Nemo Analyze: Organized Measurement

Organize Measurements

By default, all added measurement files go into the All Measurements folder.

If you have a lot of files, it may be convenient to categorize measurement files into custom-made subfolders. In the Organize Measurements dialog you can conveniently handle and organize large sets of measurement files. Go to Go to View in the ribbon bar and select Organize Measurements, or right-click on the All Measurements folder in the Workspace and select Organize.

In the Organize Measurements dialog you can create new folders, make joined measurements, and remove files from drag & drop folders. Right-click on a folder in the left-hand panel to create new folders.

Select measurements, right-click on them, and select Join to create a joined measurement.

You can also organize measurements in the Workspace. Right-click on the All Measurements item and select Add Folder.

Nemo Analyze: Creating The Data base

Adding Files to Database

When you start Nemo Analyze 5.0 for the first time, the database is empty. Adding files - measurements, BTS files, and maps - to the database may take a while, but once files have been added, they will remain in the database until you remove them.

Select File | Measurement | Open Measurement /Map/BTS/Report/Data Source File. From the Open dialog box, select the files you want to add to the database and click Open. You can select several files by holding down the Shift key.

Note: Adding files to the database may take several minutes depending on the number and size of the files.

Note: All the files need to have unique file names.

The added measurement files will appear in the All Measurements folder in the Workspace view in the left-hand side of the Nemo Analyze main window.

Adding Maps to Database

In addition to adding map files in the database through File | Measurement | Open Map, you can import image files to be used as maps. Select File |Import | Image as mapC. In the Open dialog, select the image that you want to use as a map. It can be, for example, a floorplan from a test site. After selecting the image file you need to define either the width and length of the map area in meters or the GPS coordinates for two map corners. After you click OK, the map is added in the database and it will appear in the Maps folder in the workspace.

You can create black and white copies of raster maps by right-clicking on a map in the workspace and selecting Create Black & White Copy. The map is saved with the same name with ‘BW’ added at the end of the file name.

Adding CSV Files to the Database

In addition to files produced with Nemo tools, you can import any character-separated value (CSV) ASCII data into the Nemo Analyze database. The data can be post-processed and visualized using the dataviews available in Nemo Analyze.

Select View | Tools | Database manager.

The User Manager dialog opens.

To create a new CSV import template, select the folder Database Management | CSV Templates from the directory tree, right-click on the Template field right of the directory tree, and select Add Template… from the popup menu.

The CSV Import Wizard – CSV Template File dialog opens.

Template file enables you to select a CSV file to serve as a basis for the import template. Click the browse button to browse for CSV files.

Extension enables you to define the file type the import template will apply to.

Note: It is recommended that the extensions of CSV files with different content structures are renamed to provide each type with a unique extension. For instance, four different types of CSV files, all originally with the extension .csv, could be renamed as .csv1, .csv2, .csv3, and .csv4.

Once Template file and Extension have been defined, click Next.

The CSV Import Wizard – CSV Import dialog opens.

Ignore defines the parts of the imported data set that are to be ignored when uploading the data, i.e. the parts that do not contain relevant data. Column row defines the number of top rows to be ignored. Rows allows you to define specific rows to be ignored. Rows starting with allows you to define rows starting with a specific string to be ignored.

Columns allows you to divide a CSV data set into columns. Fixed lines defines the content of each column based on the number of characters in a CSV string. For example, the setting 12, 22, 32 defines that the first twelve characters (including spaces) belong to column 1, the next 22 characters to column 2, and the next 32 characters to column 3. Fixed lines should only be used if there are no delimiters in the data set. Delimiter defines the character that separates columns in the CSV data set. You can use one of the default delimiters, i.e. comma, dot, semicolon, , or , or you can define your own delimiter character by entering a character to the Delimiter field.

Strip leading and trailing quotation marks removes leading and trailing quotation marks from each column of the imported data set.

File preview displays a preview of the CSV file contents.

Once the Ignore and Columns settings have been defined, click Next.

The CSV Import Wizard – Database Schema Definition dialog opens.

