Abstract:
A set of mutually intercommunicating units each include a transmitter arrangement and a receiver responsive to a single encoded signal. Each transmitter arrangement produces any one of the encoded signals other than its own. Each unit is associated with an important or valuable item, such as keys, cellphone, wallet/purse and the like, which are liable to being misplaced. To find a misplaced unit, any other unit is procured, and its transmitter code associated with the missing unit is energized. The missing unit responds to the transmitted code by annunciating, allowing it to be located.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to methods for location of devices, such as portable devices, which are liable to be misplaced.  
       BACKGROUND OF THE INVENTION  
       [0002]     Cellular telephones have come into widespread use. Cellular telephones must be small in order to be maximally useful, and this small size tends to result in their misplacement or “loss.” It was early realized that it was possible to locate a lost operative cellular telephone by using another telephone to ring the lost cellular telephone, whereupon the lost cellular telephone would ring or audibly annunciate, and the annunciation could be used to lead to the lost cellular telephone, whereby it could be found.  
         [0003]     Some telephones coupled to the Plain Old Telephone System (POST) are fitted with a base station and with a portable audio handpiece which communicates by radio with the base station. Just like the cellular telephone, the portable handpieces are also liable to be “lost.” Manufacturers of such base-station/radio-handpiece sometimes fit the combination with a “finding” function which includes a pushbutton switch or the like at the base station, which when pressed causes the handpiece to audibly annunciate, with the same effect of allowing the handpiece to be found.  
         [0004]     Improved or alternative location systems and methods are desired.  
       SUMMARY OF THE INVENTION  
       [0005]     A method according to an aspect of the invention is for, given one of a predetermined plurality of units, locating a desired one of the remainder of the units. Each of the units comprises a number, equal to one less than the predetermined plurality, of transmitters of differently coded signals. Each of the differently coded signals which is transmitted by one of the units is associated with one of the remainder of the units. Each of the units also comprises a receiver. Each of the receivers is responsive to the coded signals transmitted by another one of the units for generating a location or annunciator signal. The method comprises the steps of procuring at least one of the units, and, on that one of the units, enabling transmission of that one of the coded signals which is associated with the desired one of the remainder of the units. If the desired one of the remainder of the units is within range of the coded signals which are transmitted, the annunciator will sound on that unit. It is only necessary to follow the location signal to find the desired one of the units.  
         [0006]     In a particular mode of the method, the transmission of coded signals comprises the step of transmitting an individual carrier frequency for each of the units.  
         [0007]     In another particular mode of the method, the transmission of the coded signals comprises the step of transmitting a carrier signal modulated with one of a plurality of digital signals. Each of the plurality of digital codes is associated with one, and only one, of the remaining units.  
         [0008]     A method for finding a desired one of a predetermined plurality of units comprises the steps of associating with each of the plurality of units a transmitter of a number, which number is equal to one less than the predetermined number, of different coded signals, and associating with each of the plurality of units a receiver/annunciator, the receiver/annunciator of each of the plurality of units being responsive to one, and only one, of the differently coded signals, to produce an annunciation signal. The method further includes the step of energizing the receivers of each of the plurality of units. When it is desired to locate a desired one of the units, obtaining an other one of the units, and transmitting from the other one of the units that one of the different coded signals to which the receiver of the desired one of the units is responsive, whereby the receiver of the desired one of the units responds to produce an annunciation signal. The annunciation signal can of course be followed to locate or discover the desired one of the units.  
         [0009]     In a particular mode of the method, the step of energizing the receivers takes place before the step of transmitting from the other one of the units.  
