Detection of modem type and bit rate of FSK voiceband and data signals

A classification scheme to detect the modem type (e.g., 202, V.23, 103, and V.21) and bit rate (e.g., 1800, 1200, 600, 300, and 75 b/s) of frequency-shift-keyed (FSK) voice band data signals is presented. The discrimination technique is based upon simple second-order statistical parameters of the instantaneous frequency of the input signal. Good performance of the discriminator is obtained even in the presence of various analog impairments for observation windows of 0.25 to 1 s, depending upon the input signal.<
>