# US 5,710,548 A · Transmitter direction identifier > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,548 A - Document ID: US5710548A - Status: Granted - Kind: A - Application number: 08/433,184 - Filed: 1995-05-03 - Granted: 1998-01-20 - Earliest claimed: 1995-05-03 - Assignees: Ford Motor Company - Inventors: Thomas John LeMense - Web page: https://patentgrep.com/patent/US5710548A ## CPC - G07C 9/00182: {operated with unidirectional data transmission between data carrier and locks} - G01S 3/28: using amplitude comparison of signals derived simultaneously from receiving antennas or antenna systems having differently-oriented directivity characteristics - G07C 2009/00214: {by one push button} - G07C 2009/00261: {the keyless data carrier having more than one function} - G07C 2009/00793: {by Hertzian waves} - G07C 2209/63: Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES ## Abstract A transmitter direction identifier is disclosed in conjunction with an automotive keyless entry assembly. The transmitter direction identifier includes a transmitter for sending a coded signal; a receiver for receiving the coded signal from the transmitter; a spatial differentiator for identifying the direction of the transmitter relative to a receiver from the coded signal received from the transmitter, the spatial differentiator creating a location signal; and a control unit electrically connected to the spatial differentiator wherein the control unit converts the location signal into command signal for subsequent use. ## Claims ### Claim 1 A transmitter direction identifying assembly comprising: a transmitter for sending a coded signal; a receiver for receiving the coded signal from said transmitter; a spatial differentiator for locating said transmitter relative to said receiver, said spatial differentiator creating a location signal identifying direction of said transmitter relative to said receiver; and wherein said spatial differentiator includes a high comparator and a low comparator, said high comparator defining a high threshold and said low comparator defining a low threshold. ### Claim 2 An automotive keyless entry assembly for accessing an occupant compartment of an automotive vehicle by unlocking a locking mechanism associated with one of a plurality of doors, said automotive keyless entry assembly comprising: a transmitter for sending a coded signal; a receiver for receiving the coded signal from said transmitter; a spatial differentiator for locating said transmitter relative to the automotive vehicle from said coded signal received from said receiver, said spatial differentiator creating a location signal; a control unit electrically connected to said spatial differentiator, said control unit converting said location signal into an unlock signal to unlock the locking mechanism associated with one of the plurality of doors closest to said transmitter; and wherein said spatial differentiator includes a high comparator and a low comparator, said high comparator defining a high threshold and said low comparator defining a low threshold. ### Claim 3 (depends on 2) An automotive keyless entry assembly as set forth in claim 2 wherein first and second antennas are operatively connected to said receiver, each of said first and second antennas receiving said coded signal and for producing first and second antenna signals. ### Claim 4 (depends on 3) An automotive keyless entry assembly as set forth in claim 3 wherein an antenna multiplexor is electrically connected between said first and second antennas and said receiver to alternately transmit said first and second antennas signals to said receiver. ### Claim 5 (depends on 4) An automotive keyless entry assembly as set forth in claim 4 wherein said receiver includes a high comparator creating a high pulse width signal from each of said first and second antenna signals and a low comparator creating a low pulse width signal from each of said first and second antenna signals. ### Claim 6 (depends on 5) An automotive keyless entry assembly as set forth in claim 5 wherein said control unit includes a correlator for correlating said high pulse width signal with said low pulse width signal associated with each of said first and second antennas. ### Claim 7 (depends on 6) An automotive keyless entry assembly as set forth in claim 6 wherein said control unit further includes a decoder for decoding said coded signal. ### Claim 8 (depends on 7) An automotive keyless entry assembly as set forth in claim 7 wherein said receiver is a UHF receiver. ### Claim 9 A method of unlocking one of a plurality of doors to an occupant compartment of an automotive vehicle using a portable transmitter and a plurality of antennas spaced throughout the automotive vehicle, the method comprising the steps of: transmitting from the portable transmitter a coded signal, to the plurality of antennas; receiving the coded signals from the portable transmitter; receiving an antenna signal from each of the plurality of antennas representing the coded signal; measuring each of the antenna signals against a first threshold; measuring each of the antenna signals against a second threshold; locating the transmitter based on the antenna signals; and unlocking one of the plurality of doors closest to the transmitter. ### Claim 10 (depends on 9) A method as set forth in claim 9 including the step of decoding the coded signal to identify the transmitter. ### Claim 11 (depends on 10) A method as set forth in claim 10 including the step of creating pulse widths signals from the coded signals. ### Claim 12 (depends on 11) A method as set forth in claim 11 including the step correlating the pulse width signals. ### Claim 13 (depends on 12) A method as set forth in claim 12 including the step of comparing the widths of the pulses in the pulse width signals. ### Claim 14 (depends on 13) A method as set forth in claim 13 including the step of sending the coded signal associated with the pulse width signals having the larger pulse widths to be decoded. ### Claim 15 (depends on 14) A method as set forth in claim 14 including the step of alternating the antenna signal received between each of the plurality of antennas. ### Claim 16 (depends on 15) A method as set forth in claim 15 including the step of comparing each of the pulse width signals to a first threshold. ### Claim 17 (depends on 16) A method as set forth in claim 16 including the step of comparing each of the pulse width signals to a second threshold. ### Claim 18 (depends on 17) A method as set forth in claim 17 including the step of amplifying each of the antenna signals.