JPH06318963A - Mobile radio equipment - Google Patents

Abstract

PURPOSE:To stably perform transmission and reception even in the case that the oscillation frequency error is not small and to extend the error correction range of a reference oscillator by adding an offset to the frequency of the phase reference signal of a demodulator. CONSTITUTION:A demodulated data monitor circuit 11 which monitors the reliability of demodulated data outputted from a demodulator 3 and a reference signal control circuit 12 which adds the offset to the frequency to the phase reference signal in the demodulator 3 at the time of detecting th degradation of the reliability by the demodulated data monitor circuit 11 are provided. That is, the offset is added to change the frequency error detection range. Consequently, the quantity of offset is switched in time series based on the reliability of demodulated data, and the frequency of the reproduced carrier wave signal outputted from the demodulator 3 is measured by a frequency counter 4 at the time of adding the proper frequency offset, and the oscillation frequency error of a reference oscillator 7 is detected by a detecting circuit 5, and the oscillation frequency is so controlled by a control circuit 6 so that this oscillation frequency error is reduced. Thus, the frequency error detection range is extended, and the frequency stability is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is used in digital mobile radio communications using angle modulation. In particular, the present invention relates to a mobile wireless device suitable for a communication system that requires a small carrier drift. The present invention is suitable for use in digital mobile radio communication in the UHF band.

[0002]

2. Description of the Related Art In the case of performing communication by angle modulation, carrier quality drifts, so that the transmission quality deteriorates significantly. Looking at the transmission characteristics within the pass band, characteristic deterioration such as distortion of transmission signals, deterioration of frequency characteristics, and deterioration of error rate occurs. In addition, out-of-band transmission characteristics increase leakage power to adjacent channels. In order to prevent this, (1) the channel arrangement should be sufficiently wide compared to the transmission bandwidth,
Either (2) increasing the stability of the local oscillator or modulator that causes the carrier wave drift, or (3) detecting the carrier wave drift and automatically adjusting it to a desired carrier wave frequency.

However, in the method (1), considering that the effective radio frequencies are more and more limited with respect to the future increase in the communication volume, a communication system in which one radio frequency is assigned to one speech channel, in particular. Then, it is difficult to take the channel arrangement at wide intervals. In addition, even in multiplex communication and other communication methods that require a wide transmission band, narrowing of the transmission bandwidth by multilevel modulation and other technologies is being promoted due to the recent tightness of radio frequencies, and a margin for carrier drift is realized. Therefore, it is difficult to widen the wireless channel interval.

The method (2) does not pose a problem when a highly stable oscillator can be used as in the fixed wireless communication system. However, this is a problem when a small and simple mobile wireless device such as a mobile communication system is required. Generally, in a mobile wireless device, a crystal oscillator that stably oscillates at a relatively low frequency is used as a reference oscillator, and a voltage-controlled oscillator is phase-locked to obtain a carrier band frequency signal, or
A direct digital synthesizer directly oscillates a carrier wave phase-locked to generate one or a plurality of local oscillation signals. In this case, the stability of the crystal oscillator used as the reference oscillator becomes a problem.

As a crystal oscillator having improved stability against temperature change, a temperature-compensated crystal oscillator (TCXO: Temperat) is used.
ure Compensated Crystal Oscillator) is known. However, when mass production is considered under the constraint that the mobile communication device is equipped with the mobile communication device, the practical stability is considered to be about 1.5 to 2 ppm. Further, a temperature change of the oscillation frequency of the crystal is stored in a memory, and the frequency is controlled by controlling the capacitance array based on the temperature information from the temperature detecting element (DTCXO: Digitall).
y Temperature Compensated Crystal Oscillator) has also been put into practical use, and it has become possible to set the compensation accuracy for temperature changes to 0.5 ppm or less. However, none of the oscillators can compensate the oscillation frequency with respect to aging. As the method (3), a method of frequency-locking a local oscillator with a received wave having high frequency accuracy is generally used. In the case of mobile communication using the analog angle modulation method, the carrier frequency error is detected by measuring the frequency of the intermediate frequency signal with a frequency counter, and the local oscillation frequency is controlled so that the error is below a specified value. To do.
However, in the case of the digital angle modulation method, the carrier frequency is deviated because the phase deviation of each symbol is deviated due to the pattern of the data to be transmitted, and an error may occur in the measurement by the counter. As a technique for solving this, Japanese Patent Application No. 5-63762 (not yet published at the time of filing of the present application) accurately counts the frequency drift of the intermediate frequency signal by counting the frequency of the carrier regenerated by the demodulator with a frequency counter. The technique to do is shown. This technique will be described below.

FIG. 11 is a block diagram showing a conventional example of a mobile wireless device provided with a frequency stabilizing function for use in mobile communication using digital angle modulation.

