Pseudo GPS signal transmitting system in a base station

• US 5,440,491 A
• Filed: 10/18/1994
• Issued: 08/08/1995
• Est. Priority Date: 10/19/1993
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Harigae, Masatoshi, Kawano, Shuichi
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): Nguyen, Tan Q.
• Application Number:
  US08/324,503
• Time in Patent Office: 294 Days
• Field of Search: 364/443, 364/455, 364/456, 364/459, 364/460, 364/449, 364/561, 364/569, 375/1, 375/25, 375/59, 375/75, 342/357, 342/358, 342/359, 342/362, 342/407, 342/442, 342/450, 342/463, 342/352, 342/458
• US Class Current: 701/200
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters

Abstract

The object of this invention is to prevent GPS time monitor errors from effecting the distance-measuring accuracy. To achieve the object, a monitor GPS receiver receives GPS signals from each GPS satellite via a receiving antenna, senses satellite data, and obtains observation data on the basis of user clock pulses synchronized with a reference clock from a reference oscillator. A data processing unit computes a pseudo range error value from the satellite data and observation data obtained at the monitor GPS receiver on the basis of the user clock pulses, and formats these data items to generate transmission data. A transmitter combines PN codes with the transmission data on the basis of the user clock pulses to generate a pseudo GPS signal, modulates a carrier signal synchronized with the reference clock, and power-amplifies the modulated output. A transmitting antenna is directed toward a specific stationary satellite and transmits a pseudo GPS signal to a user GPS receiver via the stationary satellite.

Claims

1. A pseudo GPS signal transmitting system in a base station installed on the ground and transmitting a pseudo GPS signal for use as one of GPS satellites, comprising:

a GPS receiving antenna for picking up radio waves from GPS satellites;

a monitor GPS receiver containing a receiving section for receiving GPS signals from each GPS satellite via said GPS receiving antenna, a satellite data sensing section for sensing satellite data from the received GPS signals, a pulse generating section for generating user clock pulses synchronized with a reference clock, and an observation data calculating section for obtaining observation data from the received GPS signals on the basis of the user clock pulses;

a data processing unit containing an error data computing section for determining a pseudo range error value for the theoretical distance between a transmitting GPS satellite and a known receiving point from the satellite data and the observation data obtained at said monitor GPS receiver, and a transmission data generating section for formatting these data items in a specified manner to generate transmission data;

a transmitter containing a PN code generating section for generating PN codes for spectrum diffusion in synchronization with said user clock pulses, a pseudo GPS signal generating section for generating pseudo GPS signals by combining PN codes generated at the PN code generating section with the transmission data from said data processing unit on the basis of said user clock pulses, a carrier generating section for generating a carrier signal synchronized with said reference clock, a modulator for modulating the carrier signal generated at said carrier generating section using said pseudo GPS signal, and a power amplifier for power-amplifying the output of said modulator; and

a transmitting antenna for transmitting the pseudo GPS signal from said transmitter in a given direction, wherein the pseudo GPS signal sent from said transmitting antenna is transmitted directly or via a specific stationary satellite to a user GPS receiver.

3. A pseudo GPS signal transmitting system in a base station according to claim 1 or 2, wherein said error data computing section adds the amount of delay in the GPS signal over the entire hardware as one of data items for computing error data.

2. A pseudo GPS signal transmitting system in a base station installed on the ground and transmitting pseudo GPS signals for use as one of GPS satellites, comprising:

a GPS receiving antenna for picking up GPS signals from GPS satellites and a pseudo GPS signal from a different base station;

a monitor GPS receiver containing a receiving section for receiving GPS signals from said GPS satellites and a pseudo GPS signal from said different base station via said GPS receiving antenna, a satellite/base station data sensing section for sensing satellite data and base station data from the received GPS signals and pseudo GPS signal, a pulse generating section for generating clock pulses synchronized with a reference clock, and an observation data calculating section for obtaining observation data from the received GPS signals and pseudo GPS signal on the basis of the clock pulses;

a data processing unit containing an error data computing section for determining a pseudo range error value for the theoretical distances between a transmitting GPS satellite and a known receiving point and between the different base station and the known receiving point from the satellite data, base station data, and observation data obtained at said monitor GPS receiver, and a transmission data generating section for formatting these data items in a specified manner to generate transmission data;

a transmitter containing a PN code generating section for generating PN codes for spectrum diffusion, a pseudo GPS signal generating section for generating pseudo GPS signals by combining PN codes generated at the PN code generating section and the transmission data from said data processing unit, a carrier generating section for generating a carrier signal synchronized with said reference clock, a modulator for modulating the carrier signal generated at said carrier generating section using said pseudo GPS signal, and a power amplifier for power-amplifying the output of said modulator; and

a transmitting antenna for transmitting the pseudo GPS signal from said transmitter.