# US 8,149,897 B2 · Method and apparatus for performing signal correlation for signals received from satellites in multiple satellite systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,149,897 B2 - Document ID: US8149897B2 - Status: Granted - Kind: B2 - Application number: 11/441,798 - Filed: 2006-05-26 - Published: 2007-11-29 - Granted: 2012-04-03 - Earliest claimed: 2006-05-26 - Assignees: Global Locate, Inc. - Inventors: Charles Abraham - Web page: https://patentgrep.com/patent/US8149897B2 ## CPC - G01S 19/37: Hardware or software details of the signal processing chain - G01S 19/30: code related {(G01S19/246 takes precedence)} - G01S 19/33: Multimode operation in different systems which transmit time stamped messages, e.g. GPS/GLONASS - 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 method and apparatus for computing a convolution between a satellite signal from one of a plurality of satellite positioning systems and a pseudorandom code reference. The method and apparatus is capable of operating in multiple modes of resolution so as to enhance the sensitivity of the convolution processing. ## Claims ### Claim 1 Apparatus for processing signals from a plurality of satellite systems comprising: a tuner operable to select a first signal from a satellite in a first satellite system or a second signal from a satellite in a second satellite system; a single sideband filter operable to filter the first signal; a decimation circuit operable to subsample the filtered first signal or the second signal, wherein a subsample spacing is selectable; and a convolution processor operable to correlate the subsampled signal with a selected portion of a reference code to produce at least one partial correlation and accumulate the at least one partial correlation to produce a full convolution. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the first satellite system is a Galileo system. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the first satellite system is a Global Positioning System. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the tuner comprises a quadrature tuner operable to generate an in-phase component and a quadrature-phase component of the first signal or the second signal. ### Claim 5 (depends on 1) The apparatus of claim 1, wherein the convolution processor comprises a partial correlator operable to correlate portions of the filtered first signal or the second signal. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the decimation circuit uses a first sample spacing during a first mode and a second sample spacing during a second mode, where the first sample spacing is larger than the second sample spacing. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the first filtered signal comprises at least one of an upper sideband signal and a lower sideband signal. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the convolution processor comprises a correlation circuit operable to correlate at least one of a pilot component and a data component of the filtered first signal. ### Claim 9 A method for computing correlations of a digital signal with a pseudorandom reference code comprising: receiving at least one of either a first signal from a first satellite system or a second signal from a second satellite system, where said first signal has additional coding; single sideband filtering the first signal to create a filtered first signal; correlating the filtered first signal or the second signal with a pseudo-random reference code to produce first partial correlations; accumulating the first partial correlations to generate a full convolution; using the full convolution to establish timing and frequency synchronization dividing the pseudorandom reference code into a plurality of code segments; selecting a code segment; forming an inner product between the selected code segment and the first signal or the second signal to produce a second partial correlation, wherein the additional coding is removed from the first signal before the inner product is formed; repeating the selecting and forming steps to produce a plurality of second partial correlations; and summing the plurality of second partial correlations to form a plurality of second correlations. ### Claim 10 (depends on 9) The method of claim 9, wherein the first signal is a satellite signal from a Galileo satellite and the second signal is a satellite signal from a GPS satellite. ### Claim 11 (depends on 9) The method of claim 9, wherein the additional coding is a binary offset carrier code. ### Claim 12 (depends on 9) The method of claim 9, wherein the receiving step comprises selecting a first or second sample spacing for the first signal or the second signal, where the first sample spacing is greater than the second sample spacing. ### Claim 13 (depends on 9) The method of claim 9, wherein the filtering step generates at least one of an upper sideband signal and a lower sideband signal. ### Claim 14 (depends on 9) The method of claim 9, wherein the correlating step comprises correlating at least one of a data component or a pilot component of the filtered first signal. ### Claim 15 Apparatus for processing signals from a plurality of satellite systems comprising: a tuner operable to select a first signal from a satellite in a first satellite system or a second signal from a satellite in a second satellite system; a single sideband filter operable to filter the first signal; a decimation circuit operable to subsample the filtered first signal or the second signal, wherein a subsample spacing is selectable; and a convolution processor operable to correlate the subsampled signal with a reference code to produce a full convolution. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the first satellite system is a Galileo system and the second satellite system is a Global Positioning System. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the convolution processor comprises a partial correlator for correlating portions of the filtered first signal or the second signal. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein the apparatus comprises a synchronization processor operable to establish timing and frequency synchronization. ### Claim 19 (depends on 15) The apparatus of claim 15, wherein the tuner comprises a quadrature tuner operable to generate an in-phase component and a quadrature-phase component of a signal. ### Claim 20 (depends on 15) The apparatus of claim 15, wherein the decimation circuit uses a first sample spacing during a first mode and a second sample spacing during a second mode, where the first sample spacing is larger than the second sample spacing.