         [0010]     An individual unit of a set of a predetermined plurality of potentially intercommunicating units, where each of the units comprises electromagnetic signal transmitting means for, when energized, transmitting a selected one of a plurality, equal to one less than the predetermined plurality, of differently coded signals, and electromagnetic receiving/annunciating means for receiving and responding with annunciation to one, and only one, of the differently coded signals. The individual unit of the set also includes selection means coupled to the transmitting means, for selectively causing the transmitting means to transmit one of the differently coded signals to which one of the receiving means is responsive. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0011]      FIG. 1  is a simplified diagram illustrating a representative set of three units according to an aspect of the invention;  
         [0012]      FIG. 2  is a simplified block diagram of a first alternative of a representative unit of a set of units such as that of  FIG. 1 , where the unit includes a receiver and a pair of transmitters;  
         [0013]      FIG. 3  is a simplified block diagram of a second alternative of a representative unit of a set of units such as that of  FIG. 1 , including a receiver arrangement and a transmitter arrangement, showing the use of digital codes;  
         [0014]      FIG. 4  is a simplified block diagram illustrating another possible embodiment of the transmitter arrangement of  FIG. 3 ; and  
         [0015]      FIG. 5  is a simplified block diagram of a third alternative of a representative unit of a set of units such as that of  FIG. 1 , showing the use of frequency codes. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0016]      FIG. 1  is a simplified diagram illustrating a set  10  illustrated as including a predetermined number, namely three, portable units designated A, B, and C, but which could include some predetermined number greater than three. In  FIG. 1 , each of the three units A. B, and C bears a number of locator user interfaces in the form of pushbuttons. The number of locator user interfaces or buttons is one less than the number of units in the set. Thus, each of the units bears two locator user interfaces. In  FIG. 1 , the unit A bears user locator interfaces A B  and A C , unit B bears user interfaces B A  and B C , and unit C bears user interfaces C A  and C B . Thus, there is a locator user interface associated with each of the portable units of set  10  which is associated with each of the other units of the set. The locator user interfaces A B , A C , B A , B C , C A , and C B  may be, for example, pushbutton switches, or in the case where the set includes a large number, a rotary selector switch in conjunction with a single pushbutton switch may be more appropriate.  
         [0017]     Each of the units A, B, and C of  FIG. 1  also includes one or more transmitter units which are actuated by the locator user interfaces, for transmitting signals, possibly by way of antennas A 11 , B 11 , and C 11 , respectively. Each of the units A, B, and C, upon actuation of a particular one of the locator user interfaces of one of the units, transmits a signal, such as an electromagnetic signal, which is coded so as to be acted upon by only by that one of the other units which corresponds to the particular one of the locator user interfaces. Each unit also includes one or more receivers, which are suited to receiving and acting upon the particular coded signal with which it is associated. Thus, when a particular unit is at hand, as for example unit A of  FIG. 1 , and one of its locator user interfaces is actuated, such as locator user interface A B , unit A transmits a signal which is coded for action by unit B. The receiver of unit B receives the coded signal, and actuates its audible annunciator to thereby announce its location. On the other hand, if remote unit C is at hand, and unit B is to be found or located, the location user interface C B  would be actuated, to thereby cause a transmitter associated with unit C to transmit a signal coded for action by unit B. It should be noted that the coded signal transmitted by unit C in this second situation may be identical to the coded signal transmitted by unit A when unit B is to be found. That is, the coded signal transmitted from unit A, when received by the receiver of unit B, results in actuation of the annunciator, and the same coded signal when transmitted by unit C will also cause actuation of the annunciator of unit B. Thus, regardless of the number of units in a set of units, the maximum required number of codes is no greater than the number of units in the set.  
         [0018]      FIG. 2  is a simplified block diagram of a unit of the set  10  of  FIG. 1 . For definiteness, the unit of  FIG. 2  is designated B. As illustrated, unit B of  FIG. 2  includes a source of power  210 , which may be a battery. Unit B of  FIG. 2  also includes a first transmitter (TX)  212  coupled to battery  210  by way of locator user interface B A , illustrated as a pushbutton switch. Unit B of  FIG. 2  also includes a second transmitter (TX)  214  coupled to battery  210  by way of locator user interface B C , also illustrated as a pushbutton switch. Transmitters  212  and  214  should be associated with an antenna arrangement (not illustrated in  FIG. 2 ), which can be either individual or common. When locator user interface B A  is actuated to provide power to transmitter  212 , transmitter  212  transmits at least a carrier signal at a predetermined first radio frequency. The predetermined first radio frequency constitutes or comprises the coding in this situation, for the duration of the pushing of button B A . When locator user interface B C  is actuated to provide power to transmitter  214 , transmitter  214  transmits at least a carrier signal at a predetermined second radio frequency. The predetermined second radio frequency constitutes or comprises a second portion of the coding.  
