JPS63250584A - World clock - Google Patents

Abstract

PURPOSE:To automatically determine the local time at a certain point of place by making calculation as to what time zone the present place belongs time in accordance with the longitude and latitude in a receiver position calculated by the GPS (Global Positioning System) built in the timepiece. CONSTITUTION:The receiver 1 which receives the radio waves from the GPS satellite is built in the timepiece and the longitude and latitude of the position of the receiver 1 are determined by a processor 2. Calculation is made as to which time zone the present place belongs to by a processor 3 which converts the standard time to the local time in accordance with the longitude and latitude obtd. in such a manner. The local time is obtd therefrom. The time zone is the territory depending on the borders or state borders of various countries of the world. The closed territories of the respective time zones are stored in the form of approximation to segment lines in a memory 6. The longitude range of the respective time zones corresponding to the latitude is determined with respect to the given position of the receiver 1. The local time is determined as the corresponding time zone if the latitude of the given position of the receiver 1 exists in the prescribed range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a world clock, that is, a clock having a function of automatically determining the local time at any point on the earth.

[Conventional technology]

GPS (Global Positioning) enables high-precision positioning in real time worldwide.
As is well known, GP
The observation equation regarding the user position obtained from the S satellite is
R=p−cδtU+cδtA+n (1)
R=C(TR-TB-δts)...-(
2)...(3). The meanings of the symbols used here are as follows.

R: Observed pseudorange ρ: True distance C: Speed of light δtU: Difference between GPS system time and user clock time δtA: Radio wave propagation delay due to atmospheric influence (electronic layer, troposphere) n: Receiver noise, etc. Random component observation noise (XGr y, + zS)" GPS satellite position at signal transmission time (x + y + z): User receiver position at signal reception time T9: Signal transmission time TI (= user reception Signal reception time δt8 based on the device's clock: Since the difference TR and T6 between the GPS system time and the GPS satellite onboard clock is given by the satellite and receiver clocks, δiUtδ and δt8 must be determined by some means. GPS satellites must be
The data necessary to calculate U+δ and (xsyysyZs) is sent to the user as a positioning message.

Of the clock errors, for the clock error of the user receiver, in GPS, the user's clock bias δtU
Ha, user rank! (X, y, z) are estimated as unknown parameters.

There are two methods for estimating the unknown parameters: one is to solve the four parameters including the clock bias in a batch manner from the observation equations for the four satellites, and the other is to solve the Kalman filter or the covariance matrix P in the Kalman filter using an upper triangular matrix U and a diagonal matrix. A method has been proposed in which the user position and velocity are sequentially estimated by decomposing the solution into <UD filter.

In the former case, δ1U is modeled as a bias amount,
In the latter case, two unknown parameters, a clock bias error term and a frequency bias error term, are estimated considering that δtU changes over time. On the other hand, user number 1
Since it (x, y, z) is a fixed coordinate system centered on the earth, latitude and longitude can be determined from it. Furthermore, since the GPS system time is given in Greenwich Mean Time and is very accurate, the GPS signal reception time is given as TR-δt8.

The above is the method for calculating the position, ie, latitude, longitude, and time, ie, Greenwich Mean Time, when using GPS satellites.

In addition, related to this type of device.

For example, the one disclosed in Japanese Patent Application Laid-open No. 1668112/1984 can be cited.

[Problem that the invention seeks to solve]

The above-mentioned prior art provides a method for calculating the position, ie, latitude and longitude, and time, ie, Grignisogi Mean Time, when using GPS satellites.

5 However, as a practical matter, it is often desirable to find the local time at a certain point. in this case,
In the above-mentioned prior art, there was a problem in that the time of the Greenwich mark that was determined had to be converted based on the local location, that is, the latitude and longitude.

The present invention has been made in view of the above circumstances, and its purpose is to solve the above-mentioned problems in the conventional technology and to provide a world clock that can automatically determine the local time at a certain point. It's about doing.

[Means for solving problems]

The above-mentioned object of the present invention is to provide a clock circuit for a watch and a GP
A means for receiving radio waves from an S satellite, a processing device for calculating a self-position and a standard time at the position based on the received radio waves, and a processing device for converting the standard time into local time based on the latitude and longitude of the self-position. This is achieved by a world clock characterized in that it has a processing device.

[Effect]

The world clock of the present invention (hereinafter simply referred to as the "clock") determines which time zone the local area belongs to based on the latitude and longitude information of the receiver position calculated by the GPS receiver built into the clock. The local time is determined from this calculation.

The above-mentioned time zones, as shown in part in FIG. 2, are areas that depend on the borders and state borders of countries around the world. In the present invention, the closed regions of each time zone described above are stored in a memory in the form of piecewise linear approximation, and a given receiver position [
For (ua, ao), the longitude range Coo', no') of each time zone i corresponding to the corresponding latitude Q6 is calculated. and the longitude Q of the given receiver position. is within the range of [2° + Qo')t, the local time is determined using i as the corresponding time zone.

In this way, by first fixing the latitude fl and checking only the time zone range of longitude with respect to Q, time zone detection processing can be easily performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a timepiece that is an embodiment of the present invention.

In the figure, A is the aforementioned GPS satellite, 1 is GPS satellite A
2 is a processing device that performs positioning calculations based on the received signal; 3 is a processing device that processes a clock function; 4 is a display device; 5 is an input device; indicates memory.

