Communications: directive radio wave systems and devices (e.g. – Directive – Including a satellite
Reexamination Certificate
1998-08-28
2001-03-20
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Including a satellite
C701S213000
Reexamination Certificate
active
06204807
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a portable GPS receiver adapted to receive signals from GPS (Global Positioning System) satellites and measure locations and speeds of the receiver. More particularly, the invention relates to a GPS receiver which can be held by or worn on a human arm in order to measure locations, moving speeds and moving distances during running, walking, or other movement of the human body.
Conventionally, the GPS system has 24 GPS satellites revolving at a rate of 12 hours per turn on six orbits at an inclination angle of 55 degrees above approximately 20,200 Km around the earth. The navigation data required for positioning is transmitted from three to four or more satellites, and received by a receiver installed on the earth so that a mobile body having the receiver mounted therein may have calculated its position such as location, moving speed, etc.
Although the transmission wave by the GPS involves two kinds, i.e., L1 with a frequency of 1.57542 GHz and L2 with a frequency of 1.22760 GHz, ordinary positioning utilizes only L1. L1 is subjected to PSK modulation by a pseudo noise code (a synthetic wave of a C/A code for satellite identification and navigation data such as satellite orbit information, time information, etc.) and spread spectrum, to be transmitted.
FIG. 15
shows a block diagram of a GPS receiver for receiving radio waves as stated above. In the figure,
1501
is an antenna for receiving radio waves transmitted from the GPS satellites,
1502
is a L-band amplifying circuit for amplifying a received L-band signal,
1503
is a down-converter for performing signal conversion as described below,
1504
is a voltage comparator for digitally converting a signal supplied from the down converter
1503
,
1505
is a message decoding circuit for obtaining carrier-wave phase information corresponding in pseudo distance to the navigation data, and
1506
is a C/A code generating circuit for generating C/A codes,
1507
is a position calculating section for calculating position data. These constituent elements are systematically connected therebetween, constituting the GPS receiver.
The GPS receiver structured as described above performs signal reception, as explained hereinbelow. The 1.57542 GHz signal received by the antenna
1501
is amplified by the L-band amplifying circuit
1502
. This amplified signal is converted by the down-converter
1503
into an first IF (intermediate frequency) signal of several tens of MHz-200 MHz, and then into a second IF signal of approximately 2 MHz-5 MHz. This second IF signal is inputted to the voltage comparator
1504
and digital-converted with a clock several times the IF signal. Spread spectrum data is obtained as an output from the voltage comparator.
In the massage decoding circuit
1505
, the digital signal outputted by the voltage comparator
1504
is subjected to reverse spread spectrum with a C/A code, i.e., the same pseudo noise code as that of the satellite, which is generated by the C/A code generating circuit
1506
. Thus, carrier-wave phase information is obtained that is corresponding in pseudo distance to the navigation data. This operation is performed on a plurality of satellites. The position calculating section
1507
determines position data from the navigation data, usually, of four satellites. The position data determined by the position calculating section
1507
is supplied to the CPU for controlling operations of the entire portable apparatus, or otherwise to the outside as a digital signal.
Recently, GPS receivers as described above have been utilized for a vehicular navigation apparatus. Meanwhile, GPS receivers are also made very small and utilized as a portable apparatus for the purpose of determining a direction of a human body or a moving distance during walking, as disclosed by “Signal Receiver” in Japanese Laying-open Patent Publication No. H6-18156.
Where the conventional GPS receiver as described above is utilized to measure a moving speed or distance of a human body, if the GPS receiver is for example of a vehicular mounting type, the use of a self-navigating means such as map-matching enables a navigating operation to continue even where positioning is difficult to effect such as in tunnels or building valleys. However, where such a GPS receiver is utilized as a compact receiver for example in a portable form, it becomes difficult to incorporate CD-ROM map information therein due to smallness in size.
Also, where considering a vehicle, the moving distance or speed can be obtained from instruments installed on the vehicle. However, where the receive is of an on-arm type, the moving distance is determined from the GPS satellite. Consequently, if the satellite information becomes impossible to receive, there is a fear that the distance measurement is also impossible to carry out. Further, a human body will frequently vary in direction of movement. To accurately determine a moving distance requires continuously performing the operation of positioning. This, however, results in a problem in that the GPS receiver has an increased power consumption.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a portable GPS receiver which can measure a moving distance even where the GPS satellite information cannot be received, and which avoids continuous GPS reception to save power consumption.
A portable GPS receiver, according to one aspect of the invention, is adapted to receive a signal from a GPS satellite by a GPS receiving means to measure a position and a speed of the receiver, the portable GPS receiver comprising: a traveling pitch detecting means for detecting a traveling pitch of a human body; a timer means for determining an operating period to intermittently enable reception from the GPS satellite; a stride calculating means for calculating, based on the operating period, a traveling stride from received positioning data between two points and a pitch detected by the traveling pitch detecting means during obtaining the positioning data; and a speed/distance calculating means for calculating, based on the operating period, a traveling speed and a traveling distance from the stride determined by the stride calculating means and the pitch detected by the traveling pitch detecting means.
That is, a traveling stride, is determined from a moving distance between two points at which the GPS receiver effects positioning and a number of traveling pitches determined during the positioning. A moving distance and a moving speed are determined from the stride. This makes it possible to achieve continuous measurement even where positioning is difficult to effect such as in a tunnel or a valley between buildings. Also, the moving distance and the moving speed are determined with the stride as a reference, eliminating the necessity of continuously effecting positioning of the GPS receiving means.
In a portable GPS receiver according to another aspect of the invention, the GPS receiving means continuously effects positioning for a time period of from starting measurement of the traveling speed and the traveling distance to determining the traveling stride by the stride calculating means.
That is, the time period of continuous positioning of the GPS receiving means is minimized by performing continuous positioning only during the period from starting the measurement of a traveling speed and a traveling distance to determining a traveling stride.
In a portable GPS receiver according to a third aspect of the invention, evaluation is made after effecting GPS positioning whether a difference in advancing direction between a preceding time and a current time is within a given amount, and the positioning of the GPS receiver is continuously effected during a time period of moving a predetermined distance when there is a change in moving direction.
That is, after the GPS positioning, it is evaluated whether the difference in advancing direction between the preceding time and the present time is within a given amount or not. As a result, if there is a change in
Odagiri Hiroshi
Sakumoto Kazumi
Tsubata Keisuke
Adams & Wilks
Phan Dao L.
Seiko Instruments Inc.
Tarcza Thomas H.
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