Receiving device for receiving and demodulating spread spectrum-modulated GPS wave
AssigneeVictor Company of Japan, Ltd.
InventorYukinobu Ishigaki
Life of this patent
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Abstract
A receiving device for receiving spread spectrum-modulated GPS signal transmitted from GPS (Global Positioning System) satellites to the earth. Received GPS signals are converted into IF signals which are despread-demodulated on the basis of C/A codes, resulting in demodulated PSK signals. Carriers are reproduced from the IF signals and a clock signal for C/A code generator is produced from the reproduced carrier and a local oscillation signal. The PSK signal is demodulated on the basis of a reference frequency of a PLL circuit to obtain a navigation message.
Claims11
A receiving device for receiving and demodulating spread spectrum-modulated GPS electromagnetic waves from GPS satellites comprising:
- C/A code generator means for generating a C/A code corresponding to that of an aimed GPS satellite on a basis of a clock signal;
- frequency conversion means for converting said received GPS electromagnetic wave into at least one intermediate frequency signal by means of a local oscillation signal;
- despread-demodulation means for obtaining a PSK signal by performing a despread-demodulation by multiplying said intermediate frequency signal with said C/A code;
- carrier reproduction means for reproducing a carrier of the PSK signal from said PSK signal;
- clock signal generator means for generating a clock signal from said reproduced carrier and said local oscillation signal and supplying said clock signal to said C/A code generator means;
- and
- demodulation means for demodulating GPS data from a frequency of said reproduced carrier and said PSK signal.
A method of receiving and demodulating spread spectrum-modulated GPS electromagnetic waves from GPS satellites comprising the steps of:
- generating a C/A code corresponding to that of an aimed GPS satellite on a basis of a clock signal;
- converting said received GPS electromagnetic wave into at least one intermediate frequency signal by means of a local oscillation signal;
- obtaining a PSK signal by multiplying said intermediate frequency signal with said C/A code to perform a despread-demodulation;
- reproducing a carrier of the PSK signal from said PSK signal;
- producing a clock signal from said reproduced carrier and said local oscillation signal;
- and
- demodulating GPS data from said reproduced carrier and said PSK signal.
Dependencies are inferred from the claim text.