1. A method for determining an active code set, comprising: by an active spread code detection module: (a) receiving code detection statistics and the corresponding spread code indices, wherein the amplitudes of the code detection statistics are proportional to the probability that a spread code channel is active; (b) determining an activity threshold based on the received code detection statistics; (c) testing the code detection statistics and the corresponding spread code indices in descending order based on the amplitudes of the code detection statistics, the testing comprising: (i) placing a test spread code index, of the spread code indices being tested, in a spread code index active set when a value of the code detection statistic corresponding to the spread code index is greater than the activity threshold; (ii) removing a parent code index of the test spread code index from the spread code index active set when the parent code index is in the spread code index active set; (iii) removing the test spread code index from the spread code index active set when a child code index of the test spread code index is in the spread code index active set; (iv) performing steps (i) through (iii) until the value of the code detection statistic is not greater than the activity threshold; and (d) outputting the spread code index active set based on the testing.