Introduction » History » Version 3
Version 2 (AUGER, Anne sophie, 03/23/2015 09:06 AM) → Version 3/10 (AUGER, Anne sophie, 03/23/2015 09:42 AM)
h1. Introduction
The aim of this project is the design study 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 find a frequency band, either license-free or requiering 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
p=. !Slide1.jpeg!
To summarize the system design constraints, we can fill the mission statement below:
p=. !cahier_des_charges.png!
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:
p=. Bit rate = FPS*5,0692 * L ^1,391^ /(1000*AR)
So
p=. *Bit rate=322 Kbps*
As the link will allow data and video transmission, we will need an choose to use the MPEG4 packet format, adapted encapsulation protocol, so for multiplexing different nature content. Therefore, we must take into account have to consider extra bits: bits due to the encapsulation of data in MPEG4 frames, and we decide to define a video bit rate of 500 kbps.
The aim of this project is the design study 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 find a frequency band, either license-free or requiering 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
p=. !Slide1.jpeg!
To summarize the system design constraints, we can fill the mission statement below:
p=. !cahier_des_charges.png!
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:
p=. Bit rate = FPS*5,0692 * L ^1,391^ /(1000*AR)
So
p=. *Bit rate=322 Kbps*
As the link will allow data and video transmission, we will need an choose to use the MPEG4 packet format, adapted encapsulation protocol, so for multiplexing different nature content. Therefore, we must take into account have to consider extra bits: bits due to the encapsulation of data in MPEG4 frames, and we decide to define a video bit rate of 500 kbps.