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On this page, you will find an overview of the GPS function and how to use it to create content. |
About the GPS Function
The GPS function provides information on the current location of the handset. It is offered only on GPS-compatible i-mode handsets. The function makes it possible to create custom content based on the current location of the handset. Unlike i-area, the GPS function provides pinpoint location information using latitude and longitude.
Areas of Availability
This service can be used anywhere within Japan or overseas where the i-mode service is available.
With regards to overseas, the GPS function (referred to as the overseas GPS function) of the network assist method
1 can be used anywhere where i-mode is available just as in Japan. However, support for GPS positioning overseas is only provided for models compatible with the overseas GPS function.
Also, even models that are not compatible with the overseas GPS function may be able to perform positioning under open skies2 overseas if they are compatible with the stand-alone positioning method3, but will take a while to perform the operation.
When this service is used overseas, the latitude and longitude information may not be able to be acquired or errors may occur depending on the GPS signal strength, and the positions of latitude and longitude information acquired by positioning and latitude and longitude information displayed on maps may not match depending on the country or region of use (the errors may be remarkable in some regions).
Please see Handset Specifications for details on the network assist method, stand-alone positioning method, and models compatible with the overseas GPS function.
- 1 Network assist method
Satellite data is supplemented with data from base stations and other sources (assist data) that provide positional information over the mobile phone networks. This enables more rapid positioning. - 2 Open skies
An area without cover with a reasonably wide view of the sky. - 3 Stand-alone positioning method
A method for performing positioning with only the handset and not via the network.
How to Create Custom Content Using the GPS Function
An HTTP request is used to acquire location information. Various types of location information (current location, past location history, location information stored in the Phonebook) can be used when providing the content.
About Location Information Parameters
Here is an explanation of kinds of parameters for location information sent from the handset. The information is expressed the same way whether it is noted using the A tag or FORM tag.
| lat (latitude) | Format is dms (±dd.mm.ss.sss). Plus (+) indicates northern latitude, minus (-) indicates southern. Degrees (dd) are in units of 10 (00 to 90), and minutes and seconds (mm and ss) are in units of 60. Seconds is further specified in units of 10 up to three decimal places. Degree, minute, and second values are separated by a dot (.), and all data is written in single-byte (half-size) characters. Example: lat = +35.00.35.600 |
| lon (longitude) | Format is dms (±ddd.mm.ss.sss). Plus (+) indicates eastern longitude, minus (-) indicates western. Degrees (ddd) are in units of 10 (000 to 180), and minutes and seconds (mm and ss) are in units of 60. Seconds is further specified in units of 10 up to three decimal places. Degree, minute, and second values are separated by a dot (.), and all data is written in single-byte (half-size) characters. Example: lon = +135.41.35.600 |
| geo (datum) | Indicates the geodetic reference system used to represent the positioning result with an arbitrary text string written in all single-byte (half-size) characters.
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| x-acc (accuracy) | A parameter that indicates the accuracy range of the positioning result. Indicated by a single-byte (half-size) number.
Example: x-acc=1
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Sending the Information
The lcs attribute is added to the A tags and FORM tags. The attribute has no value. When the link containing the lcs attribute is clicked, a popup window warns the user that the handset’s current location is about to be sent. The location information is then converted and sent as a location information URL.
Statement Methods
Example of an A tag statement:
<A HREF="http:// www.docomo.co.jp/gps.cgi" lcs>
Example of an A tag statement:
<FORM method="get" action="/gps.cgi" lcs>
<INPUT type="radio" name="cat" value="Bank" checked>Bank<BR>
<INPUT type="radio" name="cat" value="TOILET">Toilet<BR>
<INPUT type="radio" name="cat" value="CV">Convenience Store<BR>
<INPUT type="submit" name="test" value="Search">
</FORM>
When the lcs attribute is added to an A or FORM tag, a popup window is displayed asking whether to send the Current Location, Location from History, or Location from Phonebook (options may not be available on certain models). If the Current Location option is selected, the handset will then acquire the current location information and a screen for confirming end of location information opens. If the user agrees to send the information, it is converted and sent as a location information URL.
The location information URL mentioned here refers to the URL of a specified site to which the location information has been appended. In general, the location information is appended after a question mark (?) in the URL string. However, if the URL to which the information will be appended already includes a question mark, the ampersand (&) is used as the dividing character instead.
Sending the information to the server (example 1)
http://www.docomo.co.jp/gps.cgi?lat=%2B35.00.35.600&lon=%
2B135.41.35.600&geo=wgs84&x-acc=3
Sending the information to the server (example 2)
http://www.docomo.co.jp/gps.cgi?id=guest&lat=%2B35.00.35.600&lon=%
2B135.41.35.600&geo=wgs84&x-acc=3
However, accuracy (x-acc) is not set if a value is not set for accuracy such as when referring to data such as Phonebook data.
Screen Transition
Caution about Handing Over Location Information
The end user confirmation popup screen that appears when sending location information is built into the handset itself. It will automatically appear when a link with the lcs attribute is clicked on. If the end user selects "No" on the confirmation screen, the information will not be sent.
