Navigational system

A user module for a navigational system comprising:

• a receiver for receiving clocking signals from a plurality of transmitters;
• a processor for computing the range to each of the plurality of transmitters based upon the corresponding clocking signals received therefrom, and for determining a current position relative to each of said plurality of transmitters;
• designation means for sequentially designating and storing a sequence of reference points defining a route from an initial position to a selected final position said route including said current position;
• a memory for storing geographical data relating to at least the current position of the user module;
• selection means for selecting geographical data relating to the current location of the user module based upon the determined current position;
• a display for providing an audio or video display of the selected geographical data and the current location of the user module relative thereto, and for providing an indication to the user of the distance and direction to a subsequent reference point in said sequence;
• and transmission means for transmitting said designated sequence of reference points to a control processor associated with at least one of said plurality of transmitters.

A method of providing navigational information comprising:

• receiving data signals from a plurality of transmitters;
• computing the range to each of the plurality of transmitters based upon a clocking signal received therefrom, and for determining a current position relative to each of said plurality of transmitters;
• designating a sequence of reference points defining a route from an initial position to a selected final position said route including said current position;
• storing geographical data relating to at least the current location in a memory;
• selecting geographical data relating to the current location from said memory;
• providing an audio or video display of the selected geographical data and the current position of the user relative thereto, and providing an indication to the user of the distance and direction to a subsequent reference point;
• and
• transmitting said designated sequence of reference points to a control processor associated with at least one of said plurality of transmitters.

A navigational system comprising;

• a plurality of first transmitters for transmitting a clocking signal to a user module;
• the user module including:
• a processor computing the range to each of the plurality of transmitters based upon the corresponding clocking signals received therefrom, determining a current position relative to each of said plurality of transmitters, and sequentially designating and storing a sequence of reference points defining a route from an initial position to a selected final position, said route including said current position;
• memory storing geographical data relating to at least the current position of the user module;
• said processor selecting geographical data relating to the current location of the user module based upon the determined current position;
• a display for providing an audio or video display of the selected geographical data and the current location of the user module relative thereto, and for providing an indication to the user of the distance and direction to a subsequent reference point in said sequence;
• and
• a second transmitter transmitting said designated sequence of reference points to a control processor associated with at least one of said plurality of first transmitters.