U.S. patent number 3,740,549 [Application Number 05/887,825] was granted by the patent office on 1973-06-19 for remote signaling system for train control.
This patent grant is currently assigned to Westinghouse Electric Corporation. Invention is credited to George M. Thorne-Booth.
United States Patent |
3,740,549 |
Thorne-Booth |
June 19, 1973 |
REMOTE SIGNALING SYSTEM FOR TRAIN CONTROL
Abstract
A remote signaling system is described for the monitoring and
control of one or more moving trains from a remote wayside location
by means of a vehicle carried antenna and signal transmitter
coupled with a track-side cable and designed to introduce a
movement variable periodic phase shift into the coupled signals
from the train back to the wayside located receiver to enable the
desired train position monitoring function. The train carried
antenna is magnetically coupled to this track-side cable
arrangement such that undesired signal changes due to train vehicle
rock and sway motion are minimized, and signal transmission
difficulties introduced by the physical position variation of the
track-side cable wires relative to the track path are minimized.
The track-side cable comprises two closely spaced signal
transmission lines each having a crossover at predetermined length
intervals, with the physical crossover of each transmission line
being equally spaced and substantially half-way between the
adjacent physical crossovers of the other transmission line. An
alternate embodiment employs a signal signal transmission line or
cable having crossovers at predetermined intervals at the
track-side. This track-side transmission line is driven by an
oscillator. Two train carried antennae, spaced a predetermined
longitudinal distance apart, receive a movement variable periodic
phase shift signal to enable the desired position monitoring
function.
Inventors: |
Thorne-Booth; George M.
(Murrysville, PA) |
Assignee: |
Westinghouse Electric
Corporation (Pittsburgh, PA)
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Family
ID: |
25391941 |
Appl.
No.: |
05/887,825 |
Filed: |
December 24, 1969 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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637684 |
May 11, 1967 |
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Current U.S.
Class: |
246/122R;
246/8 |
Current CPC
Class: |
B61L
3/225 (20130101); B60L 2200/26 (20130101) |
Current International
Class: |
B61L
3/22 (20060101); B61L 3/00 (20060101); B61l
025/00 () |
Field of
Search: |
;246/187B,167R,187R,182R,63C,8,122R ;180/98 ;179/82 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,455,381 |
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Jan 1969 |
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DT |
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1,286,533 |
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Jan 1969 |
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DT |
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Other References
Everitt, Communication Engineering (1937) pp. 334-335..
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Primary Examiner: Sheridan; Robert G.
Assistant Examiner: Libman; George H.
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention is a continuation-in-part of a copending
patent application entitled Remote Signaling System for Train
Control (changed by amendment to Relative Displacement Information
System) by George M. Thorne-Booth, Ser. No. 637,684, filed May 11,
1967, now abandoned.
The present invention is related to the invention covered by U.S.
Pat. No. 3,551,889 entitled Remote Signaling of Control Systems by
C. S. Miller Ser. No. 637,683, filed May 11, 1967, and the
invention covered by U.S. Pat. No. 3,562,712 entitled Remote
Transmission of Control Signals by G. M. Thorne-Booth and C. S.
Miller, Ser. No. 637,723, filed May 11, 1967, both of which are
assigned to the same assignee as is the present patent application.
Claims
I claim as my invention:
1. In a vehicle control system wherein a vehicle travels along a
predetermined path, apparatus for producing a signal indicative of
vehicle position, comprising:
signal transmission means including an alternating current signal
source operatively connected to a first inductive transmitter
loop;
signal receiving means including second and third inductive
receiver loops forming separate receiving channels, with said
second and third receiver loops being substantially coextensive,
elongated loops aligned with said path, said first transmitter loop
being operated to couple with both the second and third receiver
loops, with at least one of the second and third receiver loops
being formed by first and second longitudinal conductor portions
having a predetermined arrangement pattern comprising successive
lateral transpositions of said first and second conductor portions
at corresponding longitudinal intervals of said at least one of the
second and third receiver loops, to inductively receive a signal
from the first transmitter loop in alternately one and the other of
opposite phase relationships as the first transmitter loop passes
therealong;
one of said signal transmission means and said signal receiving
means being in fixed position relative to said vehicle path and the
other being movable in position with travel of the vehicle;
said first, second, and third inductive loops having predetermined
cooperative physical arrangements in a direction aligned with said
path such that the signals induced into the second and third loops
are alternately in an in-phase and in an out-of-phase relationship
to one another under travel of the vehicle along said path; and
means for comparing the phase of signal induced into the second and
third inductive loop to derive an output signal representative of
vehicle position.
