receiving a sampled signal at a first module (810), wherein the signal received at the first module has been filtered;

receiving despread symbol data for all possible spread codes at a second module (820) from the first module;

determining active codes of the possible spread codes in the filtered sampled signal by the second module;

receiving from the first module, the despread symbol data identified with the active codes, at a third module (830);

providing estimates of a symbol value and a gain based on the symbol data identified with the active codes by the third module;

receiving the symbol value and gain estimates from the third module and the active codes from the second module at a fourth module (840); and

constructing a model of the sampled transmitted CDMA downlink signal using the symbol value and gain estimates for the active codes by the fourth module.