Electronic locating system for persons receiving telephone calls

Claims

We claim:

1. The method of determining the present location of a member of a defined class of individual units the present location of which is not known from among a large population of individual units, each programmed to respond to a predetermined inquiry signal, which are normally distributed throughout a defined facility comprising the steps of:

receiving at a central station a request to establish the present location of one of said individual units;

establishing a two-way communication channel between said central station and a plurality of spaced relay stations, each relay station including a transmitter and a receiver and said relay stations being located so as to be cumulatively capable of substantially covering said facility with infrared energy;

communicating by a message coded for selecting said one individual unit over said channel with said plurality of relay stations;

causing said relay stations to transmit an inquiry signal by said infrared energy and enabling the receiver of said one or more relay stations for a predetermined time period following each such transmission;

receiving the inquiry signal at each of said individual units that is located within the coverage of said one or more relay stations;

transmitting a radiant energy acknowledgment signal from any individual unit which recognizes the inquiry signal received from a relay station to be the coded message to which it is programmed to respond;

receiving said acknowledgment signal at any of said relay stations within range of the radiant energy acknowledgment signal transmission;

transitting to said central station over said channel from any relay station which receives said acknowledgment signal an identification signal which identifies that relay station; and

utilizing at said central station any identification signal received from a relay station to determine the location of said relay station and hence the approximate location of the individual unit which transmitted said acknowledgment signal, said utilizing including, if more than one identification signal is received, repeating transmission of said inquiry signal at reduced signal level by any relay stations which responds with an identification signal to identify the relay station responsive to the lowest signal level.

2. The method of claim 1 wherein said radiant energy acknowledgment signal comprises an infrared acknowledgment signal.

3. The method of claim 1 wherein said radiant energy acknowledgment signal comprises an ultrasonic acknowledgment signal.

4. The method of claim 3 wherein said ultrasonic acknowledgment signal is transmitted on a plurality of frequencies.

5. The method of claim 3 wherein signals include data corresponding to the amount of time which elapsed between transmission of the inquiry signal and reception of the acknowledgment signal.

6. The method of claim 1 wherein said inquiry signal contains information to indicate whether the emission of a sound is desired and further comprising the step of emitting a sound from any individual unit which recognizes the inquiry signal received from a relay station to be a signal to which it is programmed to respond and which indicates that the emission of a sound is desired.

7. The method of determining the present location of a member of a defined class of individual units, each programmed to respond to a predetermined inquiry signal, from among a large population of individual units which are normally distributed throughout a defined facility comprising the steps of:

receiving at a central station a request to establish the present location of one of said individual units;

establishing a two-way communication channel between said central station and one or more of a plurality of spaced relay stations, each relay station including a transmitter and receiver and said relay stations being located so as to be cumulatively capable of substantially covering said facility with infrared energy;

selectively communicating by a coded message over said channel with said one or more of said plurality of relay stations;

causing said one or more relay stations to transit an inquiry signal by said infrared energy and enabling the receiver of said one or more relay stations for a predetermined time period following each such transmission;

receiving the inquiry signal at each of said individual units that is located within the coverage of said one or more relay stations;

transmitting a radiant energy acknowledgment signal from any individual unit which recognizes the inquiry signal received from a relay station to be a signal to which it is programmed to respond;

receiving said acknowledgment signal at any of said one or more relay stations within range of the radiant energy acknowledgment signal transmission;

transmitting to said central station over said channel from any relay station which receives said acknowledgment signal an identification signal which identifies that relay station;

upon said central station receiving an identification signal from a plurality of relay stations, determining the responding relay station closest to an individual unit by repeated further steps of modifying the coded message communicated over said channel by including within the message a command to lower the sensitivity of the relay station receiver and causing said plurality of relay stations to lower the sensitivity of their respective receivers; and

utilizing at said central station the identification signal of the last relay station whose response is received after one or more reductions in sensitivity of the relay station receivers to determine the location of said last relay station and hence the approximate location of the individual unit which transmitted said acknowledgment signal.

