controlling am reciever circuit using PC

Please help me on this project.
SPECIFICATION:
1)I want to control a AM reciever circuit with computer so that I recieve local radio transmission and listen the recieving signals on computer's sound card.
2)I want to tune channels by computer.

reciever for computer interface

3)i am working on the project local positioning system,so i need circuit diagram for that please help me,to get the reciever diagram.
thankz