Bus passenger alerting system

A system for alerting passengers, particularly school children, that the particular bus they are to board is approaching. The passengers have a receiver which senses the particular signal transmitted by the approaching bus. The passengers listen for and/or watch for a visual indication that the bus is now at the location on its route where preparations should be made for boarding. The bus carries a transmitter which sends out a specific signal identifying that bus. The signal is derived from data which was entered into a signal generator in the transmitter relating to the particular school district, the route to be traveled by the bus, and the number of the bus. Each residence where the school children are waiting has a receiver which will activate an indicating device only when the specific bus identification signal is received.

BACKGROUND OF THE INVENTION 
The present invention relates to a system for alerting passengers, 
particularly school children, of the impending arrival of a school bus. 
In a rural area, a school bus travels many miles in picking up students 
along its particular route. The students to be picked up can live in a 
diverse range of homes. Some students live close together and in turn can 
cluster at a common bus stop while others live away from the road, in fact 
sometimes so far away that the road cannot be seen. In either situation it 
would be desirable if the children could know in advance that the school 
bus was approaching and have time to gather their belongings before 
journeying to the bus stop or to the road where the bus will stop. During 
the winter and in rainy weather it would be particularly desirable for the 
students to know with a reasonable degree of certainty of the time when 
the bus will arrive so that they will have time to dress for the weather 
before starting out. Also, since school buses all too commonly become 
stuck in snow or ice along the bus route, the students would not have to 
wait an undue period of time for the bus, not knowing when or if it will 
arrive. 
Parents in school systems have been aware of this problem for some time and 
have attempted to solve it by equipping the school buses with transmitters 
which would send out a signal which could be received in the home to alert 
the school children. While this appears to be an easy solution to the 
problem, it has been anything but that. Many of the proposed systems have 
been far too complicated and in turn too expensive to be practical. Also, 
the receivers in the home were too complicated, or subject to being 
incorrectly adjusted, so that the signal was either not received or not 
received early enough to give the children time to prepare to leave for 
the bus. 
In U.S. Pat. No. 3,560,916, issued to Buckingham et al. Feb. 12, 1966, a 
transmitter is provided on the bus having a frequency-determining element 
which was controlled by the odometer cable. As the bus traveled along the 
route incremental changes in the odometer reading caused the transmitted 
signal to increase in frequency by a predetermined amount. Each home along 
the route had a receiver with a precisely tuned circuit which could 
recognize the particular frequency corresponding to the position of the 
bus at that time or at the time needed to provide warning for the school 
children to prepare to leave to meet the bus. Both the transmitter and 
receiver in this system were extremely complicated and expensive which 
caused the system to not be accepted. 
In U.S. Pat. No. 4,325,057, issued to Bishop on Apr. 13, 1982, a school bus 
approach system was disclosed in which the bus transmits a signal on a 
frequency corresponding to the route that the bus would travel. The home 
would have a receiver capable of receiving this signal and alerting the 
school children of the pending arrival of the bus. The bus driver could 
select through a switch the particular frequency the transmitter would 
send on, corresponding to the route the bus would travel. A receiver was 
provided for each home along that particular route which was capable of 
detecting the particular signal sent by the bus. The receiver at the home 
had a sensitivity control to be used to adjust the receiver so that it 
would only emit a warning signal when the bus was at a particular distance 
from the home which would provide the children with sufficient time to 
prepare to board the bus. Since the sensitivity control determined the 
point when the receiver would activate visual or audible alarm alerting 
the students of the approach of the bus, the sensitivity control became a 
source of error. If the sensitivity control was adjusted improperly so 
that it required too strong a signal, then the bus would be too close to 
the home before the receiver would become activated. On the other hand, if 
the control was set so that the receiver was too sensitive, then the 
purpose of the system was defeated since the children would prepare and 
expose themselves to inclement weather for an unnecessarily long time 
before the bus arrived. 
