Abstract:
A system and apparatus for detecting the approach of a vehicle includes an encoded signal which identifies a vehicle or route, and which is used to distinguish from different vehicles and routes. A receiver detects transmission signals above a threshold level, and responsive to reception thereof checks for one or a plurality of codes that identify particular vehicles of interest. When a desired signal is received, an alarm or indicator is generated that alerts a person. When the indicator is terminated, a lock-out period prevents undesired re-activation of the alarm or indicator based upon the same code. Unique headers enable transmission and exchange of additional data, and logical text may be provided which enables more ready viewing of coded information. The present invention has industrial applicability to public and private transportation systems, whether for passengers or other cargo.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims priority to U.S. provisional application Ser. No. 60/385,741 filed Jun. 5, 2002 and abandoned herewith, the contents which are incorporated herein by reference in entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention pertains generally to electrical communications, and more specifically to vehicle position indicators that signal a vehicle&#39;s anticipated arrival. In one more specific manifestation, the indicators are for school buses or other similar public transportation, though other manifestations are also described. 
   2. Description of the Related Art 
   Many different modes of transportation exist that utilize an operator, such as a driver, engineer or other ones of the myriad of names provided for such persons, and a vehicle to transport one or more passengers from one location to another. Operator-controlled transportation brings many universally recognized benefits. Among them are the conservation of energy, which is particularly beneficial in such instances as buses, light and heavy rail and the like. These mass transit systems also preserve real-estate by carrying many passengers in a single line in an efficient manner, while not requiring any associated automobile parking space. Where parking may be limited or completely unavailable, such as is common in larger cities or in special locations or facilities, such types of transportation may be the only viable mode of travel. Finally, in the cases of more private methods such as taxi cabs and the like, transportation is frequently made available where it would have otherwise not been possible or practical. 
   Nevertheless, operator-controlled transportation has, in many cases, garnered a reputation as eing somewhat less convenient than personal transportation for most ordinary trips. This is because the passenger must be at a pick-up location and ready for boarding well in advance of the anticipated arrival of the vehicle. This adds additional time to the trip, and also exposes the passenger to the vagaries of the environment. Such early arrival is necessitated since many of these vehicles will have a slightly variable arrival and departure time, and these vehicles will preferably not wait at any stops. Waiting at a stop would undesirably prolong the trip made by the vehicle, which would only add to the travel time and consequent inconvenience of this type of transportation for all passengers. Furthermore, the additional time to travel a route will also necessitates additional billing to compensate the operator, and reduce the availability of the vehicle for covering either the same or other routes. This is particularly true in the instance of more private modes of transportation, such as taxi cabs or the like, where wait times may be directly billed to the passenger. 
   Beyond inconvenience and minor added expense, and for many passengers an issue of greatest paramount, is the issue of safety. There are many locations where public transportation must be provided but cannot economically be provided with adequate security to ensure the safety of all passengers. One particular instance is the bus stop, which often serves as the gathering point for many diverse persons. All too often, these persons are for one reason or another more vulnerable than most. One particular instance is that of a school bus stop, where very young or small children must gather and wait for the school bus or where they will be dropped a the end of the school day. Unfortunately, these bus stops are scattered all about the country-side, from street corners to rural locations. Since the only persons traveling are school aged children, and since in many school districts transportation may be provided at different times for different age groups, it is entirely possible for kindergarten or elementary school children to be the only passengers at a stop. Further compounding the matter, at some times of the year and in some localities, the pick-up or drop-off times will be outside of daylight. While many times it is possible for the districts to avoid such scheduling, there are still some instances where this occurs. During these times, the young children are very vulnerable. Even with adults, a single or few passengers may be vulnerable and consequently unsafe. 
   In order to improve the safety and convenience of operator-controlled transportation systems, a number of systems have been developed which notify a passenger of an impending arrival of a vehicle. These systems are desirable since the transit time may be reduced, by reducing the amount of waiting at a pick-up or vehicle stop. Safety is improved, since the passenger is exposed for less time, and the vagaries of the environment, such as rain or the like, are somewhat less consequential. Where an individual will be picked up at their residence, or nearby, such systems provide ample advance notice for the passenger to be ready just as the vehicle arrives. This improves the efficiency and safety of the transit system for all. 