Table name defines the name of the template.

Columns enables you to select which columns are included in the imported data set and to define the properties of each column using Column, Column type and Format.

Decimal separator defines the decimal separator as comma or dot.

Column defines the name of the column selected in the Columns control.

Column type defines the data type of the column selected in the Columns control.

Keyword allows you to define the content type of columns containing some general data types, such as time and positioning data. Based on these defined content types, the data can be correlated with measurement files of other formats.

Format defines the data display format of the column selected in the Columns control.

Data preview displays a preview of the data set structure.

Once the properties of each column have been defined, click Finish.

The new template is displayed in the Template field of the User Manager window.

To open a CSV files using an import template, select File | Measurement | Open Measurement.

The Open dialog opens.

Select CSV import template (e.g. Template1) using the Files of type drop-down menu, browse to a folder containing measurement files with the extension defined in the template, select a file, and click Open.

Nemo Analyze: Starting Nemo

Starting Nemo Analyze

After running Setup, you will see a new Nemo Tools program group under the Programs selection in the Windows® Start menu.

• To start Nemo Analyze:

1. Double-click the Nemo Analyze.exe icon in My Computer or select it from the Start menu (Start | Programs | Nemo Tools | Nemo Analyze 5).

2. When Nemo Analyze is starting, hold down the Shift key to prevent Nemo Analyze from loading a previously used workspace.

3. When the program starts, the window below will open. In the Welcome to Nemo Analyze workbook you will find useful information about Nemo Analyze, links to related documents, and shortcuts to loading measurement and BTS files.

Using Nemo Analyze

In Nemo Analyze you can view measurement data in multiple ways. The most convenient way, however, is to focus on the Workspace user interface since it is quick and easy. For example, in the workspace you can double-click a parameter, and Nemo Analyze opens the parameter automatically in the default data view. Furthermore, you can go to View--> Workbook--> Add Data View, choose a particular data view, select a measurement, and drag a parameter from the parameter tree in the data view. You can also view several parameters in the same data view by dragging them in it. If you drag a parameter in an empty workbook, a dialog box appears and asks you to select a data view type.

If you drag a measurement file to a workbook with a data view, a dialogue box emerges asking you to select the parameter you wish to view. The filter field above the parameter tree is useful when looking for a specific parameter in a long list.

All data views are synchronized with each other based on time. Consequently, if you open two or more data views on the same measurement file but on different parameters simultaneously, and switch from one point of time in one data view to another point in time, the data in the other data views change accordingly.

Workspace

The Workspace forms the basis of the user interface in Nemo Analyze. All measurements and parameters can be found in the workspace, and from there it is convenient to drag them in various data views. See also Using Nemo Analyze. The workspace view is by default attached to the left-hand side of the Analyze main window. You can also drag it elsewhere in the window, and if you want to dock it back to the side of the main window, double-click on the Workspace.

The Workspace view consists of five pages: Measurements, Base Stations, Maps, Data Source Files, and Reports pages respectively. You can view each page via the descriptive icon tabs at the bottom of the Workspace view. You cannot create sub-folders or otherwise edit these folders.

The Measurements page in the Workspace is divided into three sections: Folders, Folder Contents, and the Parameter tree. The folders include the All Measurements folder, which shows all the files that are currently in the database, and other user-defined folders. The Folder Contents displays a list of all measurements in the folder selected in the Folders section. The name of the measurement device is also displayed when the mouse is hovered over a measurement file. The Parameter Tree shows all available parameters and KPIs for the selected file, measurement, or folder, depending on the selections in the other two sections. The KPIs can be displayed in graphs, maps, and other data views, and statistics can also be calculated from the parameter tree.

Workspace Filters

In the Workspace there are two filter functions to assist the user in rapid location of measurement files or parameters.

First, above the measurement files (see the red box) you can find the filter for measurement files. Type the name of the measurement file in the filter field to find the desired measurement file.

Second, above the parameter tree you can see the filter field for parameters. Type in the name of the parameter, and only parameters matching the name will be viewed in the parameter tree.