The antenna 1 transmits a base station transmission wave whose frequency is stable.
The frequency is converted into an intermediate frequency signal by the receiving circuit 2, and this intermediate frequency signal is demodulated by the demodulator 3 having a synchronous detection waveform or an adaptive synchronous detection waveform. At this time, the reproduced carrier wave of the demodulator 3 follows the frequency of the intermediate frequency signal on which the frequency error is superimposed. Therefore, the reproduced carrier frequency of the demodulator 3 is measured by the frequency counter 4. The carrier recovery circuit in the demodulator 3 follows the frequency drift of the intermediate frequency signal and also functions as a kind of narrow band filter to average the instantaneous frequency fluctuation due to the modulation component. Therefore, the frequency drift of the intermediate frequency signal can be accurately measured from the count value of the frequency counter 4.

As the operation clock of the frequency counter 4, for example, the output of a fixed oscillator provided in the demodulator 3 is used. This fixed oscillator is for reproducing a carrier wave in the demodulator 3 and for generating a signal serving as a phase reference for demodulation whose phase is substantially synchronized with the carrier wave. Since the frequency is not so high, it may be a relatively inexpensive one. Sufficient precision and stability are obtained.

The count value of the frequency counter 4 is input to the frequency error detection circuit 5. The frequency error detection circuit 5
This count value is compared with a preset intermediate frequency signal frequency to detect a frequency error. The detected frequency error is input to the reference oscillator control circuit 6. The reference oscillator control circuit 6 generates a frequency error compensation signal for compensating the frequency error, inputs this to the reference oscillator 7, and outputs the oscillation frequency of the reference oscillator 7 until the frequency error becomes equal to or less than a predetermined value. To control.

The reference oscillator 7 stabilized in this way
The output signal of 1 is supplied to one or more frequency synthesizers 8. The output of the frequency synthesizer 8 is used as a local oscillation signal for frequency conversion of a received wave in the reception circuit 2 and also as a local oscillation signal for frequency conversion of a transmission signal into a radio frequency in the modulation circuit 9. . The output of the modulation circuit 9 is
It is transmitted to the wireless section via the power amplifier 10. By sharing the frequency synthesizer 8 as the local oscillator of the modulation circuit 9, the transmission frequency of the mobile radio device can be stabilized to the same degree as the stable base station transmission frequency accuracy.

FIG. 12 shows a configuration example of the modulation circuit 9. A baseband digital signal is input to the modulation input terminal 91, and the angle modulator 92 generates an angle modulation signal by this signal. The local oscillation signal from the frequency synthesizer 8 is input to the local oscillation signal input terminal 93, and the mixer 9
Reference numeral 4 frequency-converts the output of the angle modulator 92 into a desired carrier frequency, and outputs it to the modulation output terminal 95. Here, the case where the local oscillation signal input terminal 93, the mixer 94, and the frequency synthesizer 8 have a single-stage configuration has been shown, but these can be configured in multiple stages and frequency conversion can be sequentially performed to obtain a desired carrier frequency. It is also possible to directly modulate a local oscillation signal having a desired carrier frequency.

[0012]

In the above-mentioned conventional example,
By counting the reproduced carrier waves output from the demodulator with the frequency counter, it was possible to stabilize the frequency with high accuracy for a frequency error within a certain limited range. However, there are restrictions on parts cost, size, etc. for the TCXO that can be installed in the mobile wireless device, and there is a limit to improving the frequency stability. The frequency synthesizer as a local oscillator
Since it oscillates in synchronization with TCXO, the frequency error increases as the carrier frequency increases. For this reason, when the phase rotation of the received modulated wave due to this reaches a level where it cannot be distinguished from the original modulation phase transition, it exceeds the frequency drift range that the demodulator can follow, and data demodulation cannot be performed normally. Will end up. Therefore, the conventional reference oscillator control has a problem that the predetermined frequency stability cannot be obtained as the carrier frequency becomes higher.

For example, in the case of QPSK modulation with the bit rate f _b , the phase inversion within one symbol time cannot follow the frequency drift exceeding ± π / 4 radians, that is, f _b / 16 [Hz]. This value has f _b of 40 kbi
2.5 k for QPSK transmission system of t / sec
It becomes Hz. This corresponds to 1.7 ppm in terms of frequency stability required for a reference oscillator of a mobile radio used in a relatively high carrier frequency, for example, 1.5 GHz band.

The TCXO used for the reference oscillator has a low frequency required for a mobile radio while ensuring a frequency stability of 1.7 ppm or less in consideration of temperature characteristics, power supply voltage characteristics, and long-term stability due to aging. It is difficult to satisfy all the characteristics such as cost, small size and light weight, and low power consumption. Therefore, it has been desired to expand the frequency error compensation range so that the allowable value of the frequency stability with respect to the reference oscillator can be relaxed.

For example, if a plurality of demodulators and fixed oscillators are used, each demodulator is operated at different phase reference signal frequencies, and a frequency stabilizing function is added to each, the frequency error detection range can be expanded over a wide range as a whole. .
However, considering the operation to mobile radio devices, it is difficult to realize from the viewpoint of circuit scale and power consumption.

