JP2000321090A - Portable rangefinder and speedometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable speedometer and rangefinder which presents the influence degree due to a global positioning system(GPS) positioning error of the average movement speed and the movement distance of a user measured by a GPS receiver. SOLUTION: In this rangefinder and speedometer, an average movement-speed computing means 13 computes the average movement speed of a user on the basis of a movement speed which is computed in a movement-speed computing means 12, a measuring and evaluation means 15 evaluates whether a change within a prescribed time in the average movement speed computed in the avarage movement-speed computing means 13 is within a prescribed amplitude range or not, and its evaluated result is displayed on a display means 16. As a result, it is possible to judge whether a computed movement distance and the computed average movement speed are subjected largely to the influence of a GPS positioning error or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention presents the reliability of a measured moving distance and moving speed by a small device such as a wristwatch, particularly when a distance / speed meter is provided with a GPS receiver. It relates to a portable distance / speed meter.

[0002]

2. Description of the Related Art GPS (Global Positioning System:
The Global Positioning System) is approximately 20,200 km
Of the 24 GPS satellites orbiting about 12 hours in six orbits with a tilt angle of 55 degrees, the navigation data necessary for positioning is received by a receiver on the earth from 3 to 4 or more satellites that are most easily received. Then, by measuring the propagation delay time, positioning calculation such as the position and the moving direction of the user is performed.

Here, the transmission frequencies of the GPS satellites include a frequency L1 (1.57542 GHz) and a frequency L2 (1.2
2760 GHz), and a C / A code whose code is open to the public for free is transmitted at 1.57542 GHz (frequency L1). Therefore, the frequency L1 is used for general positioning. . The frequency L1 is subjected to PSK (phase shift keying) modulation with a pseudo noise code (a composite wave of a C / A code for identifying a satellite and the orbit of the satellite and navigation data such as satellite orbit information and time information), and spread spectrum. Sent and sent.

FIG. 7 is a diagram showing a schematic configuration of a GPS receiver for receiving a radio wave (frequency L1) transmitted from a GPS satellite. In FIG. 7, a GPS receiver 200
Is a reception antenna 201 for receiving GPS radio waves from GPS satellites, an L-band amplification circuit 202 for amplifying a received L-band signal, and a signal conversion by multiplying the received signal by a signal generated by the local oscillation circuit 107. , A voltage comparison circuit 204 for digitally converting a signal from the down converter circuit 203, and a C / A code generation circuit 20
8, a message decoding circuit 205 for obtaining navigation data and carrier phase information corresponding to a pseudorange by multiplying the C / A code generated in step 8, and positioning data using the navigation data and the carrier phase information input from the message decoding circuit 205. And a positioning calculation circuit 206 for calculating. The local oscillation circuit 107 is a circuit that generates a signal for converting a received signal into a signal of a desired frequency.

Next, the receiving operation of the GPS receiver 200 will be described. In FIG. 7, first, the L-band amplification circuit 202 receives 1.575
A signal of 42 GHz is selectively amplified. The signal amplified by the L band amplifier circuit is output to the down converter circuit 203.
The down-converter circuit 203 converts the input signal into a first IF (intermediate frequency) signal of several tens of MHz to 200 MHz using the signal generated in the local oscillation circuit 107, and further converts the signal to 2 to 5 MHz. To a second IF signal. Then, the voltage comparison circuit 204
Inputs the second IF signal, and inputs the input second IF signal.
This signal is digitally converted using a clock several times that of the signal. Here, the digitally converted signal becomes spread spectrum data (digital signal).

[0006] The digital signal output from the voltage comparison circuit 204 is input to a message decoding circuit 205, and the message decoding circuit 205 converts the input digital signal into a C / A code generated by a C / A code generation circuit 208. A
The code (the same pseudo-noise code as that of the GPS satellite) is despread to obtain navigation data and carrier phase information corresponding to the pseudo-range.

The above operation is performed for each of a plurality of GPS satellites. Usually, navigation data and carrier phase information of four satellites are obtained, and the positioning calculation circuit 206 obtains positioning data based on these information. . Positioning calculation circuit 206
Is output to a CPU (not shown) that controls the operation of the entire device, or is output to the outside as a digital signal. GPS like this
The receiver is used as a car navigation system by combining GPS position information and map information from a CD-ROM.

