Abstract:
Disclosed is an information processing apparatus including a device for measuring a position, a time generator for generating time data representing times of day at which the positions are measured, a storage for storing data constituted by the measured position measuring and by an output of the time generator, the two outputs having an associative relation established therebetween, and an outputting device for outputting the stored data from the storage to an external entity.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to an information processing apparatus and method, and a program storage medium. More particularly, the invention relates to an information processing apparatus and method whereby measured position data and time data are acquired from satellites and stored, as well as to a program storage medium which accommodates a program constituting the method for use with the apparatus. 
     Recent years have seen the widespread acceptance of apparatuses for capturing, storing and processing images through the use of digital technology. Generally, images such as those taken by digital camera are later arranged by date, grouped into predetermined categories or otherwise sorted out by users. Such follow-up classification of images requires information about where and when the images were captured. 
     The need for image-classifying information is met illustratively by methods for associating data representing images taken by digital camera or by other means with data about where and when the image data were acquired. One such method, proposed by Japanese Patent Laid-open No. Hei 10-233985, utilizes a digital camera and a GPS (Global Positioning System) device to obtain (i.e., store) positions at which images were captured. According to this method, the GPS device is connected to the digital camera so that position information acquired by the GPS device is stored in association with the image data taken by the digital camera. 
     It is possible to incorporate position data into image data by connecting a GPS device to a digital camera as proposed by the method above. However, if the digital camera has no means of connecting with a GPS device, there is no way of acquiring the position data. 
     The present invention has been made in view of the above circumstances and provides an information processing apparatus and method as well as a program storage medium allowing position and time-of-day information to be stored into a GPS device in such a manner that the stored information is later associated with captured image data through a personal computer or the like, whereby users may edit the image data easily. 
     SUMMARY OF THE INVENTION 
     In carrying out the invention and according to one aspect thereof, there is provided an information processing apparatus comprising: a position measuring element for measuring positions; a time generating element for generating time data representing times of day at which the positions are measured by the position measuring element; a storing element for storing data constituted by an output of the position measuring element and by an output of the time generating element, the two outputs having an associative relation established therebetween; and an outputting element for outputting the stored data from the storing element to an external entity. 
     According to another aspect of the invention, there is provided an information processing method comprising the steps of: measuring positions; generating time data representing times of day at which the positions are measured in the position measuring step; and storing data constituted by an output of the position measuring step and by an output of the time generating step, the two outputs having an associative relation established therebetween. 
     According to a further aspect of the invention, there is provided an information processing method comprising the step of: outputting, to an external entity, position data representing measured positions and time data representing times of day at which the position data are obtained, the position data and the time data having been stored with an associative relation established therebetween. 
     According to an even further aspect of the invention, there is provided a program storage medium which stores a program for causing an information processing apparatus to execute the steps of: measuring positions; generating time data representing times of day at which the positions are measured in the position measuring step; and storing data constituted by an output of the position measuring step and by an output of the time generating step, the two outputs having an associative relation established therebetween. 
     According to a still further aspect of the invention, there is provided a program storage medium which stores a program for causing an information processing apparatus to execute the step of: outputting, to an external entity, position data representing measured positions and time data representing times of day at which the position data are obtained, the position data and the time data having been stored with an associative relation established therebetween. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be described in detail with reference to the following figures wherein: 
     FIG. 1 is a schematic view outlining a typical configuration of an information processing. system embodying the invention; 
     FIG. 2 is a block diagram showing an internal structure of a personal computer included in FIG. 1; 
     FIGS. 3A through 3D are schematic views sketching an appearance of a GPS device included in FIG. 1; 
     FIG. 4 is an explanatory view of the GPS device as it is attached to the personal computer; 
     FIG. 5 is an explanatory view showing a user carrying the GPS device around; 
     FIG. 6 is a block diagram depicting an internal structure of the GPS device; 
     FIG. 7 is an explanatory view of switches in the GPS device; 
     FIG. 8 is a flowchart of steps in which the GPS device operates; 
     FIG. 9 is a flowchart of steps detailing the process in step S 4  of FIG. 8; 
     FIGS. 10A,  10 B and  10 C are explanatory views of log data to be stored into the GPS device; 
     FIG. 11 is a flowchart of steps detailing the process in step S 23  of FIG. 9; 
     FIG. 12 is a flowchart of steps detailing the process in step S 7  of FIG. 8; 
     FIG. 13 is a flowchart of steps detailing the process in step S 9  of FIG. 8; 
     FIG. 14 is a flowchart of steps detailing the process in step S 77  of FIG. 13; 
     FIG. 15 is a flowchart of steps detailing the process in step S 78  of FIG. 13; 
     FIG. 16 is a timing chart in effect when the GPS device is activated continuously; 
     FIG. 17 is a timing chart in effect when the GPS device is activated intermittently; 
     FIG. 18 is a timing chart showing how the GPS device works when the mark button is operated; 
     FIG. 19 is a flowchart of steps performed by the GPS device connected to the personal computer; 
     FIG. 20 is a flowchart of steps detailing the process in step S 136  of FIG. 19; 
     FIG. 21 is a flowchart of steps detailing the process in step S 158  of FIG. 20; 
     FIG. 22 is a flowchart of steps detailing the process in step S 175  of FIG. 21; 
     FIG. 23 is a schematic view of a typical screen appearing on a display  19 ; 
     FIG. 24 is a schematic view of a typical screen that appears when an interval setting field is operated; 
     FIG. 25 is a schematic view of a typical error message generated in case of an error during data exchanges between the personal computer and the GPS device; 
     FIG. 26 is a schematic view of a data transfer indication window that appears during data exchanges between the personal computer and the GPS device; 
     FIG. 27 is an explanatory view of a typical image file structure; 
     FIG. 28 is a flowchart of steps performed by the personal computer  4  when specifying positions where image data were acquired; 
     FIG. 29 is an explanatory view of log data; 
     FIG. 30 is an explanatory view showing how an image capture position is illustratively estimated; and 
     FIG. 31 is an explanatory view of storage media for use with the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a schematic view outlining a typical configuration of an information processing system embodying the invention. A GPS device  1  receives signals from satellites, not shown, analyzes the received signals to compute positions of reception (latitude and longitude), and stores the computed position information. Satellites usually carry an atomic clock each so that the GPS device  1  may acquire time information from the signal received therefrom. The time information thus obtained is also stored. In the description that follows, the information comprising position and time information stored in the GPS device  1  will be referred to as log data. A digital camera  2  captures images of subjects, and stores data constituting the captured images onto a storage medium such as a floppy disk  3  (the images captured by the digital camera  2  are hereunder assumed to be stored on the floppy disk  3 ). 
     Besides the floppy disk  3 , other storage media such as a portable semiconductor memory  5  may be used to accommodate the images taken by the digital camera  2 . If the digital camera is equipped with a communication function, the captured image data may be transmitted through the function to another device for storage therein. 
     A personal computer  4  is connected to the GPS device  1  through a USB (Universal Serial Bus) cable and is fed with log data from inside the GPS device  1 . The personal computer  4  may also be connected to the digital camera  2  through a USB cable. Thus connected, the personal computer  4  may read image data from the digital camera  2 . It is also possible for the personal computer  4  to retrieve image data from the floppy disk  3 . 
     FIG. 2 is a block diagram showing an internal structure of the personal computer  4 . A CPU  11  of the personal computer  4  carries out various processes in accordance with programs held in a ROM (read only memory)  12 . A RAM (random access memory)  13  accommodates data and programs that may be needed by the CPU  11  during process execution. An input/output interface (I/O)  14  is connected with a keyboard  15  and a mouse  16 , sending signals from these components to the CPU  11 . The I/O interface  14  is also connected with a floppy disk drive (FDD)  17  and a hard disk drive (HDD)  18  so that data and programs are written and read thereto and therefrom. The I/O interface  14  is further connected with a display  19  as well as with the GPS device  1  via a USB port  20 . An internal bus  21  interconnects these components. 
