Note: Descriptions are shown in the official language in which they were submitted.
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The invention relates to a device for controlling a traffic-
light installation by means of vehicles equipped with devices for automatic
locating (position-finding).
The continual increase in the use of motor-vehicles, and therefore
in inner-city traffic, means that public-service vehicles, such as buses
and streetcars, must function in congested areas under increasingly difficult
conditions. However, these vehicles must be attractive to the customers and
must operate efficiently. There are also demands for higher speeds, more
frequent service, and adherence to schedules. Effective operation of inner-
city traffic therefore requires that it be possible to over-ride the green
phases of the traffic lights, and this requirement becomes even more urgent
where rescue and police vehicles are involved.
In the case of streetcars, control of the green phase is achieved
through the tracks or the overhead wires. In the case of buses, induction
loops are located a few hundred metres before the intersection. One loop
may be used merely to indicate the presence of a bus, or two loops to
measure the length of a bus, although this may lead to incorrect indications
when trucks of the same size as the buses are travelling along the same
route. This problem may be overcome by using a transmitter on the bus.
But this still means considerable expense in installing cables from the
loops to the traffic lights.
Other systems overcome this disadvantage by transmitting the
message from the vehicle directly~ and through the air, to a receiver on the
traffic light, for example by radio, ultrasonics, or infra-red radiation.
It is the purpose of the invention to provide a simple device
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for controlling a traffic-light installation by means of vehicles equipped
with devices for automatic location (position-finding).
Position-finding or locating systems for vehicles travelling along
fixed routes function by comparing two criteria, one being the predetermined
distance between the starting point and a position-indicating transmitter,
while the other is the distance between the starting point and the said
position-indicating transmitter, as indicated by the vehicle odometer. Since
the control-room is aware of the exact distance between the starting point
and the location of each position-indicating transmitter, a computer can
determine, from the distance-information received, any deviation from the
nominal value and can apply a suitable correction factor to any further
information from the relevant vehicle. This results in a high degree of
position-finding accuracy. A system of this kind, for transmitting infor-
mation between position-indicating transmitters and vehicles, uses a reading
unit on each vehicle and answering units (position-indicating transmitters)
arranged at specific intervals along the route.
According to one aspect of the invention, there is provided in an
installation for the control of a traffic light system from a vehicle, the
combination of means carried by the vehicle for supplying information for
automatic determination of position, i.e. bearing determination, a first
directional antenna for transmission/reception, carried by the vehicle for
transmission of such bearing information and having its transmission direction
oriented essentially perpendicular to the direction of travel of the vehicle,
a second directional antenna carried by the vehicle and oriented in the direc-
tion of travel of the vehicle for transmission of transfer messages or commands
$or the control of lights of such a traffic light system, means for producing
carrier waves, means for modulating said carrier waves, said means for modu-
lation is adapted to provide two types of modulated signals which are ortho-
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gonal to one another, one for the modulat;on of bearing information and theother for the modulation of transfer messages or commands, change-over switch
means selectively connecting said means for modulation to said first antenna
over a shunt means or to said second antennal and control means connected
to said change-over switch means and said means for modulation for selectively
controlling the type o:f modulation utilized and the antenna employed for a
selected transmission.
According to another aspect of the invention there is provided, in
a vehicular location system with a first directional antenna for receiving
or transmitting vehicular location related information connected to means
for demodulating received vehicular location related messages and a second
directional antenna for transmitting traffic light control messages connected
to means for modulation of a carrier signal with said traffic light control
message, an improvement wherein: said first directional antenna is oriented
substantially perpendicular to the direction of vehicular travel and said
second directional antenna is oriented substantially along the direction of
vehicular travel; and said means for modulating has a control input port and
is adapted to generate a modulated signal with a first or second type of
modulation upon sensing a first electronic signal generated by a control
means based on whether a vehicular location message or a traffic signal con-
trol message is to be transmitted; and means for connecting said generated
modulated signal to either the first or the second antenna upon sensing a
second electronic signal generated by said control means based on whether a
vehicular location message or a traffic signal control message is to be trans-
mitted; whereby said transmitted vehicular location related messages and said
transmitted traffic light control related messages are orthogonal to one
another .