The present invention solves the above problems and provides a mobile radio device capable of stably transmitting and receiving even when the error correction range of the reference oscillator is expanded and the oscillation frequency error of the reference oscillator is not so small. The purpose is to

[0017]

The mobile radio device of the present invention comprises:
A receiving circuit that receives an angle-modulated digital radio signal and outputs an intermediate frequency signal, a frequency synthesizer that supplies a local oscillation frequency to this receiving circuit, and a reference oscillator that generates a signal that serves as a frequency reference for this frequency synthesizer. Regarding the frequency of the carrier regenerated by this demodulator, which reproduces the carrier from the intermediate frequency signal output from the receiving circuit and demodulates the received signal using the signal whose phase is almost synchronized with that carrier as the phase reference signal. In a mobile radio equipped with means for detecting the frequency error of the reference oscillator from the information and means for controlling the oscillation frequency of the reference oscillator based on the output of this detecting means, the reliability of the demodulated data output by the demodulator And a phase reference signal when the data monitoring means detects a decrease in reliability of demodulated data. Characterized by comprising a means for adding an offset to the frequency.

The data monitoring means may include means for detecting the sync word of the received data frame and monitoring the detection rate.

As the information on the frequency of the reproduced carrier wave, not only the frequency is counted and used, but also control data for reproducing the carrier wave in the demodulator may be used, and the symbol phase data of the received modulated wave is used. May be.

A plurality of demodulators are provided, the data monitoring means monitors the demodulated data of at least a part of the plurality of demodulators, and the means for adding an offset is a frequency of the phase reference signal in at least a part of the plurality of demodulators. It is also possible to add a different offset to each other. Briefly, two demodulators are provided, one of the demodulators has an offset of zero and the reliability of the demodulated data is monitored, and a constant offset is added to the phase reference signal frequency of the other demodulator. , When the reliability of the demodulated data of the demodulator with zero offset is high, the demodulator can be selected, and when the reliability is lowered, the other demodulator can be selected.

Instead of adding an offset to the phase reference signal frequency of the demodulator, it is also possible to add an offset to the frequency reference of the frequency synthesizer.

[0022]

The frequency error detection range is changed by adding an offset to the frequency of the phase reference signal of the demodulator. Therefore, one demodulator equivalently operates as a plurality of demodulators having different frequency error detection ranges. Also, the offset amount is switched in time series based on the reliability of the demodulated data, and when an appropriate frequency offset is added,
The frequency of the reproduced carrier signal output from the demodulator is measured to detect the oscillation frequency error of the reference oscillator, and the oscillation frequency is controlled so that the oscillation frequency error is reduced. As a result, the frequency error detection range and the frequency compensation range can be expanded without increasing the circuit scale and power consumption, and a mobile radio device with highly accurate frequency stability can be realized.

When a plurality of demodulators are provided and an offset is added to the phase reference signal frequency of at least one of the demodulators, the plurality of demodulators can be operated in parallel in different frequency error detection ranges. An appropriate demodulator is selected based on the reliability of the demodulated data output from one or more of these demodulators, and the oscillation frequency of the reference oscillator is controlled by the reproduced carrier signal frequency of the selected demodulator. To do. As a result, the frequency error detection range and the frequency compensation range can be expanded, and a mobile radio device with highly accurate frequency stability can be realized.

When an offset is added to the frequency of the reference oscillator, which is the frequency reference of the frequency synthesizer, the intermediate frequency signal frequency of the received wave can be changed. This offset amount is switched in time series based on the reliability of the demodulated data, and when an appropriate frequency offset is added, the oscillation frequency error of the reference oscillator is detected from the output of the demodulator, and this oscillation frequency error is reduced. In this way, the oscillation frequency of the reference oscillator is controlled. As a result, the frequency error detection range and the frequency compensation range can be expanded without increasing the circuit scale and power consumption, and a mobile radio device with highly accurate frequency stability can be realized.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a mobile radio device according to a first embodiment of the present invention.

This mobile radio device includes a receiving circuit 2 which receives an angle-modulated digital radio signal by an antenna 1 and outputs an intermediate frequency signal, and a frequency synthesizer 8 which supplies a local oscillation frequency to the receiving circuit 2. A reference oscillator 7 that generates a signal serving as a frequency reference of the frequency synthesizer 8 and a carrier wave is reproduced from an intermediate frequency signal output from the receiving circuit 2, and a signal whose phase is substantially synchronized with the carrier wave is used as a phase reference signal of the received signal. A frequency counter 4 and a frequency error detection circuit 5 as means for detecting the frequency error of the reference oscillator from the information relating to the frequency of the carrier regenerated by the demodulator 3, and the frequency error detection circuit 5 The reference oscillator control circuit 6 is provided as a means for controlling the oscillation frequency of the reference oscillator based on the output of 1. The mobile wireless device also includes a modulation circuit 9 that performs modulation using the output of the frequency synthesizer 8 as a carrier, and a power amplifier 10 that amplifies the modulated wave.

