Operations and Maintenance Manual

JANUS

Multi-Protocol Reader 2.4 Operating Instructions

Confidential UM 360467-110 Revision: B Page 23 of 247

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

FILE: UM 360467-110 REV B3 MPR 2.4 CLEAN.DOCX 03/02/2021 1:01

Kapsch TrafficCom

2. OVERVIEW

Introduction

The JANUS

Multi-Protocol Reader 2.4 (MPR 2.4) is part of the Electronic Toll Collection (ETC) Subsystem. Toll

collection is the primary use of the Reader.

Overview of the MPR 2.4 Electronic Toll Collection (ETC) Subsystem

The MPR 2.4 Reader can interact with both active and passive OBUs. The MPR 2.4 is factory configured to

enable all protocols. For an in-depth description of protocols and the MPR 2.4 ETC Subsystem, see Theory of

Operations page 139.

Active OBU

For an active OBU, overhead antennas send out RF signals. As a vehicle equipped with an active OBU

approaches a toll zone, the OBU receives an RF signal from the antenna. The OBU then starts transmitting data,

which is received by the antenna and passed on to the Reader via an MRFM-S module. The Reader processes

and logs the OBU data, and then sends the information to the Lane Controllers (LCs). The Reader can also send

data back to the OBU, such as an updated toll account balance.

Passive OBU

For a passive OBU, the antenna sends out a command or a continuous wave via an RF signal. As a vehicle

equipped with a passive OBU approaches a toll zone, the OBU receives an RF signal from the antenna. If

commanded, the OBU then starts transmitting data, which is received by the antenna and passed on to the

Reader via an MRFM-S or MRFM-S Plus module. The Reader processes and logs the OBU data, and then sends

the information to the Lane Controllers (LCs). The Reader can also send data back to the OBU, such as an

updated toll account balance.

JANUS MPR 2.4 system components

Figure 2-1: A Redundant Reader shows a rack equipped with eight Smart Multi-protocol Radio Frequency

modules (MRFM-S).

A Lane Kit consists of:

• An antenna (see Figure 2-2)

• An MRFM-S( in Figure 2-1: A Redundant Reader) or an MRFM-S Plus

o NOTE: MRFM-S and MRFM-S Plus cannot be combined in one reader. 

• Two feedline adapter cables (2 for MRFM-S and 1 for MRFM-S Plus)

• One Circulator (not required for MRFM-S Plus)