         [0019]     Unit B of  FIG. 2  also includes a receiver  216  which is always connected to power source  210  so as to be continuously energized. Receiver  216  should also be associated with an antenna arrangement (not illustrated), either individual or common with those of the transmitters  212 ,  214 . Receiver  216  includes a carrier-frequency filter (F)  218  which is responsive to a carrier signal at a predetermined third frequency, which third frequency constitutes or comprises the last portion of the coding. Receiver  216  of  FIG. 2  has an output port  216   o  connected to an audio annunciator designated  220 . The combination of receiver  216  and annunciator  220  is designated  215 . In the simplest arrangement, receiver  216  of unit B responds particularly to carrier at the third frequency, and not to carrier at the first or second frequencies; that is to say, that the carrier-frequency filter  218  at the third frequency rejects carrier signals at the first and second frequencies. Thus, rejected carriers at the first and third frequencies cannot actuate the annunciator  218 , but carriers at the second frequency are not rejected by filter  218 , and go through the receiver to output port  216   o  to actuate the annunciator  220 . The actuation of the annunciator  220  by the receiver  216  can be implemented by a simple radio-frequency detector associated with the receiver or by more complex arrangements, as known to those skilled in the art.  
         [0020]     One may view the unmodulated carrier signal transmitted and responded to in the arrangement of  FIG. 2  as a form of direct-voltage or direct-current (DC) amplitude modulation (AM). Those skilled in the art know that receivers such as receiver  216  of  FIG. 2 , which respond to simple unmodulated carriers, are not robust, and are subject to unwanted responses. That is, a receiver which is responsive to a particular simple carrier frequency may not be reliable, in that the environment is full of signals, some of which may be close enough to one or more of the selected frequency(ies) to create an annunciator response.  
         [0021]      FIG. 3  illustrates another possible arrangement for the units of set  10  of  FIG. 1 . More particularly,  FIG. 3  is an alternative simplified block diagram of each unit of set  10  of  FIG. 1 . As with  FIG. 2 ,  FIG. 3  is for definiteness labelled as being unit B. Instead of being responsive to simple radio frequency, the unit B of  FIG. 3  includes a receiver  316  which receives a band of frequencies associated with a modulated carrier. The modulation may be amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), or any of a number of more complex modulations, or combinations thereof. In  FIG. 3 , the assumption is made that receiver  316  receives a frequency-modulated carrier modulated with a digital code. Frequency modulation is more resistant than AM to interference from the environment, and the use of a digital code further improves the robustness of the arrangement.  
         [0022]     In  FIG. 3 , receiver  316  includes an FM receiver (FM RX)  320  which receives (by way of an antenna arrangement, not illustrated) digital-code FM-modulated signal, processes the FM modulated signal, and demodulates the modulation to produce demodulated signal. The modulation in the form of a digital code is generated at output port  320   o  of FM receiver  320 . The digital code is applied to a digital code recognition block  322 , which coacts with a memory  324  to be responsive to a particular digital code associated with unit B. Code recognition block  322  either recognizes the received code and produces a “recognized” signal at its output port  322   o  or it does not recognize the code, and produces no recognition signal. If a “recognized” signal is generated at port  322   o , it is applied to annunciator block  220 . The combination of receiver  316  with annunciator  220  is designated  315 .  
         [0023]     Unit B of  FIG. 3  also includes a transmitter arrangement designated  330 , which includes a modulation input port  330   i . Transmitter arrangement  330  should be associated with an antenna arrangement, either individual or common with that of the receiver. Power for transmitter  330  is applied at a power port  330   p . A first digital code generator  332  coacts with a memory (not illustrated) to generate a digital code A unique or assigned to a corresponding unit A of the set of units. When locator user interface BA is pressed, power is applied to A digital code generator  332  to produce the A digital code, and power is also applied to FM transmitter  330 . The A digital code produced by digital code generator  332  is applied to modulation input port  330   i  of transmitter  330 . As a result, as long as pushbutton switch BA is actuated, FM transmitter  330  transmits FM signals modulated by the A code from code generator  332 .  