     FIGS. 3A through 3D are schematic views sketching an appearance of the GPS device  1 . FIG. 3A is a front view, FIG. 3B is a back view, FIG. 3C is a right-hand-side view, and FIG. 3D is a bottom view, of the GPS device  1 . The GPS device  1  is made up of an antenna  31  and a body  32 . The antenna  31  is attached to the body  32  in a backward swiveling manner. The body  32  is furnished with a GPS lamp  33 , a REC lamp  34  and a POWER lamp  35 , as well as a mark button  36  and a power button  37 . A PC hook  38  is also provided on the body  32 . 
     The PC hook  38 , used to attach the,GPS device  1  to a notebook type personal computer  4  (mobile computer), moves in an extendable and retractable manner with respect to the body  32 . Although FIG. 3C shows the PC hook  38  being extended (extracted) away from the body  32 , the PC hook  38  is usually retracted into the body  32  to avoid interference with nearby objects. Loaded with a spring (not shown), the PC hook  38  retracts by itself into the body  32  when released from its manually extended position. 
     The PC hook  38 , extended from the body  32  as shown in FIG. 3C, clips the GPS device  1  onto a notebook type personal computer  4 . More specifically, with the personal computer  4  opened as depicted in FIG. 4, an edge of the display  19  is sandwiched between the extended PC hook  38  and the body  32 . The components attach the GPS device  1  onto the personal computer  4 . Since the PC hook  38  is loaded with the spring as mentioned, the extended hook puts a certain amount of pressure onto the display  19  against the body  32  to prevent the GPS device  1  from falling in case of an impact or vibrations exerted on the computer  4 . 
     When the GPS device  1  is clipped onto the personal computer as shown in FIG. 4, they may constitute a navigation system used illustratively on vehicles. The personal computer  4  is made to execute an application program that runs the navigation system. The application program in operation causes the display  19  illustratively to indicate a map containing the current position of the system. Data for displaying the current position are computed using position information acquired by the GPS device  1 . Where the personal computer  4  and GPS device  1  are used as the navigation system, the antenna  31  attached pivotally to the body  32  may be suitably adjusted in angle relative to the body  32  before being fixed (i.e., at an optimal angle for receiving signals from satellites), as illustrated in FIG.  4 . 
     The GPS device  1  may be carried around by a user. In such a case, the user may retract the PC hook  38  into the body  32  to avoid interference with nearby objects. A strap may be threaded through a strap buckle  39  (FIG. 3B) on the device body, and the strap may be passed around the user&#39;s neck or hooked onto his belt for carrying purposes. Illustratively, as sketched in FIG. 5, the user may thread a long strap through the strap buckle  39  to hang the GPS device  1  from his neck for portable use. 
     As shown in FIG. 3B, the GPS device  1  has a battery lid  40  on its back. Displacing the battery lid  40  rightward as seen in FIG. 3B opens the lid. Either primary or second batteries may be used. The GPS device  1  may be designed to have a function for letting secondary batteries be recharged while they are being loaded in the device  1 . The GPS device  1  also has a USB port  42  allowing the device  1  to exchange data with the personal computer  2 . 
     FIG. 6 is a block diagram showing an internal structure of the GPS device  1 . As mentioned above, the GPS device  1  is composed of the antenna  31  and the body  32 . The body  32  includes circuits that carry out diverse processes. FIG. 6 depicts blocks that functionally categorize these circuits. An operation unit  51  includes the mark button  36  and power button  37  manipulated by the user to effect desired operations. A storage unit  52  stores log data. 
     A control unit  53  generates log data based on signals received through the antenna  31 , stores the log data thus generated, and performs processes to address signals coming through the USB port  42  or from the operation unit  51 . A power supply unit  54  supplies the necessary components of the GPS device  1  with power derived from batteries or from the personal computer  4  via the USB port  42 . A counter unit  55  performs time management, manages various counter value&#39;s (to be described later), and feeds the management information to the control unit  53 . 
     The GPS device  1  has three defined modes: GPS mode, PC mode, and storage mode. The GPS mode is selected when the GPS device  1  is connected to the personal computer  4  for use as a GPS signal receiving antenna of a navigation system. The PC mode is selected when the GPS device  1  outputs log data from the storage unit  52  or establishes various settings as instructed by the personal computer  4  connected to the GPS device  1 . The storage mode is selected illustratively for the GPS device  1  to be carried around by the user with log data held in the storage unit  52 . 
     The storage mode is further classified into three states: wake state, sleep sate, and wake-up sate. The wake state is a state in which data are being stored. In the sleep state, data storing operations are being halted. The wake-up state is a state in which the GPS device  1  is roused temporarily from its sleep state to perform a data storing operation before going back to the sleep state. 
     The GPS device  1  has switches built inside. These switches are operated by the control unit  53  depending on which of the three modes above is currently selected. More specifically, the GPS device  1  has switches  61  and  62  furnished as shown in FIG.  7 . In the GPS mode, the control unit  53  connects the switch  61  to a terminal A 1  and the switch  62  to a terminal B 1 . 
     In the PC mode, the switch  61  is connected either to the terminal A 1  or to a terminal A 2  while the switch  62  is connected to a terminal B 2 . In the PC mode, the GPS device  1  operates in keeping with commands from the personal computer  4 . If a command tells the GPS device  1  to act as a GPS instrument (i.e., to output signals received by the antenna  31 ), then the switch  61  is connected to the terminal A 1 ; if a command instructs the GPS device  1  to output log data from the storage unit  52 , then the switch  61  is connected to the terminal A 2 . The switch  61  is forcibly connected (as part of initialization) to the terminal A 1  if the GPS device  1  is judged to be currently capable of communicating (data) with the personal computer  4 ; otherwise the switch  61  is connected to the terminal A 2 . 
     In the storage mode, the control unit  53  connects the switch  61  to the terminal A 2 . Since the GPS device  1  is disconnected from the personal computer  4  when the storage mode is in effect, the switch  62  may be connected either to the terminal B 1  or to the terminal B 2  with no operative difference resulting from the two settings. Thus the switch  62  is connected to the terminal B 1  by default in the storage mode. 
     How the GPS device  1  works will now be described by referring to the flowchart of FIG.  8 . The steps making up the flowchart of FIG. 8 are performed when the GPS device  1  is not connected with the personal computer  4 , i.e., when the storage mode is in effect. Neither the GPS mode nor the PC mode applies to the workings here. 
     In step S 1  of FIG. 8, the control unit  53  checks to see if the power button  37  is operated. The process of step S 1  is repeated until the power button  37  is judged to be operated (i.e., the GPS device  1  maintains its status until the power button  37  is operated). If the power button  37  is judged to be operated, step S 2  is reached. In step S 2 , a check is made to see if the wake state is selected. 
     If in step S 2  the wake state is judged to be in effect, i.e., if the GPS device  1  is already turned on and its power button  37  is operated with log data being stored, then step S 3  is reached. In step S 3 , a check is made to see if the power button  37  is being actuated longer than three seconds. The period of three seconds is cited here merely as a typical reference value; other duration in seconds may be adopted instead. The reference value is established to serve as a criterion by which to pick one of several possibilities: the power button  37  may have been operated to turn on or off the GPS device  1 ; the power button  37  may have been actuated to execute a process of step S 7  (to be described later); or the power button  37  may have been activated inadvertently while the device is being carried around strapped illustratively to the user&#39;s belt (operational error). 