An overview of the operation of the clock of this embodiment configured as described above is as follows.
It is as follows.

A receiver 1 receives a signal from a GPS satellite A, and a processing device 2 performs positioning calculations based on the content of the received GPS signal. The calculated receiver position coordinates (x+y+z) or latitude and longitude information (Q a, Q o) and the clock bias value δtB are sent to the processing device 3 that processes the clock function.

The processing device 3 displays the latitude and longitude information of the receiver position and the time according to the input contents from the input device 5. Hereinafter, the function of converting latitude and longitude to local time performed by the processing device 3, which is the main part of this embodiment, will be explained.

First, a method of storing time zone information in the memory 6 will be described. The time zones are as shown in Figure 2.
It is generally represented as a closed region. Therefore, as illustrated in FIG. 3, by approximating one time zone i by a piecewise linear model with N□ points, the time zone i is stored in the memory 6 in a table format as shown in FIG. Information can be stored.

Based on the time zone information, the processing device 2
Latitude and longitude CQa-Qo obtained by processing PS signals)
The flowchart in FIG. 5 shows the procedure for finding the relevant time zone and converting it to local time. This will be explained below with reference to FIG.

First, each time zone is searched for the given latitude Q4. For Q, check the magnitude relationship with Ql, Q〉re, Ql;l<re, or Qj:<Qa,
Points with the relationship Q'a'>Qa are extracted.

For such a set of points, the two given latitudes are:
As shown in FIG. 7, it is always between the i-th and i+1-th points. The longitude 2° relative to the latitude Q4 on the i-th a (line indicating latitude) is given by:

In the case of a closed area, there are generally multiple corresponding locations as described above, so arrange them in descending order and calculate the given latitude for each time zone, as in (not Qo]=rCQo+Qo]f+"" In step 11), a table as shown in FIG. 6 is created. Here, the number on the right shoulder indicates the number of longitude range.

Once the table shown in FIG. 6 is created, as understood from FIG. 2, the longitude ranges in FIG. 6 at the same latitude do not intersect, so for a given longitude Q0, Ω. There is always one time zone that contains . By searching the table in Figure 6, the above Qo
Since the time zone in which the time zone is included is known (step 12), the deviation of local time from Greenwich Mean Time can be easily detected.

The clock shown in this embodiment has a function of determining the local time from latitude and longitude using the procedure described above, so that when the local time display mode is input from the input device 5 shown in FIG. , the latitude and longitude calculated by the processing device 2, the GPS satellite signal transmission time jG, the reception time j8y of the ground clock built in the processing device 3, the calculated clock bias δ, and the current clock time t.

Since the GPS time (the time that all satellites use as a reference) is Greenwich Mean Time, the Greenwich time T of the current clock time is T=(t-t9)+(ts+δt)=t+δ.

It is. The time zone is calculated from the loaded latitude and longitude data, and from this the difference δT between the local time and Greenwich time is determined, and the local time T, =T+δT is determined. By outputting this information to the display device 4, this watch can display local time all over the world.

According to the above embodiment, in a watch composed of a GPS receiver and a clock, the local time can be automatically calculated from the latitude and longitude of the self-position obtained from the GPS receiver, so that it can be used for one person's portable time. Of course, by adopting this as a clock mounted on aircraft, ships, satellites, etc. that travel around the world, it is effective to enable mobile objects to automatically detect the local time.

The time zone piecewise linear model data shown in Fig.
gT 1lae), it is also possible to prepare two types of tables, one for winter and one for summer, and to switch between them by switching from the input device 5.

It goes without saying that other methods may be used to store the time zone data in the memory.

〔Effect of the invention〕

As described above, according to one aspect of the present invention, a clock circuit for a world clock, a means for receiving radio waves from a GPS satellite, and a processing device for calculating a self-position and a standard time at the position based on the clock circuit. and a processing device that converts the standard time to local time based on the latitude and longitude of its own location, thereby realizing a world clock that can automatically determine the local time at a certain point. This has the remarkable effect of making it possible to

[Brief explanation of drawings]

Fig. 1 is a block configuration diagram of a clock that is an embodiment of the present invention, Fig. 2 is a diagram showing some of the time zones on the earth, and Fig. 3 is a block diagram of a clock that is an embodiment of the present invention.
The figure shows a piecewise linear model. Fig. 4 is a diagram showing a time zone information table, Fig. 5 is a flowchart showing a procedure for detecting a time zone and converting it to local time, Fig. 6 is a diagram showing a time zone longitude range calculation table, Fig. 7 is an explanatory diagram of the procedure of longitude calculation. A: GPS satellite, 1: receiver, 2, 3: processing device,
4: Display device, 5: Input device, 6: Memory, 1st
Figure 2 Figure 3 Figure 7 (Pe, l old) Figure 5

Claims (1)

[Claims] 1. A clock circuit for a watch, a means for receiving radio waves from a GPS satellite, a processing device for calculating a self-position and a standard time at the position based on the radio waves, and a latitude of the self-position. ,
A world clock comprising: a processing device that converts the standard time to local time based on longitude. 2. A processing device that converts standard time to local time based on the latitude and longitude of the self-location, approximates the time zone region with a polygonal line, stores it in memory, and calculates the longitude range of each time zone with respect to the latitude of the corresponding location. 2. The world clock according to claim 1, wherein the world clock has a function of determining to which time zone a corresponding position belongs by calculating .