Automatic calibration device for direct spectrum spread receiver
First Claim
1. An automatic calibration device for a direct spectrum spread receiver which restores an information signal in a transmission signal spread in accordance with a wide band spreading code by performing reverse spreading, comprising:
- receiving means for receiving the transmission signal and producing a reception signal;
switch means for changing over between the reception signal from the receiving means and a simulation signal from simulation signal generating means;
pseudo noise generating means for generating a pseudo noise code corresponding to the spreading code;
shifting means for producing delayed pseudo noise codes having different delay times on the basis of the pseudo noise code from the pseudo noise generating means;
simulation signal generating means for producing the simulation signal on the basis of two delayed pseudo noise codes from the shifting means;
first comparing means for producing a sync detection signal on the basis of an output signal of the switch means, one delayed pseudo noise code from the shifting means, and a reference voltage from a control means;
second comparing means for producing a sync holding signal on the basis of the output signal of the switch means and two delayed pseudo noise codes from the shifting means; and
the control means for receiving the sync detection signal from the first comparing means and the sync holding signal from the second comparing means, producing the reference voltage to be provided to the first comparing means, and controlling the switch means and the pseudo noise generating means;
whereinin a calibrating mode, the control means controls the switch means to choose the simulation signal, and stores the reference voltage being provided to the first comparing means and the sync holding signal; and
in a receiving mode, the control means controls the switch means to choose the reception signal, provides the stored reference voltage to the first comparing means, and controls the pseudo noise generating means on the basis of the stored sync holding signal so that synchronization of the receiver is held.
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Abstract
A simulated reception signal is produced by modulating an AC signal having the same frequency as the reception frequency with a modulating signal produced using two pseudo noise codes delayed by 1/2 or 3 chips. In a calibrating mode, in which the simulated reception signal is chosen, a reference voltage to a comparator for synchronization detection and an output voltage of a differential amplifier for synchronization holding are stored in a CPU. In a receiving mode, in which an actual reception signal is chosen, the CPU controls the comparator and a pseudo noise generator which is included in a delay lock loop on the basis of the stored data.
70 Citations
6 Claims
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1. An automatic calibration device for a direct spectrum spread receiver which restores an information signal in a transmission signal spread in accordance with a wide band spreading code by performing reverse spreading, comprising:
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receiving means for receiving the transmission signal and producing a reception signal; switch means for changing over between the reception signal from the receiving means and a simulation signal from simulation signal generating means; pseudo noise generating means for generating a pseudo noise code corresponding to the spreading code; shifting means for producing delayed pseudo noise codes having different delay times on the basis of the pseudo noise code from the pseudo noise generating means; simulation signal generating means for producing the simulation signal on the basis of two delayed pseudo noise codes from the shifting means; first comparing means for producing a sync detection signal on the basis of an output signal of the switch means, one delayed pseudo noise code from the shifting means, and a reference voltage from a control means; second comparing means for producing a sync holding signal on the basis of the output signal of the switch means and two delayed pseudo noise codes from the shifting means; and the control means for receiving the sync detection signal from the first comparing means and the sync holding signal from the second comparing means, producing the reference voltage to be provided to the first comparing means, and controlling the switch means and the pseudo noise generating means;
whereinin a calibrating mode, the control means controls the switch means to choose the simulation signal, and stores the reference voltage being provided to the first comparing means and the sync holding signal; and in a receiving mode, the control means controls the switch means to choose the reception signal, provides the stored reference voltage to the first comparing means, and controls the pseudo noise generating means on the basis of the stored sync holding signal so that synchronization of the receiver is held. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification