System for measuring position by using global positioning system and receiver for global position system

• US 5,434,787 A
• Filed: 04/08/1992
• Issued: 07/18/1995
• Est. Priority Date: 04/12/1991
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Okamoto, Takeshi, Miyazaki, Masao, Okamoto, Naoki, Ohta, Tomozo
• Primary Examiner(s): ZANELLI, MICHAEL J
• Application Number:
  US07/866,021
• Time in Patent Office: 1,196 Days
• Field of Search: 364/459, 364/449, 364/458, 364/424.04, 364/460, 342/357, 342/450, 342/451, 342/463, 342/457, 342/358
• US Class Current: 701/214
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G07C 5/008 communicating information to a remotely located station transmission systems for measured values G08C
• CPC Class Codes: G07C 5/0858 wherein the data carrier is removable

Abstract

A GPS position measuring system includes at least one mobile station and a base station associated with the mobile station. The mobile station is provided with an antenna for receiving one or more GPS signals from the corresponding GPS satellites, an amplifying and frequency converting circuit for amplifying the received signal and converting the amplified GPS signal into a signal on an IF band, an analog-to-digital converter for converting the signal on the IF band into a digital signal, and a writing unit for writing the digital signal into a memory card in order to transfer the digital signal to the base station.

Claims

1. A receiver for Global Positioning System (GPS) comprising:

receiving means for receiving GPS signals transmitted from GPS satellites located within a receivable field and transmitting in a common frequency band in an overlapping manner;

first converting means for converting said GPS signals into an Intermediate Frequency (IF) signal;

second converting means for converting said IF signal into a digital signal;

storing means for storing said digital signal at a predetermined interval of time;

reading means for reading said digital signal stored in said storing means;

detecting means for detecting ephemeris data from said digital signal read by said reading means until a number of said ephemeris data equals a number of said GPS satellites, each of said ephemeris data corresponding to one of said GPS satellites;

collecting means for collecting said ephemeris data detected by said detecting means;

calculating means, coupled to said collecting means, for calculating distance data and accuracy data from said ephemeris data, after collection by said collecting means, respectively;

selecting means, for selecting a predetermined number of distance data and corresponding ephemeris data, in accordance with respective values of said accuracy data; and

position deriving means, for deriving position data of said receiver, by using said distance data and corresponding ephemeris data selected by said selecting means, wherein

said selecting means selects said distance data and corresponding ephemeris data so as to minimize any error in said derived position data.

2. A GPS receiver according to claim 1, wherein said collecting means omits collection of said ephemeris data of one of said GPS satellites whenever said detecting means fails to detect said ephemeris data of said one of said GPS satellites.

3. A GPS receiver according to claim 1, wherein said storing means stores said digital signal at 30-second intervals.

4. A GPS receiver according to claim 1, wherein said selecting means selects four distance data and corresponding ephemeris data, in accordance with said values of said accuracy data preferentially selecting those data having the smallest error.

5. A GPS receiver according to claim 1, wherein said reading means reads said digital signal stored in said storing means at a rate which is an integer multiple of a storing rate at which said storing means stored said digital signal.

6. A GPS receiver according to claim 5, wherein said reading means reads said digital signal stored in said storing means at a rate which is 8 times the storing rate at which said storing means stored said digital signal.

7. A GPS receiver according to claim 1, wherein said storing means is an integrated circuit memory.

8. A receiver for Global Positioning System (GPS) signals comprising:

receiving means for receiving GPS signals transmitted from GPS satellites located within a receivable field and transmitting in a common frequency band in an overlapping manner,

first converting means for converting said GPS signals into an Intermediate Frequency (IF) signal,

second converting means for converting said IF signal into a digital signal;

storing means for storing said digital signal at a predetermined interval of time;

reading means for reading said digital signal stored in said storing means;

detecting means for detecting ephemeris data from said digital signal read by said reading means until a number of said ephemeris data equals a number of said GPS satellites, each of said ephemeris data corresponding to one of said GPS satellites;

collecting means for collecting said ephemeris data detected said detecting means;

calculating means coupled to said collecting means, for calculating distance data and accuracy data from ephemeris data, after collection by said collecting means, respectively;

selecting means, for selecting a predetermined number distance data and corresponding ephemeris data, in accordance with respective values of said accuracy data; and

position deriving means, for deriving position data of said receiver, by using said distance data and corresponding ephemeris data selected by said selecting means, wherein

said selecting means selects said distance data and corresponding ephemeris data so as to minimize any error in said derived position data, and

wherein said detecting and collecting means collect said ephemeris data for each satellite within a period not exceeding 30 seconds and said position deriving means completely derives said position within a period not exceeding n times 30 seconds, where n is the number of satellites from which ephemeris data were collected.

9. A receiver for Global Positioning System (GPS) signals comprising:

receiving means for receiving GPS signals transmitted from GPS Satellites located within a receivable field and transmitting in a common frequency band in an overlapping manner,

first converting means for converting said GPS signals into an Intermediate Frequency (IF) signal,

second converting means for converting said IF signal into a digital signal;

storing means for storing said digital signal at a predetermined interval of time;

reading means for reading said digital signal stored in said storing means;

detecting means for detecting ephemeris data from said digital signal read by said reading means until a number of said ephemeris data equals a number of said GPS satellites, each of said ephemeris data corresponding to one of said GPS satellites;

collecting means for collecting said ephemeris data detected by said detecting means;

calculating means coupled to said collecting means, for calculating distance data and accuracy data from ephemeris data, after collection by said collecting means, respectively;

selecting means, for selecting a predetermined number of distance data and corresponding ephemeris data, in accordance with respective values of said accuracy data; and

position deriving means, for deriving position data of said receiver, by using said distance data and corresponding ephemeris data selected by said selecting means, wherein

said selecting means selects said distance data and corresponding ephemeris data so as to minimize any error in said derived position data,

wherein said detecting and collecting means collect said ephemeris data for each satellite within a period not exceeding 30 seconds and said position deriving means completely derives said position within a period not exceeding n times 30 seconds, where n is the number of satellites from which ephemeris data were collected, and

wherein said receiver uses time-series processing in a single-channel device to simulate a multiple-channel digital processing circuit, and derives a Geometrical Dilution of Precision (GDOP) coefficient within a period not exceeding n times 30 seconds.