Introduction¶

The aim of this project is the design of a Telemetry and Telecommand (TM/TC) link between small aircrafts (ie TB20) and an antenna on top of ISAE building. There are different aspects in this work:

• regulatory aspects : we must pay for rights of emission on a given frequency band
• link budget aspects : some parameters can be adjusted to reach the wanted performance
• flight constraints have to be considered in the choice of the equipment to allow a full time link

To summarize the system design constraints, we can fill the mission statement below:

In order to define the video bit rate required for our application, knowing the aspect ratio (AR=1,78) quality of the encoded video (L=720p) and its frame cadence (FPS=12), we used the following formula:

Bit rate = FPS*5,0692 * L ^1,391 /(1000*AR)

So

Bit rate=322 Kbps

As the link will allow data and video transmission, we choose to use the MPEG4 packet format, adapted for multiplexing different nature content. Therefore, we have to consider extra bits due to the encapsulation of data in MPEG4 frames, and we decide to define a bit rate of 500 kbps.