In order to take proper advantage of the Global Positioning System, federal and provincial agencies have established three new layers of control survey networks:

1. The continuously operated GPS sites of the Canadian Active Control System (CACS)
2. The federal high accuracy Canadian Base Network (CBN)
3. The High Precision Networks (HPN's)

These three new layers of control networks not only compliment and densify the existing control networks they were specifically designed for GPS use. They are, for the most part, easily accessible and provide GPS equipment an unobstructed view of the sky.

The Canadian Spatial Reference System (CSRS) is a highly accurate, multipurpose, active and integrated geocentric reference system.

Now, for the first time we have a network that is accurate over long distances from the fundamental points (fiducial points) of the reference frame and is completely compatible with the very latest in space based positioning systems - GPS.

It provides an accessible backbone to which new surveys can be tied, and to improve the positions of the points of the existing network.

All of the layers together form the Canadian Spatial Reference System (CSRS) and supported by the various federal and provincial agencies it has become a very practical and useable tool in today's digital information society.

Summary

Despite the different names floating about in connection with reference systems, there are really only two datums and basic reference frames used in Canada - NAD27 and NAD83. All other reference systems are merely variations, some major, some minor. Even the lone exception, the ATS77 datum used in the Maritime Provinces has recently been replaced with NAD83.

The CACS/CBN/HPN network layers of control have recently provided the means to once again update the NAD83 reference frame by improving accuracy and adding the third dimension.

The important thing to note is that the improvements in network accuracy brought about by the current CSRS version of the NAD83 reference frame are another step towards a consistent system capable of supporting the countries positioning needs today and into the future. This consistency through improved network accuracy enables us to take better advantage of all that GPS has to offer.

So, what does the Canadian Spatial Reference System mean to me?

A variety of CSRS related products and services have been developed to meet the diverse positioning requirements of Canadians.

By using CSRS products and services we can be sure that the data we gather can be shared, exchanged or merged, confident that the positional information will be both consistent and compatible across digital boundaries.