[0008] The GPS receiver 200 described above is supplied as a digital ASIC (Application Specific IC) due to recent technological advances such as semiconductors. Modularization featuring small size and light weight has been achieved.

[0009] Against this background, there has been proposed a portable GPS receiving apparatus capable of measuring a moving speed and a moving distance of a person using a GPS receiver. For example, “Portable GPS” disclosed in Japanese Patent Laid-Open No. 10-325735 is disclosed.
Receiving device ”is an accurate measurement of the moving distance and moving speed required by the miniaturization by the GPS receiver,
In order to achieve continuous measurement avoiding the state in which the GPS satellites cannot be captured, a calculation is performed based on the travel distance obtained by receiving the GPS radio wave only at a predetermined timing and the signal detected by the walking detecting means. The user's step length (stride) is calculated from the number of steps of the user, and the stride data is multiplied by the number of steps to obtain the moving distance of the user.

[0010]

However, the moving distance and the moving speed measured by using the GPS receiver as in the above-mentioned "portable GPS receiver" are generally avoided due to GPS positioning. An error that cannot be included. The error factors include (1) the time error of the atomic clock (satellite clock) mounted on the satellite, and (2) the SA (Se
(3) ionospheric or tropospheric radio wave propagation errors, and (4) multipath errors due to multiple reflections from obstacles. Usually, the measurement accuracy of the GPS receiver is represented by the sum of these errors.

In particular, the largest of these error factors is (2) an error due to SA (Selective Availability), and a distance measurement error that is about 10 times as large as other error factors occurs. SA is a signal intentionally added by the U.S. Department of Defense to deteriorate navigation data measured by a GPS receiver, and introduces an error that fluctuates in a fundamental frequency of a satellite clock. The pseudorange is
Since the SA is obtained from the difference between the time of the satellite clock and the arrival time of the GPS radio wave measured by the clock of the GPS receiver, SA appears directly in this pseudorange as an error, and the moving distance and the moving speed calculated using the pseudorange also appear. This error will appear.

In particular, when measuring a moving speed or a moving distance of a relatively small speed range such as walking or running of a person, the error caused by the SA cannot be ignored. On the other hand, since SA is generated on the transmission side,
It has spatial correlation, and the error that occurs at a certain place is
A similar error is observed in the vicinity. SA
Because of this property, DGPS (Differen
If you use tial GPS, you can eliminate the effect. DGPS is a technique for removing errors common to both the GPS receiver of the reference station and the GPS receiver of the user, and is used when performing surveys over a relatively wide range.

However, in DGPS, it is necessary to set up a reference station in an area to be surveyed, and in consideration of the maintenance and operation costs of the infrastructure, a portable type that measures the moving speed and moving distance of a person walking or running. It is difficult to adopt this DGPS for distance and speedometers.

In view of the above problems, the present invention calculates and presents an average moving speed and a moving distance of a user measured by a GPS receiver and presents the calculated average moving speed and a moving distance by the error included in the presented mean moving speed and the moving distance. It is an object of the present invention to provide a portable distance / speed meter that presents the influence, that is, the reliability of the presented average traveling speed and traveling distance.

[0015]

FIG. 1 is a principle diagram of a portable distance meter or a portable distance / speed meter according to the present invention.
In FIG. 1, a portable distance / speed meter according to the present invention receives a GPS radio wave transmitted from a GPS satellite and achieves the position or moving speed of a user based on the received GPS radio wave in order to achieve the above object. GPS receiver 10 that calculates
Moving distance calculating means 11 for calculating the moving distance of the user based on the calculation result in the GPS receiver 10, time measuring means 14 for measuring the moving time of the user at the moving distance, and moving distance calculating means 11. Moving speed calculating means 1 for calculating the moving speed of the user based on the moving distance measured and the moving time measured by the time measuring means 14
2, an average moving speed calculating means 13 for calculating the average moving speed of the user based on the moving speed calculated by the moving speed calculating means 12, and within a predetermined time of the average moving speed calculated by the average moving speed calculating means 13. Measuring and evaluating means 15 for evaluating whether or not the fluctuation of the amplitude is within a predetermined amplitude range.
And a display unit 16 for displaying the evaluation result in the measurement and evaluation unit 15.