Use Case - Polygon Area Selection

With parameter filtering it is also possible to limit a query based on a user-defined area, i.e. by Polygon area selection. As a consequence, the results of a query will be limited to the user-defined part of a measurement route in the chosen data view. This is useful, for example, when you want the values of a parameter to be viewed with a value-based color set only on a part of the route on a map. In this case, the rest of the measurement route will be colored with a default color. In this example we will select Ec/No best active set as the parameter.

Select a measurement file in the Workspace and type Ec/No best active set in the Parameter Tree filter field. Right-click on the parameter and select Open With Filters In --> Map.

An empty workbook and the Analyze Wizard - Fill Parameters dialog box appear. In the dialog box select Area under Name, and press the … tab.

The Select Area dialog box appears. Select a map in the Filename field, or load one through the … tab. Next, define an area on the map by clicking on it. The Save As tab also enables you to save the map with the selected area for later use. Click OK.

The Analyze Wizard – Fill Parameters dialog box appears. Click Finish.

A new workbook opens. The measurement route on the map is colored with the Ec/No color set over the section of the route specified with the polygon area. The rest of the route is colored with the default color, here blue.

Pathloss 5.0 : GIS Setup (ch 4)

Primary and Secondary DEMS

A primary and secondary DEM can be configured. Their usage is controlled by the profile generation options under Configure - PL50L options -Terrain data. If both primary and secondary databases have been configured and are checked in the options, the program will start with the primary database. If the operation (profile or elevation backdrop) is not complete, then the secondary database will be used to fill in the missing sections. Therefore, the primary data base should have the best resolution.

The default and recommended setting is to use the primary DEM only. If the operation fails then it is a simple matter to check the secondary DEM and the user can inspect the different areas in which this DEM was used.

When a profile is first generated for the first time, the DEM file usage is written to the notepad.

Note that it is possible to configure a DEM with different data sources provided that they are both in the same database category and are referenced to the same datum. For example, in the BIL geographic database, one could load the GTOPO30.ndx index file and then add SRTM files to the index. The program would always use the SRTM file (the best resolution) if available.

The following sections provide the setup procedures for the various database formats supported by the program.

On completion of the setup procedure, generate a path profile in the terrain data section of the program. The site coordinates must be within the south-north and west-east edges of the DEM file. In the case of the BIL projected database, the following default DEM parameters may need to be changed based on the results of a test profile. In the primary or secondary DEM tab, click the File index button and then select Edit - Parameters or right click on a data cell

· byte order - change from Motorola-Spark to Intel or vice versa if the elevations are missing or erratic

· file origin - change the origin from the SW corner to the NW corner or vice versa if the elevation backdrop appears to be upside down

· treat no data values as sea level - use this setting if elevations are missing when a portion of the profile is over water. The missing values will be replaced by 0 elevations.

BIL projected DEM setup procedure

Use this option for Planet type data and ESRI GRIDASCII projected data. Select the primary or secondary DEM tab and then select the BIL projected data format from the digital elevation model drop down list. The basic setup procedure is described below:

· Set the datum and projection for the data source. All data files used in this database selection must be referenced to this datum.

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. Depending on the specific DEM format, the following options are available to import an index from external files. Select Files - Import Index.

For Planet type databases, select "text file index" item. This uses the standard text file import utility described in the general program operation section

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

If the DEM files are previously converted GRIDASCII files, then select the "GRIDASCII utm files" and multi select the DEM files. Note that the file suffix "utm" means that this is a projected DEM as opposed to a geographic DEM. The actual projection is not necessarily UTM.

The File index includes a conversion utility from ERSI GRIDASCII to a binary format. Select Convert - GRIDASCII and multi select the files to be converted. Note that the windows file open dialog includes an option to include the specific directory in the index

BIL geographic DEM setup procedure

Use this option for ESRI GRIDASCII geographic data. Select the primary or secondary DEM tab and then select the BIL geographic data format from the digital elevation model drop down list. SRTM, NED and GTOPO39 DEMS are examples of the BIL geographic DEM. Preconfigured options for these databases are available. The basic setup procedure is described below:

· Set the datum corresponding to the data source. All data files used in this database selection must be referenced to this datum. Set the projection to geographic (latitude-longitude)

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. Depending on the specific DEM format, the following options are available to import an index from external files. Select Files - Import Index.

