Sect_1.1.2

DESIGN SPECIFICATIONS

Some design specifications for a hypothetical satellite-based "Global Positioning System":

(1) Satisfy as large a range of users as possible, military as well as civilian:

From those seeking dekametre (tens of metres) level of accuracy to those seeking millimetre accuracy,
from those interested only in position, to those also requiring velocity and time information as well, and
all air, sea and land users;

without altering the basic system configuration or operation

Important for justifying the enormous investment in the system!

(2) Relatively low user cost as well as ease-of-operation:

Hence minimal complexity, low power requirement and small bulk for the user equipment.

Important for gaining widespread user acceptance!

(3) Unrestricted access by all users:

Implying global coverage, 24-hour and all-weather operation.

(4) Satisfy military positioning requirements, such as:

Suitable for all classes of platform: aircraft (jet to helicopter), ship, land (vehicle to handheld units) and space (missiles and satellites).
Real-time positioning, velocity and time determination capability.
Positioning results available on a single geodetic datum.
Level of real-time accuracy available to non-military users to be controllable.
Resistant to jamming, and careful attention to other "survivability" issues.
Non-detectability of the user, hence no requirement to transmit signals of any kind.

Important as the military is one of the strongest lobby groups for the development of such a system.