The feature of this embodiment is that it includes a demodulation data monitoring circuit 11 for monitoring the reliability of the demodulation data output from the demodulator 3, and this demodulation data monitoring circuit 11 is provided.
Demodulator 3 detects that the reliability of the demodulated data has decreased.
The reference signal control circuit 12 is provided as means for adding an offset to the frequency of the internal phase reference signal.

Similarly to the conventional example, the demodulator 3 demodulates the intermediate frequency signal with the phase of the phase reference signal as a reference, and compensates the frequency error of the phase reference signal with respect to the intermediate frequency signal based on the detected phase data. It is equipped with a feedback loop. This phase reference signal contains a reproduced carrier signal component, which is output to the outside.

The operation of the mobile radio device of this embodiment will be described below.

The received wave received by the antenna 1 is frequency-converted into an intermediate frequency signal by the receiving circuit 2 and input to the demodulator 3. The intermediate frequency signal input to the demodulator 3 includes
A frequency error based on the oscillation frequency error of the reference oscillator 7 is superimposed. If this frequency error is within the tracking range of the demodulator 3, the frequency of the reproduced carrier wave follows the intermediate frequency signal on which the frequency error is superimposed.

The reference signal control circuit 12 inputs the reference signal control data to the demodulator 3 and, as an initial state, sets the phase reference signal in the demodulator 3 so as to correspond to the predetermined frequency of the intermediate frequency signal. . The demodulated data output from the demodulator 3 is input to the demodulated data monitoring circuit 11.

As the demodulated data monitoring circuit 11, for example, a sync word detecting circuit for detecting a sync timing of a data frame which is generally equipped in a digital communication radio can be used. When the frequency error of the reference oscillator 7 is so large that the carrier recovery circuit in the demodulator 3 cannot follow it, a significant error occurs in the demodulated data.
The sync word detection rate is extremely low. Therefore, the reliability of the demodulated data can be determined by using the synchronization word detection circuit.

After it is confirmed by the synchronization word detection that the demodulated data is reliable and the carrier wave is reproduced within the tracking range of the demodulator 3, the frequency of the reproduced carrier wave which is the output of the demodulator 3 is detected. Is measured by the frequency counter 4. If no sync word is detected, demodulator 3
In order to offset the phase reference signal frequency of, the reference signal control circuit 12 inputs the reference signal control data to the demodulator 3 and detects the synchronization word again.

Here, the data output from the reference signal control circuit 12 for offsetting the phase reference signal frequency is the frequency error tracking range in the demodulator 3 when an initial value is input and the frequency error tracking after offset. It is preferable to use a value that overlaps a part of the range. That is, by offsetting the frequencies so that the frequency error detection ranges of both are continuous, instability of the carrier recovery operation at the limit frequency of the follow-up range of the demodulator 3 can be eliminated.

The frequency error detection circuit 5 detects a frequency error from the output of the frequency counter 4 by comparing it with a predetermined intermediate frequency signal frequency. The detection output is supplied to the reference oscillator control circuit 6. The reference oscillator control circuit 6 generates a frequency error compensation signal for compensating the frequency error and inputs this to the reference oscillator 7 to adjust the oscillation frequency of the frequency reference signal until the frequency error becomes equal to or less than a predetermined value. Control and stabilize operation.

TC which is generally used as the reference oscillator 7.
The tendency of the XO oscillation frequency over time and the tendency of the oscillation frequency error in the environment where the mobile radio is actually used can be known in advance from the TCXO characteristic table and the like. Therefore, in accordance therewith, the frequency offset amount by the reference signal control circuit 12 is set to control whether the oscillation frequency is increased or decreased with respect to the initial value, thereby shortening the time required for frequency stabilization. You can Further, the compensation signal of the oscillation frequency error given to the reference oscillator 7 may be stored and used as an initial value for the frequency stabilizing operation from the next time. In order to further reduce the time required for frequency stabilization, the reference oscillator 7 has been used in the past frequency stabilization operation.
It is also possible to store the error compensation signal given to the above, and use the average value or the most frequent order value as the initial value or the set value of the offset amount during the frequency stabilizing operation.

In this embodiment, the frequency error of the intermediate frequency signal is detected by utilizing the fact that the frequency of the reproduced carrier wave output from the demodulator 3 is not affected by the modulation data sequence.
By offsetting the phase reference signal frequency for demodulation to a different frequency, the phase reference for demodulation of one demodulator 3 is changed in time series, and a plurality of demodulators having different frequency detection ranges are equivalently provided. Has been realized. For this reason,
It is possible to detect and compensate for frequency error over a wider frequency range than before.

Further, the demodulator 3 and the frequency counter 4 for frequency stabilization, the frequency error detection circuit 5, the reference oscillator control circuit 6, the demodulated data monitoring circuit 11 and the reference signal control circuit 12 can all be constituted by logic circuits, Easy to make LSI. Therefore, downsizing, low power consumption, and no adjustment are possible, which is suitable for a mobile wireless device.

