3D surface plot from for loop

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MATLABmet
MATLABmet 2017-1-26
评论： John BG 2017-1-27
Hi all,
The following is my code, which calculates RF path loss between a satellite and a ground station, factoring in altitude and trajectory.
% code
f=5*10^6; %must be *10^3 less than given f. For example if f=5GHz, use 5MHz
h=700;
Gt=0;
Gr=0;
Nf=-100;
for i = 1:181
ang(i)=i-1
d(i)=sqrt(((6371+h)^2)-(6371^2)*(cos(ang(i)*(pi/180)).^2))-6371*sin(ang(i)*(pi/180));
Lp(i)=20*log10((4*pi()*d(i)*f)/(300000));
Pt=10*log10(57.27*0.193)+30; %convert to dbm
Pr(i)=Pt+Gt+Gr-Lp(i);
SNR(i)=Pr(i)-Nf
end
I can easily create 2D plots from this such as plot(ang,Lp) etc.. But I want to create a 3D plot using the surf command, which plots (ang,Lp,d).
How is this possible ?
Thanks in advance.
  1 个评论
John BG
John BG 2017-1-27
there are satellite comms examples readily available at the MATLAB file exchange.
For instance
available from
https://uk.mathworks.com/help/comm/examples/rf-satellite-link.html?s_tid=srchtitle
the channel is already modelled in some of the blocks.
John BG
<mailto:jgb2012@sky.com jgb2012@sky.com>

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回答（1 个）

Massimo Zanetti
Massimo Zanetti 2017-1-26
Most probably you don't want to plot a surface, instead a plot of a line in a 3D space. Try this:
plot3(ang,Lp,d); grid on;
Is that what you need?
  2 个评论
MATLABmet
MATLABmet 2017-1-26
Hi Massimo,
That looks more like what I want. However, I now want to bring the h value into the loop and make it range from 700:800Km. So really I need a 3 dimensional plot that represents distance, angle, and pathloss.
thanks again,
Massimo Zanetti
Massimo Zanetti 2017-1-26
编辑：Massimo Zanetti 2017-1-26
Ok, so what you need is more likely a family of curves. Consider that there is no need of any loop, thanks to Matlab implicit expansion. See here:
f=5*10^6; %must be *10^3 less than given f. For example if f=5GHz, use 5MHz
Gt=0;
Gr=0;
Nf=-100;
h = (700:5:800)';
ang = 0:180;
d = sqrt(((6371+h).^2)-(6371^2)*(cos(ang*(pi/180)).^2))-6371*sin(ang*(pi/180));
Lp = 20*log10((4*pi*d*f)/(300000));
Pt = 10*log10(57.27*0.193)+30; %convert to dbm
Pr = Pt+Gt+Gr-Lp;
SNR =Pr-Nf;
plot3(ang,Lp,d); grid on;
If this answer helped you, please accept it.

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