According to the present invention, the average moving speed calculating means 13 calculates the average moving speed from the moving speed calculated by the moving speed calculating means 12, so that the average moving speed of the user is constant. , The moving speed including the fluctuation due to the positioning error such as SA is made to converge to the actual moving speed as the average moving speed, and the convergence state of the average moving speed is evaluated by the measurement and evaluation means 15,
Since the evaluation result is displayed on the display means 16, the user can check whether the moving distance or the average moving speed displayed on the same display means 16 is greatly affected by the positioning error, that is, the user can trust the moving distance and the average moving speed. It is possible to determine whether there is.

Further, in the portable distance / speed meter according to the present invention, a plurality of predetermined times for determining the convergence state of the average moving speed are set in the measurement / evaluation means 15,
In addition to evaluating whether or not the fluctuation of the average moving speed is within a predetermined amplitude range at each of the plurality of predetermined times, the display means 16 displays an evaluation result corresponding to each of the plurality of predetermined times in multiple stages. Therefore, the user can determine in multiple steps whether or not the moving distance and the average moving speed displayed on the same display means 16 are greatly influenced by the positioning error, that is, whether or not they can be trusted. It is possible to make a judgment.

Further, the portable distance / speed meter according to the present invention displays on the display means 16 a graph showing the fluctuation of the average moving speed calculated by the average moving speed calculating means 13, so that the user can use this graph. The convergence state of the average moving speed can be visually recognized from the graph.
It is possible to determine whether the moving distance and the average moving speed displayed in 6 are greatly affected by the positioning error, that is, whether they are reliable.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a portable distance / speed meter according to the present invention will be described below in detail with reference to the drawings. The present invention is not limited by the embodiment.

FIG. 2 is a block diagram showing the configuration of the portable distance / speed meter according to the embodiment. The portable distance / velocity meter shown in FIG. 2 receives a radio wave transmitted from a plurality of GPS satellites 20 and measures the longitude and latitude of the GPS receiver 2.
1 (refer to FIG. 7 for the schematic configuration), a CPU 24 for calculating the moving distance, moving speed and average moving speed of the user by performing various arithmetic processing described later, and an LCD (li).
and an LCD drive circuit 28 for controlling the display panel 27 composed of a liquid crystal display (LCD) to display the moving distance, the average moving speed, and an evaluation level described later on the display panel 27.

In FIG. 2, reference numeral 26 denotes a ROM in which an operation program of the CPU 24 is stored;
Reference numeral 4 denotes a RAM used as a work area, reference numeral 22 denotes an input switch for instructing start of distance / speed measurement, and the like, and reference numeral 23 denotes an OSC (oscillation circuit) for generating a reference frequency signal.

Next, the operation of the portable distance / speed meter constructed as described above will be described. FIG. 3 is a flowchart showing an operation of the portable distance / speed meter according to the embodiment. In FIG. 3, first, measurement of the user's moving distance, moving speed, average moving speed, and the like is started by the user operating the input switch 22 (step S1).
01). Then, initialization is performed by substituting the initial value 0 into a comparison target average speed va0 described later (step S10).
2).

Next, time counting of the time T is started by also using a time counting counter corresponding to the time counting means 14 shown in FIG. 1 or by using another time counting counter (step S103). Then, the speed is calculated from the Doppler frequency of the GPS radio wave obtained in the GPS receiver 10 (step S104), and the distance d is calculated by accumulating the speed (step S105). Specifically, this distance d is measured by the CPU 24 for a predetermined time using a time counter corresponding to the time measuring means 14 shown in FIG.
The speed is calculated by multiplying the speed determined from the Doppler shift by the measured predetermined time. In addition to using the Doppler shift, position information is obtained at each time corresponding to the start time and the end time of the above-described predetermined time, and the distance d is obtained from the difference between the obtained two position information.
May be calculated.