FIG. 2 shows a configuration example of the demodulator 3. This configuration example is disclosed in JP-A-2-205940 and JP-A-2-2.
Japanese Patent Laid-Open No. 19747 discloses a direct phase quantization circuit 31, an adaptive carrier synchronization data generation circuit 32,
Frequency drift detection circuit 33, digital oscillator 34,
A fixed oscillator 35, an identification circuit 36 and a clock recovery circuit 37 are provided. The output of the reference oscillator 7 can also be used as the fixed oscillator 35.

The digital oscillator 34 divides the output signal of the fixed oscillator 35 and supplies it directly to the phase quantization circuit 31 as a phase reference signal. The phase reference signal contains the reproduced carrier component. The direct phase quantization circuit 31 receives the reception angle modulation signal input to the demodulator 3 from the digital oscillator 3
Quantize with the phase reference signal from 4. Identification circuit 36
Demodulates the received data from the quantized phase data.

The demodulator also includes two feedback loops to obtain a highly accurate phase reference signal. The first feedback loop is composed of a direct phase quantization circuit 31, a frequency drift detection circuit 33 and a digital oscillator 34. The second feedback loop is composed of a direct phase quantization circuit 31, an adaptive carrier synchronization data generation circuit 32 and a digital oscillator 34.

The first feedback loop is a system that functions when a frequency error occurs between the carrier frequency of the angle modulated wave and the phase reference signal frequency. The operation will be described with reference to FIGS. 3 to 6 by taking the case of QPSK modulation as an example. A signal obtained by directly phase-quantizing the intermediate frequency signal obtained by frequency-converting the received wave is shown by four phase points as shown in FIG. 3 on the signal space at the identification timing. When there is a frequency error between the phase reference signal and the carrier wave of the angle modulated wave, the phase of the angle modulated wave is always rotated in one direction and detected, as shown in FIG. This rotation angle θ
Is proportional to the frequency error, the direct phase quantization circuit 31
The rotation angle θ is converted into a numerical value by the frequency drift detection circuit 33 and the digital oscillator 34, and the obtained θ value is integrated for a certain period of time to control the frequency of the phase reference signal by the average amount. The carrier recovery circuit including the frequency drift detection circuit 33 and the digital oscillator 34 follows the frequency drift of the intermediate frequency signal and functions as a kind of narrow band filter to average the instantaneous frequency fluctuation due to the modulation component. Therefore, by measuring the reproduced carrier frequency, the frequency drift of the intermediate frequency signal with respect to the predetermined frequency can be accurately detected.

However, when the rotation angle θ caused by the frequency error exceeds π / 4 [rad], it is recognized that the rotation angle θ ^* is added to the phases of different quadrants, as shown in FIG. Therefore, correct frequency error detection becomes impossible.

The second feedback loop is a loop for instantaneously controlling the phase of the phase reference signal in the digital oscillator 34 when the carrier phase of the intermediate frequency signal fluctuates due to fading or the like. As shown in FIG. 6, the operation degenerates the relative phase data detected at each identification timing into the first quadrant, and the instantaneous phase fluctuation angle φ is detected depending on in which area the transmitted modulation signal is located. To be done. The operation of shifting the phase of the phase reference signal from the detected instantaneous phase fluctuation angle φ by the fluctuation angle φ is realized by the direct phase quantization circuit 31, the adaptive carrier synchronization data generation circuit 32, and the digital oscillator 34. As a result, the phase of the phase reference signal can be made to follow the random instantaneous phase fluctuation of the received wave carrier due to fading.

In this embodiment, an example in which an adaptive synchronous detection waveform demodulator is used as the demodulator 3 has been described, but the present invention can be similarly implemented by using a synchronous detection waveform demodulator.

FIG. 7 is a block diagram showing a mobile radio device according to the second embodiment of the present invention. This embodiment differs from the first embodiment in that control data for carrier reproduction is used as information about the frequency of the reproduced carrier.

That is, in the carrier wave recovery circuit in the demodulator 3, when the reproduced carrier wave frequency is changed by changing the frequency division ratio of the variable frequency divider composed of the logic circuit, the frequency division ratio is set. Since the output frequency is uniquely determined with respect to the control data for controlling, the control data can be extracted as frequency data and the frequency drift of the intermediate frequency signal with respect to the predetermined frequency can be detected. Specifically, the frequency data input to the digital oscillator 34 of the demodulator shown in FIG. 2, that is, the output of the adaptive carrier synchronization data generation circuit 32 and the output of the frequency drift detection circuit 33 are used.

In this case, the frequency counter 4 in the first embodiment is unnecessary, and the frequency data output from the demodulator 3 is directly supplied to the frequency error detection circuit 5. The frequency error detection circuit 5 detects a frequency error with respect to a predetermined intermediate frequency signal frequency based on this frequency data. The frequency error detected by the frequency error detection circuit 5 is input to the reference oscillator control circuit 6. The reference oscillator control circuit 6 generates a frequency error signal for compensating the frequency error and inputs it to the reference oscillator 7, and controls the oscillation frequency of the reference oscillator 7 until the frequency error becomes equal to or less than a predetermined value. Stabilize.