         [0024]     A second digital code generator  336  coacts with a memory (not illustrated) to generate a digital code C unique or assigned to a corresponding unit C of the set of units. When locator user interface B C  is pressed, power is applied to C digital code generator  336  to produce the C digital code, and power is also applied to FM transmitter  330 . The C digital code produced by digital code generator  336  is applied to modulation input port  330   i  of transmitter  330 . As a result, as long as pushbutton switch B C  is actuated, FM transmitter  330  transmits FM signals modulated by the C code from code generator  336 .  
         [0025]     In operation of a system using A, B, and C units similar to unit B of  FIG. 3 , except for the coding of the code generators, any one of the three units can be located so long as any other one of the units is available. The overall operation is similar to that described in conjunction with  FIG. 1 . The details of the functioning of each unit differs among the units, although their operation is similar except for the coding and responses thereto. More particularly, if a set of A, B, and C units exists, and if an A unit is available, its transmitter digital code generators of the A unit will be preloaded with B and C codes, and activation of either of its A B  or A C  location user interfaces (pushbutton switches in the embodiment) results in transmission of FM signal in some frequency band, modulated with the appropriate one of the B or C digital codes. The A unit will also include an A receiver, responsive to FM signals in the frequency band which are modulated by an A code. The transmitter digital code generators of the B unit will be preloaded with A and C codes, and activation of either of its B A  or B C  location user interfaces (pushbutton switches) results in transmission of FM signal in the frequency band, modulated with the appropriate one of the A or C digital codes. The B unit will also include a B receiver, responsive to FM signals in the frequency band which are modulated by a B code. The transmitter digital code generators of the C unit will be preloaded with A and B codes, and activation of either of its C A  or C B  location user interfaces (pushbutton switches) results in transmission of FM signal in the frequency band, modulated with the appropriate one of the A or B digital codes. The C unit will also include a C receiver, responsive to FM signals in the frequency band which are modulated by a C code. So long as the units are within range of each other, any one unit is available, and the user is within audible range, any desired other one of the units can be located by simply actuating the location user interface associated with the desired unit so that its annunciator is actuated, and following the annunciator signal to locate the desired unit.  
         [0026]     Those skilled in the art know that the programmable code memory for the transmitter of the arrangement of  FIG. 3  may be a single unit programmable for producing the desired transmitter codes. A unit including a microprocessor can perform most of the processing functions to generate the requisite codes and to recognize the received code.  
         [0027]      FIG. 4  is a simplified block diagram of another possible arrangement  400  of the transmitters of a B coded unit of set  10  of  FIG. 1 . In  FIG. 4 , elements corresponding to those of other FIGURES are designated by the same reference alphanumerics. In  FIG. 4 , each locator user interface or pushbutton switch is a multiple-switch element. Thus, in  FIG. 4 , switch B A  includes switch portions B A1  and B A2 , ganged for simultaneous actuation, and switch B C  includes switch portions B C1  and B C2 , ganged for simultaneous actuation. Switch portions BA 1  and BC 1  are connected together and to power input port  330   p  of FM transmitter  330 , for applying power to the transmitter when either of switches B A  or B C  is actuated. Switch portions BA 2  and BC 2  are connected to power source  216  and to A digital code generator  332  and B digital code generator  336 , respectively, for applying power to A digital code generator  332  when switch B A  is activated and to B digital code generator  336  when switch B C  is actuated. Actuation of switches BA and BC of the transmitter arrangement  400  of  FIG. 4  has the same net effect as actuation of those switches in the arrangement of  FIG. 4 .  
