Information transmission and detection with different rates are one of the main characteristics in the current and future digital communication systems.In IS-95 A CDMA system

the speech encoder has four different rates depending on the speech activities of the speaker.At the receiver

in order to reduce the complexity of the decoder and save the energy

it needs to detect which rate is used

so that it can select one matched decoder to deal with the transmitted signals.In [3]

an effective multi-rate detection algorithm was presented recently.In this paper

a new multi-rate detection algorithm is proposed.Compared with that in [3]

the proposed algorithm in this paper has comparable computation complexity and a considerable improvement on the total performance of the error rate detection probability under relatively low signal to noise ratios.