How to shorten the precision of Input voltage?

I used the compare operator ">" to detect the value that higher than a threshold.

But the value is undesirable ...

For example, the following is code:

$display("-------------AVDD5: ", V(AVDD5));
   if(V(AVDD5) > 720m && V(AVDD5) < 730m)begin
       $display("-----------[125m-range]--AVDD5: ", V(AVDD5));
   end
   else if(V(AVDD5) > 730m && V(AVDD5) < 840m) begin
        [do something]
   end

       [do something]
   else begin

   end

The result is 

-------------AVDD5: 0.0063628
-----------[fast]--AVDD5: 0.0063628

-------------AVDD5: 0.0203494
-----------[fast]--AVDD5: 0.0203494

-------------AVDD5: 0.0651065
-----------[fast]--AVDD5: 0.0651065

-------------AVDD5: 0.208329
-----------[fast]--AVDD5: 0.208329

-------------AVDD5: 0.666642
-----------[fast]--AVDD5: 0.666642

-------------AVDD5: 1.16764
-----------[fast]--AVDD5: 1.16764

-------------AVDD5: 1.66865
-----------[fast]--AVDD5: 1.66865

-------------AVDD5: 2.16965
-----------[fast]--AVDD5: 2.16965

-------------AVDD5: 2.19
-----------[fast]--AVDD5: 2.19

-------------AVDD5: 2.25513
-----------[fast]--AVDD5: 2.25513

As the mark position, i need the range [720, 730], [730, 840]

But the time range is too big (0.666666 -> 1.16764), so the if statement couldn't catch it!

Could anyone help me, thank for you a lot!!!!!