     If in step S 3  the power button  37  is not judged to be actuated longer than three seconds, an,operational error is recognized and no action takes place. If the power button  37  is judged to be actuated longer than three seconds in step S 3 , then step S 4  is reached in which a power-off process is carried out. 
     FIG. 9 is a flowchart of steps detailing the power-off process in step S 4 . When the power-off process is initiated, the supply of signals from the antenna  31  is stopped in step S 21 . In step S 22 , an end flag is set to 1. A structure of log data to be stored is explained hereunder. One piece of log data is formed as a 19-byte fixed-length data item, as shown in FIG.  10 A. The byte size, to be discussed below, is merely an example and may be replaced by any other suitable byte size. 
     Of the 19 bytes making up each log data item, one byte is assigned to flag data, 17 bytes are allocated to a log data body, and the remaining one byte is apportioned to status data. The flag data have a data structure shown in FIG.  10 B. In the single byte flag data, a start flag, an end flag, a mark flag and an O/G flag are each assigned one bit; the remaining four bits are set aside as dummies. 
     The start flag is set to 1 when indicating the first log data item recorded with the storage mode brought into effect; otherwise (i.e., when the data item in question is the second or subsequent data item recorded with the storage mode in effect), the start flag is set to 0. In like manner, the end flag is set to 1 when indicating the last log data recorded in the storage mode; otherwise the end flag is set to 0. 
     The mark flag is set to 1 when indicating a logo data item recorded by operation of the mark button  36  (to be described later in detail); otherwise the mark flag is set to 0. 
     If the O/G flag is set to 1 while the start flag is at 0, that means the log data item in question is not data stored in the current storage mode but the most recently stored data from the previous storage mode. If the O/G flag is set to 0 while the start flag is at 0, that means the stored log data item is data recorded in the current storage mode. If the O/G flag is set to 1 while the start flag is at 1 (i.e., if the flags indicate the first log data item recorded in the current storage mode), that means the log data are those recorded from beginning to end in the Tokyo geodetic system. If the O/G flag is set to 0 while the start flag is at 1, that means the log data are those stored from beginning to end in the World Geodetic System (WGS84). 
     The log data body is structured as shown in FIG.  10 C. Of the 17 bytes constituting the data body, 6 bytes stand for a time of day, 0.5 bytes for latitudinal and longitudinal hemispheres, 3.5 bytes for a latitude, 4 byte for a longitude, 1.5 bytes for a velocity, and 1.5 bytes for an azimuth. 
     The time of day is defined in terms of year, month, day, hours, minutes, and seconds based on UTC (Universal Time Coordinated). The latitudinal and longitudinal hemispheres are defined by the following data: if the most significant bit is 0, that means subsequent latitudes are in the north; if the MSB is 1, that means subsequent latitudes are in the south; if the bit next to the MSB is 0, that means subsequent longitudes are in the east; if the bit next to the MSB is 1, that means subsequent longitudes are in the west. 
     The latitude is given as seven-digit numeric data and the longitude is indicated as eight-digit numeric data. The velocity is given as three-digit numeric data in increments of one Km/h. The azimuth designates the direction in which the user is advancing and is defined by three-digit numeric data in increments of one degree in a clockwise 360-degree range with the true north set for 0. 
     Returning to the flowchart of FIG. 9, the end flag in the log data is set to 1 in step S 22 . In step S 22 , a storage process is performed. FIG. 11 is a flowchart of steps detailing the storage process. This process is carried out to have the above-described log data generated and placed into the storage unit  52  (FIG.  6 ). 
     In step S 32  of FIG. 11, the control unit  53  checks a writable area in the storage unit  52 . Specifically, a check is made to see if the writable area has enough space to accommodate one log data item, i.e., a 19-byte space in this example. If the writable area is judged to be less than 19 bytes long, step S 32  is reached in which the REC lamp  34  is illuminated. The REC lamp  34  is illustratively red in color and remains lit red as long as log data cannot be stored due to a lack of the writable area. 
     If in step S 31  the writable area of the storage unit  52  is judged to have sufficient space to accommodate the log data, step S 33  is reached. In step S 33 , the above-described log data are generated and written to a designated address in the storage unit  521 . In step S 34 , an address is set at which to store the next log data. Specifically, the address value is incremented by 19. 
     With the log data thus stored, step S 35  is reached in which the REC lamp  34  is lit for 0.1 second to notify the user of the data storage. In step S 36 , a check is made to see if the writable area has fallen short of a caution level. If the available area in the storage unit  52  is judged to have dropped below the caution level, a process is carried out to notify the user thereof. The default caution level is set for 10 percent of the capacity of the storage unit  52  (i.e., space to store log data). The caution level may be modified by the user in a manner to be described later. 
     The storage unit  52  may illustratively have a capacity large enough to store log data every second for up to 7.5 hours. In that case, the capacity of the storage unit  52  amounts to 513,000 bytes (=19 bytes×60 seconds×60 minutes×7.5 hours). If the caution level is set for 10 percent of the capacity, the level is then established at 51,300 bytes. 
     If in step S 36  the writable area is judged to be less than the caution level, step S 37  is reached. In step S 37 , the REC lamp  34  keeps blinking at intervals of 0.3 seconds, informing the user that the available area in the storage unit  52  is being exhausted. In step S 38 , a beep sound is emitted as a warning. Although the beep may sound in any tone, in any volume and in whatever melody, the sound emission should preferably be characterized by different melodies and tones depending on the current status of the GPS device  1  so that the user immediately recognizes what is happening upon hearing the sound. Illustratively, a continuous beep emission “bleep, bleep, bleep, . . . ” may be used to warn that the capacity of the storage unit  52  is getting exhausted. 
     Suppose that the user is given such a warning of a shortage in the writable area of the storage unit  52  and still fails to take action such as one to end the storage operation or to erase unnecessary log data, thus continuously storing log data and eventually letting the writable capacity of the storage unit  52  be totally exhausted. In that case, the GPS device  1  is switched off, and the stored log data are held intact unless otherwise specified by the user. There is no possibility of any stored log data forcibly or inadvertently erased or made unavailable to the user at a later date. 
     If in step S 36  the writable area is judged to be higher than the caution level, the processes of steps S 37  and S 38  are skipped, and the storage process is brought to and end. 
     With the storage process terminated step S 24  (FIG. 9) is reached in which all lamps are turned off. More specifically, the GPS lamp  33 , REC lamp  34  and POWER lamp  35  are switched out of their lighted or blinking state. In step S 25 , a beep sound is emitted to notify the user that the power-off process has ended. The beep may illustratively have a melody of “(two consecutive) bleep, bleep.” 
     Returning to the flowchart of FIG. 8, suppose that the check in step S 2  has revealed that the wake state is not in effect. In that case, step S 5  is reached in which a check is made to see if the sleep state is selected. If in step S 5  the sleep state is judged to be selected, step S 6  is reached. In step S 6 , as in step S 3 , a check is made to see if the power button  37  is being actuated longer than three seconds. If in step S 6  the power button  37  is judged to be actuated longer than three seconds, step S 4  is reached. Step S 4  has already been discussed and will not be described here further. 
     If in step S 6  the power button  37  is not judged to be actuated longer than three seconds, step S 7  is reached in which a wake-up process is carried out. FIG. 12 is a flowchart of steps detailing the wake-up process. 
     In step S 51  of FIG. 12, the control unit  52  performs initialization preparatory to starting log data storage. The initialization illustratively involves getting ready for receiving signals through the antenna  31  after leaving the sleep state in which the supply of signals received via the antenna  31  was halted (i.e., supply of power to the antenna  31  was stopped). 
