Image Transmission Network Code

Image Transmission

The image transmission network code refers to the client and server programs used to download images from the UAV to the Ground Station. The UAV is setup as the server and waits for a download request. The Ground Station acts as a client that primarily just sends download requests to the UAV. This page will explain the protocol of this network system, outline its software implementation, and describe its physical setup.

Protocol

The image transmission protocol is built on simple HTTP. The client sends an HTTP request and the server replies with an HTTP response.

Server

The image transfer server's interface supports several commands

• getImage
• capture
• shutdown

getImage:

The getImage command is sent using a GET request to the url "/getImage". An optional parameter string can be appended to specify which image is being requested (ex. /getImage?fname="image42"). A client who sends this request should receive either an image file or an appropriate error message. If no file name is given, a default (ex. "current") should be used.

capture:

The capture command is sent using a POST request to the url "/capture". An optional parameter string can be appended to specify a name for the image file (ex. /capture?fname="image01"). A client who sends this request should receive a text response containing any relevant messages. A server that receives this message should attempt to use the gphoto library to take a picture with the camera. If no file name is specified, then a default (ex. "current") should be used.

Client

Software Implementation Example

Physical Setup

The avionics package onboard the UAV is expected to be able to run the image transfer server. That onboard computer connects to our 2.4 GHz bullet antenna which acts like a wireless ethernet cable connected to the ground station's bullet antenna. Since they are essentially connected by ethernet, the computers can talk to each other using TCP/IP the same way they would over a LAN. The images transferred over the wire can be sent to processing, saved to disk, or displayed to the operators once they are received by the ground station.