2. In a vehicle control system wherein a vehicle travels along a
predetermined path, apparatus for producing a signal indicative of
vehicle position, comprising:
signal transmission means including an alternating current signal
source operatively connected to a first inductive transmitter
loop;
signal receiving means including second and third inductive
receiver loops forming separate receiving channels, and being
operative to couple with said first transmitter loop, with said
second and third receiver loops being coextensive elongated loops
aligned with said path, said second and third receiver loops each
being formed of a pair of longitudinal conductor portions
successively laterally transposed at predetermined periodic
intervals, with the periodic intervals of the second and third
receiver loops being longitudinally displaced relative to one
another to respectively receive signals which are alternately
mutually in-phase and mutually out-of-phase under travel of the
vehicle;
one of said signal transmission means and said signal receiving
means being in fixed position relative to said vehicle path and the
other being movable in position with travel of the vehicle;
said first, second, and third inductive loops having predetermined
cooperative physical arrangements in a direction aligned with said
path such that the signals induced into the second and third loop
are alternately in an in-phase and in an out-of-phase relationship
relative to one another under travel of the vehicle along said
path; and
means for comparing the phase of signal induced into the second and
third inductive loop to derive an output signal representative of
vehicle position.
3. In a vehicle control system, wherein a vehicle travels along a
vehicle travel path, apparatus for producing a signal indicative of
said vehicle's position along said vehicle travel path
comprising:
two two-wire transmission lines situated along said vehicle travel
path, with each of said two two-wire transmission lines each having
regularly recurrent line transpositions and being adjacent each
other with a position shift relative to said recurrent line
transpositions;
signal transmission means located on said vehicle, including an
inductive transmitter loop aligned relative to said two two-wire
transmission lines for inducing signals therein that are
alternately in an in-phase and in an out-of-phase relationship
relative to one another as said vehicle travels along said vehicle
travel path; and
means for comparing the phase of the signals induced into said two
two-wire transmission lines, respectively, for deriving said signal
indicative of said vehicle's position along said vehicle travel
path.
4. The combination claimed in claim 3, wherein the transposition
interval of each two-wire transmission line is equal.
Description
BACKGROUND OF THE INVENTION
It is necessary for the automated control operation of a passenger
carrying train vehicle, since human life and property are involved
and a substantially fail-safe operation of same is desired, to
monitor and control very precisely the position and movement of the
train vehicle by means of at least one wayside control station. For
this purpose information signals are required from the train to the
wayside located control equipment and from the wayside located
control equipment to the train. It is necessary to instruct
continuously each train on an individual basis in regard to its
movement and its position. Equipment reliability, signal coupling
effects, cost of apparatus and like considerations are
important.
It has been known in the prior art to employ magnetically coupled
amplitude variable signal transmission techniques between a train
carried antenna and the signal conductors leading to the wayside
control location, but these techniques have suffered in particular
from undesired coupling variations due to the rock and sway of the
train antenna relative to its track path and further from
difficulty to avoid position variations of the involved signal
conductors relative to the track path and the position of the train
carried antenna. It was also difficult to construct the prior art
antennas to enable effective and economic noise shielding
practices.
SUMMARY OF THE PRESENT INVENTION
The present invention employs an improved signal conductor
arrangement including two pairs of signal transmission conductors
or cables, each pair having a crossover located at predetermined
spaced intervals to result in a phase change of the signal induced
into that pair of cables by a magnetically coupled train carried
antenna which moves longitudinally along the length of the pair of
cables. In reference to the resulting pair of signals induced in
the respective cables, they are alternately in phase and out of
phase relative to each other, as sensed by a signal receiver placed
at the terminal end of the two pairs of cables. The two pairs of
cables are short-circuited at the end remote from this receiver,
with the receiver including a crystal filter for each pair of
cables tuned to the frequency of the signal induced into its pair
of cables. The signals are multiplied together in a phase sensitive
detector to provide train movement and train position information
for the wayside control equipment. A filter bandwidth in the order
of 8 Hertz is adequate for one contemplated embodiment, having
crossovers if the transmission cables spaced in relation to the
expected top speed of the train such that induced signal phase
reversals occur at frequencies up to 8 per second, to accept the
fundamental frequency signal from each pair of cables or signal
channel and to allow for all crystal filter tolerances involved.
The two pairs of cables can be placed side-by-side, or one on top
of the other, and in close enough proximity that adequate signal
coupling from the train carried antenna to each pair of cables is
provided.
