Abstract: A communication device can reliably find a frequency and establish frequency synchronization, despite relying on a variable reference frequency, and may do so, e.g., by searching only during one or more periods of frequency stability. Once gained, such synchronization may be held continuously. An acquisition unit receives from a control unit information about a frequency change of a reference signal. The acquisition unit may nonetheless continue to search for, e.g., a satellite at the frequency that had been in use before the frequency change of the reference signal. An acquisition unit in such a device may search over extended periods, e.g., by using two or more frequency-stable periods. The acquisition unit may, e.g., transmit information about a change in the reference frequency to a tracking unit to maintain synchronization with the satellite.

Abstract: Disclosed is a GPS receiving apparatus including a synchronous acquisition unit and a synchronous hold unit. The synchronous acquisition unit detects a correlation between a spread code of a received signal from a GPS satellite and a spread code provided by the apparatus in order to detect a phase of the spread code of the received signal and a carrier frequency of the received signal. The synchronous hold unit has a plurality of channels and allocates one of the channels to one of a plurality of GPS satellites. The synchronous hold unit also establishes initial values based on the spread code phase of the received signal following detection by the synchronous acquisition unit as well as on the likewise-detected carrier frequency of the received signal, before starting synchronous hold of the spread code and the carrier frequency regarding the signal from the GPS satellite in question while decoding the signal from the GPS satellite.

Abstract: A communication device able to reliably find a frequency and able to reliably establish synchronization of frequency even if an oscillation frequency of an oscillator changes and able to continuously hold synchronization of a carrier, wherein an acquisition unit uses a certain timewise stable area for a frequency search of a satellite so as to reliably find the frequency of the satellite, receives a frequency change of a reference signal from a control unit, performs a frequency search of the satellite at the frequency before the frequency change of the reference signal after the frequency change of the reference signal, uses two or more clock stable areas for the frequency search of the satellite to thereby make it possible to perform the frequency search of the satellite over a long time, and transmits a change to a tracking unit to establish synchronization of the frequency of the satellite where the frequency of the reference signal changes after the frequency search of the satellite.

Abstract: A GPS receiver that is capable of acquiring a GPS signal from a plurality of GPS satellites efficiently and at a high speed, and that is capable of performing a positioning calculation with a high degree of accuracy. The FFT processing result of the addition result from the PN code, stored in the memory, is multiplied by the FFT processing result of the IF data (the received data), stored in the memory, and by inverse-diffusing this result, a correlative value is obtained. By repeating this process while changing the combination of the PN codes to be added, and the synchronization acquisition processing, by a plurality of PN codes, is performed quickly with only a small amount of processing based on these results.

Abstract: Disclosed is a GPS receiving apparatus including a synchronous acquisition unit and a synchronous hold unit. The synchronous acquisition unit detects a correlation between a spread code of a received signal from a GPS satellite and a spread code provided by the apparatus in order to detect a phase of the spread code of the received signal and a carrier frequency of the received signal. The synchronous hold unit has a plurality of channels and allocates one of the channels to one of a plurality of GPS satellites. The synchronous hold unit also establishes initial values based on the spread code phase of the received signal following detection by the synchronous acquisition unit as well as on the likewise-detected carrier frequency of the received signal, before starting synchronous hold of the spread code and the carrier frequency regarding the signal from the GPS satellite in question while decoding the signal from the GPS satellite.

Abstract: To provide a GPS receiver capable of acquiring a GPS signal from a plurality of GPS satellites efficiently and at a high speed, and further, capable of performing a positioning calculation at a high degree of accuracy. The FFT processing result of the addition result of the PN code stored in the memory is multiplied by the FFT processing result of the IF data (the received data) stored in a memory, and by inverse-diffusing this result, a correlative value is obtained. By repeating this processing while changing a combination of the PN codes to be added, and the synchronization acquisition processing by means of a plurality of PN codes is performed quickly and with the small number of processing on the basis of these results.