METHOD OF LOCATION USING SIGNALS OF UNKNOWN ORIGIN Inventor: Brin L. Bskin 1
ABSTRACT The present invention encompsses method of loction comprising: using plurlity of signl trnsceivers to receive one or more multiple frequency input signls, wherein sid multiple frequency input signls re of unknown origin, nd sid signl trnsceivers re of known physicl loction, finding difference in time of the reception of the signls between ech of the signl trnsceivers, using the difference in time of reception to locte the origin of the signls, utilizing the signls locte signl trnsceiver of unknown loction.
1.Field of invention: BACKGROUND OF INVENTION This invention reltes generlly to globl positioning systems (GPS nd, in prticulr, GPS systems used for emergency loction of cellulr hndsets.. Description of relted rt 1 Vrious methods hve been put forth in order to ddress the need for n emergency cellulr loction system. One method utilizes number of cell trnsmission towers to locte cell phone user by stndrd tringultion methods. This method is limited due to the low level of hndset power in tht it is unlikely tht three or more towers will receive the signl needed for tringultion. Another method utilizes the GPS system, whereby GPS trnsceiver is locted in the cell hndset. Like the cell-tower system, this method is limited becuse of the lck of trnsmitted power, but lso due to the distnce of the stellite mounted trnsmitters from the hndset trnsceiver. 3
SUMMARY OF INVENTION 1 A unique method is introduced herein, whereby locl signls re utilized to locte n unknown-loction signl trnsceiver. In this method, three or more known-loction signl trnsceivers re used to locte one or more unknown-loction trnsmitters of signls of greter thn zero bndwidth by wy of dely differentition. A combintion of three or more signl trnsmitters comprising one or more unknown-loction trnsmitters re then utilized to locte the unknown-loction signl trnsceiver. In one embodiment, three or more stndrd television nd rdio signls re locted using three or more cell sites nd, with timing referenced to the signls received by the cell sites, cellulr hndset is locted. In nother embodiment, the dely from one or more cell sites to the hnd set is utilized, long with one or more unknown-loction trnsceiver to locte the cellulr hndset. A third embodiment utilizes mobile trnsmitters, such s emergency or police bnd rdios to locte nd utilize for hndset loction. A fourth embodiment utilizes other cellulr hndsets in order to locte cellulr hndset. The preferred embodiment employs ll four of these mens to locte cellulr hndset. 0 One method introduced herein comprises 1 mesuring the difference of dely from one or more unknown-loction signl trnsmitters to three or more known-loction signl trnsceivers. utilizing sid dely difference mesurements to locte the one or more unknown-loction signl trnsmitters. 3 locting n unknown-loction signl trnsceiver by wy of combintion of three or more signl trnsmitters comprising one or more unknown-loction trnsmitter. 4
BRIEF DESCRIPTION OF THE DRAWINGS 1 Figure 1 shows the constelltion of possible loctions using known-loction signl trnsceivers AB, AC, nd BC for vrious differences in time with respect to the trnsmission time from first known-loction signl trnsceiver to second knownloction signl trnsceiver. Figure shows the loction of specific point (x using ny two of the vector sets. Figure 3 shows point (x locted within three points A, B, nd C. Figure 4 shows point (x locted outside three points A, B, nd C. Figure shows three cell towers(t1,t,t3 nd three cellulr hndsets (H1,H,H3. Figure 6 shows nother method wherein first hndset receives signls from two towers nd second hndset receives signl from third tower. Figure 7 shows multiple hndsets used to indirectly locte hndset, whereby loction of the hndset to be found cn be ccomplished by locting other hndsets within the cell, n then using the other hndsets s known-loction trnsmitters. FULL DESCRIPTION OF THE PREFERRED EMBODIMENTS 0 In the first embodiment, remote processing sttion sends request to three or more known-loction signl trnsceivers to send return signls in order to mesure the dely from ech known-loction signl trnsceiver to the processing sttion. Ech knownloction signl trnsceiver receives signls from three or more unknown-loction trnsmitters nd sends the signls from the unknown-loction trnsmitters to the remote processing sttion. The processing sttion then mesures the difference in time between the signls received by the known-loction signl trnsceivers from ech unknownloction trnsmitter by subtrcting the respective trnsmission line delys. The net dely differences from ech unknown-loction trnsmitter to ech of the known-loction signl trnsceivers re used to locte ech unknown-loction trnsmitter t point in spce. 30
