase range (i now use 4w of rf power measured) and interference on
> > the airplane is far less
> > than the analog video tx.
> > I successfully used an 2.4 ghz rc receiver along with this 2.4 ghz video
> > transmitter (at +18dbm) with no ill effects on rc range.
> > Chris
> >
> >
> > On 05/30/2014 10:10 PM, Eduardo lavratti wrote:
> >
> > Hi Chris, how many meter  you can get with this video solution ?
> >
> >
> > ________________________________
> > Date: Fri, 30 May 2014 21:09:25 +0300
> > From: address@hidden
> > To: address@hidden
> > Subject: Re: [Paparazzi-devel] nav.h missing? SOLVED
> >
> > Hi.
> > I found a cheap 2.4 ghz frequency hopping video to mpeg4 converter with very
> > nice quality and sensitivity that i coupled with a bidirectional 2.4 ghz
> > amplifier and the airborne tracking antenna.
> > Initial test showed very good results.
> > http://www.alibaba.com/product-detail/2-4G-60MW-Single-track-digital_784242131.html
> > http://www.alibaba.com/product-detail/Digital-wireless-AV-sender-modules_858209681.html
> > http://www.alibaba.com/countrysearch/CN/vr850sf-supplier.html
> > http://www.alibaba.com/product-detail/2-4ghz-Digital-Wireless-Car-Camera_1427511862.html
> > Beware that although the item is real i can't say the same for the
> > transaction.
> > Aliexpress is the only source for it right now i think.
> > http://www.aliexpress.com/item/Free-shipping-2-4G-wireless-audio-digital-transmitter-and-receiver/1194761842.html
> >
> > The telemetry is done with the usual 9xtend modems and now i am about to
> > test this
> > http://store.rfdesign.com.au/rfd-900-radio-modem/
> > Chris
> >
> >
> >
> > On 05/30/2014 01:41 AM, alonso acuña wrote:
> >
> > Hi Chris. Can you give me some pointers on how to implement digital video
> > and secure telemetry?
> >
> >
> > On Wed, May 28, 2014 at 10:07 AM, Chris <address@hidden> wrote:
> >
> > He he he  your guess is correct.
> > The code i am flying is heavily altered towards a fixed wing platform.
> > For example i am working on a safety algorithm that guides the airplane back
> > home when gps is lost. When gps is lost (interference etc.) the airborne
> > directional antenna(s) are used for guiding the airplane back home with the
> > aid of the compass, the barometer and any available RSSI indication.
> > Of course telemetry and video are now digital and encoded.
> > Chris
> >
> >
> >
> > On 05/28/2014 06:55 PM, Felix Ruess wrote:
> >
> > Hi Chris,
> >
> > yes, I moved it to firmwares/fixedwing, as it is fixedwing specific stuff...
> > But I still wonder why you got this error, I changed it accordingly in all
> > sources... Did I miss something or was that in some of your own code?
> >
> > Cheers, Felix
> >
> >
> > On Sat, May 24, 2014 at 8:29 PM, Chris <address@hidden> wrote:
> >
> > I found it, nav.h moved to "firmwares/fixedwing/nav.h" (for fixedwings of
> > course)
> > Chris
> >
> >
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> >
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