Another serious deficiency in the Bishop system was that the bus was 
limited in the number of frequencies upon which it could transmit a 
signal. Both the receiver and transmitter were crystal controlled and only 
a small number of frequencies were available for use. Also, the patent 
provides no teaching as to how students of different ages or in different 
grades in the same school could differentiate between buses traveling on 
the same route. The distinguishing feature was the bus route and not a 
signal specific to each bus. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, a system is provided for 
identifying each bus with a unique signal which can easily be encoded into 
the transmitter. The three primary variables in any school bus system are 
the school district, which is used here as a collective term for county, 
township, parish, etc.; the route identification information; and the bus 
identification information, usually just the number. Each of these three 
variables are used to provide an input to a signal generated in the 
transmitter which results in a unique transmitted signal which 
specifically identifies the particular bus. The receivers distributed to 
the school children who would ride this bus are also preadjusted to 
receive only this unique signal. The receiver is also only provided with 
an on and off control so that there is little chance of a misadjustment 
providing too early an alarm or no alarm. 
In accordance with the present invention a system is provided for alerting 
a passenger that a particular bus is approaching. A transmitter is mounted 
in each bus for transmitting a signal specifically identifying that bus. 
The transmitter has a set of switches for entering the district, the route 
and the bus identification information. A signal generator in each 
transmitter uses the inputted data to generate a unique signal which 
specifically identifies that bus. A receiver is provided for each home 
along the route which is responsive to the particular signal transmitted 
by the bus. When the receiver senses the signal it activates an audible 
and/or visual alarm which advises the passengers that the bus is 
approaching and that preparations should be made for boarding the bus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIG. 1, the signal generator portion of the transmitter is 
shown and indicated generally by the number 10. The signal generator has 
three sources of variable input data. These are the district switches 11, 
the bus information or bus number switches 13, and the bus route switches 
15. In order to simplify the operation of the transmitter, since the 
district switches are usually set only once, these switches are placed 
internal to the transmitter cabinet. The district switches 11 are three 
position slide switches 17, 19 and 21. These three slide switches provide 
for 27 districts. Slide switch 17 is used to connect pin D1 of the encoder 
chip 23 to Vcc, to a center or open position and to a third position where 
pin D1 is grounded. Slide switches 19 and 21 perform the same switching 
for pins D2 and D3 of the encoder chip 
The decoder chip 23 is a standard Motorola MC145026T chip. The chip has a 
9-wire input and a single wire output. The input and output have not been 
referred to as a 9-bit input and a single bit output as the chip is used 
in a tri-state mode. As seen above in the description of the district 
switches 11, pins D1, D2 and D3 can either be connected to supply voltage 
Vcc, they can be open in the center position or grounded in the third 
position. Having the ability to encode the chips at three levels has 
substantially increased the available output signals. With a 9 bit input 
to the encoder one would expect 2.sup.9 or 512 combinations. Using the 
tri-state encoding, with the exception that the last wire D9 will only 
recognize two states, the total number of unique codes is 3.sup.8 .times.2 
or 13,122. It can be seen that without using extremely complicated 
circuitry or large size integrated circuit chips the compact signal 
generator of the present invention can produce over 13,000 useful signals 
where one would normally expect to obtain only 512. 
The bus route is encoded into the signal generator through a simple rotary 
switch having two wafers. The rotary switch is shown in the off position. 
When it is moved to the 1 position, pin D8 of encoder chip 23 is brought 
to the low condition. In step position 2 it is held low while in positions 
3 and 4 D8 is high. Pin D9 is low at the first position, high at the 
second, low at the third, and high at the fourth. As currently wired in 
the preferred embodiment, the bus route switch enables the selection of 
any one of four possible routes. 
The next variable to be selected is the bus information or bus number 
switch 13. The switches 13 enable a bus number from 1 to 80 to be entered 
into the signal generator. Two push-button switches are used which provide 
a binary coded decimal output each on four lines to the bus number 
translation ROM 25. The ROM 25 provides 8 outputs to a diode matrix 27 
which reduces the 8 outputs to 4 which are applied to the encoder chip 23. 
It can be seen then that the district switches 11 provide three inputs to 
the encoder chip. The bus number switches 13 provide four inputs and the 
bus route switches 15 provide two inputs, or a total of 9 inputs to the 
encoder chip. The encoder chip provides an output on pin 15 which is used 
for the preferred frequency modulation of the transmitter. Other 
modulation techniques can also be used such as amplitude modulation, phase 
and pulse modulation. 
In coding the bus number switches, the range of buses was set at 1-80. 
Obviously the switches can go as high as 99 so the states 00 and from 
81-99 were made invalid states. When any of these invalid bus numbers were 
entered into the bus number switches 13, the output of the translation ROM 
25 was taken off through a logic gate 29 and applied to a conductor 31 
where it can be sent to actuate an invalid code alarm. 
