Geographic Database

Overview
Table Structure
FIPS Codes
Timezone Information
Sources
Making Changes


Overview of the Geographic Database System

The geographic data table contains coordinates for any number of city, county, and state locations. Additionally, it holds information on time zones, elevation, FIPS codes, AFOS IDs and a daylight savings time flag. Entries must exist for every state where you expect APRS packets will originate.

The geographic database system serves two purposes:

  1. Automatic insertion of QTH information into the node table
  2. Return information about a node or other QTH

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Table Structure

Each record in the table contains the following fields:

Field
Description
state Standard two letter abbreviation. Upper-case.
county County in which the locale resides. Entries are title case and are case-sensitive.
city The place name.
fips Five-digit USGS FIPS code for locale. First two digits indicate the state while the last three designate the county.
longitude The longitude for the locale in decimal degrees (e.g., 70° 30' = 70.5°). Note that west of the prime meridian is positive, east negative.
latitude The latitude of the locale in decimal degrees (e.g., 23° 30' = 23.5°)
afos A three letter code designating the NWS office that services this locale. AFOS stands for Automation of Field Operations and Services. This is an older term that describes the computer systems that the NWS used at offices to gather weather data. It has been replaced by AWIPS, Advanced Weather Interactive Processing System. The NWS still uses the older AFOS ID to identify stations in their network.
elev Elevation of the locale in feet ASL (above sea level)
zone The timezone of this locale. This number, expressed in hours, when added to the local time gives UTC time.
dst Daylight Savings Time (DST) flag. True ('t') if the locale observes DST, false ('f') if not.

Be certain to get the accuracy of the latitude/longitude down to two decimal places. Because of the relatively small distances involved, rather bizarre results can occur from the algorithms that figure direction and distance. Note that west longitude is positive, east is negative. This is opposite of how the USGS stores the data and was dictated by the algorithm used to calculate azimuth and distance by the server.

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FIPS Codes

FIPS codes are used by the system and designate a county and state. This information is primarily used by the wxnaprd daemon when a new station is heard. The FIPS code serves as a primary lookup key in the identification process.

The wxnsamed daemon (currently under development) will also use this information to identify and log NWS watches and warnings. The NWS watches and warnings issued in SAME format rely on FIPS codes to identify affected areas. The daemon will also broadcast this information using APRS.

While not a part of the geographic data held in the gdb table, the fips table contains related data. It is presented here for completeness. Table structure is as follows:

Field
Description
fips Five-digit USGS FIPS code for locale. First two digits indicate the state while the last three designate the county.
state Standard two letter abbreviation for this FIPS code. Upper-case.
county County of this FIPS code. Entries are title case and are case-sensitive.

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World Timezones

These are the identifiers for the various worldwide time zones and represent the values that are used in the geographic database to designate the time zones.

The first field is the zone identifier. The second field is the difference in time between that time zone and UTC for that particular locale. This value is added to UTC to determine the time in that zone.

Timezone
Offset
New Caledonia -11
Eastern Australia -10
Central Australia -9
Western Australia -8
Thailand -7
Eastern Russia -6
Central Russia -5
Iran -4
Arabia -3
Eastern Europe -2
Central Europe -1
Greenwich 0
Iceland 1
Azores 2
Greenland 3
Atlantic 4
Eastern 5
Central 6
Mountain 7
Pacific 8
Alaska 9
Hawaii 10
East Alaska 11
New Zealand 12

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Geographic Data Sources

Two data sources are used:

The places file is part of the Geographic Names Information Systems database, or GNIS. It contains the place name, county, state, latitude, longitude, and elevation and other additional information.

The timezone data comes from the US Department of Transportation, who maintains this information. Information included is the city, county, state, five-digit FIPS code, AFOS ID (the NWS office for that area), timezone, and whether or not DST is observed. To comply with the requirements for use of the information, the NWS disclaimer is given below.

Use of Data and Products

The information on government servers are in the public domain, unless specifically annotated otherwise, and may be used freely by the public. Before using information obtained from this server special attention should be given to the date & time of the data and products being displayed. This information shall not be modified in content and then presented as official government material.

The user assumes the entire risk related to its use of this data. NWS is providing this data "as is," and NWS disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose. In no event will NWS be liable to you or to any third party for any direct, indirect, incidental, consequential, special or exemplary damages or lost profit resulting from any use or misuse of this data.

As required by 17 U.S.C. 403, third parties producing copyrighted works consisting predominantly of the material appearing in NWS Web pages must provide notice with such work(s) identifying the NWS material incorporated and stating that such material is not subject to copyright protection.

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Making Changes

If the information in the compiled table is incorrect or an entry needs to be added, you will first need to obtain the information listed above and then use one of the tools listed elsewhere in this documentation.

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