Therefore, when calculating the distance d, since the predetermined time is measured as described above, the speed v is calculated by dividing the calculated distance d by the predetermined time. (Step S106). Next,
An average speed va of the speed v calculated in step S106 is calculated (step S107). This step S
More specifically, 107 is performed by integrating the speed v calculated in the current step S106 with the speed v calculated in the step S106 up to the previous time, and dividing this integrated result by the number of times of integration.

The distance d and the average speed va calculated in steps S105 and S107 are displayed on the display panel 27 under the control of the LCD drive circuit 28 (step S108). Next, the average speed va calculated in step S107 is compared with the average speed va for comparison.
It is determined whether it is equal to 0 (step S109).
In practice, this determination is performed by setting a predetermined range width (amplitude due to the fluctuation of the average speed va) in advance, and then determining in step S10
The determination is made based on whether or not the average speed va calculated in step 9 is within the range of the upper and lower thresholds around the comparison target average speed va0 determined by the predetermined range width.

That is, the process of step S109 is for judging the state of the fluctuation of the average speed va calculated in step S107. When this fluctuation is within a predetermined range, that is, when the fluctuation is small, Speed v
It is assumed that a is a starting point at which convergence to the actual moving speed of the user starts.

In step S109, the average speed va
Is not equal to the average speed va0 to be compared, the average speed va calculated in step S109
Is substituted for the average speed va0 to be compared (step S11).
2), reset the time T of the time counter started in step S103 (step S113), return the processing to step S103 again, and calculate the distance d, velocity v, and average velocity va described above. repeat.

In step S109, the average speed va
Is determined to be equal to the comparison target average speed va0, a measurement evaluation process described later is performed (step S11).
0). After the process of step S110, it is determined whether or not the end of the measurement is instructed by the user operating the input switch 22 or the like (step S111). Step S11
In 1, when the end of the measurement is instructed, the processing shown in FIG. 3 is ended, and when the end of the measurement is not instructed, the processing from step S103 is repeated again.

(Measurement Evaluation Processing) Next, the measurement evaluation processing in step S110 will be described. FIG.
It is a flowchart which shows a measurement evaluation process. This measurement evaluation process determines whether or not the time T of the time counter started in step S103 of FIG. 3 has passed a predetermined time, and in response to the determination, determines the distance d and the distance d displayed on the display panel 27 in step S108. It is to evaluate whether the speed v is greatly affected by the GPS positioning error. In particular, in FIG. 4, a predetermined time set in advance for use in the determination of the time T is T0,
The evaluation result is divided into three stages of T1 and T2 (T0 <T1 <T2), and the evaluation result is represented by three evaluation levels 1 to 3 according to the value indicated by the time T.

In FIG. 4, first, in step S1 of FIG.
It is determined whether or not the time T started to count at 03 is longer than a predetermined time T2 (step S121). If the time T is equal to or shorter than the predetermined time T2 in step S121, it is determined whether the time T is longer than the predetermined time T1 (step S122). Then, step S12
If the time T is equal to or less than the predetermined time T1 in 2,
It is determined whether the time T is longer than the predetermined time T0 (step S123). Further, if the time T is equal to or shorter than the predetermined time T0 in step S123, it is determined that the average speed va has not converged, and the process proceeds to step S1 in FIG.
If the process returns to step 11 and the end of the measurement is not instructed,
Subsequently, the counting of the time T is continued.

If the time T is longer than the predetermined time T0 in step S123, a display indicating the evaluation level 1 is displayed on the display panel 27 (step S126). Step S
After the process at 126, the process returns to step S111 in FIG. 3 again, and if the end of the measurement is not instructed, the counting of the time T is continued.

If the time T is longer than the predetermined time T1 in step S122, a display indicating the evaluation level 2 is displayed on the display panel 27 (step S125). Step S
After the process at 125, the process returns to step S111 in FIG. 3 again, and if the end of the measurement is not instructed, the counting of the time T is continued.

If the time T is longer than the predetermined time T2 in step S121, a display indicating the evaluation level 3 is displayed on the display panel 27 (step S124). Step S
After the process at 124, the process returns to step S111 in FIG. 3 again, and if the end of the measurement is not instructed, the counting of the time T is continued.