     In step S 52 , the POWER lamp  35  is lit green to notify the user that the wake-up state is selected. The POWER lamp  35  is illuminated (or blinks) either green or red depending on the status of the device. Likewise the GPS lamp  33  is lit (or blinks) either green or red depending on the status of the device. Other colors may be adopted for the illumination. In this example, the colors of green and red are assumed to be used for purpose of illustration. 
     In step S 53 , a beep sound is emitted to notify the user that the wake-up state is now in effect. The beep may illustratively have a melody of “(a single) bleep” 
     When ready to store log data, the GPS device  1  enters the wake state for along as a predetermined wake time in which log data may be stored. The wake time is a period of time in which the sleep state is canceled (to continue the wake-up state). The user may set the sleep state for a desired period of time in a process to be described later. A default wake time period of, say, 10 minutes (600 seconds) may also be used if desired. 
     The storing of log data or other predetermined process is carried out until the wake time thus established elapses. Once the wake time has passed, the sleep state is resumed. The sleep state is restored either following the wake time or upon operation of the power button  37  by the user. 
     In step S 55 , the POWER lamp  35  blinks red at intervals of four seconds and the GPS lamp  33  is turned off, notifying the user that the sleep state is resumed (the POWER lamp keeps blinking at intervals of 4 seconds as long as the sleep state is in effect). In step S 56 , a single bleep sound is emitted. 
     In this manner, the sleep state may be interrupted for as long as needed by the user to perform the log data storage process. 
     Returning to the flowchart of FIG. 8, suppose that in step S 5  the sleep state is not judged to be in effect. In that case, step S 8  is reached in which a check is made to see if the power button  37  is being actuated longer than three seconds. If in step S 8  the powder button  37  is not judged to be actuated longer than three seconds, the operation is regarded as an operational error and nothing in particular is carried out in response. 
     If in step S 8  the power button  37  is judged to be actuated longer than three seconds, step S 9  is reached. Since the wake state is negated in step S 2  and the sleep state is denied in step S 5 , the GPS device  1  is deemed to be in a switched-off state. In that state, the user&#39;s obviously intentional operation of the power button  37  is interpreted as his or her desire to turn the device on. Thus a power-on process is carried out in step S 9 . 
     FIG. 13 is a flowchart of steps detailing the power-on process. In step S 71  of FIG. 13, the control unit  53 , given a signal from the operation unit  51 , judges that the power button  37  has been operated and performs initialization accordingly for power-up. In step S 72 , the POWER button  37  is lit green. 
     In step S 73 , the start flag is set to 1 and the O/G flag is set to 1 or 0. As discussed above, the O/G flag is set to 1 if the Tokyo geodetic system is in effect with the start flag at 1; the O/G flag is set to 0 if the WGS84 is in effect with the start flag at 1. When the flags are thus set, step S 74  is reached in which a storage process is performed. The storage process was already discussed in reference to the flowchart of FIG.  11  and thus will not be described further. 
     In step S 75 , a single bleep sound is emitted to notify the user that the GPS device  1  is now switched on. In step S 76 , a check is made to see if the sleep time is set to zero. The sleep time is a designated period of time in which the sleep state is allowed to continue after the most recent storage of log data. In other words, the sleep time is a parameter that specifies when to store log data. 
     If the sleep time is set to zero, that means the wake state is allow to continue in the absence of the sleep state. If the sleep time is set to a value other than zero, then the sleep state is to continue for as long as the period of time defined by the;value, to be replaced later by the wake state. In other words, the sleep state and the wake state are alternated so that log data are stored intermittently (i.e., only in each wake state). The wake state may continue for up to a period defined as a maximum wake time. 
     The sleep time and the wake time may be defined by the user as desired. By default, the sleep time is set illustratively to two minutes (120 seconds) and the wake time to 10 minutes (600 seconds). 
     If in step S 76  the sleep time is judged to be other than zero, step S 77  is reached in which all intermittent operation process is performed. FIG. 14 is a flowchart of steps detailing the intermittent operation process. In step S 91  of FIG. 14, the counter unit  55  (FIG. 6) on which to count the wake time is set to the currently established wake time. 
     In step S 92 , GPS data are acquired, generally at intervals of one second. If the GPS data are derived from signals currently received from satellites, the data are used as new data. If no signal can be received from satellites for the. movement, the most recently acquired data from satellites are utilized as old data. In step S 93 , a check is thus made to see if the GPS data obtained in step S 92  are new data (based on signals from satellites). 
     If in step S 93  the GPS data are not judged to be new data, step S 94  is reached. In step S 94 , the value on the counter unit  55  is decremented by one (i.e., by 1 second). In step S 95 , a check is made to see if the counter value has reached zero. In other words, it is determined whether the wake time has expired. If in step S 95  the counter value is not judged to be zero, step S 92  is reached again and subsequent steps are repeated. If in step S 95  the counter value is judged to be zero, step S 97  is reached. 
     If in step S 93  the GPS data are judged to be new data, step S 96  is reached for a storage process. The storage process has already been discussed and thus will not be described here further. With the storage process completed, step S 97  is reached in which the control unit stands by in a sleep state that may last for as long as a predetermined sleep time. Specifically, in intermittent operation, the storage process is carried out the moment GPS data are obtained from signals coming from satellites after the wake state has been brought into effect once the storage process is performed, the sleep state is resumed immediately. Power dissipation is minimized because the sleep state is restored immediately after new GPS data are acquired. 
     If the predetermined sleep time for the sleep state is two minutes, if the predetermined wake time for the wake state is one minute, and if the GPS device is indoors or otherwise located not to be able to receive signals from satellites, then log data are stored every three minutes. If the GPS device is outdoors or otherwise located to be able to receive signals from satellites easily and if log data are stored one second after the wake state is selected, then the log data are stored approximately every two minutes thereafter. 
     If no signal is received from satellites in the wake state (i.e., if no new data are obtained), then the process of step S 96  is never carried out. In that case, no log data are stored. 
     If in step S 97  the predetermined sleep time has expired in the sleep state, step S 91  is reached again. The wake state is then selected again and subsequent steps are repeated. 
     The steps above constituting the flowchart of FIG. 14 are carried out as an interruption when the power button  37  is operated, when the writable area in the storage unit  52  has been exhausted, or when the supply of power from the power supply unit  54  (with batteries) is stopped. Suitable processes are performed depending on what has actually taken place. 
     Returning to the flowchart of FIG. 13, suppose that in step S 76  the sleep time is judged to be zero. In that case, step S 78  is reached in which a continuous operation process is carried out. FIG. 15 is a flowchart of steps detailing the continuous operation process. In step S 111  of FIG. 15, the counter on which to count an interval time is set to a predetermined interval time. The interval time is used to designate the recording density of log data and may be set to a period between one second and one hour. The default interval time is illustratively five seconds, which means log data are stored at intervals of five seconds. 
     The processes in steps S 112  through S 116  are the same as those in steps S 92  through S 96  of FIG.  14  and thus will not be described further. After, the storage process of step S 116  is completed, step S 117  is reached in which the control unit stands by for a period defined by the remaining counter value (a state in which log data storage or other process is not performed). 
     Illustratively, if the interval time is set for five seconds, the control unit stands by for five seconds, then stores log data, then stands by for another five seconds, and so on. When the standby state in step S 117  ends, step S 111  is reached again, and subsequent steps are repeated. 
     Log data are recorded only when signals can be received from satellites. If no signals are received from satellites, no log data are recorded and the standby state is selected. If the interval time is set for longer than one minute, the standby state is replaced by the sleep mode. This makes it possible to minimize power dissipation in the continuous operation process as in the case of the intermittent operation process. 
