Global positioning system course acquisition code receiver

A GPS satellite receiver for locking to a satellite signal, the receiver comprising in combination:

• means for receiving the satellite signal;
• first coupling means;
• down-converting means connected to said receiving means by said first coupling means, said down-converting means for down converting to a first frequency the frequency of a signal developed from said received satellite signal;
• second coupling means;
• a hard limiter connected to said down-converting means by said second coupling means, said hard limiter for converting from analog-to-digital form a signal developed from said down-converted satellite signal;
• third coupling means;
• carrier-synthesizer means for generating a first signal having a frequency established by carrier-synthesizer-means-driving signals;
• Q-counter means connected to said hard limiter by said third coupling means and connected to said carrier-synthesizer means, said Q-counter means for developing signals representing a count which is incremented at each of a series of times marked by said first carrier-synthesizer-means-generated signal when a signal developed from a signal developed by said hard limiter has a predetermined one of two states and decremented at each of said first carrier-synthesizer-means-generated-signal marked times otherwise;
• and
• controller means connected to said carrier-synthesizer means and connected to said Q-counter means, said controller means being responsive to said Q-counter-means-developed signals and operative to develop said carrier-synthesizer-means-driving signals so as to lock the frequency of said first carrier-synthesizer-means-generated signal to said down-converter-means first frequency.