Integrated GPS-inertial system

• US 6,750,816 B1
• Filed: 02/12/2003
• Issued: 06/15/2004
• Est. Priority Date: 02/12/2003
• Status: Expired due to Term

• Current Assignee: Novatel Incorporated (Hexagon AB)
• Original Assignee: Novatel Incorporated (Hexagon AB)
• Inventors: Kunysz, Waldemar
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US10/365,281
• Time in Patent Office: 489 Days
• Field of Search: 342/357.14, 342/357.06, 342/357.12, 701/213, 701/220
• US Class Current: 342/357.59
• CPC Class Codes: G01S 19/35 Constructional details or hardware or software details of the signal processing chain
• CPC Class Codes: G01S 19/49 whereby the further system is an inertial position system, e.g. loosely-coupled

Abstract

A GPS-inertial system that is suited to new installations as well as the retrofitting of GPS receivers includes inertial sensors that are incorporated into the housing of the GPS antenna. The outputs of the inertial sensors are modulated onto a radio frequency carrier that has the same frequency as the GPS carrier, using the same data modulation arrangement as that used by the GPS system. The inertial measurements are thus sent to the receiver on the same cable as the RF signals from the antenna, and the receiver recovers the data from the sensor signals with the same arrangement that is used for data recovery from GPS position signals. Consequently, software modifications of existing GPS receivers can provide position and velocity estimates generated from the outputs of the inertial sensors.

Claims

1. A receiver for the demodulation and processing of ranging signals and from orbiting satellites, the receiver comprising:

A) multiple channels, each of which is configured to demodulate said ranging signals and recover satellite data from said signals;

B) control means for

a. assigning to each a channel a signal source whose signals are to be demodulated in that channel, and

b. processing data received from the ranging signals;

C) an RF generator that has the same frequency as the satellite carrier frequency,

D) modulating means for modulating the output of said generator with unique pseudo random codes and modulating the codes with associated inertial data to produce pseudo ranging signals, and

E) the receiver channels correlate the ranging and pseudo ranging signals received by the receiver with local replicas of the pseudo random codes used by the modulating means and the satellites with the control unit assigning said channels to respective signal sources by selecting the code replicas used by said channels.

2. A remote antenna unit for connection by an RF link to a receiver that demodulates and processes ranging signals transmitted by orbiting satellites, said antenna unit comprising:

A) an antenna for receiving said ranging signals, coupled to said RF link for transmission of said ranging signals to said receiver,

B) a plurality of inertial sensors providing inertial data,

C) a radio frequency generator, and

D) means for modulating the output of said generator with said inertial data in the same manner as the ranging signals are modulated with satellite data, thereby to provide pseudo ranging signals; and

E) means coupling the pseudo ranging signals to said RF link for transmission to said receiver.

3. The remote antenna unit of claim 2 wherein the radio frequency generator has the same frequency as the carrier frequency transmitted by the satellites.

4. A receiver system for the demodulation and processing of ranging signals, the receiver system comprising:

A) multiple channels, each of which is configured to demodulate the ranging signals and recover associated data from the ranging signals;

B) an RF link to transmit signals to the multiple channels;

C) an antenna for receiving ranging signals from satellites, the antenna coupled to the RF link for transmission of the ranging signals;

D) a plurality of inertial sensors providing inertial data;

E) a radio frequency generator, and

F) means for modulating the output of the generator with the inertial data in the same manner as the ranging signals are modulated with satellite data, thereby to provide the pseudo ranging signals; and

G) means coupling the pseudo ranging signals to the RF link for transmission to the multiple channels.

5. The receiver system of claim 4 further including a control unit for

assigning to each a channel a signal source whose signals are to be demodulated in that channel, the control means assigning to selected channels the signal sources associated with the inertial data; and

processing the satellite and the inertial data received from the ranging signals.

6. The receiver system of claim 5 wherein

the RF generator has the same frequency as the satellite carrier frequency,

the modulating means modulates the output of the RF generator with unique pseudo random codes and modulates the codes with the inertial data,

the channels correlate the signals received by the receiver with local replicas of the pseudo random codes, and

the control unit assigns the channels to respective signal sources by selecting the code replicas used by the channels.