     As with the intermittent operation process, the above steps constituting the flowchart of FIG. 15 are carried out as an interruption when the power button  37  is operated, when the writable area in the storage unit  52  has been exhausted, or when the supply of power is stopped. 
     Below is a description of what takes place when the mark button  36  is operated. In the storage mode with the wake state or wake-up sate in effect, operating the mark button  36  carries out a specific process. In the wake or wake-up state, GPS data may or may not be acquired (i.e., signals from satellites may or may not be received by the antenna  31 ). 
     If the mark button  36  is operated while GPS data are being acquired, position and time information in effect at the time of the button operation is stored as log data. In that case, any interval time set for the storage mode is disregarded. That is, log data are stored the moment the mark button  36  is operated; there is no specific timing for log data to be stored. The same holds when the current GPS data cannot be acquired. With no GPS data received from satellites, however, it is impossible to store (or generate) log data including position information based on the new GPS data. In such a case, log data are generated in a manner including the most recent position information (old data) based on signals from satellites. 
     Time information is supplied by the counter unit  55 . In managing its own time, the counter unit  55  corrects the time on the basis of signals received from satellites. If the mark button  36  is operated with no signals acquired from satellites, the counter unit  55  supplies the self-managed time information to the control unit  53 . In turn, the control unit  53  generates log data that include the supplied time information, and stores the generated log data into the storage unit  52 . 
     As described, data to be stored by operation of the mark button  36  are accompanied by a mark flag (set to 1) when actually recorded. If the log data contain old data, they are stored with the O/G flag set to 1. 
     The storing of log data outlined above is described below in more detail with reference to timing charts in FIGS. 16 through 18. FIG. 16 is a timing chart in effect when log data are stored in the continuous operation process in the storage mode. The GPS device  1  is switched on by operation of the power button  37  at a given point in time. This sets the start flag to 1 and initiates log data storage. In the continuous operation process, log data are stored at intervals of a predetermined interval time. 
     In FIG. 16, the time interval is thus the same between P 0  and P 1 , between P 1  and P 2 , . . . , and between P 5  and P 6 . The GPS lamp  33  is lit green when signals from satellites are normally received, and glows red if the signals are not received normally. As long as the satellite signals are normally received at each predetermined interval time (with the GPS lamp  33  lit green), log data are stored (at P 0 , P 1 , P 3 , P 5 , P 6 ). If the signals are not normally received (with the GPS lamp  33  glowing red), no log data are stored (at P 2 , P 4 ). 
     When log data are normally stored, the REC lamp  34  is lit red. If no log data are recorded, the REC lamp  34  is not illuminated. If the power button  37  is operated to designate removal of power during log data storage, log data with an end flag are stored and the log data storage process comes to and end. The POWER lamp  35  keeps glowing green from the time the start flag is stored until the end flag is set. 
     The storing of log data by the intermittent operation process in the storage mode will now be described with reference to the timing chart of FIG.  17 . As in the case of the continuous operation process, a start flag is set upon power-up and an end flag is set at power-off in correspondence with the log data stored concurrently. The GPS lamp  33  is lit green when the satellite signals are normally received and glows red when the signals are not normally received. During the intermittent operation process, the wake state (with the POWER lamp  35  lit green) and the sleep state (with the POWER lamp  35  blinking red) are alternated. In the wake state, the GPS lamp  33  glows either green or red depending on the status of signal reception as described above. In the sleep sate, the GPS lamp  33  is turned off. 
     If signals are normally received from satellites in the wake state, log data are stored (at P 0 , P 1 , P 3 ). If the satellite signals are not normally received in the wake state (i.e., while the wake time elapses), no log data are stored (at P 2 ). As soon as log data are stored, the sleep state is selected. The immediate resumption of the sleep state is designed to minimize battery power dissipation during the intermittent operation process. 
     Described below with reference to the timing chart of FIG. 18 is the storing of log data by operation of the mark button  36  during the intermittent operation process in the storage mode. Before operating the mark button  36 , the user needs to check the status of the GPS device  1 . More specifically, the user must check whether the GPS device  1  is switched on and, if the device is found active, must check whether the wake state or the sleep state is in effect. 
     The checks above may be carried out by viewing the POWER lamp  35 . If the POWER lamp  35  is not lit, the user knows that power is still off. In that case, the power button  37  is operated to switch on the GPS device  1 . If the POWER lamp  35  is seen blinking red at intervals of four seconds, the user recognizes the sleep state. The power button  37  is then actuated (for less than three seconds) to bring the GPS device  1  into the wake-up state. 
     FIG. 18 depicts the state transitions outlined above. The user&#39;s operation of the power button  37  in the sleep state brings about the wake-up state. In the wake-up state, the GPS lamp  33  starts glowing green if satellite signals are being received and is lit red if the signals are not received, as described. The user checks that the GPS lamp  33  is lit green, before operating the mark button  36 . The mark button  36  is operated by the user with his or her express intention to store position information in effect at a particular point in time. Thus the mark button  36  is operated in principle while the GPS lamp  33  is being lit green. 
     Operating the mark button  37  stores the position information at that point in time. The timing chart of FIG. 18 indicates illustratively that the mark button  36  is operated while the GPS lamp  33  is glowing green. It is presumed, however, that the user can also operate the mark button  36  while the GPS lamp  33  is glowing red. 
     In the latter case, the user presumably operates the mark button  36  in order to mark (i.e., store) at least the current time while being aware that position information is not obtainable because the GPS lamp  33  is glowing red. In that case, log data are stored which include, as position information applicable to the most recent log data, the time information managed by the counter unit  55  and supplemented by the old flag (with the O/G flag set to 1). Thus the position information is not made up of the data in effect just when the mark button  36  was operated, whereas the time information is constituted by the current time supplied by the counter unit  55 . 
     As described, when certain information is stored by operation of the mark button  36 , that information is recorded together with the mark flag (set to 1). 
     When the storing of log data storage is terminated by operation of the mark button  36 , the wake-up state remains in effect until the predetermined wake time expires or until the user operates the power button  37 . In the example of FIG. 18, the user operated the power button  37  before the wake time expired. 
     The GPS device  1  is powered by batteries (located under the battery lid  40 ) while the above-described log data storing operation is being performed (i.e., when the GPS device  1  is operating alone). The batteries are exhausted progressively and drop eventually to a level too low to sustain log data storage or other operation. Prior to that eventuality, the user must be warned of the reduced battery level. 
     The control unit  53  (FIG. 6) keeps watching the battery level. If the remaining battery time is judged to have dropped below a predetermined level (e.g., 10 percent of the fully charged state), the control unit  53  sounds a continuous beep sound (bleep, bleep, bleep, . . . ) and causes the POWER lamp  35  to blink red at intervals of 0.3 seconds. The blinking continues until the batteries are totally exhausted or until the user turns off power. The user may establish a desired threshold battery level as a criterion below which the exhausted-battery warning is issued. 
     The log data thus stored into the storage unit  52  are sent to the personal computer  4  through the USB port  42 . Where the personal computer  4  is connected with the GPS device  1  by means of a USB cable , the GPS device  1  is powered by the personal computer  4 . How the GPS device  1  works when connected to the personal computer  4  through the USB will now b e described by referring to a flowchart in FIG.  19 . 
     In step S 131  of FIG. 19, the control unit  53  checks to see if a USB cable (not shown) is connected to the USB port  42 . Step S 131  is repeated until the USB cable is judged connected to the USB port  42 . When thus connected, the personal computer  4  powers the GPS device  1 . In order to minimize power dissipation of the personal computer  4 , the computer is arranged to power the GPS device  1  only when the latter needs to be powered. Thus in step S 132 , a check is made to see if an application program requiring data from the GPS device  1  has been started up on the personal computer  4 . 