An alternate embodiment of the invention employs a single pair of
conductors or cables having crossovers located at predetermined
spaced intervals along its length and driven by an oscillator so
that a phase change of magnetic field occurs along the length of
the pair of conductors. The resulting far magnetic field about the
cable is alternately of one and the other of reverse phases. A pair
of train carried antennae are carried by the train in a
predetermined longitudinally spaced relationship. A distance of
separation equal to one-half the interval of crossover is used in
one contemplated embodiment, although any distance except a
distance equal to the crossover interval or a multiple thereof may
be used. The signal received by the antenna will alternately be in
phase and out of phase, and are multiplied together in a phase
sensitive detector to provide train movement and train position
information.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 shows the train to wayside signal transmission cable
arrangement of the present invention;
FIG. 2 shows one train to wayside signal transmission cable
arrangement of the prior art.
FIG. 3 shows one contemplated signal receiver termination for the
train to wayside signal transmission cable arrangement of FIG.
1;
FIG. 4 shows one contemplated wayside to train signal transmission
circuit arrangement;
FIG. 5 shows one suitable manner to effect signal coupling in
relation to the relative positions of different portions of the
same train.
FIG. 6 shows an alternate embodiment of invention including
diagrammatic illustration of certain alternate position situations
and their relationship to a waveform; and
FIG. 7 illustrates a preferred form of transmission line having
crossovers.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The present remote signaling system is operative with a fixed
signaling block communication system for train control in which the
immediate position of each train is defined by its presence in one
such signaling block, with the length of a block being as short as
a couple hundred feet or as long as 3,000 feet. As shown in FIG. 1
a loop antenna 10 is adapted to be carried by a train vehicle and
driven by a high powered oscillator or train transmitter 12, such
that the loop antenna 10 passes over and is magnetically coupled to
each of the first pair of signal conductors 14 and a second pair of
signal conductors 16. Each pair of signal conductors is provided
with physical cross-overs 18 as shown in FIG. 1 at regular length
intervals, such that approximately 35 feet of spacing is provided
between each cross-over of each cable, with the cross-overs of the
pair of cables 14 occurring at substantially half-way between the
locations of the adjacent cross-overs of the pair of cables 16.
Thusly longitudinal movement of the train carried antenna 10 along
the length of the transmission cables causes variation of signal
coupling resulting in a relative phase reversal each time that the
antenna 10 passes over one of the cross-overs 18. These relative
signal phase reversals are sensed by a wayside receiver 20 to
monitor the train position and the train movement in terms of
velocity and acceleration through signals supplied by the train
carried antenna 10.
In one contemplated embodiment of the remote signaling system shown
in FIG. 1 the individual conductors of the pair of cables 14 are in
the order of 2 inches apart and are to be laid between the track
rails upon which the train moves. The loop antenna 10 is carried at
the head end of the vehicle and driven from a crystal controlled
oscillator, such as the train transmitter 12, and is positioned in
proximity such that it is magnetically coupled to both of the
transmission cables 14 and 16. The transmitter 12 is operative at a
frequency in the order of 10 KHZ and induces into each transmission
cable 14 and 16 signals having the same frequency. As the train
vehicle moves along the length of the transmission cables, the
resulting induced signals in the two transmission cables are
alternately in phase and out of phase as the loop antenna 10 moves
over the cross-over locations 18 of the respective cables 14 and
16. The transmission cables 14 and 16 are shown side by side in
FIG. 1 however it should be understood that they can be positioned
one on top of the other. It is contemplated that in the practice of
the present invention the spacing between the antenna 10 relative
to the position of the transmission cables 14 and 16 may vary in
the order of 3 to 15 inches and a lateral or sideways misplacement
of the transmission cables relative to the intended location of
same in the order of 6 inches is not unlikely. It is contemplated
for one embodiment of this invention that the train transmitter 12
will be effective to satisfactorily couple an induced signal into
the transmission cables 14 and 16, such that the position and
movement of the train can be reliably monitored, with the power of
the train transmitter 12 being in the order of 30 microwatts.
In FIG. 2 there is shown one train to wayside signal transmission
cable arrangement of the prior art, wherein a Greek square wire
transmission cable 24 is provided at a location adjacent the track
and preferably between the two rails of the track such that a train
carried antenna 26 is magnetically coupled with the Greek square
wire in regard to signals transmitted from a train oscillator 28.