         [0028]     Another possible modulation scheme uses a transmitter (of any type) modulated by one of a plurality of modulation frequencies, where the selected modulation frequencies are selected to correspond to the various members of the set of units. In  FIG. 5 , representative B unit  500  includes a power source  216  connected to a receiver  516  (of the same type as the transmitter) for continuous actuation thereof, and for receiving modulated signals addressed to the B unit. B unit receiver  520  produces at its output port  520   o  a replica of the modulation frequency with which the received signal is modulated. This may or may not correspond with the modulation frequency to which the B unit  500  is responsive. The modulation signal is coupled to a B frequency identification block  522 , which does not respond to modulation frequencies other than the selected B modulation frequency, and responds to the B modulation frequency to produce a response signal at receiver output port  516   o . The B frequency identification unit  522  may be a discrete filter, or a virtual filter defined by a filter response of a processor. The response signal is applied to annunciator  220  to produce the annunciation signal for locating the B unit. The combination of receiver  516  with annunciator  220  is designated  515 .  
         [0029]     B unit  500  of  FIG. 5  also includes a transmitter arrangement including a transmitter  530  including a modulation signal input port  530   i . The arrangement of  FIG. 5  also includes ganged B A  and B C  pushbutton actuators. B A  pushbutton includes a first portion B A1  and BC pushbutton includes a first portion B C1 , either of which, when actuated, couples power to transmitter  530 . The B A  pushbutton includes a second switch portion B A2  ganged with portion B A1  which, when actuated, couples power to an A oscillator or frequency generator  532 . A oscillator  532 , when actuated, generates one of a plurality of tones or frequencies which is assigned to the A unit receiver of the set of units. The B C  pushbutton includes a second switch portion B C2  ganged with portion B C1  which, when actuated, couples power to a C oscillator or frequency generator  536 . C oscillator  536 , when actuated, generates one of a plurality of tones or frequencies which is assigned to the C unit receiver of the set of units.  
         [0030]     In operation of a system using A, B, and C units similar to unit B of  FIG. 5 , except for the frequencies of the code generators, any one of the three units can be located so long as any other one of the units is available. The overall operation is similar to that described in conjunction with  FIG. 1 . The details of the functioning of each unit differs among the units, although their operation is similar except for substitution of a frequency for the direct modulation of  FIG. 2  or the digital coding of and the responses thereto. As described above, if a set of A, B, and C units exists, and if an A unit is available, its transmitter frequency code generators will be preloaded with B and C codes, and activation of either of its A B  or A C  location user interfaces (pushbutton switches in the embodiment) results in transmission of signal in some frequency band, modulated with the appropriate one of the B or C frequency codes. The A unit will also include an A receiver, responsive to signals in the frequency band which are modulated by an A code. The transmitter frequency code generators of the B unit will be preloaded with A and C codes, and activation of either of its B A  or B C  location user interfaces (pushbutton switches) results in transmission of signal in the frequency band, modulated with the appropriate one of the A or C frequency codes. The B unit will also include a B receiver, responsive to signals in the frequency band which are modulated by a B code. The transmitter digital code generators of the C unit will be preloaded with A and B codes, and activation of either of its C A  or C B  location user interfaces (pushbutton switches) results in transmission of signal in the frequency band, modulated with the appropriate one of the A or B frequency codes. The C unit will also include a C receiver, responsive to signals in the frequency band which are modulated by a C code. So long as the units are within range of each other, any one unit is available, and the user is within audible range, any desired other one of the units can be located by simply actuating the location user interface associated with the desired unit so that its annunciator is actuated, and following the annunciator signal to locate the desired unit.  
         [0031]     While not specifically mentioned above, it will be clear that the units of the set may, and preferably must, perform other functions than self-finding. For example, the various different units of a set may be clipped or otherwise affixed to a set of keys, to a wallet or ladies&#39; purse, to a laptop computer or Blackberry, to a cellular telephone, andor to a POST telephone base terminal (and also to its radio handset). They may be associated not only with the abovementioned items but also with an automobile, motorcycle or other vehicle, in which case the annunciation at the vehicle may be by sounding the horn. Tools and electrical equipment, and generally any item of value or portable item which is capable of being misplaced can usefully be attached to a unit of a set according to the invention. In the case of a cellphone, laptop or other electronic equipment, a unit according to the invention may be incorporated into the body thereof.  
