Appendix G - Glossary

Term	Definition
Antenna	Used to energize and read passing RFID tags mounted on railcars, locomotives, EOT’s, and various other equipment. Each site requires a minimum of two antennas.
Articulated car	A group of rail platforms that are permanently connected, usually sharing a truck/boogie between platforms. They are tagged and treated as though they were a single car. Common articulated cars are the type used to transport shipping containers.
Axle acquisition subsystem	The group of system components within the larger AEI system that acquires and timestamps axle/wheel event data. The axle acquisition subsystem employs wheel detectors, amplifiers (TDA105) and TDA-104 and CPU interrupt processor.
Back door	The “Back Door” is the alternative method of logging into the APU-102. It is generally used only for diagnostics when the Mini-Remote Support (MRS) program is running. It allows you to dial in to the APU, transfer individual files, and download new code. However, these functions are not menu-driven. Not supported in version 5.0 +
Battery charger	Most sites operate on a “battery plant” and the charger maintains the charge state of the batteries.
Battery tags	These tags have batteries installed to augment their read range. The tag’s power circuits are always energized by the battery, but they do not transmit data unless in the presence of a signal from the RF unit. The most common usage is on the End Of Train devices (EOT).
Buffers	A feature of the AI1200 Reader Module that allows the reader to store up to 1000 tags before the APU-102 software must read them out. In the event that tags begin to back up, which may occur at busy sites, buffering provides the APU-102 additional time to process tag data.
Check tag sequence	A Reader Logic Board feature that verifies the system can read and process tags. The check tag sequence can be initiated from either system menu. Additional check-tag equipment is required at the site. Refer to 4.0 APU-102 User Interface for detailed instructions on initiating this sequence.
Clean consist	A front-to-back listing of all railcars and locomotives in the train. The list is compiled by the APU-102 and transmitted to the host system for post processing. Also called simply a “consist.”
Compact Flash	The Compact Flash (CF) emulates a hard drive and replaces rotational media in applications where temperature, shock, vibration or other environmental factors would prohibit the use of conventional disk drives.
Compatibility mode	Two AR2200 RF modules connected to two AI1200 readers, each operating one antenna “full time” as opposed to multiplex mode. The first AR2200/AI1200 controls antenna 0 and the second set controls antenna 1. Commonly used at high speed and restricted clearance sites. Also called Dedicated mode.
Dedicated RF mode, dedicated RF unit	See Compatibility mode.
DiskOnChipÒ (DOC)	The DOC device contains a BIOS extension, the TFFS (True Flash File System) and flash memory in a single 32-pin chip ranging up to 96 MB. The DOC emulates a hard drive and replaces rotational media in applications where temperature, shock, vibration or other environmental factors would prohibit the use of conventional disk drives.
Distributed Processing	A hardware and software solution to allow wayside defect equipment without an RFID sub-system to collect RFID data from remote systems on the same track corridor. The RFID data can then be combined with data harvested from the defect detector to report a tagged consist with the defect reported on the appropriate car.
Dynamic Tag	This is a tag that is connected to a computer on-board the equipment that can supply supplemental information along with the standard tag data. The most common dynamic tags are those mounted on the locomotives. The locomotive’s computer updates the tag with information such as fuel level, generator status, coolant temperature, etc.
Early Warning Report	A partial consist that is sent before the train has cleared the site.
Fix-up Logic	Layers of post-processing to account for, multi-track processing, stray tag elimination, handling known exceptions, specialty cars, and erroneous tag data.
Front door	When the APU application software is running, you connect to the APU-102 via the “Front Door” of the system. The Front Door allows you to define the system parameters and individual session parameters, delete trains, and view the systems log. The Front Door is always used to connect to the APU application unless there is a problem with the APU application software.
Hut	An equipment enclosure at an AEI site that houses the APU-102, TDA-105, battery charger and batteries, loop detector, power supply, AC Power Fail Transformer, and Lightning Protection Panel components. Also called a “bungalow” or “instrument house.”