Figure 1 shows the constelltion of possible loctions using known-loction signl trnsceivers AB, AC, nd BC for vrious differences in time with respect to the trnsmission time from first known-loction signl trnsceiver to second knownloction signl trnsceiver. As n exmple, the constelltion lbeled.8 is represents set of points where the trnsmission time from ny point on the rc to point A is equl to the trnsmission time to point B plus 80 % of the trnsmission time from point A to point B. Figure shows the loction of specific point (x using ny two of the vector sets. Using vector sets AB nd AC, the constelltions.4 nd.8 cross to locte point (x. Using vector sets AB nd BC, the constelltions.4 nd -. cross to locte point (x. Using vector sets AC nd BC, the constelltions.8 nd -.4 cross to locte point (x. Figure 3 shows point (x locted within three points A, B, nd C. A mthemticl 1 representtion follows: ( AB ( AC ( BC b b c ( Z ( Z c ( Z ( Z ( Z bcos( φ ccos( φ b( Z AB AC ccos(π φ AB φ AC Where Z represents the dely from (x to A, nd b nd c represent the difference in dely 0 from (x to B nd C with respect to the distnce from (x to A. Z, φ AB, nd φ AC re unknowns, they cn be found mthemticlly or by itertion with the three independent equtions shown bove. With the three vribles known, the x nd y coordintes of the trnsmitter (x cn be found. Figure 4 shows point (x locted outside three points A, B, nd C. A mthemticl representtion follows: 6
( AB ( AC ( BC b b c ( Z ( AC( Z c ( Z ( Z bcos( φ ccos( φ b( Z 1 ccos( φ + φ 1 Agin, Z represents the dely from (x to A, nd b nd c represent the difference in dely from (x to B nd C with respect to the distnce from (x to A. Z, φ 1, nd φ re unknowns, they cn be found mthemticlly or by itertion with the three independent equtions shown bove. With the three vribles known, the x nd y coordintes of the trnsmitter (x cn be found. The remote processing sttion sends request to n unknown-loction signl trnsceiver, either directly or by wy of one of the known-loction signl trnsceivers, to send return signl in order to mesure the dely from the unknown-loction signl trnsceiver to the processing sttion. 1 The unknown-loction signl trnsceiver receives the signls from the three or more unknown-loction trnsmitters nd sends the signls from the unknown-loction trnsmitters to the remote processing sttion. 0 The processing sttion then mesures the dely from ech of the three or more unknownloction signl trnsmitters to the processing sttion, by wy of the unknown-loction signl trnsceiver nd finds the dely from the unknown-loction signl trnsmitters to the unknown-loction signl trnsceiver by compring the signl received by the unknown-loction signl trnsceiver nd the signl received by ny one of the three or more known-loction signl trnsceivers nd by subtrcting the dely from the unknownloction signl trnsceiver to the processing sttion. 7
With ech of the points of trnsmission known, the signl dely from ech point of trnsmission to the unknown-loction signl trnsceiver known, stndrd tringultion methods cn be used to find the unknown-loction signl trnsceiver. In other words, the loction of the unknown-loction signl trnsceiver is clculted by mesuring the difference of reception in time of three or more independent signls to ech of the known-loction signl trnsceivers nd to the unknown-loction signl trnsceiver. In second embodiment, the loction of the unknown-loction trnsmitters is s described in the first embodiment. A second method of loction of the unknown-loction trnsceiver is described herein. 1 0 In the second embodiment, the remote processing sttion sends request to n unknownloction signl trnsceiver, by wy of one or more of the known-loction signl trnsceivers, to send return signl in order to mesure the dely from the unknownloction signl trnsceiver to sid one or more of the known-loction signl trnsceivers in order to mesure the dely from the unknown-loction signl trnsceiver to the one or more of the known-loction signl trnsceivers. The unknown-loction signl trnsceiver receives the signls from one or more unknownloction trnsmitters nd sends prt or ll of the signls from the unknown-loction trnsmitters to the remote processing sttion, by wy of the one or more of the knownloction signl trnsceivers. 30 The processing sttion then mesures the dely from ech of the one or more unknownloction signl trnsmitters to the processing sttion, by wy of the unknown-loction signl trnsceiver nd finds the dely from the unknown-loction signl trnsmitters to the unknown-loction signl trnsceiver by compring the signl received by the unknown-loction signl trnsceiver nd the signl received by ny one of the three or 8
