Global positioning system and global positioning apparatus

• US 6,483,457 B2
• Filed: 09/13/2001
• Issued: 11/19/2002
• Est. Priority Date: 05/31/2000
• Status: Expired due to Term

• Current Assignee: MiTAC International Corporation (MiTAC Holdings Corp.)
• Original Assignee: Magellan Systems Japan, Inc., Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation), Magellan Corporation (Thales SA)
• Inventors: Hirata, Seiichiro, Lyusin, Sergy V.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US09/950,719
• Publication Number:
  US 20020093452A1
• Time in Patent Office: 432 Days
• Field of Search: 342/357.12, 342/357.05, 342/357.06, 375/150
• US Class Current: 342/357.62
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence

Abstract

A Global Positioning System carries out Doppler correction of a C/A code sequence after a frequency conversion, and calculates a pseudo range by performing correlation calculation between the C/A code, which is obtained by summing up the C/A code sequence beginning from a polarity inversion boundary determined at a correlation peak detecting step ST10, and a C/A code generated in a GPS terminal. When a received electric field detected by a received electric field intensity detector 11 is good, the current position is determined from the pseudo range and the navigation data extracted by the GPS terminal itself, whereas when the received electric field is poor, the current position is determined from the pseudo range and the navigation data sent from an external apparatus.

Claims

1. A GPS positioning method comprising the steps of:

performing Doppler correction to a GPS signal based on Doppler information derived from the GPS signal and obtaining a data sequence having a polarity;

performing Doppler correction to the data sequence based on the Doppler information;

performing polarity inversion based on navigation data derived from the GPS signal and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the third step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position.

2. The GPS positioning method according to claim 1, wherein the Doppler correction to the GPS signal in the first step is performed based on the Doppler information derived from the GPS signal and frequency deviation information with respect to a frequency of a local oscillator.

3. The GPS positioning method according to claim 2, further comprising the step of shifting at least one of the Doppler information and the frequency deviation information with respect to the frequency of the local oscillator when the correlation peak value is not obtained and performing the Doppler correction to the GPS signal based on the shifted information.

4. The GPS positioning method according to claim 3, wherein the variation is performed according to a binary scan method.

5. The GPS positioning method according to claim 2, wherein the first step includes a step of multiplying the GPS signal by a GPS carrier sine data and a GPS carrier cosine data orthogonal to each other so as to obtain I signal data having a carrier component removed therefrom and Q signal data having a carrier component removed therefrom, respectively, and wherein

the second step includes a step of multiplying the I signal data and the Q signal data by sine data and cosine data, respectively, the sine data and the cosine data each constituting a frequency deviation being included in a frequency deviation component obtained as a result of summing the Doppler information and the frequency deviation information, so as to obtain an I signal of the data sequence and a Q signal of the data sequence orthogonal to each other.

6. A GPS positioning method comprising the steps of:

obtaining a data sequence having a polarity from a GPS signal;

dividing the data sequence into predetermined sections;

subjecting the sections obtained in the first step to polarity inversion based on navigation data derived form the GPS signal, and calculating a cumulative sum of values at the same bit position in the respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the third step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position obtained for each of the sections.

7. A GPS positioning method comprising the steps of:

obtaining a data sequence having a polarity from a GPS signal;

performing polarity inversion based on navigation data derived from the GPS signal and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the second step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position; and

shifting the navigation data according to a binary scan method when a desired peak value is not obtained and performing polarity inversion using the shifted navigation data.

8. A GPS positioning method comprising the steps of:

obtaining a data sequence having a polarity from a GPS signal;

performing polarity inversion based on navigation data derived from the GPS signal and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the second step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position; and

shifting the navigation data when a desired peak value is not obtained and performing polarity inversion using the shifted navigation data, wherein

the sixth step is repeated until a maximum of the correlation peak value is obtained.

9. A GPS positioning method comprising the steps of:

obtaining a data sequence having a polarity from a GPS signal;

performing polarity inversion based on navigation data derived from the GPS signal and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the second step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position;

wherein

when the correlation peak value is obtained, the correlation calculation is completed.

10. A GPS positioning method comprising the steps of:

obtaining a data sequence having a polarity from a GPS signal;

receiving information including navigation information from an external apparatus and determining a communication delay in the navigation data based on a time required for communication with the external apparatus;

performing polarity inversion based on the navigation data shifted by the communication delay and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

performing a correlation calculation using the C/A code based on a result of the third step;

determining a correlation peak position based on a correlation peak value obtained as a result of the correlation calculation; and

determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position.

11. The GPS positioning method according to claim 10, further comprising the steps of:

transmitting a signal to an external apparatus maintaining time;

receiving a time signal including time information from the external apparatus;

adjusting a local time to the time maintained by the external apparatus based on the time received time information, a time when the signal is transmitted to the external apparatus and a time when the time signal is received; and

calculating the time required for communication with the external apparatus based on the adjusted time.

12. A GPS terminal comprising:

a first Doppler correction unit performing Doppler correction to a GPS signal based on Doppler information derived from the GPS signal and obtaining a data sequence having a polarity;

a second Doppler correction unit performing Doppler correction to the data sequence based on the Doppler information;

a data processing unit performing polarity inversion based on navigation data derived from the GPS signal and calculating a cumulative sum of values at the same bit position in respective blocks each having a length of a C/A code;

a correlation calculation unit performing a correlation calculation using the C/A code based on a result of a process in the data processing unit;

a pseudo range calculation unit determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on the correlation peak position determined by said correlation calculation unit.

13. The GPS positioning terminal according to claim 12, further comprising:

a frequency deviation detection unit for detecting a frequency deviation with respect to a frequency of a local oscillator and outputting frequency deviation information; and

a frequency conversion unit subjecting the GPS signal to frequency conversion using the local oscillator, wherein said first Doppler correction unit performs the Doppler correction to the GPS signal subjected to the frequency conversion based on the Doppler information derived from the GPS signal and frequency deviation information, and obtains a data sequence having a polarity.

14. The GPS terminal according to claim 13, further comprising a storage unit storing the frequency deviation information indicating variation of the frequency deviation with temperature, wherein said frequency deviation detection unit selects and outputs the frequency deviation information in accordance with the temperature.

15. The GPS terminal according to claim 13, wherein said frequency deviation detection unit detects frequency deviation based on a reference signal supplied from an external apparatus.

16. The GPS terminal according to claim 13, wherein said local oscillator is stabilized based on the reference signal obtained from the external apparatus.

17. The GPS terminal according to claim 13, further comprising:

an analog-to-digital conversion unit converting the GPS signal subjected to the frequency conversion into a digital signal, wherein

a sampling rate of said analog-to-digital converting unit is variable.

18. A GPS terminal comprising:

a data sequence obtaining unit obtaining a data sequence having a polarity from a GPS signal;

a data dividing unit dividing the data sequence into predetermined sections;

a data processing unit subjecting the sections obtained by said data dividing unit to polarity inversion based on navigation data derived from the GPS signal, and calculating a cumulative sum of values at the same bit position in the respective blocks each having a length of a C/A code;

a correlation calculation unit performing correlation calculation using the C/A code based on a result of the process in said data processing unit; and

a pseudo range calculation unit determining a pseudo range between a GPS terminal and a satellite corresponding to the C/A code based on a correlation peak position obtained by said correlation calculation unit for each of the sections.