%
% FUNCTION 2.6 : "cp0201_transmitter_2PPM_TH"
%
% Simulation of a UWB transmitter implementing 2PPM with TH
%
% Transmitted Power is fixed to 'Pow'.
% The signal is sampled with frequency 'fc'.
% 'numbits' is the number of bits generated by the source.
% 'Ns' pulses are generated for each bit, and these pulses
% are spaced in time by an average pulse repetition period
% 'Ts'.
% The TH code has periodicity 'Np', and cardinality 'Nh'.
% The chip time has time duration 'Tc'.
% Each pulse has time duration 'Tm' and shaping factor
% 'tau'.
% The PPM introduces a time shift of 'dPPM'.
%
% The function returns:
% 1) the generated stream of bits ('bits')
% 2) the generated TH code ('THcode')
% 3) the generated signal ('Stx')
% 4) a reference signal without data modulation ('ref')
%
% Programmed by Guerino Giancola
%
function [bits,THcode,Stx,ref]=cp0201_transmitter_2PPM_TH
% ----------------------------
% Step Zero - Input Parameters
% ----------------------------
Pow = -30; % Average transmitted power (dBm)
fc = 50e9; % sampling frequency
numbits = 7000; % number of bits generated by the source
Ts = 3e-9; % frame time, i.e. average pulse
% repetition period [s]
Ns = 1; % number of pulses per bit
Tc = 1e-9; % chip time [s]
Nh = 3; % cardinality of the Time Hopping code
Np = 30000; % periodicity of the Time Hopping code
Tm = 0.5e-9; % pulse duration [s]
tau = 0.25e-9; % shaping factor for the pulse [s]
dPPM = 0.5e-9; % time shift introduced by the PPM [s]
G = 0;
% G=0 -> no graphical output
% G=1 -> graphical output
% ----------------------------------------
% Step One - Simulating Transmission Chain
% ----------------------------------------
% binary source
bits = cp0201_bits(numbits);
% repetition coder
%repbits = cp0201_repcode(bits,Ns);
[output_bchen]=encode(bits);
oun=length(output_bchen)
% Time Hopping code
THcode = cp0201_TH(Nh,Np);
% Pulse Position Modulation + TH
[PPMTHseq,THseq] = ...
cp0201_2PPM_TH(output_bchen,fc,Tc,Ts,dPPM,THcode);
% Shaping filter
power = (10^(Pow/10))/1000; % average transmitted power
% (watt)
Ex = power * Ts; % energy per pulse
w0 = cp0201_waveform(fc,Tm,tau);% Energy Normalized pulse
% waveform
wtx = w0 .* sqrt(Ex); % pulse waveform
Sa = conv(PPMTHseq,wtx); % Output of the filter
% (with modulation)
Sb = conv(THseq,wtx); % Output of the filter
% (without modulation)
% Output generation
L = (floor(Ts*fc))*Ns*(numbits/7)*15;
Stx = Sa(1:L);
ref = Sb(1:L);
% ---------------------------
% Step Two - Graphical Output
% ---------------------------
if G
F = figure(1);
set(F,'Position',[32 223 951 420]);
tmax = numbits*Ns*Ts;
time = linspace(0,tmax,length(Stx));
P = plot(time,Stx);
set(P,'LineWidth',[2]);
ylow=-1.5*abs(min(wtx));
yhigh=1.5*max(wtx);
axis([0 tmax ylow yhigh]);
AX=gca;
set(AX,'FontSize',12);
X=xlabel('Time [s]');
set(X,'FontSize',14);
Y=ylabel('Amplitude [V]');
set(Y,'FontSize',14);
for j = 1 : numbits
tj = (j-1)*Ns*Ts;
L1=line([tj tj],[ylow yhigh]);
set(L1,'Color',[0 0 0],'LineStyle', ...
'--','LineWidth',[2]);
for k = 0 : Ns-1
if k > 0
tn = tj + k*Nh*Tc;
L2=line([tn tn],[ylow yhigh]);
set(L2,'Color',[0.5 0.5 0.5],'LineStyle', ...
'-.','LineWidth',[2]);
end
for q = 1 : Nh-1
th = tj + k*Nh*Tc + q*Tc;
L3=line([th th],[0.8*ylow 0.8*yhigh]);
set(L3,'Color',[0 0 0],'LineStyle', ...
':','LineWidth',[1]);
end
end
end
end % end of graphical output
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