function [p_obs] = p_observed(sensor, env)F=sensor.F;rmax=sensor.rmax;rho=sensor.rho;dB=sensor.db;sb=sensor.sb;sr=sensor.sr;ee=sensor.ee;ef=sensor.ef;delta=env.delta;M=env.M;d=env.d;Ee = ((1-d)*(1-ee)+d*ef);Ef = (d*(1-ef)+(1-d)*ee);p_obs=0;for r=0:floor(sr/delta)    p_obs=p_obs + r;endfor r=ceil(sr/delta):ceil((rmax+sr)/delta)    p_obs=p_obs+r*Ee^(dB*max(0,r*delta-sr)^2/delta^2);    % version with p_n    %p_obs=p_obs + r * min(1, (Ee^(dB*r^2) + 0.5*Ee^(dB*(r*delta-sr)^2/delta^2)*min(1, Ef*dB*(2*r*delta*sr-sr)^2/delta^2)));end