In the present embodiment, since it is not necessary to measure the reproduced carrier frequency using the frequency counter, high speed frequency stabilizing operation becomes possible. Further, since the frequency counter is unnecessary, there is an advantage that the circuit scale can be reduced.

FIG. 8 is a block diagram showing a mobile radio device according to the third embodiment of the present invention. This embodiment differs from the first and second embodiments in that the symbol phase data of the received modulated wave is used as the information on the frequency of the reproduced carrier wave.

That is, the symbol phase data obtained by detecting the received modulated wave is extracted from the demodulator 3 and input to the frequency error detection circuit 5, and the frequency error with respect to the predetermined intermediate frequency signal frequency is detected from the phase rotation amount.
The demodulator 3 may be any demodulator as long as it can output the symbol phase data at the time of detection, and any demodulator of a synchronous detection waveform, an adaptive synchronous detection waveform or a delayed detection waveform may be used. For example, when the adaptive synchronous detection demodulator shown in FIG. 2 is used, the direct phase quantization circuit 31
Take the output of.

The following frequency stabilization operation is the same as in the first and second embodiments, and the frequency error detected by the frequency error detection circuit 5 is input to the reference oscillator control circuit 6.
The reference oscillator control circuit 6 generates a frequency error signal for compensating the frequency error and inputs it to the reference oscillator 7, and controls the oscillation frequency of the reference oscillator 7 until the frequency error becomes equal to or less than a predetermined value.

Similar to the second embodiment, this embodiment does not need to measure the reproduced carrier frequency by using the frequency counter, so that the high-speed frequency stabilizing operation can be performed and the frequency counter is not necessary. Has the advantage of being small.

FIG. 9 is a block diagram showing a mobile radio device according to the fourth embodiment of the present invention. This embodiment includes a plurality of demodulators 3-1 and 3-2, and the plurality of demodulators 3-1 and 3-.
2, at least a part thereof, in this example, the demodulator 3-1 is provided with a demodulation data monitoring circuit 11 as means for monitoring the demodulation data thereof, and the frequency of the phase reference signal of each of the demodulators 3-1 and 3-2 The difference from the first embodiment is that the reference signal control circuit 13 is connected to the demodulator 3-2 as means for applying different offsets to each other. Demodulator 3-1,
3-2 uses a common fixed oscillator, and the reference signal control circuit 13 sets the phase of the demodulator 3-2 so that the detectable frequency ranges of the demodulators 3-1 and 3-2 are continuous. Apply a constant frequency offset to the reference signal.

The reception wave received by the antenna 1 is frequency-converted into an intermediate frequency signal by the reception circuit 2, and the demodulator 3-
Input to 1 and 3-2. Under the control of the reference signal control circuit 13, the demodulator 3-2 is set to a phase reference signal frequency different from that of the demodulator 3-1 for the same intermediate frequency signal. The reproduced carrier signals output from the demodulators 3-1 and 3-2 are supplied to the frequency counter 4 via the signal selection circuit 14. In the initial state, the signal selection circuit 14 connects the side of the demodulator 3-1 that uses the correct phase reference signal frequency to the frequency counter 4.

The demodulated data monitoring circuit 11 includes a demodulator 3-1.
The sync word is detected from the demodulated data output of 1 to determine whether or not the demodulator 3-1 is performing a normal carrier wave reproducing operation. When the sync word is detected, the signal selection circuit 14 is controlled to select the output of the demodulator 3-1.
The frequency counter 4 measures the frequency of the reproduced carrier wave output by the demodulator 3-1. If the demodulated data monitoring circuit 11 does not detect a synchronization word, the signal selection circuit 1
The demodulator 3-2 is selected by 4 and the reproduced carrier signal of this demodulator 3-2 is measured by the frequency counter 4.

The output of the frequency counter 4 is supplied to the frequency error detection circuit 5, which compares the frequency error detection circuit 5 with a predetermined intermediate frequency signal frequency to detect the frequency error. The output signal of the frequency error detection circuit 5 is supplied to the reference oscillator control circuit 6. The reference oscillator control circuit 6 generates a frequency error compensation signal for compensating the frequency error, inputs this to the reference oscillator 7, and controls the oscillation frequency of the reference oscillator 7 until the frequency error becomes equal to or less than a predetermined value. Control and stabilize.

Although the case where only one of the two demodulators is monitored and a fixed frequency offset is added to the other is explained here, both of the two demodulators are monitored and each of them is monitored according to the monitoring result. The frequency offset can be changed in time series. Also, three or more demodulators can be provided. It is also possible to adopt a configuration in which the error of the reproduced carrier frequency of each of the plurality of demodulators is detected. Further, similarly to the second or third embodiment, the frequency error can be detected by the control data or the symbol phase data for carrier recovery.

In this embodiment, a plurality of demodulators are operated in different continuous frequency ranges, and an appropriate demodulator is selected based on the reliability of demodulated data output from at least one demodulator. As a result, the frequency error can be detected over a wider frequency range than before.

