A communications system may include a transmitting device for transmitting a modulated signal therefrom based upon input data, and a receiving device for receiving the modulated signal from the transmitting device. The transmitting device may include a modulator, a baseband injected pilot carrier (BPIC) generator for generating BPIC data, and a framer for interleaving BPIC data with the input data to define data frames input to the modulator. The receiving device may include a demodulator, a frame recoverer, and a BPIC detector cooperating with the demodulator for demodulating the modulated signal from the transmitting device based upon the BPIC data and cooperating with the frame recoverer for recovering the data frames also based upon the BPIC data.