Signal receiver for global positioning system

A GPS signal receiver comprising:

• a PN code generator for producing a PN code identical to a PN code in a received GPS signal which is transmitted from a GPS satellite, the PN code produced by said PN code generator being controllable in phase;
• a PN code correlator for correlating the received GPS signal with the PN code produced by said PN code generator so as to code-strip the received GPS signal;
• A signal search unit for monitoring a correlated output signal from said PN code correlator and controlling the phase of the PN code produced by said PN code generator to search for a correlated output signal having a signal strength in excess of a predetermined value;
• a signal determining unit for determining said correlated output signal in excess of said predetermined value as being produced by a GPS radio wave which arrives at said GPS signal receiver through a direct path from the GPS satellite, wherein said signal determining unit includes a discriminator for discriminating said GPS signal from two correlated output signals, both of said two correlated output signals having signal strengths above said predetermined value and said two correlated output signals differing in phase from each other;
• and
• a signal tracking unit for controlling the phase of the PN code produced by said PN code generator to track a peak of the correlated output signal that is determined as being produced by said GPS radio wave.