JP2770974B2 - Wireless communication apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to a communication apparatus using frequency division multiple access (FDMA) that modulates with a digital signal, and in particular, a digital signal having a narrower band than a radio frequency. The present invention relates to a wireless communication device and a method for transmitting.

(Prior Art) In a wireless communication apparatus applied to a communication system in which a reception band is extremely narrow with respect to a wireless frequency, it is necessary to minimize an error in an oscillation frequency of a local oscillator in the apparatus. For this reason, the conventional wireless communication device has provided a constant temperature bath and put a crystal oscillator in the constant temperature bath to reduce the oscillation frequency error.

For example, Kakinuma et al.'S "frequency stabilization technology using slip control PLL" and the 1988 IEICE Spring National Convention collection of papers show a conventional method that reduces the oscillation frequency error without placing a crystal oscillator in a thermostat. The technology is shown. That is, in this conventional technique, the temperature characteristic of a crystal oscillator is measured and stored in a storage circuit, and at a predetermined temperature, the stored content is read out and corrected by a frequency correction circuit.

(Problems to be Solved by the Invention) However, in a device provided with a thermostat, power consumption is large, and it is difficult to apply the device in a field such as mobile communication where power consumption is limited as much as possible. Further, in the related art in which the characteristics of the crystal oscillator are stored in the storage circuit, even if the temperature characteristics of the oscillation circuit can be compensated, it is not compensated for a change with time. Also, in the conventional AFC circuit, when the spectrum is deviated due to a transmission pattern or the like, if the frequency of the local oscillator is controlled based on this signal, there arises a problem that the frequency of the local oscillator is erroneously controlled.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a wireless communication apparatus and method for calibrating the frequency of a local oscillator using a predetermined wireless channel, overcoming the disadvantages of the prior art.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a radio communication apparatus using frequency division multiple access, which receives a communication channel for transmitting communication information and a frequency calibration channel for calibrating the frequency. Local oscillation means for outputting a local oscillation signal for selecting these channels, inputting a first signal to set the frequency of the local oscillation signal, and correcting the set frequency by inputting a second signal And an error detecting means for comparing the frequency of the intermediate frequency signal at the time of receiving any of the calibration channel and the communication channel with a reference frequency to detect an error of the local oscillation means, and storing an error value detected by the error detecting means. It has storage means and error correction control means for outputting a second signal corresponding to the error value to the local oscillation means.

Further, according to the present invention, the radio communication system in the radio communication apparatus which is frequency-division multiple-accessed and has its own local oscillation means is provided with a local oscillation means before performing information communication or at a predetermined time during non-information communication. Receiving a radio channel for frequency calibration, detecting a frequency error of the local oscillator by the radio channel, storing a value of the detected frequency error, and setting an output frequency of the local oscillator to a predetermined frequency based on the stored frequency error value. To be corrected.

(Operation) According to the present invention, when communication is not being performed, a radio channel provided for calibration is received, a frequency error of the local oscillation means of the own station is detected, and this error value is stored in the storage means. Remember. Then, the output frequency of the local oscillation means is corrected to a predetermined frequency based on the error value stored in the storage means at the time of communication.

(Embodiment) Next, an embodiment of a wireless communication apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a functional block diagram of a receiving system is shown as an embodiment of the wireless communication apparatus according to the present invention.
It should be noted that, in the figure, each component of the wireless communication apparatus which is not directly related to the present embodiment is not shown.

The wireless device 30 has an antenna 32, from which a communication channel for performing a plurality of information communications is input to the input terminal 1. In order to calibrate the error of the local oscillator 15 of the device 30, the radio device 30 inputs an error calibrated radio channel to which a predetermined radio channel is assigned to the input terminal 1. A signal such as a non-modulated carrier wave, for example, that can easily detect the frequency of the reference oscillation source of the own station is transmitted to the calibration radio channel.

The device side of the input terminal 1 is connected to the input terminal 2 of the mixer 12. Mixer 12 also has input terminal 5 connected to local oscillator 15.
, From which a local oscillation signal S0 is input. The mixer 12 is a frequency conversion circuit that extracts the intermediate frequency of the signal input from these input terminals and outputs the signal to the output terminal 4. Terminal 4 is connected to the input of intermediate frequency amplifier 16. The intermediate frequency amplifier 16 is an amplifier circuit for amplifying the received intermediate frequency, and outputs the amplified signal from the output terminal 7 to, for example, the inside of the device 30.

