Abstract: A door opens for an authenticated user by being tapped by a communication device. A physical access control system actuates upon receiving a wireless request triggered by a pattern of indicia in the vicinity of a portal. A hand-held communication device transmits a portal access control signal when it recognizes a pattern of bursts in signal amplitude. A mobile device has a sensor package, communication circuits, and a processor. Upon determining proximity to a controlled portal, the sensor package enables a pattern recognition circuit. Upon receiving a success indicia from the pattern recognition circuit, the communication circuits authenticate with the controlled portal, e.g. causing a door to open. A sensor package may be enabled by accelerations from bumping the device; tapping the device against a door, wall, or table. A pattern may be related to a number, or a sequence, or combination of slows, pauses, and quicks, or a single acceleration.