Recent Topics - Rotate.Aero Wed, 18 Oct 2017 16:46:52 +0000 MYOB en-gb Desktop Streaming - by: Mark Desktop Streaming of ADS-B Transponder Data
I’ll start with a quick discussion of hardware first. The Raspberry Pi does not have enough balls (memory and processor power) to handle a constant desktop stream. I tried on two different Pi’s with the same results. The stream would function normally for approximately 2-3 hours and then the units just completely went offline.

There might have been some alternate factors playing a part in this. I turned on the VNC function on both Pi’s to view the unit remotely with RealVNC (which is provided free on the Pi). It is possible that VNC was providing an extra load on the units. CPU usage floated around 50%-60% with DUMP1090, nginx (server), ffmpeg (streamer), one feed to FlightRadar24, one feed to Plane Finder, and VNC running at the same time. A CPU temperature indication can be placed in the toolbar. With all the above items running, CPU temps ran up to 70-80 degrees (even with a fan blowing on the units).

I realized more computing power was needed. I installed the Raspberry Pi Desktop (Jessie) on to a Dell Inspiron Micro, quad core with 8 GB of memory (At the time of this post, the system has been streaming for over 24 hours with no issues). This could be somewhat overkill though, I would guess a dual core with 4GB would probably work fine.

My first concern was if the RTL receiver (NooElec R820T) would work using the DUMP1090 install described here It worked fine. As a note: I had to do the blacklist described here

I have found a link that describes how to set up the Pi to start DUMP1090 automatically, but I haven’t found a way to view DUMP1090 data with an automatic start. I found sudo cd /dump1090 and then ./dump1090 –interactive –net starts the receiver up and displays received data.

The FlightRadar24 feed can be installed and activated from instructions provided here
The Plane Finder feed can be installed from instructions provided here Because of the fact I was using a separate computer and not a Pi, I installed via the i386 commands.

Both feeds were set up as AVR(TCP) with an address port 30002

With everything up and running I was able to view both the feeds in a browser FR24 at localhost:8754 or computer’s local IP:8754 (use the ifconfig command to verify the unit’s IP) and Plane Finder at localhost:30053

The feed was quite a bit more difficult to solve. I found a link that got my nginx server running.

ffmpeg (or really avconv) was installed via this command: sudo apt-get install libav-tools which I found here

The actual command to start the stream was pieced together from digging through several ffmpeg sites. I am “not” a skilled coder and I really have no clue as to the command's components. I just know it works. (previous tries resulted in fuzzy screens or only half the desktop being displayed.)

To start nginx:


To start the stream:

avconv -f x11grab -framerate 30 -video_size 1824x984 \
-i :0.0+0,0 -c:v libx264 -preset veryfast -maxrate 1984k -bufsize 3968k \
-vf "format=yuv420p" -g 60 -c:a aac -b:a 128k -ar 44100 \
-f flv rtmp://

The video size is determined by your actual screen resolution and the address (192.whatever) is the computer’s own internal LAN IP.
I believe that there are no firewall setting changes needed on any Raspberry distro and I didn’t dig into that at all.
Port 1935 will need to be opened on your router for the unit’s IP address.

The stream can be seen with VLC (Network Stream) using either the internal IP:1935/live or your external address:1935/live (with port 1935 open on router). The stream address is rtmp://your IP:1935/live

As a side note: I found using sudo -i will give you admin privileges without having to type sudo before every command.]]>
ADS-B Receivers Sat, 07 Oct 2017 22:52:54 +0000
Landing Gear Control - by: Mark REAL pain.

Otherwise, some learning was accomplished: A hydraulic selector valve and a hydraulic load valve are used to retract and extend the gear. From my best guess, the load valve (supplies pressure) is used for both up and down. The selector valve appears only to be used in the up direction. I'm assuming that when the solenoid is powered on the selector valve it pushes on a spring that normally keeps the valve porting fluid for a gear down condition.

Wiring depicted in the 421 maintenance manual.

Condition when gear handle selected up.

Gear up and locked when gear handle selected down.

ATA 32 Landing Gear Tue, 26 Sep 2017 17:52:58 +0000