Wireless IP telemetry

The goal of this project is to control (fly) my quadcopter as from a normal pc with a usb joystick or gamepad. The APM Planner ground station software from DIYdrones support IP based telemetry via UDP. The arducopter firmware has build in telemetry code and a dedicated serial connection to send and recieve all data. So we just have to add a serial to wifi module.


My choice is the Lantroni MatchPort® b/g module. Because it can handle high data rates, it has a good tx power and you can connect any type of wlan antenna to maximaze tx/rx distance. But these features make it a bit more heavy then other modules. Compared to other modules it consumes a lot more. But if you want speed, power and distance then you have to deal with this.


Some features:
Wired Ethernet-to-wireless bridging
Bulletproof security with IEEE 802.11i-PSK,WPA-PSK, TKIP and optional 256-bit AES end-to-end encryption
Full TCP/IP stack,web server and Windows deployment software
wlan data rates: 1Mbps up to 54Mbps
Two serial channels: up to 921 Kbps data rate
8 real time general I/O configurable pins
3.3V-level signals
Output Power: 14dBm +2.0 dBm
Receive Sensitivity: -91dBm @ 1Mbps

To get this thing to work with the the diydrones ardupilot I configured it this way:
- cpu performance: low -> this is more than enough performance the handle everything it has to do.
- wlan power management: OFF -> default it is ON but this gives laggy/sturring data stream. Working with udp we want a steady smooth data stream. So make sure to set this to OFF
- wlan data tx rate -> 1mbps -> this is more then enough speed, setting it to 1mbps will give you max range.
- serial 1 protocol: RS232 -> note that is will operate at 3.3v TTL level
- serial 1 baud rate: 57600 -> this is the default confiration in the ardupilote firmware
- enable packing -> enabled (gap time 12ms) -> if you do not enable this fuctions the wifi module will tx data only when the MTU data block is full (1400b) and that will cause a hughe lag in our data stream. So enable this function.
- match 2 byte sequence: yes, 0D & 0A -> adding this will force the wifi to tx data when ar CRLF arrives from the serial data comming from ardupilot.
- send frame immediate: yes

documents about this module can be found on the lantronix website or my google drive

IP Camera (FPV)

Some time ago I bought an Edimax Wireless IP Camera to use as FPV (first person view) solutions in my quadcopter project. But I noticed that it will be very difficult to control the quad live via the videostream from the wireless IP cam because there is to much lag. The IP cam also has a FOV (field of view) of only 40 degrees. For FPV solutions a FOV of > 90 is adviced. But still I can use the IP cam as live view and recorder.

So I disambled the Wireless IP Camera and made a mounting board to place the cam on the quad. The mounting board is a aluminium plate (1mm) total weight 38 grams. That is less then useing the original houseing of the ipcam itself. At the first try-out I reversed voltage polarity, so I burned the IP Cam.  But After some testing I found out that only the voltage regulation cirquit on board of the ip cam if defective and that I can bypass this section by connection a battery (or external voltage regulater) behind this section. So IP Cam fixed!

After mounting the IP Cam to the quad I got a total weight of 1420grams.  Adding an external voltageregulator + wiring to power the IP Cam will give me a total weight of 1450 grams. So estimated flight time with extra weight + ip cam consumption, only 5 min.
Weather is bad so currently I can't make/upload a real flight fpv video.

(update 2 nov 2012, due to bad weather again a little garage flight)