function b = mk_bt(instclass, a, avg_flag)

if nargin == 2, avg_flag = 0; end

bb = [a.bt.vel(1:2, :); mean(a.bt.range)];

if avg_flag,
   b = mstdgap(bb, 2);
else
   b = bb;
end

b(isnan(b)) = 1e38;