The output side of the amplifier 16 is also branched and connected to the input terminal 8 of the frequency error detection circuit 18, and the amplified intermediate frequency is also sent to the detection circuit 18. The input terminal 11 of the detection circuit 18 is connected to a reference oscillation source 10 of the local oscillator 15 described later. The error detection circuit 18 is a circuit that detects a frequency error by inputting a signal input from the amplifier 16 and a reference frequency signal Sf from the oscillation source 10. The detection circuit 18 is connected to the storage circuit, and the detected frequency error signal is sent to the circuit 20. Note that the frequency error detection circuit 18 may be a normal frequency discriminator, and in this case, a signal from the terminal 10 is not required.

The storage circuit 20 is a memory that stores the received frequency error signal, that is, the frequency error value. The memory 20 is connected to the error correction circuit 22. The error correction circuit 22 is a correction circuit that corrects the oscillation frequency of the local oscillator 15. That is, the correction circuit 22 reads the frequency error value stored in the storage circuit 20 to correct the oscillation frequency of the synthesizer 14 of the local oscillator 15 described later.

The local oscillator 15 includes the reference oscillation source 10 and the synthesizer 14. The reference oscillation source 10 is, for example, a signal source such as a crystal oscillator, and its reference frequency Sf is input to the frequency error detection circuit 18 and the synthesizer 14. The synthesizer 14 has a reference frequency Sf input from the reference oscillation source 10.
Is a frequency synthesizer that converts a signal to a frequency set by the channel control signal S1 and outputs the converted signal to the input terminal 5 of the mixer 12.
Synthesizer 14 also provides a correction signal from error correction circuit 22.
The frequency set by the control signal S1 is corrected by S2.

For example, before performing information communication, in order to correct the local oscillator 15, the channel control signal S1 is sent to the synthesizer 14 to switch to a radio channel for calibrating the frequency error.
Add. Here, the frequency of the synthesizer 14 when the error calibration radio channel for calibrating the frequency error is selected is f2, the frequency error of the local oscillator 15 is fe, and the frequency of the error calibration radio channel is f1.

Mixer 12 determines the frequency of the error calibration radio channel signal.
f1 and local oscillation signal of synthesizer 14 {(f2 + fe)} (=
S0) and outputs the intermediate frequency signal {f1− (f2 + fe)} to the terminal 4. The intermediate frequency amplifier 16 amplifies the center frequency from the terminal 4 and outputs the intermediate frequency to the output terminal 7 and the frequency error detection circuit 18. The error detection circuit 18 receives the reference frequency signal Sf from the reference oscillation source 10 and converts a frequency {(f1-f2) -fe} of the input signal from a reference value (f1-f2) obtained by converting the reference frequency signal Sf. The error fe is detected by comparison. When the error detection circuit 18 detects the error fe, the error value
Df is output to the storage circuit 20 and stored therein. The error correction circuit 22 receives the error value Df from the memory 20,
The frequency error of the synthesizer 14 is corrected.

When the frequency error correction is completed, the channel control signal S1
Is switched from the frequency error calibration wireless channel to a wireless channel for performing information communication. When the information channel is selected, the error correction circuit 22 outputs an error correction signal S2 corresponding to the oscillation frequency of the synthesizer 14 based on the error value Df of the memory 20, and the local oscillator 15 outputs a predetermined oscillation frequency. To control. Therefore, mixer 12
It is possible to convert the signal of the information communication channel into an intermediate frequency signal having no error and output the intermediate frequency signal to the intermediate frequency amplifier 16. Note that such a frequency error correction process may be performed during non-information communication or the like.

As described above, according to the present embodiment, before performing information communication or when there is no information communication such as at the time of non-information communication, by switching to a predetermined wireless channel for calibrating the frequency error, it is determined that the local oscillator 15 has been corrected. Become. For this reason, at the time of necessary information communication, communication can be normally performed even in a communication system using a modulated signal whose spectrum is biased by a digital signal for which automatic frequency control is difficult.