8. The method of determining the present location of a member of a defined class of individual units from among a large population of individual units, each programmed to respond to a predetermined inguiry signal, which are normally distributed throughout a defined facility comprising the steps of:

receiving at a central station a request to establish the present location of one of said individual units;

establishing a two-way communication channel between said central station and one or more of a plurality of spaced relay stations, each relay station including a transmitter and a receiver and said relay stations being located so as to be cumulatively capable of substantially covering said facility with infrared energy;

selectively communicating by a coded message over said channel with said one or more of said plurality of relay stations;

causing said one or more relay stations to transmit an inquiry signal by said infrared energy and enabling the receiver of said one or more relay stations for a predetermined time period following each such transmission;

receiving the inquiry signal at each of said individual units that is located within the coverage of said one or more relay stations;

transmitting a radiant energy acknowledgment signal from any individual unit which recognizes the inquiry signal received from a relay station to be a signal to which it is programmed to respond;

receiving said acknowledgment signal at any of said one or more relay stations within range of the radiant energy acknowledgment signal transmission;

transmitting to said central station over said channel from any relay station which receives said acknowledgment signal an identification signal which identifies that relay station;

upon said central station receiving an identification signal from a plurality of relay stations, determining the responding relay station closest to an individual unit by repeated further steps of modifying the coded message communicated over said channel by including within the message a command to reduce the power of the relay station transmitter and causing said plurality of relay stations to reduce the power of their respective transmitters; and

utilizing at said central station the identification signal of the last relay station whose response is received after one or more reductions of the relay stations transmitter power to determine the location of said last relay station and hence the approximate location of the individual unit which transmits said acknowledgment signal.

9. The method of claim 1 wherein said two-way communication channel is established over a power line.

10. The method of determing the present location of a member of a defined class of individual units the present location of which is not known from among a large population of individual units each programmed to respond to a predetermined inquiry signal which are normally distributed throughout a defined facility comprising the steps of:

receiving at a central station a request to establish the present location of one of said individual units;

establishing a two-way communication channel between said central station and at least one plurality of groups of spaced relay stations, each relay station including a transmitter and a receiver and said relay stations being located so as to be cumulatively capable of substantially covering said facility with radiant energy the detectable signal level from relay stations of different groups overlapping thereby substantially eliminating dead zones but wherein each relay station of a group covers an area which does not overlap with a detectable signal the areas covered by each of the other relay stations in the same group;

communicating by a coded message over said two-way communication channel with each of said groups of relay stations in sequence;

causing all of the relay stations of each said group in said sequence to transmit an inquiry signal by said radiant energy and enabling the receivers of the respective group relay stations for a predetermined time period following each such transmission;

receiving the inquiry signal at each of said individual units that is located within the coverage of any of the relay stations;

transmitting a radiant energy acknowledgment signal from any individual unit which recognizes the inquiry signal received from a relay station to be a signal to which it is programmed to respond;

receiving said acknowledgment signal at a receiver of any of said relay stations that is enabled and is within range of the radiant energy acknowledgment signal transmission;

transmitting to said central station over said channel from any relay station which receives said acknowledgment signal an identification signal which identifies that relay station; and

utilizing at said central station a first identification signal received from a first group relay station to determine the location of said first group relay station and hence the approximate location of the individual unit which transmitted said acknowledgment signal; said utilizing including identifying the relay station of a second group if a second identification signal is received whereby said approximate location is determined to be within the overlap area covered by the responding first and second group relay stations.

11. The method of claim 10 wherein upon said central station receiving an identification signal from a plurality of relay stations, the method for determining the location of an individual unit is repeated adding the further steps of including within the coded message communicated over said channel a command to lower the sensitivity of the relay station receiver and causing said relay stations to lower the sensitivity of their respective receivers.

12. The method of claim 10 wherein upon said central station receiving an identification signal from a plurality of relay stations, the method for determining the location of an individual unit is repeated adding the further steps of including within the coded message communicated over said channel a command to reduce the power of the relay station transmitter and causing said relay stations to reduce the power of their respective transmitters.

13. The method of claim 10 wherein each of said groups of relay stations performs the step of transmitting an identification signal at a separate time period in said sequence.