FIG. 10 is a block diagram showing a mobile radio device according to the fifth embodiment of the present invention. This embodiment does not add an offset to the phase reference signal frequency in the demodulator,
The addition of an offset to the frequency reference of the frequency synthesizer differs from the above-described embodiment. That is, the reference oscillator control circuit 15 changes the intermediate frequency signal frequency of the received wave by adding an offset to the oscillation frequency of the reference oscillator 7, and the offset amount is used to determine the reliability of the demodulated data obtained by the demodulated data monitoring circuit 11. Based on the time series.

The reference oscillator control circuit 15 inputs a reference oscillator control signal corresponding to a predetermined intermediate frequency signal frequency to the reference oscillator 7 as an initial value. The demodulated data output from the demodulator 3 is the demodulated data monitoring circuit 1
Input to 1.

Output from the demodulator 3 after it is confirmed by the synchronization word detection in the demodulation data monitoring circuit 11 that the reliability of the demodulation data is high and the carrier recovery is performed within the tracking range of the demodulator 3. The frequency of the reproduced carrier to be reproduced is measured by the frequency counter 4. When the sync word is not detected, the reference oscillator control circuit 15 outputs a signal for adding an offset to the oscillation frequency to the reference oscillator 7, offsets the intermediate frequency signal frequency input to the demodulator 3, and monitors the demodulated data. The circuit 11 detects the sync word again.

Here, the amount of frequency offset by the reference oscillator control circuit 15 is set to be smaller than the frequency error detection range in the demodulator 3 so that a part of the frequency error detection range before and after the offset overlaps. Is good. That is, by making both frequency error detection ranges continuous, it is possible to eliminate the instability of the carrier recovery operation at the limit value of the tracking range of the demodulator 3.

The frequency error detection circuit 5 detects the frequency error from the output of the frequency counter 4 by comparing it with a predetermined intermediate frequency signal frequency. The output signal is input to the reference oscillator control circuit 15. In the reference oscillator control circuit 15, in order to compensate the frequency error, a frequency error compensation signal corresponding to the sum frequency of the offset frequency and the frequency error is generated and input to the reference oscillator 7, and the frequency error is predetermined. The oscillation frequency is controlled until it becomes less than or equal to the specified value.

TC generally used as the reference oscillator 7
The tendency of secular variation of the oscillation frequency of the XO and the tendency of the oscillation frequency error in the environment where the mobile wireless device is actually used can be known in advance from the TCXO characteristic table and the like. Therefore, in accordance therewith, the reference oscillator control circuit 15 controls whether the frequency offset amount is increased or decreased with respect to the initial value.
Thereby, the time required for frequency stabilization can be shortened. Further, the compensation signal of the oscillation frequency error given to the reference oscillator 7 may be stored and used as an initial value for the frequency stabilizing operation from the next time. Further, in order to reduce the time required for frequency stabilization, the error compensation signals given to the reference oscillator 7 in the past frequency stabilization operation are stored, and their average value or the most frequent value is used for frequency stabilization. It can also be used as an initial value or a set value of the offset amount at the time of the conversion operation.

When an appropriate frequency offset is added to the reference oscillator 7 in this way, the signal output from the demodulator 3 is input to the frequency counter 4, and the frequency error detection circuit 5 uses the count value to detect the frequency error. Is detected and the oscillation frequency is controlled by the reference oscillator control circuit 15 so that the frequency error is reduced. As a result, it becomes possible to detect and compensate for a frequency error over a wider frequency range than before.

In the above description, the structure in which the reproduced carrier wave is measured to detect the frequency error has been described. However, as in the second or third embodiment, the control data for carrier wave reproduction is used as the information on the frequency of the carrier wave. Alternatively, symbol phase data can be used.

Further, the demodulator and the frequency counter for realizing the frequency stabilizing function, the frequency error detection circuit 5 and the reference oscillator control circuit 15 can all be constituted by logic circuits, which facilitates LSI implementation. Therefore, downsizing, low power consumption, and no adjustment are possible, which is suitable for a mobile wireless device.

[0069]

As described above, the mobile radio device of the present invention is used in a digital mobile communication system that uses angle modulation, and in a configuration in which frequency stabilization is performed using a base station transmission wave as a reference, the reference of the transmission / reception frequency is used. It is possible to expand the oscillation frequency error detection range and the compensation range of the reference oscillator that generates a signal that becomes Therefore, the frequency can be stabilized even when the oscillation frequency error of the reference oscillator is large.

In the present invention, when offsetting the frequency of the phase reference signal which is the phase reference of the detection in the demodulator, one demodulator is effectively operated as a plurality of demodulators having different phase reference signal frequencies. be able to. Therefore, the frequency error detection range and the frequency compensation range can be expanded without increasing the circuit scale and power consumption, and highly accurate frequency stabilization can be realized.

When the control data or the symbol phase data for carrier recovery in the demodulator is used as the information on the frequency of the recovered carrier, the frequency counter is not necessary. Both the control data and the symbol phase data are data originally generated in the demodulator, and the circuit scale can be reduced and high-speed and highly accurate frequency stabilization can be realized.