   Exemplary of the prior art systems, and each incorporated herein by reference for their specific teachings, are U.S. Pat. No. 5,021,780 to Fabiano et al; U.S. Pat. No. 4,325,057 to Bishop; U.S. Pat. No. 4,297,672 to Fruchey et al; U.S. Pat. No. 4,713,661 to Boone et al; U.S. Pat. No. 6,191,708 to Davidson; U.S. Pat. No. 4,350,969 to Greer; U.S. Pat. No. 5,144,301 to Jackson et al; U.S. Pat. No. 5,400,020 to Jones et al; U.S. Pat. No. 5,680,119 to Magliari et al; and U.S. Pat. No. 6,184,802 to Lamb. The patents of the prior art may somewhat generally be grouped according to the techniques which are provided to enable advance notice. One approach, illustrated by Jackson et al, is to use a low-power transmitter which triggers an audible or visual signal when close enough to a receiver. This technique requires very little capital cost, and may therefore be implemented readily by many transit systems and providers. However, there are few available unique frequencies in the radio spectrum, and interfering signals can cause the receiver to falsely trigger. In areas where several transportation vehicles will simultaneously operate, it can be extremely difficult to avoid triggering from the wrong vehicle. Such false alerts render the system relatively ineffective for all but the most rural of routes. 
   One approach which avoids the false triggering is illustrated, for exemplary purposes, by Jones et al. Using this system, a transportation vehicle is provided with relatively advanced electronics that may, for example, employ position detection systems such as GPS, Loran or the like, together with various sensors to detect the status of the transit vehicle. The transit vehicle may then be monitored for movement, and an arrival schedule predicted with some reliability. Passengers then subscribe to the system provider, who may use an automated dialing system with unique ring to notify the passengers at the appropriate time that the transit vehicle is approaching. For systems with fewer subscribers, this type of system offers several advantages. First of all, the location and status of each transit vehicle may be monitored very accurately. The relatively high capital cost of the equipment is limited to the transit vehicles, and not further multiplied by any passenger equipment. Unfortunately, when volumes of passengers increase, the amount of time required for timely notification also increases. Said another way, while everything is conveniently centralized, the load upon the central system may increase to a level which is greater than that which may be managed. Consequently, as the numbers of subscribing passengers increase, the system becomes substantially more expensive and more difficult to operate and maintain. 
   In all of these prior art systems, there is little in the way of flexibility provided to the subscriber, beyond how much advance notice the subscriber wishes to receive. Consequently, these systems are optimized for mass transit systems which are simply announcing the anticipated arrival of the transit vehicle at a particular stop. 
   SUMMARY OF THE INVENTION 
   In a first manifestation, the invention is a system for detecting the approach of a vehicle. Within the system, a vehicle transmitter operatively transmits at least one code. A code generator generates a representative code selected from a plurality of codes which is representative of the vehicle transmitter and discernable from others of the plurality of codes. The code generator is operatively coupled to the vehicle transmitter, to thereby couple the representative code to vehicle transmitter for transmission of a signal therefrom. A receiver remote from the vehicle transmitter has a signal receiver operatively monitoring for transmitted signals at a signal strength of at least a first threshold. A code demodulator responds to the signal receiver and extracts representative code from such a signal. A code detector compares the representative code to at least one user-selected code and generates an indication of identity therewith. 
   In a second manifestation, the invention is a means for alerting a person to a location of a transmitter at a first instant of time. The alerting means has a transmitter, and also a receiver spatially disparate to the transmitter. Both transmitter and receiver are tuned to a common transmission signal. A threshold of the common transmission signal is detectable by the receiver, and a code carried by the common transmission signal identifying the transmitter is also detectable by the receiver. A means within the receiver is provided for comparing the code to stored values and responsive to a match therewith generating a signal indicative of a match. 