         [0032]     A method according to an aspect of the invention is for, given one of a predetermined plurality (3) of units of a set ( 10 ) of units, locating a desired one of the remainder (2) of the units. Each of the units comprising a number (2), equal to one less than the predetermined plurality (3), of transmitters ( 211 ;  329 ;  429 ;  529 ) of differently coded (direct, digitally coded, frequency coded) signals. Each of the differently coded signals (B, for example) which is transmitted by one of the units (A, for example) is associated with one (B) of the remainder of the units (B, C). Each of the units of the set ( 10 ) also comprises a receiver ( 216 ;  316 ;  516 ). The receiver ( 216 ;  316 ;  516 ) of each unit (A, B, C) is responsive to the coded signals transmitted by another one of the units for generating a location or annunciator signal. The method comprises the steps of procuring at least one of the units (B, for example), and, on that one of the units, enabling transmission of that one of the coded signals (A or C) which is associated with the desired one of the remainder of the units. If the desired one of the remainder of the units is within range of the coded signals which are transmitted, the annunciator ( 220 ) will sound on that unit. It is only necessary to follow the location signal to find the desired one of the units.  
         [0033]     In a particular mode of the method ( FIG. 2 ), the transmission of coded signals comprises the step of transmitting an individual carrier frequency for each of the units.  
         [0034]     In another particular mode ( FIG. 3 ) of the method, the transmission of the coded signals comprises the step of transmitting a carrier signal modulated with one of a plurality of digital signals. Each of the plurality of digital codes is associated with one, and only one, of the remaining units.  
         [0035]     In yet another particular mode ( FIG. 5 ) of the method, the transmission of coded signal includes the step of transmitting a signal modulated by one of a plurality of frequencies, which may be audio frequencies, where each of the plurality of audio frequencies is associated with one, and only one, of the remaining units.  
         [0036]     A method for finding a desired one of a predetermined plurality (3 in the example) of units (A, B, C) comprises the steps of associating with each of the plurality (3) of units (A, B, C) a transmitter ( 211 ,  329 ,  429 ,  529 ) of, or for transmitting a number of different coded signals, which number is equal to one less than the predetermined number (that is, one less than three, or two). The method also comprises associating with each of the plurality of units a receiver/annunciator ( 215 ;  315 ;  515 ), the receiver/annunciator ( 215 ;  315 ;  515 ) of each of the plurality of units (A, B, C) being responsive to one, and only one, of the differently coded signals, to produce an annunciation signal. The method further includes the step of energizing the receivers ( 215 ,  315 , and  515 ) of each of the plurality of units (A, B, C). When it is desired to locate a desired one of the units (say unit B), obtaining an other one of the units (such as unit A or C), and transmitting from the other one of the units (A or C) that one of the different coded signals (C) to which the receiver/annunciator ( 215 ;  315 ;  515 ) of the desired one (unit C) of the units is responsive, whereby the receiver/annunciator ( 215 ;  315 ;  515 ) of the desired one (C) of the units responds to produce an annunciation signal. The annunciation signal can of course be followed by the user to locate or discover the desired one of the units.  
         [0037]     In a particular mode of the method, the step of energizing the receivers takes place before the step of transmitting from the other one of the units.  
         [0038]     An individual unit, according to an aspect of the invention, of a set of a predetermined plurality (three in the example) of potentially intercommunicating units (A, B, C), where each of the units (A, B, C) comprises electromagnetic signal transmitting means ( 211 ,  329 ,  439 ,  529 ) for, when energized, transmitting a selected one of a plurality, equal to one less than the predetermined plurality (three minus one is two), of differently coded signals, and electromagnetic receiving/annunciating means ( 215 ,  315 ,  515 ) for receiving and responding with annunciation to one, and only one, of the differently coded signals. The individual unit of the set also includes selection means (BA; BA 1 , BC 1 ) coupled to the transmitting means ( 211 ,  329 ,  439 ,  529 ), for selectively causing the transmitting means to transmit one of the differently coded signals to which one of the receiving means is responsive.