     If in step S 132  the relevant application program is not judged to be activated, step S 133  is reached. In step S 133 , a check is made to see if the wake state is selected (including a wake state brought about while the wake-up state is in effect). If in step S 133  the wake state is judged to be selected, step S 135  is reached. If the wake state is not judged to be in effect in step S 133 , step S 134  is reached. 
     In step S 134 , a check is made to see if the GPS device  1  is in the sleep state. If in step S 134  the sleep state is judged to be in effect, step S 135  is reached. Control is passed on to step S 135  in one of two ways: when the wake state was judged to be selected in step S 133 , or when the sleep state was judged to be in effect in step S 134 . This is a stage where the GPS device  1  is being switched on. 
     When the user connects the GPS device  1  to the personal computer  4 , it is presumed that the GPS device  1  is to be utilized in the GPS mode or in the PC mode. This necessitates terminating the wake state or sleep state that is a state for data storage. Thus a power-off process is carried out in step S 135 . The power-off process has already been discussed and will not be described here further. 
     If in step S 134  the sleep state is not judged to be in effect, i.e., if the GPS device  1  is judged turned off, then the processing of FIG. 19 comes to an end. 
     If in step S 132  the relevant application program is judged to be active on the personal computer  4 , step S 136  is reached for a GPS mode process. FIG. 20 is a flowchart of steps detailing the GPS process. 
     In step S 151  of FIG. 20, the GPS device  1  is initialized preparatory to starting the GPS mode process. The initialization illustratively involves suitably setting the switches  61  and  62  (FIG. 7) and making arrangements to receive the supply of power from the personal computer  4 . In step S 152 , GPS data start getting acquired. In step S 153 , the switches  61  and  62  are operated so as to output signal information received via the antenna  31  to the personal computer  4  through the USB port  42 . 
     In step S 154 , a check is made to see if any data are input from the personal computer  4 . Basically, the GPS device  1  in the GPS mode only supplies position and time information to the personal computer  4  and receives no data therefrom. If in step S 154  any data are judged to be output by the personal computer  4  to the GPS device  1 , that means the user wants to operate the GPS device  1  by means of the personal computer  4 . In other words, the user&#39;s desire to switch to the PC mode is recognized. Thus if any data from the personal computer  4  are detected in step S 154 , step S 155  is reached. 
     In step S 155 , a check is made to see if the data from the personal computer  4  specify a switchover to the PC mode. If in step S 155  the data from the personal computer  4  are not judged to be something designating a switchover to the PC mode, then the data are regarded as irrelevant to the GPS device  1  and step S 156  is reached. Step S 156  is also reached when no data are judged to be admitted from the personal computer  4 . 
     In step S 156 , a check is made to see if the relevant application program has been activated. If control has been passed on to the GPS mode process outlined in FIG. 20 (i.e., process of step S 136  in FIG.  19 ), that means the application program utilizing the GPS device  1  as a GPS antenna has been started up. The check in step S 156  is intended to keep constantly watching whether the relevant application program is active. 
     In judging that the relevant application program is off, the above check in step S 156  allows the GPS device  1  to be turned off to minimize power dissipation since the GPS device is currently not needed. Turning off the GPS device  1  cuts off the supply of the currently unnecessary power from the personal computer  4 , which translates into savings of power resources in the computer  4 . 
     Thus if the relevant application program is judged to be inactive in step S 156 , step S 157  is reached in which the GPS device  1  is switched off. If in step S 156  the application program is judged to be on, step S 152  is reached again and subsequent steps are repeated (i.e., the GPS mode is maintained). 
     If in step S 155  the input data are judged to be those specifying a switchover to the PC mode, step S 158  is reached in which a PC mode process is performed. FIG.  21  is a flowchart of steps detailing the PC mode process. In step S 171  of FIG. 21, a check is made to see if any data are input from the personal computer  4 . If in step S 171  no data are judged to come from the personal computer  4 , step S 172  is reached. 
     In step S 172 , a check is made to see if the application program relevant to the GPS device  1  has been started up on the personal computer  4 . This process is the same as that in step S 156  of FIG.  20  and thus will not be discussed further. Whatever mode is currently in effect, constant checks are made on whether or not the application program relevant to the GPS device  1  is active so as to minimize power dissipation both in the personal computer  4  and in the GPS device  1 . 
     If in step S 172  the relevant application program is judged to be on, step S 171  is reached again and subsequent steps are repeated (i.e., the PC mode is maintained). If the relevant application program is judged to be off in step S 172 , step S 157  (of FIG. 20) is reached and the GPS device  1  is switched off. 
     If in step S 171  any data are judged to be input from the personal computer  4 , a check is made to see if the input data constitute a command designating a switchover to the GPS mode. If in step S 171  the data are judged to be the command specifying transition to the GPS mode, step S 174  is reached for a GPS mode process The GPS mode process is constitute d by the steps making the flowchart in FIG.  20 . Thus from step S 174 , control is returned to step S 151  (of FIG. 20) and subsequent steps are repeated. 
     If in step S 173  the input data are not judged to constitute a command designating a switchover to the GPS mode, step S 175  is reached for a command analysis and execution process in which the command from the personal computer  4  is analyzed and the operation specified thereby is carried out. FIG. 22 is a flowchart of steps detailing the process of analyzing and executing the command from the personal computer  4 . 
     In step S 201  of FIG. 22, a check is made to see if the command is a reset command. If the command is judged to be a reset command, step S 202  is reached for a reset process. As described above, the GPS device  1  has a plurality of parameters such as those defining the sleep time and wake time. These parameters may be set as desired by the user. The reset process, when carried out, resets the user-defined parameters to the default parameter values. 
     If in step S 201  the command is not judged to be the reset command, step S 203  is reached. In step S 203 , a check is made to see if the command is a USB power command. If in step S 203  the command is judged to be one related to the supply of power through the USB, step S 204  is reached. In step S 204 , the supply of power through the USB is turned on or off as designated by the command. 
     If in step S 203  the command is not judged to be the USB power command, step S 205  is reached. In step S 205 , a check is made to see if the command is an antenna power command. If in step S 205  the command is judged to be one related to the supply of power to the antenna  31 , step S 206  is reached. In step S 206 , the supply of power to the antenna  31  is turned on or off as specified by the command. 
     If in step S 205  the command is not judged to be the antenna power command, step S 207  is reached. In step S 207 , a check is made to see if the command is an ID output command. If in step S 207  the command is judged to be one designating the output of a device ID, step S 208  is reached in which an ID code unique to the GPS device  1  in question is output. 
     If in step S 207  the command is not judged to be the ID output command, step S 209  is reached. In step S 209 , a check is made to see if the command is a storage dump command. If in step S 209  the command is judged to be one designating a dump of the storage unit  52 , step S 210  is reached in which a dump process is started. The dump may be halted halfway. Thus if in step S 209  the command is not judged to be the storage dump command, step S 211  is reached in which a check is made to see if the command is a dump halt command. 
     If in step S 211  the command is judged to be the dump halt command, step S 212  is reached for a dump halt process. If in step S 211  the command is not judged to be the dump halt command, step S 213  is reached. In step S 213 , a check is made to see if the command is a read command. If in step S 213  the command is judged to be one designating a read operation from the storage unit  52 , step S 214  is reached. In step S 214 , the data designated by the command are read from the storage unit  52 . 
