# US 10,310,052 B2 · Method, apparatus, and computer program product for real time location system referencing in physically and radio frequency challenged environments > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,310,052 B2 - Document ID: US10310052B2 - Status: Granted - Kind: B2 - Application number: 15/492,537 - Filed: 2017-04-20 - Published: 2017-08-03 - Granted: 2019-06-04 - Earliest claimed: 2014-06-05 - Assignees: Zebra Technologies Corporation - Applicants: Zebra Technologies Corporation - Inventors: Edward A. Richley; Belinda Turner; Chang Wang - Web page: https://patentgrep.com/patent/US10310052B2 ## CPC - G01S 5/06: Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence) - G01S 5/021: {Calibration, monitoring or correction (G01S5/0252 takes precedence)} - G01S 5/0236: {Assistance data, e.g. base station almanac} - H04B 1/16: Circuits - H04L 41/0803: Configuration setting - H04W 4/02: Services making use of location information - H04W 4/029: Location-based management or tracking services - 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 - H04B: TRANSMISSION - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) ## Abstract Systems, methods, apparatuses, and computer readable media are disclosed for improving, in some examples, reference in a location system. In one embodiment, a method is provided comprising: receiving reference tag blink data from a plurality of receivers; calculating, using a processor, a reference phase offset between the plurality of receivers; and generating a suspended reference phase offset table, wherein a suspended reference phase offset table is generated by causing the reference phase offset to be stored in a memory for later tag location calculations. ## Claims ### Claim 1 A method comprising: receiving reference tag blink data from a plurality of receivers; calculating, using a processor, a reference phase offset between the plurality of receivers; analyzing a plurality of reference phase offset calculations for at least one reference tag receiver pair over a time interval; and generating a suspended reference phase offset table in an instance in which the plurality of reference phase offset calculations for the at least one reference tag receiver pair satisfy a stability threshold, wherein a suspended reference phase offset table is generated by causing the reference phase offset to be stored in a memory for later tag location calculations. ### Claim 2 (depends on 1) The method of claim 1, wherein the reference phase offset is the difference between a reference clock time at receipt of the reference tag blink data at a respective plurality of receivers. ### Claim 3 (depends on 1) The method of claim 1, further comprising: receiving tag blink data; and calculating tag location data, wherein calculating the tag location data is based on a time difference of arrival of the tag blink data at the plurality of receivers and adding the reference phase offset of the suspended reference phase offset table. ### Claim 4 (depends on 1) The method of claim 1, further comprising determining a radio frequency receiving period with low radio frequency interference, wherein the radio frequency receiving period comprises a period in which radio frequency interference satisfies a predetermined threshold. ### Claim 5 (depends on 1) The method of claim 1, further comprising determining a radio frequency receiving period with low physical interference, wherein the radio frequency receiving period comprises a period in which physical interference satisfies a predetermined threshold. ### Claim 6 An apparatus comprising a processor and a memory including computer program code, the memory and computer program code configured to, with the processor, cause the apparatus to: receive reference tag blink data from a plurality of receivers; calculate a reference phase offset between the plurality of receivers; analyze a plurality of reference phase offset calculations for at least one reference tag receiver pair over a time interval; and generate a suspended reference phase offset table in an instance in which the plurality of reference phase offset calculations for the at least one reference tag receiver pair satisfy a stability threshold, wherein a suspended reference phase offset table is generated by causing the reference phase offset to be stored in a memory for later tag location calculations. ### Claim 7 (depends on 6) An apparatus according to claim 6, wherein the reference phase offset is the difference between a reference clock time at receipt of the reference tag blink data at a respective plurality of receivers. ### Claim 8 (depends on 6) An apparatus according to claim 6, wherein the memory and computer program code are further configured to, with the processor, cause the apparatus to: receive tag blink data; and calculate a tag location data, wherein calculating the tag location data is based on a time difference of arrival of the tag blink data at the plurality of receivers and adding the reference phase offset of the suspended reference phase offset table. ### Claim 9 (depends on 6) An apparatus according to claim 6, wherein the memory and computer program code are further configured to, with the processor, cause the apparatus to determine a radio frequency receiving period with low radio frequency interference, wherein the radio frequency receiving period comprises a period in which radio frequency interference satisfies a predetermined threshold. ### Claim 10 (depends on 6) An apparatus according to claim 6, wherein the memory and computer program code are further configured to, with the processor, cause the apparatus to determine a radio frequency receiving period with low physical interference, wherein the radio frequency receiving period comprises a period in which physical interference satisfies a predetermined threshold. ### Claim 11 A computer program product comprising a non-transitory computer readable medium having program code portions stored thereon, the program code portions configured, upon execution to: receive reference tag blink data from a plurality of receivers; calculate a reference phase offset between the plurality of receivers; analyze a plurality of reference phase offset calculations for at least one reference tag receiver pair over a time interval; and generate a suspended reference phase offset table in an instance in which the plurality of reference phase offset calculations for the at least one reference tag receiver pair satisfy a stability threshold, wherein a suspended reference phase offset table is generated by causing the reference phase offset to be stored in a memory for later tag location calculations. ### Claim 12 (depends on 11) A computer program product according to claim 11, wherein the reference phase offset is the difference between a reference clock time at receipt of the reference tag blink data at a respective plurality of receivers. ### Claim 13 (depends on 11) A computer program product according to claim 11, wherein the program code portions are further configured, upon execution, to: receive tag blink data; and calculate tag location data, wherein calculating the tag location data is based on a time difference of arrival of the tag blink data at the plurality of receivers and adding the reference phase offset of the suspended reference phase offset table. ### Claim 14 (depends on 11) A computer program product according to claim 11, wherein the program code portions are further configured, upon execution, to determine a radio frequency receiving period with low radio frequency interference, wherein the radio frequency receiving period comprises a period in which radio frequency interference satisfies a predetermined threshold. ### Claim 15 (depends on 11) A computer program product according to claim 11, wherein the program code portions are further configured, upon execution, to determine a radio frequency receiving period with low physical interference, wherein the radio frequency receiving period comprises a period in which physical interference satisfies a predetermined threshold.