FIG. 5 is a graph showing the relationship between the speed v (herein referred to as the instantaneous speed) calculated after the start of the measurement and the elapsed time and the relationship between the average speed va and the elapsed time. Note that this graph shows that the user has about 0.40 m /
It is an experimental result when walking in s. As shown in FIG. 5, the calculated instantaneous speed fluctuates at an irregular amplitude centered on the speed of 0.40 m / s.
This is based on the positioning error mainly caused by

In FIG. 5, the average speed va has begun to converge starting from the time when the elapsed time is around 1250 seconds. Therefore, in this experimental result, the time T measured by the time counter after the elapsed time from the start of the measurement becomes 1250 seconds is an important factor in the measurement evaluation processing shown in FIG. For example, FIG.
In the measurement / evaluation processing shown in FIG.
Are set to 50 seconds, 150 seconds, and 450 seconds, respectively, when the elapsed time reaches 1300 seconds in the graph of FIG.
When the time reaches 400 seconds, the display of the evaluation level 2 is performed,
When the elapsed time reaches 1700 seconds, the display of the evaluation level 3 is performed.

That is, an increase in the period during which the fluctuation of the average speed is small is closer to the average speed that converges, that is, the effect of the averaging becomes remarkable and is included in the obtained average speed. This indicates that the influence of the GPS positioning error is small. Therefore, the display of the evaluation levels 1 to 3 indicates the degree of the influence of the GPS positioning error in a stepwise manner, and presents the reliability of the distance d and the average speed va displayed on the display panel 27 to the user. is there.

FIG. 6 shows an evaluation level 1 for the display panel 27.
It is a figure which shows the example of a display of No.-3. In FIG. 6, the display panel 27 displays the average speed va calculated in step S107 in FIG.
The distance d calculated in step S105 of FIG.
Is displayed. Furthermore, the above-mentioned evaluation levels 1 to 3
Are displayed in stages as level bars L1 to L3.

Therefore, according to the embodiment of the present invention, the moving distance, the moving speed, and the average moving speed of the user are calculated based on the GPS radio waves obtained by the GPS receiver 10, and the calculated average moving speed is calculated. Is determined to have converged to the vicinity of the actual moving speed of the user when the fluctuation within the predetermined range has been continued for a predetermined time, and the calculated average moving speed is determined by the positioning error such as SA due to the positioning error. Since the display shows that the influence is not significantly included,
By visually recognizing this display, the user determines whether the moving distance or the average moving speed currently displayed on the display panel 27 is greatly affected by the positioning error, that is, whether the moving distance or the average moving speed is reliable. can do.

In the embodiment described above, in steps S104 and S105 of FIG. 3, the speed is calculated from the Doppler frequency of the GPS radio wave obtained by the GPS receiver 10, and the speed is calculated by accumulating the speed. The displayed distance d is displayed as a moving distance on the display panel 27, but a new distance is calculated using the average speed va calculated in step S107 in FIG. 3, and this distance is used as the moving distance of the user on the display panel 27. May be displayed.

In the above description, the evaluation result in the measurement and evaluation process is represented by three levels of evaluation levels 1 to 3. However, the display may be performed by other levels of evaluation levels. When only one stage is selected, for example, in addition to the display such as the level bars L1 to L3 in FIG. 6, an evaluation mark such as M3 in FIG. 6 can be displayed or blinked. .

[0041]

As described above, according to the present invention, the moving distance, moving speed and average moving speed of the user are measured based on the GPS radio wave transmitted from the GPS satellite, and the average moving speed is measured. Since the influence of the GPS positioning error on the average moving speed is evaluated based on the fluctuation and the evaluation result is presented, the user can determine whether the moving distance or the average moving speed displayed on the display means such as the display panel is the GPS positioning error. It is possible to judge whether or not it is greatly affected by the above, that is, whether or not it is credible.

