JPH09275386A - Receiver for multi-carrier system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct stable automatic frequency control with a wide lock range by detecting a phase change of one optional carrier in a multi-carrier so as to obtain frequency deviation thereby reducing the effect of multi-path and fading. SOLUTION: An automatic frequency section 30 detects a phase change in one optional carrier obtained by an FFT and eliminates a modulation component from the detected phase change and a modulation elimination section 32 detects fluctuation in a local oscillator. The modulation elimination section 32 discriminates at which quadrant a reception symbol is in existence. The rotated reception symbol represents a phase shift of a carrier on the Y axis, Thus, the frequency is controlled by feeding back the frequency to the local oscillator so that the phase shift in the carrier is eliminated. Then a statistic processing section 33 averages a phase shift of the carrier from which a modulation signal is eliminated and on the occurrence of multi-path in the object carrier, the adverse effect is reduced. Then a feedback variable control section 34 conducts the feedback control proportional to a magnitude of the phase shift of the carrier from which the modulation signal is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-carrier type receiver adopting an orthogonal frequency division multiplexing (OFDM) system, and more particularly to reducing an error in automatic frequency control against multi-path and fading. .

[0002]

2. Description of the Related Art FIG. 18 is a diagram showing an outline of a multi-carrier type receiver adopting a conventional orthogonal frequency division multiplexing system. The same components are denoted by the same reference numerals or symbols throughout the drawings. As shown in the figure, the multi-carrier type receiver uses QPSK (Quadri) for each of the multi-carriers in the orthogonal frequency division multiplexing system.
an antenna 1 that receives a radio wave transmitted through a transmission path after being modulated by phase phase shift keying), a band pass filter 2 that is connected to the antenna 1 and removes an unnecessary signal, and a band pass filter A high frequency amplifier 3 which is connected to 2 and amplifies the received signal; multipliers 4 and 5 which separate the amplified signal into an in-phase component (I) and a quadrature component (Q) for direct conversion; 90 ° phase shifter 6 connected, and phase shifter 6 and multiplier 4
A local oscillator 7 for outputting a desired high frequency signal to the
And 5 to form a baseband, low-pass filters 8 and 9, variable gain amplifiers 10 and 11 connected to them, and A / D converters 12 and 13 (Analog) connected to them, respectively. to DigitalConvert
er), squarers 14 and 15 connected to them, an adder 16 that adds the results thereof, a square root calculator 17 that performs a square root operation of the addition results, and a serial-parallel converter 18 that is connected to the square root calculator 17. An FFT 19 (Fast Fourier Transform) connected thereto, a parallel-serial converter 20 connected to the FFT 19 to form a received symbol sequence, and an automatic frequency controller 21 and an automatic gain controller 22 connected to the FFT 10. And D / A converters 23 and 24 respectively connected to these,
The low pass filter 25 and the low pass filter 25 are connected to the local oscillator 7 and the low pass filter 25, respectively.
The low pass filter 26 controls the high frequency amplifier 3 and the variable gain control units 10 and 11.

In the automatic gain control section 22, the FFT1
The amplification gain is controlled based on the DC component obtained in step 9. Further, the squarers 14 and 15, the adder 16, the square root calculator 17, the serial-parallel converter 18, the FFT 19, and the parallel-serial converter 20 are formed in a DSP (digital signal processor).

Now, assuming that the reception input is S (1), the oscillation output of the local oscillator 7 is S (2), and the output of the phase shifter 6 is S (3), S (1) = E1 sin (ω1t + θ) (1) S (2) = E0 sin (ω0 t) (2) S (3) = E0 cos (ω0 t) (3) where the multiplication outputs of the multipliers 4 and 5 are based on the above equation. S (4)
And S (5) respectively, S (4) = S (1) .S (2) = E1 sin (.omega.t + .theta.). E0 sin (.omega.t) =-1 / 2E1 E0 {cos (.omega.1t + .omega.t + .theta. ) −cos (ω1 t−ω0 t + θ)} (4) S (5) = S (1) · S (3) = E1 sin (ω1 t + θ) · E0 cos (ω0 t) = 1 / 2E1 E0 {sin (Ω1 t + ω0 t + θ) + sin (ω1 t−ω0 t + θ)} (5), and since the low-pass filters 8 and 9 block the preceding items of the equations (4) and (5), their output S (6)
And S (7) are, respectively, S (6) = 1 / 2E1 E0 cos (ω1 t-ω0 t + θ)} (6) S (7) = 1 / 2E1 E0 sin (ω1 t-ω0 t + θ)} (7) If ω1 = ω0, then S (8) = 1 / 2E1E0cos (θ) (8) S (9) = 1 / 2E1E0sin (θ) (9)

