Abstract: An enforcement transponder system includes an enforcement reader in communication with an enforcement transponder. The transponders are written to identify when and where toll has been collected from a user of a toll road. In one embodiment, the system includes one or more roadside toll collection systems. This allows enforcement/verification of toll collection from SOV traffic on HOT lanes.

Abstract: A mobile enforcement reader (MER) includes an antenna, a reader coupled to receive signals from the antenna and a control/display unit (CDU) coupled to the reader. The CDU selects a receive direction and processes signals provided thereto from the reader. When the MER and a transponder are in proximity, the MER interrogates the transponder and receives information related to toll payment. The MER allows enforcement officials to monitor payment by single occupancy vehicle (SOV) traffic for use of high occupancy traffic (HOT) lanes.

Abstract: A Manchester decoder and clock recovery circuit for recovering Manchester encoded data and a clock synchronized with the incoming data. The circuit uses an oversampling rate of eight times the data rate, and a reduction in circuit elements to reduce the circuit power consumption requirements. The circuit operates in a search mode and in a tracking mode. A clock phase generator produces eight phase clocks, used by a sampling and majority vote circuit to determine the decoded data value. During the tracking mode, the phase of the synchronized clock can be adjusted during data reception.