     If in step S 213  the command is not judged to be the read command, step S 215  is reached. In step S 215 , a check is made to see if the command is a write command. If in step S 215  the command is judged to be one designating the writing of data to the storing unit  52 , step S 216  is reached. In step S 216 , the data designated by the command are written to the storage unit  52 . 
     The command analysis outlined in FIG. 22 is only an example and may be replaced by variations embracing other commands provided to execute varieties of processes. The flowchart in FIG. 22 thus describes in an illustrative fashion how any of such commands from the,personal computer  4  is typically analyzed and how a relevant process is carried out in accordance with the result of the analysis. 
     The processing of FIG. 22 is performed every time a command is input. At the end of the processing in FIG. 22, step S 171  of FIG. 21 is reached again and subsequent steps are repeated. Upon completion of the processing in FIG. 21, step S 157  of FIG. 20 is reached and the GPS device  1  is switched off. When the processing of FIG. 20 is terminated, the processing of FIG. 19 is also brought to an end. When the GPS device  1  is connected to the personal computer  4  through the USB, the steps in FIGS. 19 through 22 are carried out as described above. 
     In order to output a desired command illustratively in the manner outlined in FIG. 22, the user is required to perform necessary operations on a screen of the display  19  of the personal computer  4 . FIG. 23 shows a typical screen on which such operations are carried out. 
     On the display  19 , a setting window  71  appears on which to operate (i.e., set) parameters for determining the way the GPS device  1  should operate. The setting window  71  is made up of three major portions: an operation setting area  72 , a memory setting area  73 , and a battery setting area  74 . The operation setting area  72  comprises an interval setting field  75  in which to set a log storage interval, and an effective time setting field  76  in which to set an effective wake-up time. 
     The memory setting area  73  is constituted by an alarm setting field and a clear button  77 . The alarm setting field allows the user to set a threshold percentage of the remaining memory capacity (of the storage unit  52 ) as a criterion below which an alarm is issued. The clear button  77  is operated to clear all stored log data. As described earlier, log data keep being written to the storage unit  52  unless erased intentionally by the user. To ensure a sufficient writable capacity, the user should operate the clear button  77  periodically to clear the storage unit  52 . 
     The battery setting area  74  constitutes a field in which to set a threshold percentage of the remaining battery charges as a criterion below which an alarm is issued. Under the battery setting area  74  are three buttons: a reset-to-default button  78 - 1 , an OK button  78 - 2 , and a cancel button  78 - 3 . The reset-to-default button  78 - 1  is operated to reset the user-established parameters to the default values. The OK button  78 - 2  is operated to confirm the end of the parameter setting. The cancel button  78 - 3  is operated to cancel any parameters that have been set so far but are considered unnecessary, or to close the setting window  71 . 
     In setting parameters in various areas or fields, the user points a cursor where desired on the screen by operating the mouse  16  (FIG. 2) or a similar pointing device and by clicking on or otherwise manipulating the device. For example, the user may point a cursor  79  to the interval setting field  75  by operating and clicking on the mouse  16 . This causes a pull-down menu  81  to appear as shown in FIG.  24 . The menu  81  indicates values that may be used as an interval for log storage. A scroll bar appears on the right-hand side of the pull-down menu  81 , allowing the user to display the hidden values when operated. 
     Illustratively, the log storage interval may be set for any one of 1 second, 3 seconds, 5 seconds, 10 seconds, 30 seconds, 1 minute, 3 minutes, 5 minutes 10 minutes, 30 minutes, and 60 minutes (1 hour). The pull-down menu  81  may be arranged to contain a field in which any other time period may be set as desired. In setting the interval, the user should take into account the circumstances under which log data are to be stored. For example, if log data are expected to be recorded during walking, the moving speed is not very high so that a relatively long interval of, say, 10 or 30 minutes may be selected. If log data are expected to be stored during a trip by car, the moving speed is high and thus a relatively short period of, say, 30 seconds or 1 minute should be selected to keep frequent logs. 
     Other parameters may also be set in like manner. Obviously, arrangements may be made not merely to pick one of the values contained in the pull-down menu  81  but to point the cursor  81  to the field in question so that the currently displayed value may be directly changed as desired. 
     Every time the OK button  78 - 2  is operated, the data denoting the established parameter(s) are output from the personal computer  4  to the GPS device  1 . In such a case, the GPS device  1  receives a write command requiring the old parameter value(s) to be replaced by the newly established parameter(s). More specifically, in step S 215  of FIG. 22, the received command is judged to be one designating a write operation to the storage unit  52 . Step S 215  is followed by step S 216  in which the parameter value(s) is written to the storage device accordingly. 
     In case an error occurs for some reason during data exchanges between the personal computer  4  and the GPS device  1 , an error message such as is shown in FIG. 25 appears on the display  19 . 
     The setting window  71  is not limited in design to what is shown in FIG. 23; any other design may be adopted instead. A plurality of setting windows are provided in which to operate and set up the GPS device  1 . Although not shown, there is provided a window by which to dump log data from the storage unit  52  of the GPS device  1  to the HDD  18  (FIG. 2) of the personal computer  4 . If that dump window is opened and operated by the user for a dump, a data transfer indication window such as one in FIG. 26 appears on the display  19  to indicate the data transfer status. 
     If the user operates the cancel button in the window of FIG. 26, the GPS device  1  interprets the action as a dump halt command in step S 211  of FIG.  22 . Step S 211  is followed by step S 212  in which the dump process is halted. As a result, the data transfer indication window of FIG. 26 disappears. 
     As described, the log data including position and time information and stored in the GPS device  1  may be supplied to the personal computer  4 . On the personal computer  4 , the user can edit, in conjunction with the supplied log data, the image data captured by the digital camera  2  (FIG. 1) and recorded on the floppy disk  3 . 
     When recording image data, the digital camera  2  associates data making up each image with a time stamp illustratively using a digital camera format DCF (Design rule for Camera File) defined by the JEIDA (Japan Electronic Industry Development Association). More specifically, as shown in FIG. 27, an image file accommodating an image taken by the digital camera  2  is constituted mainly by a header and an image data body. The header stores data about the image held in the image data body. One of the data items making up the header is a time of day at which the image in question was captured. 
     Described below with reference to a flowchart of FIG. 28 is how the personal computer  4  operates in determining the position where a specific image was taken by the digital camera  2 . In step S 231  of FIG. 28, the personal computer  4  reads log data from the GPS device  1  connected via the USB. The log data thus read out are placed illustratively into the RAM  13  (FIG.  2 ). When written to the memory, the log data are arranged in the ascending order of chronology. Each log data item is furnished with a counter value starting at zero. FIG. 29 depicts an example of log data placed into the personal computer  4 . 
     The log data in FIG. 29 are made up of 32 log data items. The log data constitute a group of data items recorded from the time the GPS device  1  was turned on until it was switched off. In other words, a log data group starts with a log data item whose start flag is set to  1  and ends with a log data item whose end flag is at 1. Of the data items constituting the log data body in FIG. 29, only those composed of a time stamp each are shown. The times are seen here taken at intervals of 30 seconds from 10:18:00 to 10:33:30. The log data items, numbered with counter values  0  through  31 , are arranged chronologically on the basis of the time data held in the log data body. 
     In step S 232 , the data constituting a target image to be processed are read. The read operation is performed as follows: from that floppy disk  3  in the FDD  17  (or from the portable semiconductor memory  5  or a remote source over a network) which holds image data taken by the digital camera  2 , image data having the data structure shown in FIG. 27 are read into the RAM  13  or onto the HDD  18 . At this point, all image data may be read from the floppy disk  3  and placed illustratively into the RAM  13  before the data making up the target image is retrieved from the RAM  13 . Alternatively, the image data may be read one image at a time from the floppy disk  3 . 