S (8) and (9) are input to the squarers 14 and 15, and their outputs are S (10) and S (1).
1), the output of the adder 16 is S (12), and the square root calculator 1
7 output S (13), S (10) = S (8) ² = 1 / 4E1 ² E0 ² cos ² (θ) (10) S (11) = S (9) ² = 1 / 4E1 ² E0 ² sin ² (θ) (11) S (12) = 1 / 4E1 ² E0 ² {cos ² (θ) + sin ² (θ)} = 1 / 4E1 ² E0 ² (12) S (13) = {S (12)} ^1/2 = 1 / 2E1 E0 (13), which enables direct conversion.

FIG. 19 is a diagram for explaining the automatic frequency control unit 21. As shown in the figure, the automatic frequency control unit 21
Compares the magnitudes of the obtained levels A and B with the level sections 211 and 212 for obtaining the levels A and B of each carrier by inputting the two carriers A and B from the FFT 19, and based on this comparison result. In addition, it has a comparison unit 213 for controlling the local oscillator 7 via the D / A converter 23 and the like.

FIG. 20 is a diagram for explaining the control characteristics of the automatic frequency control unit 21. As shown in (a) of the figure, the received signal S (1) has a wide frequency band, and there is no carrier at the center of a large number of carriers, so the received signal S (1) is dipped.
This figure (b) shows the carrier obtained by FFT 19 by directly converting the frequency of the received signal S (1), and the two carriers A and B are located on both sides of the center of many carriers. . If the local oscillator 7
If the transmission frequency of the carrier shifts, the levels of the two carriers A and B are biased, so it is possible to control the local oscillator 7 by detecting this bias.

[0008]

However, in the above-mentioned multi-carrier type receiver, when multipath fading occurs, the levels of the two carriers A and B fluctuate, and erroneous frequency control to the local oscillator 7 is performed. However, there is a problem that it adversely affects the entire receiver.

Therefore, the present invention has been made in view of the above problems.
An object of the present invention is to provide a multi-carrier type receiver capable of appropriately performing automatic frequency control even when multi-fading occurs.

[0010]

In order to solve the above-mentioned problems, the present invention provides a multicarrier type receiver for receiving phase-modulated multicarriers, in which the phase is changed from the in-phase and quadrature phase components of the multicarrier. A phase change detection unit that detects a change, a phase modulation removal unit that removes a phase modulation component from the in-phase and quadrature components of the detected phase change to detect a shift in the phase change, and a shift in the phase change in a plurality of carriers. And a feedback amount control unit for performing automatic frequency modulation by feeding back the time derivative of the statistically processed shift of the phase change to the local oscillator as the shift of the frequency. Further, the phase modulation removing unit represents the detected phase change by a Lissajous waveform, and moves to one point by rotation to remove the phase modulation component and detect the shift of the phase change. The phase modulation removing unit removes the phase modulation component from the in-phase and quadrature components of the detected phase change using a low-pass filter, and displays the removed in-phase and quadrature components in a Lissajous waveform, Detect the deviation. By this means, by detecting the frequency of the main carrier of the broadcast wave and the frequency of the signal wave of the local oscillator of the receiver by the phase change, it is possible to reduce errors due to multipath, fading and other level fluctuations, and a good automatic frequency Control can be realized.

The statistic processing unit averages the phase change deviations of a plurality of arbitrary carriers of the multi-carriers and outputs them to the feedback amount control unit, or, for the plurality of arbitrary carriers of the multi-carriers, The deviations of the phase change are obtained, and they are arranged in order of magnitude, and those having a predetermined order are output. By this means, it is possible to reduce the adverse effects even if there is interference in some of the target carriers.

The statistic processing unit obtains the deviations of the phase changes for arbitrary plural carriers of the multi-carriers, and averages the remainders after removing the abnormal values. By this means, good automatic frequency control can be realized despite the abnormality of the carrier due to interference. Instead of the carrier that generates the abnormal value, a different phase change shift of the carrier may be used at the next sampling. By this means, there is a high possibility that a carrier that generates an abnormal value will be in a multipath environment at the next moment, so by using another carrier, detection of an abnormal value is avoided.

The statistical processing section divides the multi-carriers into a plurality of groups, and randomly selects a plurality of the multi-carriers from the plurality of groups. By this means, a more averaged and good automatic frequency control can be realized. The feedback amount control unit weights the carrier according to the magnitude of the shift in the phase change of the carrier. By this means, the convergence of the automatic frequency control is improved, and at the same time, the stability at the time of convergence is improved.

