paparazzi-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Paparazzi-devel] digital video link anyone?


From: Chris
Subject: Re: [Paparazzi-devel] digital video link anyone?
Date: Sat, 11 May 2013 20:10:54 +0300
User-agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130329 Thunderbird/17.0.5

Hi.
Have you posted your efforts in DIYdrones? (if yes then i have seen your setup, very very nice for me
as my airplane can lift this setup easily)
First of all i consider long range anything above 20km but usually above 40km. I haven't tried a digital link in actual flight only on the ground (1km) as a test
and i wasn't impressed with its performance vs price.
The frame rate would vary drastically for a given power, i didn't used an amplifier for 1km just the directional antennas as i needed to calculate how far i can get with a given rf power. About the rotomotion system, one friend of mine has this setup from rotomotion and it can do 15km easily but it consumes a lot of space and it is rather heavy for an airplane, not to mention pricey. Now the second system from vfm store is one way which might be better but the seller still hasen't answered a couple questions i had so i didn't bought it yet. If it hasn't got the same picture quality as an analog PAL camera then i will not buy it and test it. So far the best system i have used is an analog tx with video scrambler, 2 steerable antennas (a 5 element yagi, one on each wing) and a power amplifier (address@hidden) mounted on a 3.1m span airplane. The only problem is that it is heavy as it needs large lipo batteries (only the linear amp draws 10A so i need to turn on the vtx only when needed) and that the antenna system is complicated. Finally i got hold of making high gain yagi antennas perfectly matched but i am searching for something simpler like this
http://www.learningace.com/doc/2795149/2da44f2ac03124199b1d13881857375b/awpl_design-of-a-multidirectional-high-gain-compact-yagi-antenna
Chris



On 05/11/2013 07:00 PM, address@hidden wrote:
Rotomotion uses a board similar to that. They also have a full-blown hub
and wifi tx onboard and these are on gasser choppers.

How far did you go with digital video and what do you consider long range?

I worked on a setup and ground decoder to minimize latency. Unfortunately
the wing loading turned out to be unfavourable,
so it never flew very far, only about 100 meters. I was working with an
arecont IP cam, a 3-pos "CyberData POS router board" powered by 5V,
sparkfun ethernet breakout board (W5100) and Ubiquiti Long Range wifi
modules. The UBNT PicoStation can be taken apart to keep weight
down. I was using a Circular Wireless SPW antenna with Luxul CP 11dBi
antenna.  I have not been able to find reasonable alternatives for
wifi that allows transmission of both video and custom data on the same
link. So if you know of any, would be happy to hear about it.

The W5100 chip is quite crappy to write data to. Every byte of data
requires the transfer of 4 bytes in total over SPI.

Rgds,

Gerard




reply via email to

[Prev in Thread] Current Thread [Next in Thread]