SUMMARYIn this letter a novel decorrelating detector for multicode system is proposed and analysed. Multicode transmission is an alternative technique for providing multirate data to multiple users. However, it suffers from an inter-channel-interference when the signal is transmitted over a multipath channel. The proposed receiver processes the received message in a symbol-by-symbol fashion, which reduces the computational complexity of the decorrelating receiver considerably comparing to the more traditional approach, where the full frame is processed at a time. Simulation results show that the performance improvement is substantial using the proposed receiver, e.g. the irreducible BER can be lowered as much as 2 orders of magnitude @ 20 dB.