   OBJECTS OF THE INVENTION 
   Exemplary embodiments of the present invention solve inadequacies of the prior art by providing an amplitude activated, code controlled receiver which uses unique headers that enable special communications and functions between transmitter and receiver. The receiver is also preferably provided with an ability to lock out the receiver for a particular interval to prevent undesirable re-triggering by the same vehicle, and to be able to trigger on and identify more than one transit vehicle at a time. Where necessitated, RF collision detection and avoidance may also be incorporated. 
   A first object of the invention is to provide an enhanced transportation monitoring and alerting system. A second object of the invention is to provide the enhancements using a combination of existing low-cost and proven approaches, integrated with several novel key features that greatly increase the flexibility and utility of the present invention over that of the prior art without driving the costs to socio-economically unacceptable levels. Another object of the present invention is to enable very high volumes of users, both transmitters and receivers, without conflict or false signaling. A further object of the invention is to enable simultaneous monitoring of more than one transit vehicle. Yet another object of the present invention is to enable system upgrades without requiring replacement or retooling of existing capital equipment. A further object of the invention is the enabling of a lock-out, which permits one monitored channel to be disabled or locked out for a predetermined time period. Another object of the invention is to enable capacity for data transmission or exchange through the use of unique codes and headers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other objects, advantages, and novel features of the present invention can be understood and appreciated by reference to the following detailed description of the invention, taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  schematically illustrates a preferred system for detecting the approach of a specific vehicle designed in accord with the teachings of the present invention. 
       FIG. 2  illustrates a preferred transmitter and receiver pair used in the preferred system of  FIG. 1  by block diagram. 
       FIG. 3  illustrates a preferred coding technique. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Manifested in the preferred system  10  for detecting the approach of a vehicle  15 , the present invention provides a relatively low-powered vehicle-carried transmitter unit  100 . The particular power level which may be required will depend upon the size of the route traveled, relative spacing between intended stops and the like, though for the purposes of illustration only and not limiting thereto, in the preferred embodiment a transmitter operating at approximately 433 Mhz may be powered for short burst transmissions at a peak power level that will typically be within a range of 100 milliwatts and 5 Watts. Those skilled in the art will understand that this power level will also be dependent upon the sensitivity of receivers  200  that transmitter  100  is being used in association with. For many urban or suburban applications, a range of only a few city blocks may be adequate for providing the intended notice, though much greater distances maybe desired, depending upon the most desirable lead times and size of the overall route. In other words, for a route which only encompasses a few block radius, transmitter power levels may be decreased and/or receiver sensitivity decreased such that receivers such as receiver  200  will not be continuously activated. For rural routes that span many miles, much higher transmitter power levels and receiver sensitivities will produce greater advance notice. 
   While a bus is illustrated in  FIG. 1  as the preferred transit vehicle  15 , any other types of transit vehicles will be understood to be included, as described herein above and in the references incorporated herein by reference. Consequently, thoroughfare  20  may be a road, river, or even air in the case of an airplane. Transit vehicle  15  will be understood to be any type of vehicle which is designed for carrying a passenger  40 . Furthermore, transit vehicle  15  will also be understood to encompass other types of vehicles that are instead be provided for such industry as the transport of packages or for other application. 
   Passenger  40  will most preferably be located within audible or visual range of receiver  200 , such as within a shelter  30 . Shelter  30  may include a house, apartment or other dwelling, but is not limited thereto. In fact, receiver  200  may be designed to be portable and bodily-carried by passenger  40 , if so desired. Nevertheless, for many typical applications, it is anticipated that shelter  30  may be a dwelling. Transmitter  100  will generate a signal such as radio waves  17 , which at some finite distance will be within range of reception of receiver  200 . This will in turn trigger receiver  200  to notify passenger  40 . The method of notification in preferred system  10  is a combination of sound and light, and may be switched therebetween to signal different distances. In other words, a first visual alarm may be triggered, followed by a subsequent audible alarm as the transit vehicle  15  gets sufficiently closer to cross another threshold. Most preferably, the notification will be sufficiently advanced to permit passenger  40  to reach boarding site  25  at the same time or just slightly before transit vehicle  15 . In one method conceived herein, the invention will have application to persons affiliated with the passenger, such as parents or guardians who will be meeting their child at a bus stop, or care-givers who may be similarly expecting a person under their care to arrive. Using the preferred system  10 , both the passenger  40  and a guardian or care-giver may obtain advance notification. 