14. A communication and locating system that operates within a defined facility comprising:

a plurality of individual transmitter-receiver units each of said units including means programmed to be responsive to a predetermined radiant energy inquiry signal and including means for transmitting a radiant energy acknowledgment signal in response to receiving said predetermined inquiry signal to which it is programmed to respond;

a plurality of groups of relay stations located so as to be cumulatively capable of substantially covering said facility with transmissions of radiant energy at detectable signal level for said units and in which each relay station of a group covers an area that is distinct from the areas covered by each of the other relay stations in the same group, each of said relay stations including means for transmitting the radiant energy inquiry signal to said individual units in response to coded meassages, said inquiry signals containing information indentifying a particular individual unit whose location is sought;

a central station including means for establishing a two-way communication channel between said central station and a plurality of said relay stations and for communicating by a coded meassage sequentially with said relay stations one group at a time over said channel, said coded message identifying the particular individual unit to be identified in the inquiry signal;

each of said relay stations including means operable after receiving said coded message for receiving an acknowledgment signal from said individual units and sending an indentification signal over said communication channel to said central station, said identification signal identifiying the sending relay station and indicating whether an acknowledgment signal was received by said sending relay station; and

said central station further including means for receiving any identification signals from said relay stations and determining therefrom the approximate location of any particular individual unit responding to said coded message whereby a single response identifies said location as the area covered by the responding relay station and more than one response identifies said location as the overlap area covered by the responding relay stations.

15. The system of claim 14 wherein said radiant energy for transmitting said inquiry signal is infrared energy.

16. The system of claim 15 wherein said radiant energy acknowledgment signal comprises an ultrasonic acknowledgment signal.

17. The system of claim 16 wherein said ultrasonic acknowledgment signal is transmitted on a plurality of frequencies.

18. The system of claim 16 wherein each of said relay stations includes means for measuring the time that elapses between the transmission of an inquiry signal and the reception of an acknowledgment signal and means for including said time data within the indentification signal.

19. The system of claim 14 wherein said radiant energy acknowledgment signal and said radiant energy inquiry signal are both infrared signals.

20. The system of claim 14 wherein said central station includes means for coding said coded message to request that the particular individual unit identified in said message emit a sound and wherein said relay stations form said inquiry signal to request the emission of a sound in accordance with said coded message and wherein each of said individual units includes means for emitting a sound in response to receiving an inquiry signal, to which said respective unit is programmed to respond, which requests the emission of a sound.

21. A system according to claim 14 wherein said individual transmitter-receiver units normally operate in a low-current requirement condition operable to receive a wake-up signal to bring said units to full power operating condition and each of said relay stations initially transmitting said wake-up signal for each transmission to the said individual units.

22. The system of claim 14 wherein each of said groups of relay stations has a separate time period in which a relay station in that group can send an identification signal to said central station.

23. The system of claim 14 wherein said central station includes means, responsive to the reception of a plurality of identification signals, for commanding the responding said relay stations to lower the sensitivity of their respective receivers.

24. The system of claim 14 wherein said central station includes means, responsive to the reception of a plurality of identification signals, for commanding the responding said relay stations to reduce the power of their respective transmitters.

25. A communication and locating sytem comprising:

a control station;

a plurlaity of relay stations each covering an identified space within the area covered by said system; and

a badge station for each individual to be located by the system;

said control station comprising:

means for entering coded information identifying a person receiving an incoming call;

a non-active memory storing data identifying likely locations of the persons to be located by the system;

means responsive to entry of person-identifying data for searching said memory for the likely location of the person identified by said data entry;

means for communicating a transmission request to one or more of said relay stations selected to be in communication with the likely locations of the person identified; and

receiving means for receiving an identification signal from a relay station that has received an acknowledgment signal from a badge station, said identification signal identifying the location of the particular relay station that received the acknowledgment signal;

said relay stations each comprising;

means for receiving said transmission request from said control station;

means responsive to receiving said transmission request for radiating a coded inquiry signal into the particular identified space covered by said relay station;

means for receiving a radiated acknowledgment signal from a badge station within said identified space and developing a located response that indicates whether an acknowledgment signal was received; and

