Overview

Coding Scheme

Instruments

Mission Matlab Code

Turbo Code Details

Turbo Code Programming

Communications References

Communication Systems

Matlab code:

% Introduction:

% The Goal of this Code is to make an estimate of the number of Relays

%necessary to achieve a reliable communication channel between the earth

%and the HD imaging Satellite Probe. The last link would

%be a relay orbiting around the earth and Transmitting the information

 

%Variables

YL=9460730472580.8e03;

c=3e+08;

F=27e+09;

%BW=0.05e+03;

BW=20;

Eb_N0=10^0.2;%reliable channel with Turbo Codes BER 10^-6

k=1.3807e-23;

T=6;% open Space between relays

T2=150;

Pt_dB=30;% Power of transmission 10kW(?)

%R=50;%rate bit of the link

R=0.02e+03;

V = 100e6; % m/s velocity of probe

f_Dop = V*F/c;

 

Ant_rad=7;% meters

nu=0.9%efficiency

G_dB = 10*log10(nu*4*pi*(pi*Ant_rad^2)*(F^2/c^2));%gain of the antenna

Phi_theta=32000/10^(G_dB/10);%3dB angular aperture in degree

 

Gr_db = G_dB; Gt_db = G_dB;

 

SNR=Eb_N0*R/BW;

SNR_dB=10*log10(SNR)% The required SNR for Reliable Channel with Trubo Code

%Noise Power

N_dB=10*log10(k*BW*T)

 

%this part estimates the maximum Range for a reliable

% Channel implementing Turbo Code

 

r=10^((Pt_dB+Gr_db+Gt_db-10*log10((4*pi)^2*F^2/c^2)- N_dB - SNR_dB)/20);

 

% light Years....

 

r_YL=r/YL

%value of the main lobe aperture at next reciever

Aperture=sqrt(Phi)*pi/180*r% in meters

% Required number of Relays

N_relay=10.5/r_YL

 

 

%This second part is aimed to validate the Choice of different rates and

%values

 

 

CNR_dB=Pt_dB+Gr_db+Gt_db -10*log10((4*pi)^2*F^2/c^2)...

 - 20*log10(10.5*YL/N_relay)- N_dB

CNR=10^(CNR_dB/10);

%Maximum Channel Capacity for each connection

MAX_C=BW*log2(1+CNR)

% Required CNR for R<C reliable Channel and BER 10^-6

 

 

%Imaging

%Using LORRI Telescope and CDD process Please Refer Documentation for

%specifcations

 

resolution=1024*1024%pixels

 

%Visible Colors

 

size_bits=24% 24 bits per Pixel

 

Image_size=resolution*size_bits/3%  using zip compression of 1/3

Transmission_Time_Image=Image_size/R/3600/24 %in Days

 

%Part 2 We were able to find the limits of a

%reliable communication link, in this part will use the previous results

%and a number of Relay of 5 to estimate The transmitted power needed in

%order to save energy

N_Designed_Relays=13

CNR_dB_link_relay=Pt_dB+Gr_db+Gt_db -10*log10((4*pi)^2*F^2/c^2) - ...

    20*log10(10.5*YL/N_Designed_Relays)- N_dB

 

Pt_dB_per_Relay=-(Gr_db+Gt_db-10*log10((4*pi)^2*F^2/c^2)- N_dB - SNR_dB)...

    +20*log10(10.5*YL/N_Designed_Relays)