When a plurality of demodulators are used to add an offset to the phase reference signal frequencies of at least some of the demodulators, the plurality of demodulators can be operated in parallel with phase references of different frequencies, and high speed operation is possible. In addition, highly accurate frequency stabilization can be realized.

When an offset is added to the frequency of the signal that is the reference of the transmission / reception frequency, the frequency error detection range and the frequency compensation range can be expanded without increasing the circuit scale and power consumption, and highly accurate frequency stabilization can be achieved. realizable.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a mobile wireless device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing an example of a demodulator.

FIG. 3 is a diagram showing a symbol phase at an identification timing.

FIG. 4 is a diagram showing phase rotation in the case where a frequency error exists between a phase reference signal and a carrier wave of an angle modulated wave.

FIG. 5 is a rotation angle θ caused by a frequency error of π / 4.
The figure which shows the case where it exceeds.

FIG. 6 is a diagram showing a state in which relative phase data detected at each identification timing is degenerated in the first quadrant.

FIG. 7 is a block diagram showing a mobile wireless device according to a second embodiment of the present invention.

FIG. 8 is a block diagram showing a mobile wireless device according to a third embodiment of the present invention.

FIG. 9 is a block configuration diagram showing a mobile wireless device of a fourth embodiment of the present invention.

FIG. 10 is a block configuration diagram showing a mobile wireless device of a fifth embodiment of the present invention.

FIG. 11 is a block diagram showing a conventional mobile radio device.

FIG. 12 is a diagram showing a configuration example of a modulation circuit.

[Explanation of symbols]

 1 Antenna 2 Reception Circuit 3, 3-1, 3-2 Demodulator 4 Frequency Counter 5 Frequency Error Detection Circuit 6, 15 Reference Oscillator Control Circuit 7 Reference Oscillator 8 Frequency Synthesizer 9 Modulation Circuit 10 Power Amplifier 11 Demodulated Data Monitoring Circuit 12, 13 reference signal control circuit 14 signal selection circuit 31 direct phase quantization circuit 32 adaptive carrier synchronization data generation circuit 33 frequency drift detection circuit 34 digital oscillator 35 fixed oscillator 36 identification circuit 37 clock regeneration circuit 91 modulation input terminal 92 angle modulator 93 local Oscillation signal input terminal 94 Mixer 95 Modulation output terminal

Claims (6)

[Claims] 1. A receiving circuit that receives an angle-modulated digital radio signal and outputs an intermediate frequency signal, a frequency synthesizer that supplies a local oscillation frequency to the receiving circuit, and a signal that serves as a frequency reference for the frequency synthesizer. A reference oscillator that is generated, a demodulator that regenerates a carrier from the intermediate frequency signal output from the above receiving circuit, and a demodulator that demodulates the received signal using a signal whose phase is almost synchronized with the carrier as a phase reference signal. In the mobile radio device comprising means for detecting the frequency error of the reference oscillator from the information on the frequency of the carrier wave generated, and means for controlling the oscillation frequency of the reference oscillator based on the output of the detecting means, Data monitoring means for monitoring the reliability of the demodulated data output by the device, and this data monitoring means reduces the reliability of the demodulated data. Mobile radio, characterized in that a means for adding an offset to the frequency of the phase reference signal on detecting. 2. The mobile radio device according to claim 1, wherein said data monitoring means includes means for detecting a synchronization word of a received data frame and monitoring the detection rate thereof. 3. The mobile radio device according to claim 1, wherein the information on the frequency of the reproduced carrier wave is control data for reproducing the carrier wave in the demodulator. 4. The information on the frequency of the reproduced carrier wave is symbol phase data of a received modulated wave.
Alternatively, the mobile wireless device described in 2. 5. A plurality of demodulators are provided, and the data monitoring means is configured to monitor demodulated data of at least a part of the plurality of demodulators, and the means for adding the offset is one of the plurality of demodulators. 5. The mobile radio device according to claim 1, further comprising means for adding different offsets to the frequency of the phase reference signal in at least a part. 6. A receiver circuit for receiving an angle-modulated digital radio signal and outputting an intermediate frequency signal, a frequency synthesizer for supplying a local oscillation frequency to the receiver circuit, and a signal serving as a frequency reference for the frequency synthesizer. A reference oscillator that is generated, a demodulator that regenerates a carrier from the intermediate frequency signal output from the above receiving circuit, and a demodulator that demodulates the received signal using a signal whose phase is almost synchronized with the carrier as a phase reference signal. In the mobile radio device comprising means for detecting the frequency error of the reference oscillator from the information on the frequency of the carrier wave generated, and means for controlling the oscillation frequency of the reference oscillator based on the output of the detecting means, Data monitoring means for monitoring the reliability of the demodulated data output by the device, and this data monitoring means reduces the reliability of the demodulated data. Mobile radio, characterized in that a means for adding an offset to the oscillation frequency of the reference oscillator upon detection of the.