     FIG. 2  illustrates the most preferred transmitter  100  and receiver  200  by block diagram. Those skilled in the art of electrical communications will recognize that the internal components are preferred, but that there will be many known alternatives to each of the more basic components found therein. Transmitter  100  includes a power source  140 , which in the preferred embodiment illustrated in  FIG. 2  is the vehicle battery. Most vehicle power is fraught with noise and interfering spikes, and will frequently be of the wrong amplitude. Consequently, a power regulator  150  will be provided to ensure the appropriate potential and to protect against damaging spikes or noise. Microprocessor  120  will most preferably not only include the microprocessor chip, but all necessary associated components, which is known to depend upon the specific microprocessor. For example, crystal oscillators, resistors, filter capacitors, memory including volatile, non-volatile, magnetic and other known types, and any of a multitude of other components are known to be used in association with the microprocessor chip, and are understood to be include herewith. A means or method for selecting a particular unique identification will most preferably be provided to transmitter  100 , and, in the preferred embodiment of  FIG. 2 , that method is through the inclusion of thumbwheel selector switches  110 . These switches may frequently be Binary-Coded Decimal (BCD) switches, which for each switch will reproduce in binary digital form a representation of from zero to nine. Just one of these BCD switches would allow the transmitter ten different unique identifications, while two would allow  100 , and so forth in powers of ten. Other means for selecting this code may be used as desired, including but not limited to keypads, other coded switches, keys or even received codes from another transmitter, to name just a few of the many possibilities. 
   Microprocessor  120  in preferred transmitter  100  will use selector switches  110  or other equivalent means to generate a unique transmitter code that uniquely identifies vehicle  15 . Most preferably, the unique transmitter code will be generated immediately upon the application of power from vehicle battery  140 , using appropriate programming of microprocessor  220 , and, in such instance, power regulator  150  will desirably be connected through a key or ignition switch or the like. The transmitter code will be continuously or periodically conducted from microprocessor  120  to RF generator  130  for appropriate amplification, modulation and the like to boost the code to both Radio Frequency (RF) and sufficient power levels as described herein above. In the preferred embodiment, Manchester encoding is used together with a data transmission rate of 2400 baud. Microprocessor  120  will simply turn RF generator  130  on and off at the appropriate times. Given the foregoing data transmission rate, about 22 milliseconds are required to transmit the desired five bytes. Similar to other components, RF generator  130  may also take the form of an integrated circuit and all associated components, as this will simplify the construction, lower manufacturing costs, and provide similar benefits as are known in the art. The amplified RF signal is then transmitted through antenna  160  to produce radio waves  17  illustrated in  FIG. 1 . 
   In the preferred embodiment, microprocessor  120  will be programmed so that when selector switches  110  are set to a total value of zero, or, in the case of two or more BCD switches, each switch set to zero, microprocessor  120  will not communicate a code to RF generator  130 , and will preferably disable transmission therefrom. In the preferred embodiment, microprocessor  120  will also selectively provide power to each one of the switches, when two or more are used. In such case, the outputs from each switch may be passed through blocking diodes, to permit microprocessor  120  to individually poll each switch and thereby reduce the numbers of input lines required into microprocessor  120 . 
   A preferred message assembled by microprocessor  120  will include five bytes of data. The hex representation of the message will preferably be as follows: 
                                   41   fixed header       03   remaining byte count       0X   switch value       YZ   switch value       CC   checksum for the entire message                    
To each byte of data, the microprocessor will preferably add a start bit and a stop bit. X, Y and Z represent the values that appear in selector switches  110 , assuming three BCD switches, while the checksum CC allows receiver  200  to verify the integrity of the received message.