means for transmitting said located response in said identification signals to said receiving means in said control station;

said badge stations each comprising;

coded responsive radiation receiving means for detecting said coded inquiry signal individual to a particular badge from a local relay station; and

radiation transmitting means responsive to a detected coded inquiry signal for originating an acknowledgment radiating signal back to the local relay station;

said control station including:

means for identifying the number for placing a telephone call to a telephone set located near the location of the badge station which originated said acknowledgment signal; and

means operable upon failure to obtain an acknowledgment signal from the relay stations selected at the likely location of the person identified for repeating the transmission request in time sequence to selected relay stations until each said particular identified space has been radiated with said coded inquiry signal without simultaneous time and space overlap of signals in any said identified space to produce unambiguous response from the local relay stations nearest said badge station originating an acknowledgment signal.

26. A system according to claim 25 wherein said radiated signals are infrared energy.

27. A system according to claim 26 wherein communication between said control station and said relay stations is by carrier current via wire circuits.

28. A system according to claim 25 wherein said radiated signal from said relay station is infrared energy and said radiation from said badge station is ultrasonic energy.

29. A system according to claim 28 wherein said relay station includes means for detecting the range to a responding badge station.

30. Apparatus according to claim 25 wherein said badge station is battery powered and includes means normally operating said badge station in quiescient low current condition and means responsive to a wake-up signal from one or more of said relay stations for powering said badge station to full power operation.

31. A communication and locating system comprising:

a control station;

a plurality of relay stations each covering an identified space within the area covered by said system; and

a badge station for each individual to be located by the system;

said control station comprising:

means for entering coded information identifying a person receiving an incoming call;

a memory storing data identifying likely locations of the persons to be located by the system;

means responsive to entry of person-identifying data for searching said memory for the likely location of the person identified by said data entry;

means for communicating a transmission request to one or more of said relay stations selected to be in communication with the like locations of the person identified; and

receiving means for receiving an identification signal from a relay station that has received an acknowledgment signal from a badge station, said identification signal identifying the location of the particular relay station that received the acknowledgment signal;

said relay stations each comprising;

means for receiving said transmission request from said control station;

means responsive to receiving said transmission request to radiate a coded inquiry signal into the particular identified space covered by said relay station;

means for receiving a radiated acknowledgment signal from a badge station within said identified space and developing a located respnse that indicates whether an acknowledgment signal was received; and

means for transmitting said located response in said identification signals to said receiving means in said control station;

said badge stations each comprising;

coded responsive radiation receiving means for detecting said coded inquiry signal individual to a particular badge, from a local relay station; and

radiation transmitting means responsive to a detected coded inquiry signal for originating an acknowledgment radiating signal back to the local relay station;

said control station including;

means for identifying the number for placing a telephone call to a telephone set located near the location of the badge station which originated said acknowledgment signal; and

means, operable upon failure to obtain an acknowledgment signal from the relay stations selected at the likely location of the person identified, for repeating the transmission request in time sequence to all relay stations, wherein said identified spaces covered by said system include spaces having a plurality of relay stations with partially overlapping coverage and said control station includes means responsive to multiple response from the same badge station via plural different location relay stations for reducing the signal detection sensitivity of said plural relay stations to select the relay station receiving the strongest badge originated signal.

32. Apparatus according to claim 29 wherein said control station is responsive to plural range data from plural relay stations originating from the same badge station for determining the location of said badge station relative to said plural relay stations.

33. The method of determining the present location of a member of a defined class of individual units the present location of which is not known from among a large population of individual units, each programmed to respond to a predetermined inquiry signal, which are normally distributed throughout a defined facility comprising the steps of:

receiving at a central station a request to establish the present location of one of said individual units;

establishing a two-way communication channel between said central station and a plurality of spaced relay stations, each relay station including a transmitter and a receiver and said relay stations being located so as to be cumulatively capable of substantially covering said facility with infrared energy;

communicating by a message coded for selecting said one individual unit over said channel with said plurality of relay stations;

causing said relay stations to transmit an inquiry signal by said infrared energy and enabling the receiver of said relay stations for a predetermined time period following each such transmission;

