[Paparazzi-devel] Support for multiple communication links

[Cameron Lee]

Hello everyone,

I'm a fourth year Electrical Engineering student interested in working on an aspect of Paparazzi for a class of mine. I'm planning on adding support for multiple communication links at both the GCS and on the autopilot. Similar to item 6 in the wishlist (http://paparazzi.enac.fr/wiki/Software_Wish_List): 

> The possibility to use multiple ground modem connected to a single ground station. The RSSI could be use to dynamically choose which currently has the best signal. This would allow the use of different antennas on each of the modems or have antenna pointing in different directions(?Possibly more hardware related)


Here's a description I've written up:

> The goal is to improve the open source Paparazzi autopilot by adding support for multiple communication links to provide redundancy and increased flexibility. Currently, a single bi-directional serial data link enables the autopilot to provide telemetry to the ground station and the ground station to provide commands to the autopilot. This serial data link is usually created using RF radios and if it’s lost for any reason, all communication with the autopilot is lost. If two data links can be created, then communication can be maintained even if one of the links is lost. Typically, the two links would be of different varieties: two different frequencies, or a short-range high-throughput link and a long-range low-throughput link, or the same type of radio, but with different types of antennas, other combination.
> This project will involve enabling the autopilot and the ground station to each transmit their data through multiple links as well as receive data through multiple links. Receiving data through multiple links will involve deciding which link to take as correct based on the data coming in through all available links.

Before I start working on this, I figured that I should ask for feedback - is this functionality indeed useful? Is this the best way to go about it? Is this project achievable (in particular on the autopilot side - will it take too much system resources)? Any tips or advice would be appreciated. Also, how difficult would it be to have different telemetry sent out over each link?

Thanks,

Cameron