 
   While radio waves are used in the preferred embodiment, other techniques of electrical communication through the ether are contemplated herein as well, and may include such techniques as directional microwave transmission, optical transmission including infra-red and laser techniques, or other diverse means and method. Distance-dependent transmission in the preferred embodiment provides a natural and low-cost method for establishing a threshold distance for triggering the receiver. 
   Receiver  200  in the preferred embodiment includes an antenna  260  and RF demodulator  230 . RF demodulator  230  may be a single chip integrated circuit, or may include a variety of sections and stages including the various known heterodyning and demodulation techniques known in the art. Further, RF demodulator  230  does not have to include frequency shifting or demodulation, depending upon the nature of the signal being transmitted from transmitter  100 . The output from RF demodulator  23  is conveyed in the form of a digital signal or word to microprocessor  220  for further processing. 
   Microprocessor  220  receives various human input through selection bank  210 , which, in the preferred embodiment, includes mode control  212 , a rotary selector knob  214 , and a quiet control  216 . These inputs are in the preferred embodiment achieved using interrupt processing, well known and documented in the field of microprocessors. In the preferred embodiment, mode control  212  and quiet control  216  may be implemented as simple switches. The human-understandable output is provided through display  270  and audio alarm  280 , both which are well-known and understood in the field of microprocessors. In the preferred embodiment, display  270  will be implemented as an LCD display, though the myriad of display devices, including interactive devices such as touch screens and the like, are contemplated herein. Power supply  240  may simply be a wall outlet converter, though batteries or battery back-up and the like are contemplated herein. 
   In operation in accord with the preferred embodiment, microprocessor  220  is programmed for four modes of operations, including ‘RECEIVE’, ‘SET CHANNEL’, ‘SET CODE’, AND ‘ENABLE/DISABLE’. The current operating mode may be indicated in display  270  and controlled through mode control input  212 . Activating mode control input  212 , which in the preferred embodiment is implemented by simply pressing a switch button, will cycle through each of the operating modes. Receiver  200  is not limited to these four modes of operation, and may include fewer or more modes as required for a particular application. 
   The normal mode, and preferably the one activated upon start-up, is the ‘RECEIVE’ mode. In this state, receiver  200  is waiting for appropriated coded transmissions from a nearby transmitter. If such a transmission is detected, which consists of RF demodulator  230  detecting an appropriate signal, an interrupt is sent to microprocessor  220 . This will cause microprocessor  220  to attempt to decode the data, based on the previous settings and internal timers. Manchester encoding of the preferred five byte message allows receiver microcode to synchronize with the transmitted message. If the decoded signal is one which was previously selected for monitoring, microprocessor  220  will activate audio alarm  280 . 
   When a person no longer wants to hear the alarm, ‘QUIET’ control  216  may be pressed to deactivate alarm  280  for the particular vehicle unique identification code. In the preferred embodiment, the ‘QUIET’ control will automatically disable activation on that code for thirty minutes. 
   Due to the routes which are often required to pick up all of the intended passengers, a transit vehicle  15  may often be forced to serpentine through a region. This serpentine pattern will cause prior art distance-based systems to falsely activate each time transit vehicle  15  gets close to receiver  200 . In other words, receiver  200  will not only trigger the first time vehicle  15  gets within reception range, but will again trigger each time thereafter. The present invention overcomes this limitation by using microprocessor  220  through programming to nullify the active alarm, and provide a lock-out for a pre-determined or programmable time period. In the most preferred embodiment, this time period has been selected to be one-half of an hour, though those skilled in the art will understand that this time period may be of different duration or may be user-determined, depending upon the cost and complexity deemed acceptable or desirable for receiver  200 . 
