Übersicht
Die richtige Interpretation der Kartendaten, die Sie für eine bestimme Funkmodellierungs- oder Planungsaufgabe benötigen, ist für den Erfolg eines Projektes von zentraler Bedeutung. In den folgenden Abschnitten finden Sie einige einfache Vorgaben, die aufzeigen, wie ADTI Netzbetreibern, Regulierungsbehörden, Beratern und Systemintegratoren dabei helfen kann, sicherzustellen, dass sie ihre Anforderungen spezifizieren und realistische Budgets für den Datenerwerb erstellen können.

Map data

There are five data layers that may be needed:

DEM: The digital elevation model (DEM). This is a three-dimensional model of the environment in which radio network performance predictions are to be made. Essentially it comprises a grid of points, at each point there is a height - either ground height, building height or composite ground plus building. The DEM is specified by its resolution (the granularity of the grid in x, y and z axes) and the accuracy of the data (how well it actually represents the environment that it aims to model). Accuracy can be specified in terms of its error (Root Mean Square Error etc.) over reality and the date when the data was captured compared to the ground use change over the time since.

Raster images: Raster images give an essential backdrop on screen to the planning task. Generally these are in the form of maps often scanned from paper or acquired from mapping agencies as digital images. In some cases there can be utility in using higher resolution aerial photography but generally in planning there is little value in seeing the cars on the roads when in fact the requirement is for coverage across an area of the town. In choosing an image it is important that it has meaning to both planning team and their customer.

Vectors: Vectors can be used to represent ground usage features such as discrete buildings and vegetation, specific areas where performance is mandatory or even countries or areas where interference must be minimised. Vector data is invaluable in setting objectives for the planning team and in some cases is used within propagation algorithms.

Clutter data: Ground use data or clutter files can be used in place of actual building dimensions to represent degrees of urbanisation or vegetation. This data is often used in VHF and UHF propagation models. Like the DEM the clutter file can be specified in terms of its error compared to reality but here much broader agreement is all that is needed. This file can also be used to define the traffic demand across areas of ground or for the generation of subscribers for use in statistical modelling.

Geo-marketing data comprising data about customers and potential customer areas such as post codes with spot or vector area representation, actual customer locations with details of his business and propensity to use telecommunications services or test point data for use in frequency coordination. This is often available in text form with grid reference for location.

ATDI has the ability to source and create all the map data needed by any planning or modelling project. Where in-house knowledge is required we can also give the user the know-how and tools to do the work himself.

ATDI offer a free download of map data. The area is limited to a 100x100km square and at a resolution of 500m. Click on the link below and enter the centre point coordinates.

Click here for free map data

SRTM Cartographic Data
For radio planners wanting to reuse cartographic data, SRTM is the cost-effective alternative to Ordnance Survey data since it carries no royalties and can be used as required - all for a simple, one-off cost.

Using the data supplied by NASA's Shuttle Radar Topography Mission (SRTM) ATDI is now able to supply digital terrain models of any region of the world with greater resolution than available before from public sources.
In 2000, the American space shuttle performed a ten-day SRTM flight, during which a woldwide topographic survey was performed using the interferometric radar technique.  The data obtained during this survey (which covered about 80% of the surface of the planet with a resolution of around 1 arc second), has now been made available by NASA with a planimetric resolution of 3 arc seconds.

The SRTM data offers a level of accuracy at least equal to traditional sources but also its technical specifications are clear and consistent across the whole planet, which represents a real first in the domain of medium resolution cartography.
ATDI is now able to take the SRTM data and, using its powerful ICS Map Server software, apply the relevant treatments to process the raw data for use in radio modelling (tiling, geoconversion, addition of coastline, etc) and provide a complete digital terrain model (DTM) of regions in the world between latitudes 60 degrees North to 56 degrees South, with minimal delivery delays and reduced costs.  When converted, the DTM has a planimetric resolution of 90 metres at the latitude of the area of interest.  The altimetric resolution is 16 metres.

For more information contact Peter Paul on +44 (0)1293 522052 or email peter.paul@atdi.co.uk