Now referring to FIG. 2, the signal generating portion 10 of the 
transmitter can be seen occupying the upper left-hand portion of the block 
diagram. The output of the signal generator 33 is applied to an oscillator 
35 whose frequency is controlled by a crystal 37. The information on line 
33 is used to frequency modulate the oscillator 35. The output of the 
oscillator is then fed through a tripling stage 39, a doubler 41, a second 
doubler 43, and a buffer 45 to an amplifier driver 47 which drives the 
output amplifier 49. The output of the amplifier 49 is then fed through an 
output harmonic filter 51 to an output connector 53 mounted on the 
transmitter cabinet. The output of the transmitter is at 154.570 MHz at 2 
watts. The signal is uniquely encoded with the information from the signal 
generator 10. The transmitter block diagram is representative of a typical 
transmitter and is not meant to limit the invention in any way. 
When many buses are operating in the same area and have their transmitters 
running, it is possible for the strongest transmitter to capture one or 
more of the receivers in the vicinity. In order to prevent this from 
happening the transmitter does not run continuously. A timer 55 is used to 
control the transmitter. It is preferably set so that the transmitter will 
operate at either approximately 4 or 8 second intervals. 
In order to further reduce the possibility of several transmitters 
transmitting at the same time, the output of the master clock 57 is 
applied to a binary counter 59. The binary counter is offset by a signal 
derived from the units' bus numbers 13 over the lines 61. Using a delay 
signal derived from the bus number further reduces the possibility that 
all of the transmitters will be transmitting at the same time. The 
variable shift caused by the variable number selection from the bus number 
switch causes the output 63 of the binary counter to be applied to the 
encoder chip 23 at a time later than the original starting of the master 
clock 57. 
The output of the master clock 57 is also applied to an audible alarm 
control 65 which is used to activate an audio device 67 such as a 
piezo-electric siren. The alarm device 65 is actuated by the route switch 
15 over the line 69 each time the transmitter is turned on. The bus driver 
is reminded that the proper route must be entered by the sounding of the 
audio device. The audible alarm is also driven by the all-zero detector 29 
over the line 71 when a bus number of 00 or higher than 80 is entered into 
the bus number switches 13. 
The transmitter uses the electrical system 80 of the bus for power. A fuse 
81 protects the electrical system from any faults in the transmitter. A 
power switch 83 is part of the bus route selection switch. When the bus 
route selection switch is turned, the power switch 83 is closed. A voltage 
regulator 85 is used to provide regulated voltage to the logic circuits 
and to the crystal oscillator 35. The regulator 85 is connected to a 
second voltage regulator 87 which provides regulated voltage to the 
multiplier stages in the transmitter. The power output of the transmitter 
is controlled by the DC level control 89 which controls the power input to 
the output amplifier stage 49. A pair of indicator lights 91 and 93 are 
used to show that the transmitter is turned on and that the transmitter is 
transmitting, respectively. The power-up reset 95 is used to clear the 
counter 59. It is also used to set the audible alarm, indicating to the 
operator that the route switch should be activated. 
The output of the transmitter 53 can be connected through a suitable 
coaxial cable to an antenna mounted on the outer surface of the bus, 
preferably near the roof. The antenna can be either fixed or magnetically 
held in place on the roof of the bus. 
From the previous discussion it can be seen that many different inputs are 
employed to generate the unique signal used to identify the bus. The face 
of the transmitter 100, however, as shown in FIG. 3 is extremely simple. 
The control panel has the route switch 15 which also controls the power 
applied to the transmitter, the indicator lights 91 and 93, which show 
that the transmitter is on and when it is transmitting, the bus number 
selection switch 13 and a small alarm or beeper 67. A test switch 101 is 
also on the panel and can be pressed by the bus driver to actuate the 
transmitter to see that it is indeed functioning before starting out on 
the route. The bus driver merely selects the particular route, which also 
turns the transmitter on, and causes the audio alarm 67 to be reset and 
silenced. The driver enters the proper bus number and the bus is ready to 
move. During the course of the day the route or run number may be changed 
several times by the bus driver while the bus number remains the same. If 
an emergency occurs and the bus must take the route or run of another bus, 
then the bus number can be changed to correspond to that of the bus being 
replaced, and the bus is then ready to go out and pick up those passengers 
which would have been picked up by the disabled bus. The transmitter on 
the bus will send out the same signal that the disabled bus would have 
sent out. 
