depth = 250;   % This is the assumed target depth
figure('Name', 'Range Circles');
for i = 1:length(tp_time)
    range = tp_sr(i)^2-depth^2;
    if range > 0
        plot(x(i)+range^0.5*cos([1:360]*2*3.14159/360), y(i)+range^0.5*sin([1:360]*2*3.14159/360), 'r');
    end
    hold on
end

for i =1:length(x)
  utm_zone(i) = {'10 S'};
end

Xtick_easting = get(gca, 'xtick');
Ytick_northing = get(gca, 'ytick');
[dummy, Xtick_lon] = utm2deg(Xtick_easting, Ytick_northing(1)*ones(1,length(Xtick_easting)), char(utm_zone(1:length(Xtick_easting))));
[Ytick_lat, dummy] = utm2deg(Xtick_easting(1)*ones(1,length(Ytick_northing)), Ytick_northing, char(utm_zone(1:length(Ytick_northing))));
set(gca, 'xticklabel', Xtick_lon, 'yticklabel', Ytick_lat);