     In step S 233 , the counter value regarding the log data to be processed is initialized to zero. In step S 234 , a check is made to see if the counter value is less than the number of all log data items plus one. In other words, it is determined whether all log data items are subject to the processes in step S 234  and subsequent steps. In this case, the counter value has just been set to zero and thus it is judged to be less than the total log data item count plus one, so that step S 235  is reached. 
     In step S 235 , the “preceding” log data item is set to the counter value and the “next” log data item is set to the counter value plus one. The preceding and the next log data items are chronologically adjacent to each other (i.e., having consecutive counter values), the preceding log data item being earlier by one time increment than the next log data item. In step S 236 , a check is made to see if the time of the preceding log data item was earlier than the time at which the image was taken. In other words, it is determined whether the time stamp of the preceding log data item represents a time of day previous to the time included in the target image data to be processed read in step S 232 . 
     If in step S 236  the time stamp of the preceding log data item is judged to be earlier than the time of the image capture, step S 237  is reached. In step S 237 , a check is made to see if the time stamp of the next log data item is subsequent to the time of the image capture. 
     If in step S 237  the next log item is,not judged to be subsequent to the time of the image capture, step S 238  is reached in which the counter value is incremented by one. Regarding the log data having the newly established counter value, the processes of step S 234  and subsequent steps are repeated. 
     If in step S 237  the time stamp of the next log data item is judged to be later than the time of the image capture, step S 239  is reached. In step S 239 , the position where the image was taken is estimated. How the position of the image capture is typically estimated is described below with reference to FIG.  30 . If the time of the image capture is, say, “10:32:40,” then the process of step S 236  judges that the log data items with counter values  0  through  28  (from “10:18:00” to “10:32:00”) have time stamps each preceding the time of the image capture. In step S 237 , the next log data item is not judged to have a time subsequent to that of the image capture. Thus steps S 234  through S 238  are repeated. 
     When the counter value reaches  29  (i.e., when the preceding log data item is associated with the time stamp of “10:32:30” and the next log data item with “10:33:00”), the process of step S 236  judges the time of the preceding log data item to be earlier than the time of the image capture. In step S 237 , the time of the next log data item is judged to be later than the time of the image capture. This is the state shown in FIG. 30 in which the time of the image capture is situated between two log data items. 
     In this example, the time of the image capture is “10:32:40,” preceded by the preceding log data item with the time of “10:32:30” and followed by the next log data item with the time of “10:33:00.” Where the two log data items and the time of the image capture are plotted on the time base as sketched in FIG. 30, the point indicating the time of the image capture is considered to divide internally a line segment connecting the two points representing the two log data items. If the point denoting the time of the image capture is assumed to divide, in proportions of 1:2, the distance between the two points representing the two log data items, then the position of the image capture can be estimated on the basis of the position information representing the two log data items. 
     In the example above, the position information on the log data item with the time of “10:32:30” is constituted by N42° 32′35″ and E135° 12′20′, whereas the position information about the log data item having the time of “10:33:00” is made of N42° 35′35″ and E135° 00′40″. Because of the assumption that the position information spanning the two positions of the log data items is internally divided in proportions of 1:2, the north latitude (N) of the position of the image capture is estimated at N42° 33′35″. Based on the same assumption, the east longitude (E) of the position of the image capture is estimated at E135° 0840 20″. The estimates carried out as described above in step S 239  determine the position of the image capture corresponding to the image capture time. 
     There may be a case in which the time of the image capture matches the time of a given log data item, i.e., the case where the proportions of internal division are 0:X (X is a value contingent on the storage interval between log data items). In that case, the position information about the log data item in question is estimated to represent the position where the target image data were acquired. 
     In terms of log data storage intervals, the GPS device  1  works as described in one of two modes: continuous mode in which log data are stored every second, and intermittent mode in which log data are recorded at intervals of up to 3,600 seconds (1 hour). Due to obstacles, the GPS device  1  may sometimes be unable to receive signals normally from satellites (i.e., unable to store log data containing accurate position information). If signals from satellites are not received in the intermittent mode or because of obstacles, there are no log data available containing position information corresponding to (i.e., matching) the times of day at which image data were acquired. Such eventualities can be overcome by estimating the position of the image capture in the manner described above. 
     When the image capture position is estimated (i.e., determined) in step S 239 , step S 241  is reached. In step S 241 , the data representing the image capture position are associated with the target image data to be processed before they are all written illustratively to the HDD  18 . 
     Suppose that in step S 234  the counter value is judged to be larger than the total log data item count plus one, or that in step S 236  the time of the preceding log data item is not judged to be earlier than the time of the image capture (since comparison with the image capture times proceeds chronologically, the judgment that the time of the preceding log data item was not earlier than the time of the image capture signifies that all log data items are subsequent to the image capture time). In such cases, step S 240  is reached. 
     In step S 240 , it is judged that the position of the target image data to be processed cannot be estimated. In step S 241 , the image data are stored together with a data item indicating the absence of estimates about the image capture position. 
     In the foregoing description, two log data items closest chronologically to the time of the image capture were shown retrieved before estimates of an image capture position were carried out. Alternatively, there may be provided a step in which to search for a log data item whose time matches an image capture time. Estimates of the image capture position are performed only in the absence of any matching log data item. 
     The image data thus associated with specific positions of the image capture may be displayed as thumbnail images at the corresponding positions on a digital map, or may be grouped into suitable zone categories according to the position information. Such editing work is carried out by use of an appropriate application program. If certain image data are displayed on the digital map and if the position information associated with that image has been acquired intentionally by the user (i.e., if the position information is derived from specific log data stored by the user&#39;s operation of the mark button  36 ), then an indication attesting to the user&#39;s choice may be displayed as needed. 
     The log data need not be limited in their use to being associated with image data. Alternatively, the log data may be sorted out chronologically and plotted on a digital map in the sorted order. The data thus plotted provide a track traveled by the user. 
     The examples above have been shown centering on how to deal with still pictures obtained by the digital camera  2 . However, this is not limitative If the invention. The invention also applies to moving picture data captured by a digital video camera or like equipment. In practicing satellite-based position measurement, the GPS may be replaced by the GLONASS (Global Orbiting Navigation Satellite System). 
     The processes discussed above may be implemented either by hardware or by software. If a series of processes is implemented by software, programs constituting the software are loaded from a program storage medium into a computer having a hardware structure dedicated to the software or into a general-purpose personal computer capable of executing diverse functions based on various programs that may be installed therein. 
     The program storage medium from which to load programs into the personal computer  4  for execution may be any one of such media as magnetic disks  131  (including floppy disks), optical disks  132  (including CD-ROM (Compact Disc-Read Only Memory) and DVD (Digital Versatile Disc)), a semiconductor memory  134  or like package medium, and a hard disc drive constituting a ROM  112  or a storage unit  118  into which programs are stored temporarily or permanently. Programs are stored onto the program storage medium from wired or wireless communication media such as local area networks, the Internet, or digital satellite broadcast links through such interfaces as routers and modems where necessary. 
     In this specification, the steps in which to describe the programs offered by the program storage medium may or may not be carried out chronologically in the described sequence. These steps include processes that may be executed in parallel or on an individual basis. 
     In this specification, the term “system” refers to a totality of multiple devices configured. 
     As described above and through the information processing apparatus, the information processing method, and the program storage medium according to the present invention, time data are generated to denote times of day at which measured position data are generated. Log data are then generated including at least the measured position data and the time data. With the log data placed in storage, either the measured position data and time data are all output, or the log data are retrieved from storage for output. These features help enhance the versatility of the inventive information processing apparatus for obtaining measured position data. 
     As many apparently different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.