Radio positioning of a mobile receiver using a virtual positioning reference

A method for obtaining radio positioning information relevant to a position of an autonomous vehicle, said method comprising:

• determining the position of the autonomous vehicle as being at a first known position;
• when the autonomous vehicle is at said first known position:
• scanning for signals from terrestrial transmitters of a plurality of different transmitter types, said plurality of different transmitter types including at least one type of transmitter that transmits signals of opportunity that are not intended for navigational use;
• distinguishing from among said signals a first signal transmitted by a first terrestrial transmitter having a known first transmitter location;
• analyzing said first signal to identify a distinguishable, predictably repeated first code word and a repeat rate thereof;
• and
• establishing a virtual positioning reference by logging the first known position together with a local time at which a first instance of the predictably repeated first code word is received by the autonomous vehicle from the first terrestrial transmitter, the local time being measured relative to a clock that is local to the autonomous vehicle;
• running the local clock during movement of the autonomous vehicle from the first known position to a second position, said second position being unknown;
• when the autonomous vehicle is at the second position, using the local clock to determine a first time difference between when the virtual positioning reference is predicted to receive a second instance of the first code word and when the autonomous vehicle actually receives the second instance of the first code word, and thereby determining radio positioning information relevant to the second position of the autonomous vehicle;
• and
• controlling a movement of the autonomous vehicle according to guidance information that includes the radio positioning information.

A method for obtaining and recording radio positioning information relevant to a position of a vehicle, said method comprising:

• determining the position of the vehicle as being at a first known position;
• when the vehicle is at said first known position:
• scanning for signals from terrestrial transmitters of a plurality of different transmitter types, said plurality of different transmitter types including at least one type of transmitter that transmits signals of opportunity that are not intended for navigational use;
• distinguishing from among said signals a first signal transmitted by a to first terrestrial transmitter having a known first transmitter location;
• analyzing said first signal to identify a distinguishable, predictably repeated first code word and a repeat rate thereof;
• and
• establishing a virtual positioning reference by logging the first known position together with a local time at which a first instance of the predictably repeated first code word is received by the vehicle from the first terrestrial transmitter, the local time being measured relative to a clock that is local to the vehicle;
• running the local clock during movement of the vehicle from the first known position to a second position, said second position being unknown;
• when the vehicle is at the second position, using the local clock to determine a first time difference between when the virtual positioning reference is predicted to receive a second instance of the first code word and when the vehicle actually receives the second instance of the first code word, and thereby determining radio positioning information relevant to the second position of the vehicle;
• and
• recording the positioning information and storing the positioning information for subsequent presentation to a user.