receiving the inquiry signal at each of said individual units that is located within the coverage of said one or more relay stations;

transmitting a radiant energy acknowledgment signal from any individual unit which recognizes the inquiry signal received from a relay station to be the coded message to which it is programmed to responde;

receiving said acknowledgment signal at any of said relay stations within range of the radiant energy acknowledgment signal transmission;

transmitting to said central station over said channel from any relay station which receives said acknowledgment signal an identification signal which identifies that relay station; and

utilizing at said central station any identification signal received from a relay station to determine the location of said relay station and hence the approximate location of the individual unit which transmitted said acknowledgment signal, said utilizing including repeating, if more than one identification signal is received, transmission of said inquiry signal by any relay stations which respond with an identification signal and reducing the sensitivity of the radiant energy receivers of said any relay stations to identify the relay station responsive to the lowest signal level.

This invention relates to a system with the ability to locate a transmitter-receiver unit (Badge) worn by a person while in a particular facility such as a hospital, an airport, a department store, a large legal office, a manufacturing complex and/or many other business or service organizations. More particularly, the system is able to determine the number of the most appropriate telephone to which to route a call for the person wearing the Badge that has been located.

Of the locating systems actually in use today, a paging system utilizing a microphone and many loudspeakers is the most frequently encountered. In this system a voice usually requests the desired person to call a telephone number or the operator so an incoming call or a call from within the facility can be connected to the nearest appropriate phone to the person being called. This type of paging system tends to cause annoyance to many others not involved with the call. In addition, such a loudspeaker paging system is usually slow.

A number of other "silent" paging systems have been devised which use lights and/or symbols to indicate that there is a telephone message for one of a very limited number of people. Alternatively, radio paging systems are available which alert a specific person to come to a telephone, but the radio receivers and central transmitting facilities are usually quite expensive. An elaborate intercom system is sometimes used to avoid bothering everyone in the facility by selecting only one speaker in a particular room to page a person for whom a telephone call is waiting. Such a system has no way of knowing whether or not the desired person will hear the message. None of these prior systems have a locating ability or the ability to automatically connect the call to the most appropriate telephone without talking to one or more persons.

An ultrasonic locating system has been disclosed by Lester in U.S. Pat. No. 3,696,384. The Lester system provides one transceiver in each room to search all rooms for a particular pocket unit. The location of the pocket unit is determined to be the room containing the transceiver which receives a response from the pocket unit. However, if more than one transceiver receives the response from the pocket unit, Lester makes no provision for identifying the room containing the pocket unit. Transceivers may pick up signals from other rooms when the doors to the rooms are not completely closed.

Lester uses ultrasonic signals to and from the badges. Thus, his system is slower than one which uses energy, such as infrared, which travels at the speed of light as opposed to the speed of sound. Speed is important in a large system which must handle the placing of many calls in a short time span. The use of ultrasonics also must contend with the problem of the Doppler frequency shift caused by movement of the pocket transceiver unit, for example, when the carrier of the pocket unit is walking. It is possible that the frequency of the transmitted signal from the unit may be shifted outside the bandwidth of the receiver, especially when the receiver has a narrow bandwidth as is the case with using piezoelectric crystals as transceiver's as disclosed by Lester.

SUMMARY OF THE INVENTION

This system is directed to a method and system for locating a member of a large population of individual units within a defined facility. The units could be transmitter-receiver badges carried by people or the units could be located in items such as automobiles whose location is desired. The facility may be an office, a building, a garage or a number of buildings.

According to the present invention, a central station receives requests to establish the location of one of the units. Relay stations are located about the facility in such a manner as to be able to cover the facility with radiant energy. A two-way communication channel is established between the central station and one or more of the relay stations and the central station sends out a coded message identifying the searched for unit. The one or more relay stations transmit an inquiry signal in response to the coded message. If the individual unit identified in the coded message receives the inquiry signal, it will transmit an acknowledgment signal. The relay stations which receive the acknowledgment signal will send identification signals to the central station identifying the respective relay stations. The central station determines the location of the unit from the identity of the relay station or stations which are within range of the unit to receive the acknowledgment signal and thus provided the central station with identification signals.

