For your consideration
Hi Everybody,
Already having an ADS-B solution (NavWorx and AFS-4500), it didn't seem to make sense to duplicate the work that the NavWorx was doing (receiving and decoding ADS-B messages). So I took the StraTux project and substituted the NavWorx for the SDR and gen_gdl90 program. I wrote a simple Python script that essentially listens on the NavWorx's RS-232 TX line and re-broadcasts the ADS-B messages via WiFi so that ForeFlight Mobile (FFM) could take it in.
Things that don't seem to work just quite right:
- GPS Altitude. As noted in the bottom left corner of the FFM pictures as '-------'.
- Traffic positions appear delayed. Comparing the AFS-4500's display with what I saw out the window with what I saw on FFM, the AFS-4500 and actual won hands down. On one occasion, a jet landing into Austin was way off my left wingtip and several thousand feet higher. The AFS display had it spot on. FFM had it way behind and to my left.
- Traffic altitudes were off compared to the AFS-4500 display. At most they seemed about 1000 ft off. This may coincide with the lack of 'GPS Altitude' mentioned earlier.
- Course was delayed. Prior to reaching KSOA, I made a U-Turn. It took FFM maybe 30-60 seconds before it showed the correct course.
What seems to work but has not been confirmed as accurate:
- SIGMETs and AIRMETs
- WX RADAR and looping
- Surface Winds
As this was my first foray into FFM and ADS-B, I may have other info available that I don't know how to access/display properly. For example, at times I was receiving data from three ADS-B antennas but I don't know how to display their location.
Some screen shots I got today:
http://caura.homenet.org/gallery/d/28935-2/IMG_0060.PNG
http://caura.homenet.org/gallery/d/28939-2/IMG_0061.PNG
http://caura.homenet.org/gallery/d/28942-2/IMG_0062.PNG
To make this work, I used:
- A copy of StraTux - mainly for the WiFI Access Point work.
- RPi Model B
- RS-232 / USB Dongle
- Cigarette Lighter to USB Power Adaptor to power the RPi
- Some wire, connectors, and a DB-9 that plugs into the above RS-232 / USB Dongle
During development, I used a USB / RS-232 dongle that plugs into the RPi's GPIO pins.
Bear in mind that this is highly alpha level stuff and nothing about it is guaranteed. If you are interested in helping out, drop me a line and I'll share the source code and any notes.
Today's test flight was about 1.5 hours. I am planning on going to the Bad Lands fly-in , WX permitting, and I intend on taking this contraption and seeing how it does for the long haul (about 6.5 hours).
Question to the folks using StraTux: Have you compared FFM's ADS-B display with a known good ADS-B display solution?
Regards,