Intermodal site	A site that handles up to three tiers (Tier 0, Tier 1, and Tier 2) to read the tags of conveyed equipment on railcars, such as trailers, chassis, and containers
ITC	Inter-Track Communication. A link between 2 APU-102s to share train acquisition data.
Lobe width	The read window that represents width of the RF field radiation pattern at the track.
Log-Periodic Antenna (aka Low-boy)	Small antenna typically used where there are height restrictions governing equipment placement.  They are typically placed at signal height between tracks in multi-track sites.
Multiplex mode	The AEI System uses one RF unit to control two antennas. The RF unit switches (multiplexes) the RF between both channels (antennas) as a train passes, reading tags from both sides. This mode is commonly used at unrestricted sites or low-speed, restricted sites.
NetMenu	A menu system to allow locally networked APU-102s and other co-located wayside equipment to be accessed remotely via a single phone line.
NetModem	A host reporting sub-system that allows locally networked APU-102s to report out via a single dial-up modem and phone line.
Normal mode	See Multiplex mode.
Parapanel Antenna	Large antenna typically used where there are no height restrictions.  They are usually placed about 10-12’ from track center.
Passive tag	Tags that derive all their power from the RF energy field as the train passes the site. They do not emit any signal until activated by the RF energy field generated by the RF unit. Passive tags are generally used on railcars and locomotives.
Presence detector	A system of circuits that provide external train presence when a train has stopped. There are many types of presence detectors used - loop detectors and active track circuits are the most common.
RF module/RF unit	A component of the RFID subsystem that provides power to the system’s antennas and transfers tag information from the antennas to the Reader Logic Board for processing and storage.
RFID subsystem	A network of system components within the larger AEI system that obtains train data from the electronic tags and transfers it to the APU-102. Antennas, tags, an RF module, and Reader Logic board comprise the RFID subsystem.
Reader module	A self-contained computer module that communicates with the APU-102 via an RS232 connection. It controls RF power to the antennas and interprets tag information read by the RF units.
Segment	Each wheel detector configuration the APU-102 uses consists of a minimum of two “segments”. Each segment of the wheel detector produces a signal as the wheel passes. When a wheel passes over both segments, train presence, or one axle count, is determined. Because there are at least two segments placed at a fixed distance apart, the APU-102 is able to determine speed. The order of the segments determine direction of travel. The left segment is identified as the “A” segment and the right segment is identified as the “B” segment. Each segment produces a different pulse. For more information on how segments are used to determine presence, direction, and speed, see the section Detecting Presence, Speed, and Direction in 2.7 APU-102 Data Processing.
Self test	The Self Test is a series of diagnostics that include a check on the APU EPROMs and RAM, an analysis of the wheel detector, RFID and presence activity from previous trains as well as periodic, communication checks with the Reader Logic Board, dial-up modem and network, and other functions to ensure the reliability of the system.
Sequence number	The sequential number assigned to the train after data has been captured and saved. This number, which ranges from 1 to 9999, is submitted to the Report process for delivery to the host.
T-zero event	The first event (or synchronizing event) the APU-102 sees for each train. It is considered the starting point of the train. When the APU-102 sees the first event for a train, it resets a master clock to zero. All subsequent data seen by the APU-102 is timestamped based on this time. The T-zero event can be provided to or received from interconnected equipment to synchronize external data.
Tag	Also called an RFID tag. A device mounted on railcars and locomotives that transmits information about the particular vehicle.
Tag files	Separate files where the APU-102 stores captured events that were each timestamped from the master system clock. Not to be confused with RFID tags, though some tag files will have RFID tag data.
Timebase synchronization	A system of cross-referencing and timestamping train data received based on a particular wheel event and time. See “T-Zero Event” in this glossary and 2.7 APU Data Processing earlier in this manual.
Uniqueness logic	A function of the Reader Logic Board that prevents storing the same tag more than once per read cycle.
Wheel detector	Also called a wheel transducer or wheel sensor. A device that determines initial train presence, train movement (direction and speed), and axle patterns for train processing.
XTrack	Multi-Track data connection and processes to share train acquisition data with up to 10 APU-102s.