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According to one advantageous configuration of the object of the
application, an antenna change-over switch is provided, the outputs from
which may be connected selectively to the antenna for traffic-light control
or through a branching circuit to the position-finding system, the said
change-over switch being triggered by a control circuit in such a manner
that it is connected to the relevant output according to the information
supplied to its input in the form of modulation signals for the transmission
of relevant information (position-finding information or enquiry messages).
It is desirable for enquiry messages to be modulated on a carrier
in a modulating procedure which is at right angles to the position-finding
system.
According to still another advantageous configuration of the
object of the invention, provision is made for additional position-selective
information to be transmitted to other receivers installed along the route
These may be, for example, arrival information which is transmitted to an
arrival indicator at bus stops.
The invention is explained hereinafter in greater detail, in con-
junction with the examples of embodiment illustrated in the drawing attached
hereto, wherein: Figure 1 is a block wiring diagram of the position-finding
system with combined traffic-light control; Figure 2 shows a bus in
street operation, with the necessary position-finding and control devices
on the bus and along the edge of the street.
The top row in the block diagram in Figure 1 contains the elements
of the position-finding system. Connected to one side of branching circuit
1 is transmitting/receiving antenna 2 which is aligned with antenna 3 of
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answering unit 4 (the position-indicating transmitter). Connected to the
other side of branching circuit 1 are a frequency-converter 5, a unit 6 for
analog signal processing, and a unit 7 for digital signal processing. Data
are released by digital signal processor 7.
The position-finding system is extended by devices for traffic-
light control (APS) comprising an antenna-change-over switch 8, one output
of which is connected to branching circuit 1, while a second output is con-
nected to additional transmitting antenna 12 for the traffic-light control.
Antenna 12 is aligned with antenna 13 on traffic-light receiver 14. One
input to antenna-change-over switch 8 is connected to a change-over modu-
lator 9 to which a fixed-frequency oscillator 10, with a frequency f = 2.45
GHz, for example, is connected. The two outputs from a control switch 11
are connected to antenna-change-over switch 8 and modulator 9.
This position-finding system is expanded in such a manner that
enquiry messages can also be suitably modulated and transmitted. In this
connection, provision is made for selecting a modulating procedure at right
angles to the position-finding system, which ensures optimal interference -
decoupling of the two functions, even when several vehicles are in use
simultaneously. Thus, if for instance, the position-finding function is
being carried out with amplitude shift-keying (ASK), then frequency shift-
keying (FSK) is used for the enquiry message. Modulator 9 is controlled
and changed over by control switch 11, to one input I of which information
regarding the type of transmission is fed, while the APS message is fed to
second input II thereof. Either an ASK signal (an amplitude-modulated,
low-distortion-factor signal) is fed~ through simultaneously triggered
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antenna-change-over switch 8, through branching circuit 1,
to the position-finding device, or an FSK (frequency-modulated)
signal is fed to transmitting antenna 12 which transmits a
message to traffic-light receiver 14. Provision is also made
to provide the individual sections along the route with mark-
ings (identification), so that incoming messages are evaluated
only by the traffic lights for which they are intended.
Antenna-change-over switch 8, which may also be
omitted if necessary, is an advantageous way of providing
further decoupling of the position-finding and control areas of
the circuit.
Figure 2 shows a bus in street operation, the
roof of which carries a transmitting/receiving antenna 2 for
the position-finding system (the traffic-control system), with a
direction of radiation at right angles to the direction of
travel, and an additional antenna 12 radiating in the direction
of travel. Transmitting/receiving antenna 2 is in radio com-
munication with an answering unit 4 (a position-indication
transmitter) secured to a light pole 20 at the side of the
street. Antenna 12 radiates to receiver 14 on traffic-light
22, through which additional control of the traffic-light
installation is carried out.
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