Code detection to assist a symbol-level equalizer in a receiver is described. In an embodiment, code detection uses adaptive Infinite Impulse Response (IIR) filtering to determine spreading code usage information and active code channels in a received signal. The spreading code usage information indicates if a spreading code associated with a code channel is among spreading codes used in the received signal. In another embodiment, the spreading code usage information is determined based on a forgetting factor associated with the filtering of a symbol power associated with the code channel.