Each home where the school children wait for the bus has a radio receiver 
specifically encoded to receive the matching signal transmitted by the 
school bus. As mentioned previously, the receiver is extremely simple to 
operate. The only external control is the power on/off switch. All of the 
encoding switches used to set the receiver to receive a specific signal 
from a bus are internal to the receiver cabinet. As shown in FIG. 4, the 
receiver has an antenna 111 which is preferably of the collapsible type 
which can be telescoped into the receiver cabinet when not in use. Other 
antennae, such a fixed antenna or a so-called "rubber duck" antenna, can 
also be used. 
The output of the antenna is fed to an RF amplifier and high frequency 
filter 113 which receives, amplifies and selects the 154.570 MHz signal. 
The output of the amplifier is in turn fed to a high frequency mixer 115 
which also receives a signal from the local oscillator 117 to produce an 
intermediate frequency signal of 10.7 MHz which is sent to an IF amplifier 
119. The output of the IF amplifier is then fed to a low frequency mixer 
121 where it is mixed with the output from a low frequency oscillator 123 
to provide a signal which is fed to a ratio detector 125. The signal 
emitted by the transmitter on the school bus is encoded by frequency 
modulation. The receiver then uses frequency modulation techniques for 
deriving the intelligence from the transmitted signal. The output of the 
ratio detector where the FM signal is demodulated, is fed through a DC 
level shifter 127 and then to the data decoding circuit 129, which is 
similar to the encoding circuit 23. The decoder uses a similar chip to 
that previously described for the encoding circuit using tri-state 
switching from a plurality of three position slide switches 131 and a 
single two position slide switch 133 to derive the output signal. The 
output signal is then fed to a low frequency oscillator 135 where it is 
then used to drive an audible alert device, such as a beeper. The signal 
can also be used to blink or cause a visible indicator 139 to become 
illuminated. The power source for the receiver is not shown as it can be 
either a battery or an internal power supply using the available house AC 
current through a step-down transformer, rectifier, filter and voltage 
regulator, as is well known. 
As mentioned above, the slide switches 131 and 133 are internal to the 
receiver cabinet. When a receiver is issued to a parent or guardian, the 
slide switches are set at the school to enable the receiver to decode the 
specific signal transmitted by the school bus to be used to carry his or 
her children. With the encoding system of the present invention, the 
receiver should only be activated by the specific signal transmitted by 
the specific school bus to which the school children are assigned. Since 
the school bus assignments are usually made on the first day of school in 
the fall, the receiver can be adjusted and then sealed and distributed. 
The parent or guardian need only be concerned with turning the receiver on 
and off and not having to worry about the receiver tuning and/or 
sensitivity. 
It can be seen from the above description that a school bus alert system is 
provided which can simply and economically generate a specific bus 
identification signal and receive that specific identification signal. The 
system is extremely simple to use by the bus driver in that the driver 
only has to be concerned with the number of the bus and the route to be 
driven. The parent or guardian, on the other hand, only has to be 
concerned with turning the receiver on to receive the unique signal 
transmitted by the school bus to which the children are assigned. 
The present invention is not meant to be limited to the specific circuits 
and circuit elements disclosed. Other electronic devices can obviously be 
substituted to accomplish the same purposes. Also, the well known 
microprocessor can also be used to incorporate many of the disclosed 
circuit functions. While this substitution is obvious that choice was not 
made in order to reduce the complexity of the entire system. A keypad 
could be used to encode the microprocessor, however, this would add 
unnecessary complexity and would require the bus driver to handle a 
challenging task. Simplicity in operation is an important aspect of the 
present invention. 
Likewise, the invention is not meant to be limited to school bus 
applications. The system is equally applicable to any situation where a 
person would desire to be alerted to the approach of a specific type of 
vehicle, or as an example and not by way of limitation, the refuse 
collection. 
Though the invention has been described with respect to a specific 
preferred embodiment thereof, many variations and modifications will 
become apparent to those skilled in the art. It is therefore the intention 
that the appended claims will be interpreted as broadly as possible in 
view of the prior art to include all such variations and modifications. 
The embodiments of the invention in which an exclusive property privilege 
is claimed are defined as follows.