(Effects of the Invention) According to the present invention, in a communication apparatus using frequency division multiple access, a predetermined radio channel for performing frequency calibration is provided, and this frequency calibration is performed before information communication or when there is no communication. Radio channel to be performed, and the output frequency of the local oscillation means is configured to be corrected to a predetermined frequency. Therefore, a narrow band frequency division multiple access communication system in which the reception band is, for example, 1/100000 or less with respect to the radio frequency is used. realizable.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of a wireless communication device according to the present invention. Explanation of Signs of Main Parts 10 Reference Oscillator 12 Mixer 14 Synthesizer 15 Local Oscillator 16 Intermediate Frequency Amplifier 18 Error Detection Circuit 20 Memory 22 Error Correction Circuit 30 Wireless communication device

Claims (3)

(57) [Claims] 1. A wireless communication device which is frequency division multiple access, comprising: a receiving means for receiving a communication frequency signal of a communication channel for transmitting communication information and a calibration frequency signal of a frequency calibration channel for calibrating the frequency; A first local oscillation frequency signal or a second local oscillation frequency signal is input, an intermediate frequency signal is formed from the communication frequency signal and the first local oscillation frequency signal, and the calibration frequency signal and a second local oscillation frequency signal are formed. Frequency conversion means for forming an intermediate frequency signal from the oscillating frequency signal, and converting a reference frequency signal into the first local oscillating frequency signal or the second local oscillating frequency signal with a first control signal and outputting the converted signal. Local oscillation means for controlling the frequency of the first local oscillation frequency signal or the second local oscillation frequency signal to be output by a second control signal; Receiving an intermediate frequency signal formed from the calibration frequency signal and the second local oscillation frequency signal from the frequency conversion means;
Receiving a reference frequency signal from the local oscillating means, forming a reference intermediate frequency signal from the received reference frequency signal, comparing the formed reference intermediate frequency signal with the frequency of the received intermediate frequency signal; Error detection means for forming an error value; storage means for storing an error value from the error detection means; and error correction control means for forming the second control signal corresponding to the error value from the storage means. When the frequency conversion means receives a communication frequency signal,
The wireless communication apparatus according to claim 1, wherein said local oscillation means forms a first local oscillation frequency signal corresponding to a second control signal from said error correction control means. 2. The apparatus according to claim 1, wherein said local oscillation means includes: a reference oscillation source for generating said reference frequency signal; and a reference frequency signal from said reference oscillation source, said reference oscillation signal being generated by said first control signal. The first local oscillation frequency signal or the second local oscillation frequency signal is converted and output, and the output first
And a synthesizer for controlling the frequency of the local oscillation frequency signal or the second local oscillation frequency signal by the second control signal. 3. A wireless communication method in a frequency division multiple access wireless communication apparatus, the method comprising: performing information communication before or during non-information communication;
Converting the generated reference frequency signal into a first local oscillation frequency signal using a first control signal; and either before performing information communication or during non-information communication,
While receiving the calibration frequency signal of the frequency calibration channel for calibrating the frequency, receiving the converted first local oscillation frequency signal, and converting the intermediate frequency signal from the received calibration frequency signal and the first local oscillation frequency signal Forming, receiving an intermediate frequency signal formed from the calibration frequency signal and the first local oscillation frequency signal, receiving the generated reference frequency signal, and generating a reference intermediate frequency from the received reference frequency signal. Forming a signal, comparing the formed reference intermediate frequency signal with the frequency of the received intermediate frequency signal, forming an error value by the comparison; storing the formed error value; Forming a second control signal corresponding to the obtained error value, and using the first control signal to generate the generated reference frequency signal when performing information communication. Converting the second local oscillation frequency signal to a second local oscillation frequency signal and controlling the frequency of the converted second local oscillation frequency signal by the formed second control signal; and a communication frequency of a communication channel when performing information communication. Receiving the signal, receiving the controlled second local oscillation frequency signal, and forming an intermediate frequency signal from the received communication frequency signal and the second local oscillation frequency signal. Wireless communication method.