The determination of the signal modulation format for a channel is an important aspect of the operation of a signal receiver. A method (700) is described including the steps of receiving (710) a signal, comparing (720) a sample of the received signal to a first threshold value and a second threshold value, creating (720) a signal profile based on the comparison, and selecting (750) a modulation format for the received signal based on the signal profile. An apparatus (500) is also described including a ring counter (510) that receives a sample of an input signal, compares the sample to a first threshold value and a second threshold value, and creates a signal profile for the input signal, a signal profiler (550) that compares the signal profile for the input signal to at least two reference profiles, and a detector (560) that determines a modulation format for the input signal based on the comparison in the signal profiler (550).