Operations and Maintenance Manual

MPR 4.1

Reader Maintenance Instructions

Confidential UM UM360479-100 Revision: Draft B4 Page 72 of 246

All information contained herein is proprietary to, and may only be used with express, written permission from, Kapsch TrafficCom Canada Inc.

FILE: UM360479-100 REV B4 DRAFT WIP MPR-4.1 READER OPERATIONS AND MAINTENANCE MANUAL (002).DOCX

05/25/2022 11:18

Kapsch TrafficCom

4. THEORY OF OPERATIONS

This section offers a more detailed overview of the Reader components than the introductory

overview provided in Overview Section 2 page 21.

MPR 4.1 Reader can communicate with both active and passive OBUs. The Reader uses a combination

of Time Division Multiplexed (TDM) and Frequency Division Multiplexed (FDM) periods to read

active and passive OBUs respectively.

Each Antenna Port and antenna pair, referred to as a port, creates an RF capture zone on the

roadway. The antennas are usually situated to create overlapping capture zones between ports. One

reader can support up to 4 ports. When required, multiple readers can be synced together to support

additional ports.

The reader processes the OBU information and provides transaction reports to the Lane Controller

interfaces. When required, the reader can write data to the OBU.

Active OBUs

Active OBUs are battery powered and transmit a signal to the Reader antennas. As a vehicle equipped

with an active OBU approaches a toll plaza, the OBU receives a trigger signal from the Tx antenna. The

OBU then starts transmitting data, which is received by the Rx antenna.

The MPR 4.1 decode the active OBU signal and processes and logs the OBU data and then sends the

information to the Lane Controllers (LCs). The Reader may also send data back to the active OBUs,

such as an updated toll account balance.

Passive OBUs

Passive tags are not battery powered and cannot transmit a signal. As a vehicle equipped with a

passive OBU approaches the antenna, the OBU receives a transmit signal from the antenna. This

signal is then reflected from the passive OBU back to the antenna. The reflected signal is uniquely

modulated by each passive OBU, allowing the OBU to be identified.

The MPR 4.1 decodes the passive OBU signal and processes and logs the OBU data and then sends the

information to the Lane Controllers (LCs). The Reader may also send data back to the active OBUs,

such as an updated toll account balance.

Capture zones

The capture zone is the area of antenna RF coverage. An antenna can communicate with an OBU once

the OBU enters the antenna’s capture zone. These capture zones and the number of antennas

required per lane varies depending on the site and/or lane configuration.