According to an embodiment of the system of the present invention, there are three elements including a Control Console, a plurality of Relay Stations, and a plurality of Badges. The Control Console acts as the central station and the Badges act as the units. The system of the present invention has distributed intelligence, that is, there is a microprocessor or microcomputer in each element of the system. Each element of the system is capable of performing fairly complex functions on command. This system approach reduces the amount of communication between units to a minimum to perform a specific function. An additional advantage of the distributed intelligence approach is the ability to modify the characteristics of the system to optimize for various modes of operation.

The Control Console is in control of all other elements of the system. In an embodiment of the system of the present invention which uses a manual telephone switchboard, a cathode ray tube or television type display monitor and a keyboard are used to interface with the operator. The operator will insert via the keyboard a person's name or assigned telephone number when a call for him or her arrives at the switchboard. The Control Console microprocessor will automatically search a memory for information that would indicate the most likely location of the person being called at that time. Such information was previously stored in memory based on daily patterns or, if desired, by the fact that the person to be located answered or placed a call at a specific phone within the last few minutes. The Control Console will then address a relay station in the "most likely" area and request a broadcast of an inquiry signal containing the Badge number of the person to be located.

If the Control Console does not find a most likely place for locating the call recipient, such as would be the case when the person being located is a visitor on the premises, or it has initiated a direct call to the normal location of the named individual and no response is received, the Control Console determines that an all-points search is required.

The Badge will respond to the inquiry signal if it is within range of the Relay Station. When the Relay Station receives the responses from the Badge it sends its own (Relay) identification and an indication that a positive response was obtained from the desired Badge. Upon receipt of a positive response the Control Console looks in its memory for an appropriate telephone nearest to the responding Relay Station and displays the number of that telephone to the operator. When the Badge responds it will also alert the person wearing the badge with a "chime" or other suitable alert that there is a call for him or her about to be placed on the nearest appropriate phone.

The nearest appropriate phone will depend upon the type of office or facility. In some places, it will actually be the nearest phone. In other facilities, it will be an appropriately marked "Red", "Blue", "White", or otherwise identified "appropriate" phone for the purpose. In certain areas, such as a hospital, it may be appropriate for the person being called to walk to a phone and dial a specific number. All of these conditions can be handled by placing the corresponding instructions into the Control Console master program. In all of the above situations, the telephone number required to reach the person being called will appear on the display so that the operator can complete the call.

In an alternative embodiment of the system of the present invention an automatic switchboard system is used. Here, the assigned number of the person being called will be intercepted by the locating system. The Control Console will proceed as in the description of the manual system to determine the number of the telephone most appropriate to complete the call in the minimum time. This number will be transmitted to the switchboard for completion of the connection.

The system of the present invention derives an advantage from using infrared radiation. Infrared radiation travels at the speed of light which is much quicker than the speed of sound. This enables the system to be used to handle heavy traffic.

In the present system, when ultrasonic energy is used, transmission of signals is made at two frequencies. This avoids the problem of nulls created by multipath. Also the bandwidth of the transceivers used in the present invention is made wide enough to accommodate Doppler frequency shift corresponding to Badge speeds of up to seventeen miles per hour relative to the relay station.

The method and system of the present invention has the advantages of being able to function in a very large room. Several relay stations may be placed in the same room. When more than one of the relay stations is within the range of the individual unit being searched for, a search can be repeated. In the repeated search, the power of the relay station transmitters can be reduced or alternatively the sensitivity of the relay stations receivers can be lowered. In this manner, the location of a badge within a large room can be narrowed to the nearest relay station. The relay stations with overlapping coverage belong to different groups so that they will communicate with the Control Console at different times thereby avoiding interference. It is also possible under the present invention to use ultrasonic energy in the acknowledgment signal transmitted by the badge and to measure the time between the inquiry signal and the acknowledgment signal. When the Control Console receives the time information it can determine which relay station is nearest the badge.

According to a still further advantage of the present invention, the badge has a processor means so that it can understand commands sent out by the relay station. For instance, the relay station when sending an inquiry signal can command the badge to chime or not to chim