Multiple wireless sensor assemblies are individually attached to standard biopotential electrodes, which are placeable on a subject's body at locations for biopotential signal recording. The sensor assemblies, which are electrically isolated, simultaneously measure potential voltages from the body sites in accordance with a synchronization. The measured signals are amplified, digitized, and filtered, and then sent wirelessly to a monitoring system. The monitoring system receives multiple sensor signals and constructs biopotential vectors depending on the placement and number of the sensors. The sensor signals are referenced to a common virtual center bias to synthesize a common mode rejection.