A communications system provides for accurate fingerprinting of devices across a communications channel. A transmitter device modifies a physical layer signal prior to transmission as a function of signal modification parameters. A receiver device classifies a received physical layer signal and to outputs a classification indicator and a score. The receiver further analyzes the classification indicator and the score to produce an updated set of signal modification parameters provides the parameters to the transmitter device. The transmitter device, in turn, updates its signal modification parameters accordingly, thereby generating subsequent communications that more clearly indicate a fingerprint of the transmitter device.