With the train carried antenna 26 in the position shown in FIG. 2,
a maximum coupling is effected to induce a maximum amplitude signal
into the transmission cable 24 which maximum amplitude signal is
received by a wayside receiver 30. As the train carried oscillator
moves along the transmission cable and assumes the position 26'
shown by dotted lines, the induced signal attains a minimum
amplitude value in regard to the signal induced into the
transmission cable and received by the wayside receiver 30. Thusly
the movement and position of the train carried antenna 26 can be
monitored by the wayside receiver in terms of available pulses
which can be counted, the number of such pulses indicating the
amount of movement along the length of the transmission cable and
the frequency of said received pulses indicating the movement
velocity and acceleration of the train carried antenna 26. The
arrangement of FIG. 2 is more susceptible in regard to the movement
of the train carried antenna in a direction perpendicular to the
length of the transmission cable 24 due to rock and sway of the
train as it moves along the track and further requires a
substantially higher power level of the train oscillator 28, in the
order of 50 watts peak, for a single train vehicle to be reliably
monitored by the wayside receiver 30.
In FIG. 3 there is shown one contemplated train to wayside signal
receiver termination for the signal transmission cable arrangement
shown in FIG. 1 and including transmission cables 14 and 16.
Coupling transformers 34 and 36 are provided to assure desired DC
signal isolation, with the induced signal from the transmission
cable 14 passing through a crystal filter 38 and the induced signal
from the transmission signal 16 passing through a crystal filter 40
which are tuned to the fundamental frequency, in the order of
10KHz, of the respective channels and have a bandwidth in the order
of 8 Hertz to pass the phase reversal rate. If desired, signal
limiter circuits can be provided to remove noise components of the
received signals. A phase sensitive detector 42 provides the output
pulse signal 44, in the order of 8 Hertz, illustrated in FIG. 3,
which pulse signals can be counted to monitor the position of the
train carrying the antenna 10 shown in FIG. 1 and further can be
followed in regard to frequency variation for monitoring the
movement in terms of velocity and acceleration of the train carried
antenna 10 shown in FIG. 1.
In FIG. 4 there is shown one contemplated wayside to train signal
transmission circuit arrangement of the present invention, whereby
a wayside transmitter 50 induces substantially equal communication
signals into the transmission cable 14 and the transmission cable
16, which cables are short circuited at their end remote from the
phase sensitive detector 42 and are connected through a physically
separated and remote conductor 52 to complete the signal
transmission path relative to the wayside transmitter 50. The
coupling transformers 34 and 36 are provided with center tapped
primary windings and it is to the center taps 54 and 56 of these
respective windings that the signal provided by the wayside
transmitter 50 is connected. This results in an equal balance of
signal energy induced into each conductor of the transmission
cables 14 and 16 and in effect four parallel conductors for these
signals are provided thereby relative to a train carried antenna 58
which is operative with a train receiver 60 for receiving the
command signals from the wayside transmitter 50. These command
signals can be in the form of frequency modulated pulse coded speed
command signals for the train and, for example, are utilized to
instruct the train in regard to whatever movement or operation of
the train is desired after the actual position and movement of the
train is known through the above described operation of the
apparatus shown in FIGS. 1 and 3. These command signals are
described in greater detail in the above referenced copending
applications.
FIG. 5 shows one suitable manner to effect signal coupling in
relation to sensing the relative positions of different portions of
the same train. A first antenna 70 is provided at the head end of
the train and a second antenna 72 is provided at the rear end of
the train, with the antenna 70 being operative with a train
transmitter 74 operating at frequency A and the antenna 72 being
operative with a different train transmitter 76 having a frequency
B to thereby provide a means for sensing the length of the train.
The induced signals from the antenna 70 as sensed by the
terminating wayside located receiver are in accordance with the
position of the antenna 70 along the length of the transmission
cables 14 and 16 as are the induced signals from the antenna 72
effective to make the wayside located receiver aware of the
physical location of the antenna 72. Therefore any position
difference between the antennas 70 and 72 sensed by the wayside
receiver is in accordance with the length of the train. The
direction of motion of the train can be determined by the change of
the position of the respective antennas 70 and 72. If for some
reason the head end of the train became separated from the tail end
of the train, the resulting positional difference change between
the sensed positions of the antennas 70 and 72 would indicate the
relative positions of the head end and trailing end of the train,
and relative to each antenna its direction of motion may be deduced
by the wayside receiver as are the velocity and acceleration
obtainable by differentiation of the received pulse signals.
It should be noted that the train to wayside signal transmission
cable arrangement shown in FIG. 1 has the substantial advantage
that it is more certain in its operation and requires less power to
provide a more reliable monitoring and control of the train
associated with the antenna 10 and the train transmitter 12.