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

For SRTM hgt files, a file open dialog is used to multi select the hgt files. The index will be created using the file name for the extents and the file size for the resolution.

If the DEM files have been previously converted GRIDASCII files, then select the "GRIDASCII geo files" and multi select the DEM files.

The File index menu includes a conversion utility from ERSI GRIDASCII to a binary format. Select Convert - GRIDASCII and multi select the files to be converted. Note that the windows file open dialog includes an option to include the specific directory in the index

NED (CONUS) setup procedure

This is a specific implementation of the BIL geographic DEM. The term CONUS refers to the 48 contiguous states. The BIL file has the following characteristics:

· the data origin is the north west corner.

· data format can be 16 bit integers or 8 bit integers depending on the elevation range in the file

· byte order is big-endian (Motorola)

· the spacial reference is geographic with a resolution of 1, 1/3 and 1/9 arc seconds. The datum is NAD83. Spacial details are given in external ESRI blw and hdr files

Select the primary or secondary DEM tab and then select the NED (CONUS) data format from the digital elevation model drop down list. The datum is automatically reset to NAD 83 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. The following options are available to import an index from external files. Select Files - Import Index.

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

If the DEM files have been previously converted GRIDASCII files, then select the "GRIDASCII geo files" and multi select the DEM files.

NED (Alaska) setup procedure

This is a specific implementation of the BIL geographic DEM for Alaska. The BIL file has the following characteristics:

· data is referenced to the center of a cell

· data is organized in rows running from west to east starting in the north west corner.

· the data format is a 16 bit integer

· byte order is big-endian (Motorola)

· the spacial reference is geographic with a resolution of 2 arc seconds. The datum is currently NAD27. Spacial details are given in external files ESRI blw and hdr files

Select the primary or secondary DEM tab and then select the NED (Alaska) data format from the digital elevation model drop down list. The datum is automatically reset to NAD 27 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. The following options are available to import an index from external files. Select Files - Import Index.

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

If the DEM files have been previously converted GRIDASCII files, then select the "GRIDASCII geo files" and multi select the DEM files.

SRTM (World) setup procedure

SRTM data provides 3 arc second world wide coverage in the latitude range 60°N to 60°S. One arc second data is available for the United States. The data is available in ESRI BIL format and in 1 degree by 1 degree hgt files. This is a specific implementation of the BIL geographic data format with the following characteristics.

· the data origin is the north west corner.

· data format can be 8 or 16 bit integers in the ESRI BIL format. The hgt files use 16 bit integers.

· byte order is big-endian (Motorola)

· the spacial reference is geographic. The datum is WGS84. Spacial details are given in external files in the ESRI BIL version and are derived from the file name

Select the primary or secondary DEM tab and then select the SRTM (World) data format from the digital elevation model drop down list. The datum is automatically reset to WGS 84 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. The following options are available to import an index from external files. Select Files - Import Index.

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

For SRTM hgt files, a file open dialog is used to multi select the hgt files. The index will be created using the file name for the extents and the file size for the resolution.

If the DEM files have been previously converted GRIDASCII files, then select the "GRIDASCII geo files" and multi select the DEM files.

GTOPO30 (World) setup procedure

The GTOPO30 DEM provides world wide coverage with a 30 arc second resolution. This is a specific implementation of the BIL geographic data format with the following characteristics.

· data is organized in rows running from west to east starting at the north west corner.

· data format is 16 bit integers

· byte order is big-endian (Motorola)

· the spacial reference is geographic with a resolution of 30 arc seconds. The datum is WGS84. Spacial details are predefined in the program

Select the primary or secondary DEM tab and then select the GTOPO30 (World) data format from the digital elevation model drop down list. The datum is automatically reset to WGS 84 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. Note that the complete index is automatically set The following options are available to add additional file indexes from external files. Select Files - Import Index.