Further, according to the present invention, a plurality of predetermined times for determining the convergence state of the average moving speed are set, and the fluctuation of the average moving speed falls within a predetermined amplitude range for each of the plurality of predetermined times. In addition to evaluating whether or not there is, the display means displays the evaluation results corresponding to each of the plurality of predetermined times in multiple stages, so that the user can use, for example, the moving distance and the average moving speed displayed on the same display means. However, it is possible to determine in a multi-step manner how much the positioning error is affected by the positioning error, that is, how reliable the positioning is.

Further, according to the present invention, a graph showing the fluctuation of the calculated average moving speed is displayed on the display means, so that the user can visually recognize the convergence state of the average moving speed from this graph. For example, it is possible to determine whether the moving distance or the average moving speed displayed on the same display means is greatly affected by the positioning error, that is, whether the moving distance or the average moving speed is reliable.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a portable distance / speed meter according to the present invention.

FIG. 2 is a block diagram showing a configuration of a portable distance / speed meter according to the embodiment.

FIG. 3 is a flowchart showing an operation of the portable distance / speed meter according to the embodiment.

FIG. 4 is a flowchart illustrating a measurement evaluation process according to the embodiment.

FIG. 5 is a graph showing a relationship between an instantaneous speed and an elapsed time and a relationship between an average speed and an elapsed time.

FIG. 6 is a diagram showing an example of display of an evaluation level according to the embodiment.

FIG. 7 is a diagram showing a schematic configuration of a conventional GPS receiver.

[Explanation of symbols]

 10, 21 GPS receiver 11 Moving distance calculating means 12 Moving speed calculating means 13 Average moving speed calculating means 14 Clocking means 15 Measurement evaluating means 16 Display means 20 GPS satellite 22 Input switch 23 OSC 24 CPU 25 RAM 26 ROM 27 Display panel 28 LCD drive circuit

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Hideaki Nagasuma 1-8 Nakase, Mihama-ku, Chiba-shi AC12 AD02 5J062 AA09 AA11 AA12 AA13 BB05 CC07 DD05 EE04

Claims (4)

[Claims] 1. A moving distance, a moving speed, and an average moving speed of a user are measured based on a GPS radio wave transmitted from a GPS satellite, and a GPS positioning error at the average moving speed is measured based on the fluctuation of the average moving speed. A portable distance / velocity meter that evaluates an influence and presents the evaluation result. 2. A portable distance / speed meter having a GPS receiver for receiving a GPS radio wave transmitted from a GPS satellite and calculating a position or a moving speed of a user based on the received GPS radio wave, Moving distance calculating means for calculating the moving distance of the user based on the calculation result in the machine; time measuring means for measuring the moving time of the user at the moving distance; moving distance calculated by the moving distance calculating means; Moving speed calculating means for calculating the moving speed of the user based on the moving time measured in the above, and mean moving speed calculating means for calculating the average moving speed of the user based on the moving speed calculated by the moving speed calculating means. And a variation within a predetermined time of the average moving speed calculated by the average moving speed calculating means is within a predetermined amplitude range. Whether the measurement evaluating means for evaluating the portable distance and speed meter characterized by comprising a display means for displaying the evaluation results of the measurement evaluating means. 3. The measuring and evaluating means sets a plurality of the predetermined times, evaluates whether or not the fluctuation of the average moving speed is within a predetermined amplitude range at each of the plurality of predetermined times, and displays the display. 3. The method according to claim 2, wherein the display unit displays an evaluation result corresponding to each of the plurality of predetermined times in multiple stages.
Portable distance and speedometer described in. 4. A portable distance / velocity meter having a GPS receiver for receiving a GPS radio wave transmitted from a GPS satellite and calculating a position or a moving speed of a user based on the received GPS radio wave, Moving distance calculating means for calculating the moving distance of the user based on the calculation result in the machine; time measuring means for measuring the moving time of the user at the moving distance; moving distance calculated by the moving distance calculating means; Moving speed calculating means for calculating the moving speed of the user based on the moving time measured in the above, and mean moving speed calculating means for calculating the average moving speed of the user based on the moving speed calculated by the moving speed calculating means. And display means for displaying a graph showing the variation of the average moving speed calculated by the average moving speed calculating means. Portable distance and speed meter characterized by comprising a.