JPH08204510A - Frequency control method and device for controlling frequency - Google Patents

Abstract

PURPOSE: To provide a reference frequency with higher precision with a simple and inexpensive device configuration. CONSTITUTION: A reception circuit 11 receives an input signal received from a base station or a relay station and a CPU 13 analyzes part of a signal resulting from the received signal demodulated by a demodulation circuit 12 to calculate a frequency deviation. The frequency deviation is corrected to update reference frequency data stored in a memory 14 and the updated reference frequency data are D/A-converted by a D/A converter 15. A variable reference frequency oscillating circuit 16 generates a reference frequency based on the data and a PLL synthesizer loop 17 generates a local signal and it is mixed with a reception frequency at the reception circuit 11 and the mixed signal is demodulated by a demodulation circuit 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frequency control method and apparatus for a mobile terminal in a general wireless system using a base station, a relay station and the like.

[0002]

2. Description of the Related Art FIG. 2 shows the configuration of a conventional frequency control device using a digital control method in a mobile terminal. In FIG. 2, 21 is a receiving circuit, 22 is a demodulation circuit,
23 is a CPU, 24 is a read-only memory (RO
M), 25 is a D / A converter, 26 is a variable reference frequency oscillation circuit, and 27 is a PLL synthesizer loop.
The CPU 23 reads the reference frequency data from the memory 24 and passes the control data to the D / A converter 25. D / A
The converter 25 converts the reference frequency data into an analog signal based on the passed control data and passes it to the variable reference frequency oscillation circuit 26. The variable reference frequency oscillation circuit 26 is
The reference frequency is oscillated and passed to the PLL synthesizer loop 27. The PLL synthesizer loop 27 oscillates a local frequency based on this reference frequency and passes a local signal to the receiving circuit 21. In the receiving circuit 21, the local frequency of this local signal and the frequency of the input signal received from the base station or relay station are combined to generate an intermediate frequency, and the demodulation circuit 22
The received input signal is demodulated by and a part of it is delivered to the CPU 23.

FIG. 3 shows the configuration of a conventional frequency control device using an analog control method in a mobile terminal.
In this example, the variable reference frequency oscillating circuit 34 oscillates a reference frequency, and the PLL synthesizer loop 35 oscillates a local frequency based on this reference frequency to pass a local signal to the receiving circuit 31. The local frequency of the signal and the frequency of the received input signal are combined to generate an intermediate frequency, the demodulation circuit 32 demodulates the received input signal, and a part thereof is passed to the CPU 33.

As described above, in the conventional frequency control device for the mobile terminal, the accuracy of the reference frequency is determined only by its own internal circuit.

[0005]

However, in the above-mentioned conventional frequency control device, since the accuracy of the reference frequency depends only on its own internal circuit, if the reference frequency is deviated due to some reason, it is still in operation. There is a problem in that it is difficult to correct, and it is also difficult to correct the deviation of the reference frequency due to changes over time or fluctuations in the power supply voltage.

The present invention solves such a conventional problem, and provides a frequency control method and a device therefor capable of obtaining a highly accurate reference frequency with a simple and low-priced device configuration. To aim.

[0007]

In order to achieve the above object, the present invention constantly corrects its own reference frequency by the reception frequency from a base station or a relay station having a more accurate reference frequency oscillation circuit. The correction value is continuously updated as new reference value data.

[0008]

Therefore, according to the present invention, the basic data of the reference frequency is constantly updated with the data obtained by self-correcting the reception frequency, so that only the temperature compensation is highly accurate due to the characteristics of the reference frequency oscillation circuit. Therefore, the frequency shift due to the change over time or the fluctuation of the power supply voltage can be allowed in a considerably wide range, and the circuit configuration can be simplified and the cost of the component parts can be reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of an embodiment of the present invention. In FIG. 1, 11 is a receiving circuit, 12 is a demodulation circuit, 13 is a CPU, 14 is a memory (RAM) that can be written and read at any time, 15 is a D / A converter, 16 is a variable reference frequency oscillation circuit, and 17 is a PLL synthesizer. It is a loop. The CPU 13 reads the reference frequency data from the memory 14 and passes the control data to the D / A converter 15. The D / A converter 15 converts the reference frequency data into an analog signal based on the passed control data, and passes the analog signal to the variable reference frequency oscillation circuit 16. The variable reference frequency oscillation circuit 16 oscillates the reference frequency and passes it to the PLL synthesizer loop 17. The PLL synthesizer loop 17 is
The receiver circuit 1 oscillates a local frequency based on this reference frequency.
Pass the local signal to 1. In the receiving circuit 11, the local frequency of this local signal and the frequency of the input signal received from the base station or relay station are combined to generate an intermediate frequency,
The demodulation circuit 12 demodulates the received input signal, part of which is CP
Hand it over to U13. The CPU 13 analyzes the input signal, calculates the frequency shift, corrects the frequency difference, updates the reference frequency data in the memory 14, and outputs to the D / A converter 15 based on the updated reference frequency data. Send control data and repeat the above operation.

As described above, according to the above embodiment, the self reference frequency is constantly corrected by the reception frequency from the base station or the relay station having the higher precision reference frequency oscillation circuit, and the correction value is newly set. Since it is kept updated as reference value data, in the stand-alone specification of the variable reference frequency oscillator circuit, if only the temperature characteristics are suppressed with high accuracy, other frequency stability will always be maintained as long as the equipment is in operation. It can be equivalent to a station or relay station.

[0011]

As is apparent from the above embodiment, the present invention constantly corrects its own reference frequency according to the received frequency and continuously updates the correction value as new reference value data. The frequency accuracy of the mobile terminal in the system can be made similar to that of the base station or the relay station, and the configuration of the reference frequency oscillator can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a frequency control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional digital control type frequency control device.

FIG. 3 is a block diagram showing the configuration of a conventional analog control type frequency control device.

[Explanation of symbols]

 11 receiver circuit 12 demodulator circuit 13 CPU 14 memory (RAM) 15 D / A converter 16 variable reference frequency oscillator circuit 17 PLL synthesizer loop

Claims (2)

[Claims] 1. A frequency control method in which a self reference frequency is constantly corrected by a reception frequency and the correction value is continuously updated as new reference value data. 2. Control means for analyzing a signal obtained by demodulating a received input signal from a base station or a relay station to calculate a frequency shift, correcting the frequency difference, and updating the reference frequency data held in the memory. And a means for D / A converting the updated reference frequency data, and a means for generating a reference frequency based on the D / A converted data.