For ESRI Arc Info/Grid BIL files, select the "bil, hdr, blw files" item and load any file with these suffixes. Note that the windows file open dialog includes an option to include the specific directory in the index.

For SRTM hgt files, a file open dialog is used to multi select the hgt files. The index will be created using the file name for the extents and the file size for the resolution.

If the DEM files have been previously converted GRIDASCII files, then select the "GRIDASCII geo files" and multi select the DEM files.

DTED setup procedure

DTED (Digital Terrain Elevation Data) is the US Defense Mapping Agency binary terrain data format. The basic DTED data format is given below:

· data is written in columns from south to north starting in the south west corner. each column begins with a header and ends with a check sum of the elevations.

· the elevation data is defined at the intersection of the row column grid lines

· data format is a 16 bit integer

· byte order is big-endian (Motorola)

· the datum is WGS84. the spacial reference is geographic. The east - west resolution is 3 arc seconds DTED level 1 and 1 arc second for DTED level 2. The north - south resolution varies with latitude as shown below for DTED level 1 data

0 to 50° - 3 sec 50° to 70° - 6 sec 70° to 75° - 9 sec 75° to 80° - 12 sec 80° to 90° 18 sec

Select the primary or secondary DEM tab and then select the DTED data format from the digital elevation model drop down list. The datum is automatically reset to WGS 84 using a geographic (latitude - longitude projection). The basic setup procedure is given below:

· Click the Setup button and set the main directory for the DEM files. This will depend on the selected directory structure as described below

· DTED files can be indexed using the main default directory or individual directories for each file. Another option is to used a defined directory structure and a file naming convention for these file. In the following arrangements the file name suffix is dt1 for level 1 data and dt2 for level 2 data.

USDMA defined directory names are based on the longitude e.g W072. File names in that directory are based on the latitude e.g. N34.dt1. In this arrangement the file would be (main directory)\W072\N34.dt1.

Canadian DTED file naming convention - this is the same as the USDMA convention with four zeros added to the directory and file names. The file name in this case would be (main directory)\W0720000\N340000.dt1.

the Pathloss version 4.0 file naming convention uses the latitude and longitude e.g. W072n34.dt1. The file name is unique and does not depend on the directory name. The files can be all located in a single directory or can be saved in a user defined data structure based on latitude or longitude. Using the directory format specifier "%x%03X" the file name would be (main directory)/W072/W072N34.dt1

· USGS 1:25000 ASCII DEM files can be converted to the DTED file format. This can be carried out from the Setup dialog or the File index. In the file index, the conversion will automatically create an index.

· If the file index method is used, click the File Index button. The select the Files - DTED file index menu item. Mu lit select the DTED files to create the index

CDED (Canada) setup procedure

CDED (Canadian Digital Elevation Data) files are provided in the USGS 1:250 000 ASCII DEM file format. These are available in a 3 arc second resolution for 1:250 000 scale mapping and 0.75 arc seconds for 1:50 000 scale mapping. The files are converted to a DTED file format with the suffix "dtd". The basic format is shown below:

· Data is written in columns from south to north starting in the south west corner. Each column begins with a header and ends with a check sum of the elevations.

· the elevation data is defined at the intersection of the row column grid lines

· data format is a 16 bit integer

· byte order is big-endian (Motorola)

· The datum is NAD83

· The the spacial reference is geographic (latitude - longitude). The grid spacing is based on the coordinates at a maximum and minimum resolution of 0.75 and 3 arc seconds for the 1:50 000, and 3 and 12 arc seconds for the 1:250 000 respectively, depending on latitude.

Select the primary or secondary DEM tab and then select the CTED (Canada) data format from the digital elevation model drop down list. The datum is automatically reset to NAD83 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory for the DEM files.

· Click the File index button. Then select the Files - DTED file index and multi select the DTED files. The index lines will be created based on the file header information.

· The ASCII CDED files must be converted to the DTED format to be used in the program. In the File index select the convert menu item. Multi select the CDED files and the conversion will automatically generate the index for the converted files.

USA 3 sec compressed setup procedure

Three arc second terrain data for the United States in a compressed format is available for use with the Pathloss program. This data has been taken directly from the USGS 1:250,000 ASCII DEMs. The elevations in these files are in meters relative to mean sea level. The south-north resolution is 3 arc seconds. Below 50° the west-east resolution is 3 arc seconds. Between 50° and 70° the resolution is 6 arc seconds and 9 arc seconds above 70°.The error checking on these files consisted of the following verifications.

· Each elevation must be within the range specified for both the entire file and the specific column.

· The absolute value of all elevations including the maximum and minimum values must be less than 10000 meters.

A total of 29 files did not pass this criteria and these were edited. The majority of errors involved the maximum elevation in the file. Other errors included extreme elevations (-32467) at the end of columns. These files have all been edited. None of the changes involved interpolating elevations. Most of the errors occurred at sea level.

All files are contained on a single CD-ROM and are organized in directories based on longitude under a main directory 3SEC_USA. The directory names are based on the longitude of the southwest corner of file e.g. W095. The file names are based on the longitude and latitude of the southwest corner. At latitudes less than 50º, the files have been split into two halves at the central longitude of the file. The letter L (left) or R (right) is appended to the file name. The file suffix is always cte (compressed terrain elevations). As an example, the file W095N44R.CTE represents the western half of the one degree block whose southwest corner is located at 44º north and 95º west. The file is located in the directory 3SEC_USA\W095 on the CD-ROM. The basic setup procedure is given below:

Select the primary or secondary DEM tab and then select the USA 3 sec compressed data format from the digital elevation model drop down list. The datum is automatically reset to WGS84 using a geographic (latitude - longitude projection).

· Click the Setup button and set the main directory to the location of the 3SEC_USA directory.

· As this database uses a file naming convention in a fixed directory structure, a file index is not used and the setup procedure is complete

Pathloss 5.0 : GIS Setup (ch 3)

Digital Elevation and clutter Models

The following description is applicable to both digital elevation and clutter models. The term DEM (digital elevation model) is used for both elevations and clutter databases. A DEM is a regular array (rows and columns) of data. These rows and columns can be considered to form two different arrangements

· The rows and columns form an x-y axis grid. The data is defined at the intersections of the x and y grid lines.

· The rows and columns form rectangular cells. The data represents the average value in the cell area and is defined at the center of the cell.

The horizontal extent of the data is determined by the grid spacing or the cell size and the number of rows and columns. Suppose the xy grid spacing is one kilometer and the cell size is also one kilometer. A horizontal extent of 100 kilometers would require 101 rows / columns for grid referenced data and 100 rows / columns for cell referenced data.

The horizontal reference can be in geographic or projected coordinate system. For example the data base might be described as a 3 arc second in the case of a geographic reference or 30 meters in database using a UTM projection. In both cases the horizontal datum must be known.

Some DEMS use a file naming convention is used to identify the horizontal extents. In others, the spacial data is in For example the SRTM hgt files are in one degree by one degree blocks. The file name is based on the south west corner coordinates and the resolution of either 3 arc seconds or 1 arc second is determined by the size of the file. Other databases provide the spacial information in external files

The usual data format is an unsigned 16 bit integer. This can represent any elevation in meters relative to sea level or an index into a clutter definition table. Some DEMs will use 8 byte integers provided that the actual range of data values can be accommodated. Other DEMS use floating point numbers.

The actual data file contains only the elevations or clutter values and is written as a continuous sequence of data values. The file may contain a header describing the extents and resolution of the file or this information may be available in external files Several common formats are given below.

· data is written in columns from south to north starting at west edge and proceeding to the east edge

· data is written in rows from west to east starting at the south edge and proceeding to the north

· data is written in rows from west to east starting at the north edge and proceeding to the south edge

BIL file format

BIL ("Band Interleaved by Line) is a generic GIS data file format. A single band (elevation or clutter) is used in all databases in this program and this would be more correctly denoted by BSQ (Band Sequential). BIL files have the following characteristics.

