I would like to simulate the effects of jitter, but instead of using the standard jitter model, I would like to just randomly delay (positive and negative time) the clock signal. I input the clock signal and then use the latest crossing function and timer to generate a signal.  The following is the code I have written:


module timer_test(input_clk, output_clk,rand_tp);
input input_clk;
electrical input_clk;
output output_clk;
electrical output_clk;
output rand_tp;
electrical rand_tp;


parameter integer start_range=-100;
parameter real fs=1/1n, vth=0.5;
integer seed, end_range;
real ran_num,period,d,rand_t,previous,latest;
analog begin
   @(initial_step) begin
       seed = 50;
       end_range=100;
       previous=0;
   end
   ran_num = $rdist_uniform(seed, start_range, end_range);
   rand_t=ran_num*1p;
   period=1/fs/2;
   @(cross(V(input_clk)-vth,+1))begin
            previous=latest;
   end        
   @(timer(latest+100p))begin
            d=1;
   end
   @(timer(latest+period+100p))begin
            d=0;

   end
   latest=last_crossing(V(input_clk)-vth, +1);
V(output_clk)<+transition(d, 0, 30p, 30p);
V(rand_tp)<+transition(rand_t,0,0,0);
end
endmodule

The problem is that the random number generated doesn't delay the signal created by the timer function.  Is there a way to generate random delay?

Thank you