Browse Prior Art Database

Radio Frequency Detection Device

IP.com Disclosure Number: IPCOM000112622D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 90K

Publishing Venue

IBM

Related People

Burnam, JB: AUTHOR [+6]

Abstract

Described is a hardware implementation for detecting the presence of objects utilizing a radio frequency detection device. This disclosure describes the use of the device for detecting railroad train presence, however, the device can be incorporated in other radio frequency carrier applications where detecting changes in carrier signal strength provides valuable information.

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Radio Frequency Detection Device

      Described is a hardware implementation for detecting the
presence of objects utilizing a radio frequency detection device.
This disclosure describes the use of the device for detecting
railroad train presence, however, the device can be incorporated in
other radio frequency carrier applications where detecting changes in
carrier signal strength provides valuable information.

      In the prior art, methods for detecting railroad car presence,
such as high frequency track circuits, track resonant circuits, or
audio frequency overlays, required careful analysis of track circuit
configurations so as not to interfere with other track circuitry.
The concept described herein utilizes a radio frequency detection
device that does not require track information to detect train
presence.

      With the regulation requiring that railroad cars in North
America be tagged with a set of Radio Frequency Identification (RFID)
tags, the railroad cars have been installed with both tags and
reader/antenna systems in order to read the tag information.  This
along with wheel detector information is used by a software
application program to determine the standing order of the train by
serial number, owner, railcar type, etc.  A train presence signal is
also required because if a train stops at a reader site, the wheel
detector system identifies this event as the end of the train.  As a
result, a train presence signal is needed to prevent the wheel
detectors from identifying this event as the end of the train.

      The radio frequency detection device takes advantage of the
reader equipment that is already required for reading tag
information.  The normal operation of reading tags is that the
reader, by way of a radio frequency module and antenna, is constantly
transmitting a carrier signal in search of a tag.  When a tag is
present within the antenna field, the tag modulates the carrier and
reflects its unique information.  The radio frequency detection
device uses a separate antenna to monitor the frequency of the
carrier signal.  When a train...