· the data is referenced to the center of a cell

· data is organized in rows running from west to east. The origin can be in the south west or north west corner.

· data format can be 16 bit integer, 8 bit integer or IEEE floating point

· byte order can be big-endian or little-endian ( Motorola - Intel)

· the spacial reference can be geographic or a projection such as UTM. The file contains only the elevation or clutter data. An external file index is used to define the extents of each file.

· Planet data is an example of BIL projected data. The US NED is a an example of BIL geographic data.

File Locations

Other that the Site coordinates tab, each tab includes a Setup button which specifies the location of the files associated with that tab. These files can be located in individual directories or in a main or common directory. If a directory is specified for a file, the program first looks for the file in that directory. If the file is not found or the file directory is not specified, the program looks for the file in the main directory.

File Index

A file index specifies the extents and resolution of the data files. This is the lookup table which maps the coordinates of a point to the database file name. The mapping procedure checks for file with overlapping areas and uses the file with the higest resolution. The File index uses a standard grid data entry form for which details are provided in the general program operation section. The following fields are used:

· west, east, south, north edges

· number of rows and columns

· x and y cell sizes

· UTM zone - standard meridian this field is only used on projections which have been specified as variable

Either the cell sizes or the number of rows and columns can be specified. The other fields will be calculated. If only the x cell dimension is entered, it is assumed that the y cell is the same size.

All dimensions must correspond to the specified projection. For example a DTED file (geographic) would have the edges specified in degrees and the cell size in seconds as follows:

west edge = 105W, east edge = 104W, south edge = 51N, north edge = 52N, x cell = 6 (seconds) y cell = 3 (seconds)

UTM projected data would have all units expressed in meters as in the example line below

west edge = 535590.0 m, east edge =545590.0 m, south edge = 721330.0 m, north edge = 731330.0, x cell = 10m

mention temporary file index here

talk about how the index is used and always the best resolution

Import Methods

Select Files - Import index on the File index menu bar. A submenu of the available import methods is displayed. The following methods to import an index are used:

· if the data files include header information or uses a file naming convention, a standard windows file open dialog is use to multi select the files. The headers are read and the index is automatically generated. Examples of this method are DTED and SRTM hgt files

· ESRI Arc Info/Grid employ separate files with the suffixes hdr, blw, and prj files to define the extents and projection of the data file which usually has a bil suffix. These files can be used to automatically generate an index item for the file.

· A text file index is included in Planet type data sets. This file can be imported using the standard text import utility described in the general program operation section.

· The file index menu may include an item to convert an ASCII file to the binary DEM format. This procedure will automatically generate an index for the converted file.

DEM Parameters

Right click on an index item or select Edit - Parameters from the File index menu bar. The DEM Parameters dialog shows the default DEM configuration.

· data type - default value - do not change

· byte order - A change may be necessary when using the generic BIL projected and geographic formats.

· location - default value - do not change

· units - default value - do not change

· no data value - changes allowed based on specific data file information.

· treat no data values as sea level - the default value is false. Users can change this based on actual knowledge of the area.

· read data as.. The default setting are "4 point weighted average" on DEMs and single point on clutter data bases. If the DEM contains embedded building data, this should be set to a single point read

· file organization - default value - do not change

· file origin - on BIL data, this setting effectively turns the display upside down. A change may be necessary when using the generic BIL projected and geographic formats

Pathloss 5.0 : GIS Setup (ch 2)

Site coordinates

The first step is to set the datum and projection as described above. All site coordinates must correspond to the datum specified here. This tab also includes several data entry and formatting options

Hemisphere selection

Internally, the program uses the standard convention of positive latitudes in the northern hemisphere and positive longitudes in the eastern hemisphere. The user has the option of setting any hemisphere as positive as a data entry convenience. When site data is imported into the program, the hemispheres are defined in the import procedure.

Latitude format

If the latitudes are positive in the northern hemisphere, a minus sign before the degrees will change the entry to a southern latitude. If the southern hemisphere is selected, the opposite is true. Alternately, the letters `N' and `S` can be used to specify a northern or southern latitude respectively.