more known-loction signl trnsceivers nd by subtrcting the dely from the unknownloction signl trnsceiver to the processing sttion. 1 With ech of the points of trnsmission known, the signl dely from ech point of trnsmission to the unknown-loction signl trnsceiver known, nd the dely from the unknown-loction signl trnsceiver to the one or more of the known-loction signl trnsceivers known, ny combintion of the one or more of the known-loction signl trnsceivers nd the one or more unknown-loction signl trnsmitters is utilized in stndrd tringultion methods to find the unknown-loction signl trnsceiver. In third embodiment, mobile trnsmitters, such s police bnd rdios re locted using similr method s in the first embodiment. In this method, however, the reception of signls must be time mrked s they rrive t the processing sttion since the loction of the trnsmitter is constntly chnging. Loction of the unknown-loction trnsceiver is s with the first or second method introduced herein. 0 In fourth embodiment, three known-loction trnsceivers, in combintion with other unknown-loction trnsceivers re used to locte the first unknown-loction trnsceiver. Becuse cellulr hnd sets, regrdless of whether or not in use, re in communiction with nerby cell sites, nd hnd sets within the sme cell communicte t different frequencies, ech hndset in the cell cn be used s repeter. Figure shows three cell towers(t1,t,t3 nd three cellulr hndsets (H1,H,H3. The processing sttion pings ech hndset in order to find the dely between the hndset nd the corresponding tower nd the dely from ech tower to the processing sttion. If n djcent hndset receives the return signl from its neighboring hndset, the dely between the two hndsets is used for loction. In other words, djcent hndsets re used s repeters. 30 As n exmple, if H3 receives the return signl from H, the dely cn be found between H nd H3 providing tht the communiction between ech hndset nd its 9
corresponding tower re t different frequencies, becuse the processor is wre of when the signl ws sent to H nd the delys between the hndsets nd corresponding towers re known. Two possibilities for loction of both H nd H3 re indicted. If H1 is ble to receive the return signl from H or H3, tringultion to H nd H3 is possible. 1 Figure 6 shows nother method wherein first hndset receives signls from two towers nd second hndset receives signl from third tower. Pinging of the first hndset by the corresponding towers revels two possibilities for loction, communiction between hndsets revels the true loction of both hndsets. Figure 7 shows multiple hndsets used to indirectly locte hndset, whereby loction of the hndset to be found cn be ccomplished by locting other hndsets within the cell, n then using the other hndsets s known-loction trnsmitters. Although H hs no communiction with H1 nd H, communiction with H3 nd H4 is possible. With the delys between T1 nd H1, T nd H, H1 nd H4, H3nd H, T nd H3, T nd H4 known, H1 through H4 cn be locted nd used to find H. 0 30 In the preferred embodiment, the four methods described bove re utilized to locte cell hndset. In this embodiment, the remote processor pings three or more cell sites in order to find the dely between the sites nd the processing sttion. Trnsceivers ttched to the cell sites scn the re in order to find locl trnsmitters nd other hndsets. The remote processor then loctes ny trnsmitters by wy of the method described in method one herein. The remote processor then pings the cell hndset to be locted in order to find the dely from the hndset to ny cell sites in which the hndset is communicting. The cell hndset, which contins similr trnsceiver s the cell sites, long with one or more cell sites, is instructed to receive one or more of the trnsmitters found so tht n pproximtion cn be mde regrding the loction of the hndset. Once n pproximte loction is found, The remote processor then instructs cell sites ner the trnsmitters to ccurtely locte the locted trnsmitters. The processor lso mkes n evlution of trnsmitter loction ccurcy bsed on the distnce from the cell sites used to locte the trnsmitter to the corresponding trnsmitter nd bsed on how optimum the cell sites re
locted round the trnsmitter. Bsed on this ccurcy, the remote processor selects the trnsmitters which will provide the highest ccurcy of hndset loction. If this selection comprises nerby cell hndset, the nerby hndset nd ny cell towers in communiction with the nerby hndset re instructed to find the dely from ech of the towers in communiction with the nerby hndset nd to use the nerby hndset s signl repeter. If mobile trnsmitter is to be utilized, the processor time stmps the dely informtion to ccount for vrying loction. Any combintion of loction methods described herein re utilized to locte the cell hndset. The process continuously repets to find new, more optimum trnsmitters. As n exmple, n emergency vehicle rdio would likely become trnsmitter s it pproches the hndset. 1 11