   Before detecting a transit vehicle  15 , receiver  200  must first be directed to desired codes to receive. In other words, receiver  200  has the capability for receiving and correctly identifying a large number of transit vehicle codes. However, at any given time, only one or a select few codes will be of any interest to a particular passenger. Consequently, these particular codes need selected. In the preferred embodiment, this is accomplished using the ‘SET CHANNEL’ mode. Turning rotary knob  214  will scroll through the available channel numbers. These channel numbers represent the available quantity of codes that can be monitored at a given time. In other words, if receiver  200  is capable of monitoring for a total of eight different unique codes, then there will be eight available channels. Once a channel is selected, then the mode button is pressed to select ‘SET CODE’. Once again, rotary knob  214  is turned until the desired transit vehicle code is selected. Contemplated herein is the ability to either display this data in code form, or to provide intelligent interpretation of the code for the application. This might, for exemplary purposes only and not limited thereto, take the form of logical text being displayed for the corresponding route. For example, the code may be 531, but that might represent the “downtown” city bus. Rather than displaying “531”, “downtown” or other similar more descriptive text, hereinafter referred to as logical text which conveys either through words or abbreviations recognizable meaning, may alternatively be displayed, once again depending upon the complexity and pricing desired for receiver  200  and system  10 . 
   When the desired code is displayed, activating mode control  212  once again until ‘RECEIVE’ is displayed will select the particular code. The foregoing procedure may be used to set transit vehicle codes for as many channels as are available. In the preferred embodiment, there are eight channels, though more or less may readily be implemented in light of the present disclosure. 
   At some point, a person may want to temporarily disable detection of a specific vehicle code. To do this, one first puts receiver  200  in the ‘SET CHANNEL’ mode, turns rotary knob  214  to select the desired channel, pressing the mode button to put receiver  200  in ‘ENABLE/DISABLE’ mode, and finally turning rotary knob  214  to change the status to either enable or disable status. To return to normal operation, a person must only activate mode control  212  until receiver  200  is again in ‘RECEIVE’ mode. 
   A sample Manchester code is illustrated in  FIG. 3 . This code, as aforementioned, permits internal synchronization. The code suppresses dc and low-frequency signal components. 
   The use of the five byte word of the present invention permits additional novel flexibility. More particularly, herein above the hex representation  41  designates a fixed header. This header may be altered for different purpose, which permits a wide range of transmitted and received functions. For example, a unique header may be selected that designates a message corresponding to the current time and date. Use of this header will cause all receivers within range to time synchronize. Bus codes and route information may be transmitted to each receiver using a different header code value. So, for example, the bus ID “531” referenced above that corresponds to “downtown” may be set or changed through transmitted information using the unique header. Text messages may be similarly sent, and special configuration information or reprogramming may similarly be transmitted. One particularly beneficial feature contemplated herein, though somewhat more expensive, is the ability to equip both vehicles and passengers with full transceivers, each including hardware similar to both transmitter  100  and receiver  200 . In such instance, it would be possible to transmit text both to and from the transit vehicle  15 . In some cases, such as school bus routes where the passenger will not be taking the bus, the bus may then be alerted without having to stop and wait for any passenger. In the case of commercial delivery services, it is commonplace for a courier to be obligated to stop at each major customer for pick-up, regardless of whether any packages are to be dropped off or picked up. Using the capability of the present unique headers and bi-directional communication, such unwarranted courier stops may be avoided. 
   While the foregoing details what is felt to be the preferred embodiment of the invention, no material limitations to the scope of the claimed invention are intended. Further, features and design alternatives that would be obvious to one of ordinary skill in the art are considered to be incorporated herein. For example, the numbers and possibilities for the type of modulation are nearly limitless, including Amplitude Modulation, Frequency Modulation, Frequency Shift Keying, Phase-Shift Keying, spread-spectrum, and the myriad of other techniques. The operating frequencies are equally as variable, dependent upon the desired transmission characteristics, power and range, as well as available spectrum for the present use. Other similar variables too numerous to specifically mention are considered incorporated herein. Consequently, the scope of the invention is set forth and particularly described in the claims hereinbelow.