Note that the latitude hemisphere selection also affects the zone in the Universal Transverse Mercator projection. The redundancy between UTM coordinates in the northern and southern hemispheres is removed by specifying the zone as north or south (e.g. 10N). A negative zone number has the effect of specifying the opposite hemisphere in the same manner as a negative latitude.

Northern Hemisphere Selected Southern Hemisphere Selected

Data Entry Result Data Entry Result

49 32 24 49 32 24.0 N 49 32 24 49 32 24.0 S

-49 32 24 49 32 24.0 S -49 32 24 49 32 24.0 N

49 32 24 S 49 32 24.0 S 49 32 24 N 49 32 24.0 N

Longitude Formats

If the longitude is set to the western hemisphere, a minus sign before the degrees will change the entry to an eastern longitude. If the eastern hemisphere is selected, the opposite is true. Alternately the letters `E' and `W` can be used to specify a eastern or western longitudes respectively.

Western Hemisphere Selected Eastern Hemisphere Selected

Data Entry Result Data Entry Result

115 32 24 115 32 24.0 W 115 32 24 115 32 24.0 E

-115 32 24 115 32 24.0 E -115 32 24 115 32 24.0 W

115 32 24 E 115 32 24.0 E 115 32 24 W 115 32 24.0 W

Precision

Geographic coordinates can be formatted to the nearest second, nearest 0.1 second or the nearest 0.01 second. This does not affect the calculations, because the coordinates are saved as double precision numbers.

Latitude Longitude Data Entry Format

Latitudes and longitudes are entered in degrees, minutes and seconds separated by space, or in decimal format or any combination of these two methods. The following examples illustrate the format:

Data Entry Format Geographic Defaults Settings

Latitude

49 049 00 00.00 N northern hemisphere - nearest 0.01 second

49.5 049 30 00 S southern hemisphere - nearest second

49 30 01 049 30 01.0 N northern hemisphere - nearest 0.1 second

49 30.5 049 30 30.00 S southern hemisphere - nearest 0.01 second

49 049 00 00.00 S northern hemisphere - nearest 0.01 second

49.5 049 30 00.00 N southern hemisphere - nearest 0.01 second

Longitude

122 122 00 00.00 W western hemisphere - nearest 0.01 second

122.5 122 00 00 E eastern hemisphere - nearest second

122 12 02 122 12 02.0 W western hemisphere - nearest 0.1 second

-122 14.5 122 14 30.00 E western hemisphere - nearest 0.01 second

Advanced Site Coordinate Options

Reference latitude and longitude coordinates to WGS84

The following example illustrates the use of this option

Projection British National Grid

Datum Ordnace Survey Great Britain 1936

Region England.

The initial grid coordinates are X = 540000, Y = 235000 meters

The corresponding latitude and longitude are 51 59 43.25N and 00 02 21.85E. Note that these coordinates are referenced to the OSGB36 datum.

Suppose now that these coordinates were inadvertently used assuming a WGS84 datum. The error would be 113.6 meters in X and 47.7 meters in Y.

If the "Reference latitude and longitude coordinates to WGS84" option is checked, then a two step conversion is used from latitude - longitude (WGS84) to British National Grid XY. The intermediate latitude longitude in OSGB36 would not appear.

Latitude Longitude - to grid coordinate calculation sequence.

If the user enters the latitude and longitude, the projected grid coordinates are calculated and vice versa. Note that the calculation uses the major and minor axis of the ellipsoid.

Suppose the user has taken the UTM eastings and northings for a series of sites from a topographic map and entered these into the program. The user then notices that the datum was incorrectly set and therefore the latitude and longitude values are wrong. To salvage the work, the user would set the calculation sequence to "Recalculate the latitude - longitude from the projected XY coordinates" and then change the datum.

Projected coordinate system designation

This option specifies the grid coordinate labels in data entry forms and reports.

The easting and nothing designations are unambiguous; however X and Y designations can have opposite meanings on some projections. For example, in the Swiss National Grid system, X corresponds to northing and Y to easting.