Correlator for spread spectrum receiver
View Patent ↗The present invention discloses correlation architecture in the application of full-digital GPS (Global Positioning System) receivers. According to the present invention, a satellite C/A code generator is employed to generate N-bit parallel code data at a time, and a Doppler frequency generator is used to generate N-bit parallel Doppler frequency data at a time. Signals received by the receiver can be temporarily stored in a buffer that provides N-bit parallel reception data to a correlation circuit. In the correlation circuit, a N-bit multiplier is used to multiply the N-bit reception data by the N-bit C/A code data and the N-bit Doppler frequency data to generate multiplication results. The N-bit multiplication results are thereafter summed up in parallel by a digital summator. Accordingly, the correlator of the present invention can improve circuit performance and save the required cost.
1. In a spread spectrum receiver capable of receiving signals from a plurality of transmitters, an apparatus comprising:
a buffer for storing said received signals and generating parallel reception data associated with said received signals;
a channel searcher for processing said parallel reception data in a parallel format and determining whether any of said plurality of transmitters is found in a position-division manner; and
a plurality of channel trackers for processing said parallel reception data in said parallel format and tracking said found transmitter in a channel-division manner after said channel searcher finds at least one of said plurality of transmitters,
wherein said channel searcher comprises:
a code generator for generating a set of identification codes associated with one of said plurality of transmitters and providing N-bit parallel code data;
a plurality of search engines for processing said N-bit parallel code data in said position-division manner and providing a plurality of correlation results; and
a detector for determining whether said set of identification codes is correspondent with said received signals in response to said plurality of correlation results.
2. The apparatus as claimed in claim 1 , wherein each of said plurality of search engines comprises:
a multiplier for multiplying said N-bit parallel code data by said N-bit parallel reception data to generate an N-bit multiplication result; and
a summator for summing said multiplication result.
3. The apparatus as claimed in claim 2 , wherein each of said plurality of search engines further comprises a coherence integrator, a squarer, and a non-coherence integrator sequentially coupled between said summator and said detector.
4. The apparatus as claimed in claim 1 , wherein said channel searcher further comprises a frequency generator for generating a frequency signal and providing N-bit parallel frequency data to be multiplied by said N-bit parallel reception data by a multiplier within each of said plurality of search engines.
5. The apparatus as claimed in claim 1 , wherein each of said plurality of channel trackers comprises:
a code generator for generating a set of identification codes associated with one of said plurality of transmitters and providing N-bit parallel code data;
a channel control for controlling the generation of said set of identification codes in said channel-division manner;
a correlation circuit for generating a correlation result in response to said N-bit parallel code data and said parallel reception data; and
a detector for determining whether said set of identification codes is correspondent with said received signals in response to said correlation result.
6. The apparatus as claimed in claim 5 , wherein said correlation circuit comprises:
a multiplier for multiplying said N-bit parallel code data by said parallel reception data to generate an N-bit multiplication result; and
a summator for summing said multiplication result.
7. The apparatus as claimed in claim 6 , wherein each of said correlation circuit further comprises a coherence integrator, a squarer, and a non-coherence integrator sequentially coupled between said summator and said detector.
8. The apparatus as claimed in claim 5 , wherein each of said plurality of channel trackers further comprises a frequency generator coupled to said channel control for generating a frequency signal in said channel-division manner and providing N-bit parallel frequency data to be multiplied by said parallel reception data by a multiplier.
9. In a spread spectrum receiver capable of receiving signals from a plurality of transmitters, an apparatus comprising:
a buffer for storing said received signals and generating parallel reception data associated with said received signals;
a channel searcher for processing said parallel reception data in a parallel format and determining whether any of said plurality of transmitters is found in a position-division manner; and
a plurality of channel trackers for processing said parallel reception data in said parallel format and tracking said found transmitter in a channel-division manner after said channel searcher finds at least one of said plurality of transmitters,
wherein each of said plurality of channel trackers comprises:
a code generator for generating a set of identification codes associated with one of said plurality of transmitters and providing N-bit parallel code data,
a channel control for controlling the generation of said set of identification codes in said channel-division manner,
a correlation circuit for generating a correlation result in response to said N-bit parallel code data and said parallel reception data, and
a detector for determining whether said set of identification codes is correspondent with said received signals in response to said correlation result.
10. The apparatus as claimed in claim 9 , wherein said correlation circuit comprises:
a multiplier for multiplying said N-bit parallel code data by said parallel reception data to generate an N-bit multiplication result; and
a summator for summing said multiplication result.
11. The apparatus as claimed in claim 10 , wherein each of said correlation circuit further comprises a coherence integrator, a squarer, and a non-coherence integrator sequentially coupled between said summator and said detector.
12. The apparatus as claimed in claim 9 , wherein each of said plurality of channel trackers further comprises a frequency generator coupled to said channel control for generating a frequency signal in said channel-division manner and providing N-bit parallel frequency data to be multiplied by said parallel reception data by a multiplier.