Reference is now made to FIG. 6, which shows an alternate
embodiment of a position monitor system in accordance with the
present invention. An oscillator or transmitter 78 generates a
continuous wave signal which is driven into a periodically
transposed cable 79 in fixed position on the railway track wayside.
The physical configuration of this cable is like the configuration
of those in FIG. 1. However, here the cable is used as a
transmitting antenna, but the principles of transportation are the
same, providing a phase of electromagnetic field which alternately
reverses itself with each consecutive transposed section of the
cable. This is symbolically depicted in FIG. 6 for four of the
transposition sections of cable 79 by phase symbols below those
sections. The cable is used to monitor position relative to a stop
position adjacent a passenger platform 79a. A pair of spaced
receiving antennas 80 and 81 are carried by the railway vehicle and
are positioned where they pass above the transposed cable. The
receiving antennas are positioned sufficiently close above the
cable then when an individual antenna is above a transposition
section of cable, it will pick up signals from that section in
preference to signals from other sections of the cable. It is to be
understood, however, that the receiving antennas have enough
distance separating them from the cable to couple therewith in
accordance with the well known principles of far field
electromagnetic behavior.
In the illustrated situation the interval of transposition is L,
and the fixed longitudinal spacing of the two receiving antennas is
L/2. As the receiving antennas move along the cable, they will
respectively receive signals which are alternately in-phase and
out-of-phase with each other, depending on the position over the
transposed cable.
The signals picked up by the receiving antennas are fed to two
separate channels. The respective channels include preamplifier and
transient clipper stages 82a, 82b, crystal filters 83a, 83b, and
amplifier-limiter stages 84a, 84b. The two channels are then
brought together in a phase sensitive detector 85. Detector 85 is
of a type which detects the relative in-phase and out-of-phase
relationship of the signals in the two channels, such as the type
in which these signals are multiplied together. The output of the
phase sensitive detector is a signal indicating either the in-phase
or the out-of-phase relationship of the two channels. This signal
is fed to a Schmitt trigger circuit 86, which squares up the signal
to make it suitable as a digital input to utilization
equipment.
This mode of operation is diagrammatically illustrated in FIG. 6 by
the phantom line alternate positions 80', 81' and 80", 81" of the
pair of antennas, and the waveform 88. The waveform 88 represents
the instantaneous Schmitt trigger output conditions corresponding
to the position of the centerline between the pair of receiving
antennas 80, 81 relative to the cable 78. This center has been
shown by the dashed vertical lines 89', 89" positioned midway
between the receiving antennas for alternate positions 80', 81' and
80", 81", respectively. The positions 80', 81' of the antennas are
such that they will pick up in-phase signals from the cables, and
at this instant the output of the Schmitt trigger circuit will be
at its HIGH logic state, as shown by the waveform. As the vehicle
moves along the cable to the right, the antennas will move to
positions 80", 81", where they then receive signals from sections
such that the received signals are out-of-phase, and the Schmitt
trigger output is at its LOW state, as shown. As the railway
vehicle moves along the track, the output of the Schmitt trigger
circuit will be double the frequency at which the vehicle passes
transposition sections. This signal is then passed to the equipment
which utilizes the position of vehicle formation. An example of
equipment which utilizes this signal is a mass transit vehicle
positioned stop system, such as disclosed in U.S. Pat. No.
3,519,805, Ser. No. 686,512, filed Nov. 29, 1967 by George M.
Thorne-Booth entitled Vehicle Stopping Control Apparatus. That
equipment counts the cross-over of transposed cables as the train
passes over a cable adjacent the station. The count is used for the
purpose of controlling speed to achieve a desired deceleration to
stop at a particular position alongside the platform. In one
contemplated use of the present invention with that system, a
transposition interval of L=12 inches is used.
The relationship between transposition interval and distance
between the receiving antennas has been illustrated in the drawing
as a ratio 2:1, and this produces a square wave, as shown. However,
it can be shown that a pulsed output corresponding to the count of
passed crossovers will be generated for a variety of distances of
separation of the antennas, including separation distances which
are less than L, and distances which are greater than L. The
desired pulsed output will not be produced if the separation
distance is L itself, or an exact multiple of L.
The transposed cables illustrated in FIGS. 1, 5 and 6 are
configured with the individual wires bent diagonally at each
crossover location. This has been done to better illustrate the
concept of crossover. In practical embodiments it has been found
that cable configuration in which the conductors are bent
substantially transversely to the axis of the cable, as illustrated
by cable 90, FIG. 7, produces a sharper waveform.
While preferred embodiments of the invention have been described,
it should be understood that the various modifications and changes
in arrangement of parts may be within the scope and spirit of the
present invention.
* * * * *