Multipath Processing for GPS Receivers

a multi-path processing and receiver technology, applied in the field of spread spectrum receivers, can solve the problems of limited acceptance, difficult maintenance of continuous reception from 4 gps satellites, increased complexity and cost of such combined systems, etc., and achieve the effect of reducing the multi-path

a multi-path processing and receiver technology, applied in the field of spread spectrum receivers, can solve the problems of limited acceptance, difficult maintenance of continuous reception from 4 gps satellites, increased complexity and cost of such combined systems, etc., and achieve the effect of reducing the multi-path

US20080205493A1Inactive Publication Date: 2008-08-28KOHLI SANJAI +1
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  • Multipath Processing for GPS Receivers
  • Multipath Processing for GPS Receivers
  • Multipath Processing for GPS Receivers

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[0047]FIG. 1 is an overview illustration of the operation of a GPS car navigation system according to the present invention. The GPS car navigation system, described below in greater detail with respect to FIG. 2, is mounted in car 10 which is moving along the center of roadway 12. NAVSTAR satellite 14, in the lower left quadrant of the figure, is in view of car 10. A simulated GPS circular overhead display, positioned approximately over intersection 22 of roadway 12 and roadway 16 indicates that satellite 14 is between 0° and 45° degrees of elevation above the horizon as viewed from car 10.

[0048]For the purposes of illustration, satellite 18 is positioned overhead between the elevation angles of 0° and 45° degrees. However, the line of sight between satellite 18 and car 10 is obscured by buildings 20 so that satellite 18 is not in view of car 10 at the position along roadway 12 as shown. Similarly, the line or sight between satellite 19 and car 10 is obscured by buildings 21. Howe...

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Abstract

A GPS receiver system determines the presence of trackable signals at code delays less than the prompt delay being tracked for a particular signal and changes the prompt delay to correspond to the smallest code delay having a trackable signal. Trackable signals at large code delays are multipath signals and may be separately tracked to aid in dead reckoning. The trackable signals at code delays not adjacent to the current tracked prompt delay may be tracked in the same channel as the prompt delay so that all satellite channels are continuously evaluated for multipath signals being tracked or a non-satellite specific channel may be used to sequentially step through the satellite signals to evaluate multipath on a satellite by satellite basis.

Description

RELATED APPLICATIONS[0001]This is a continuation of application Ser. No. 09 / 778,269, filed Feb. 6, 2001 which is a continuation of application Ser. No. 09 / 049,306, filed Mar. 28, 1998, now U.S. Pat. No. 6,249,542 which claims the benefit of application Ser. No. 60 / 042,868, filed Mar. 28, 1997.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates in general to spread spectrum receivers and in particular to GPS navigation systems, such as those used in terrestrial navigation for cars, trucks and other land vehicles, operated in environments with substantial multipath interference.[0004]2. Description of the Prior Art[0005]Car navigation is conventionally performed using highway and street maps aided, to some degree, by distance measurements from external sensors such as odometers. Improvements over the last 10 years in Global Positioning System, or GPS, satellite navigation receivers has spawned several GPS car navigation systems.[0006]Conventional GPS...

Claims

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Application Information

Patent Timeline
28 Aug 2008
Publication
US20080205493A1
IPC
H04B1/707; G01S19/30; G01C21/26; G01C22/00; G01S1/00; G01S5/14; G01S19/34; G01S19/47; G01S19/48; G01S19/50; H04B1/7085; H04B1/7115; H04B7/216
CPC
G01C21/26; G01C22/00; G01S19/11; G01S19/22; G01S19/29; G01S19/30; H04B2001/70706; G01S19/37
Inventors
KOHLI, SANJAI; CAHN, CHARLES R.