The feedback amount control unit stops the feedback when the deviation of the phase change of the carrier is small. By this means, once automatic frequency control stabilizes, it does not change unless the environment of the receiver changes for a considerable time. For this reason, a more stable oscillation frequency can be obtained as compared with the case where control is performed unnecessarily. The first automatic frequency control unit is composed of the phase change detection unit, the phase modulation removal unit, the feedback amount control unit, and the statistical processing unit, and further, the two carriers located at the center of the multicarrier are A second automatic frequency control unit for feeding back the detected level deviation detected by comparing the levels to a local oscillator, wherein the first automatic frequency control unit is coarsely adjusted, and the second automatic frequency control unit is Used as a fine adjustment. By this means, stable automatic frequency control with a wide pull-in range can be realized.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. An automatic frequency control unit 30 is provided in place of the conventional automatic frequency control unit 21 in a multi-carrier type receiver. FIG. 1 is a diagram showing an example of an automatic frequency control unit 30 of a multi-carrier type receiver according to the present invention. As shown in the figure, the automatic frequency control unit 30
Is a phase change detection unit 31 that detects a phase change of any one carrier obtained by the FFT 19, and a modulation removal unit 32 that removes a modulation component from the detected phase change and detects a fluctuation of the local oscillator 7. A statistical processing unit 33 that statistically processes fluctuations of the local oscillator 7 in each carrier, and a feedback amount control unit 34 that improves responsiveness and convergence to the local oscillator 7 with respect to the acquired fluctuations of the local oscillator 7. To have.

The in-phase component I: sinγ _i and the quadrature component Q: cosγ _{i of the} QPSK phase modulation component are input from the FFT 19 to the phase change detector 31. Here, FFT19
Output fi multicarrier with, when a carrier of the multicarrier and _{ω i, f i = a i} sinω i t + b i cosω i t = (a i 2 + b i 2) 1/2 sin (ω i t + γ _i ) (14) γ _i = tanb _ii / a _i (15) Therefore, sin γ _i and cos γ _i are defined as follows.

Sin γ _i = b _i / (a _i ² + b _i ² ) ^1/2 (16) cos γ _i = a _i / (a _i ² + b _i ² ) ^1/2 (17) FIG. 2 is shown in FIG. It is a figure explaining the phase change detection part 31 of.
As shown in the figure, the phase change detection unit 31 uses the phase modulation component of the multi-carrier ω _i as the in-phase component I: sin γ this time.
_{i, j} and quadrature component Q: cosγ _{i, j}
Delayed by the sampling period (j: ordinal number of sampling), the previous in-phase component I: sinγ _{i, j−1} , quadrature component Q: co
Delay units 311 and 312 for storing sγ _j-1 and a multiplier 313 for multiplying the in-phase component I of this time by the quadrature component Q of the previous time
, A multiplier 314 that multiplies the previous in-phase component I by the current quadrature component Q, a multiplier 315 that multiplies the current in-phase component I by the last in-phase component I, a current quadrature component Q, and the last quadrature component A multiplier 316 that multiplies Q, an adder 317 that outputs the in-phase component I ′ of the phase change by adding the output of the multiplier 313 and the inverted output of 314, and the multipliers 315 and 31.
An adder 318 for adding the outputs of 6 and outputting the quadrature component Q ′ of the phase change is provided.

Here, the in-phase component I'of the phase change is S (1
4), the quadrature component Q 'and S (15), S (14 ) = sinγ i, j · cosγ i, j-1 -cosγ i, j · sinγ i, i-1 = sin (γ i, j - γ _{i, j-1} ) = sin Δγ _i (18) (= ξ) S (15) = cos γ _{i, j} · cos γ _{i, j-1} + sin γ _{i, j} · sin γ _{i , i-1} = cos (γ _{i , j} −γ _{i, j−1} ) = cos Δγ _i (19) (= η).

Next, the phase modulation removing section 32 will be described. FIG. 3 is a diagram in which the in-phase component I ′ and the quadrature component Q ′ of the phase change are represented by a Lissajous waveform. Since the received symbol is modulated by QPSK as shown in FIG.
The phase change is represented. Here, the variation of the four symbols is due to the variation of the oscillator of the local oscillator. Furthermore, as shown in this figure (b), this Lissajous waveform is rotated 45 ° counterclockwise. Assuming that the in-phase component and the quadrature component of the phase change after rotation are x and y, x = ξ cos α−η sin α (16) y = ξ sin α + η cos α (17) where α (= 45 °) is the rotation angle and ξ , Η are the original in-phase component and quadrature component, respectively. In this way,
It is possible to determine which of the four quadrants the received symbol is in by expressing it by x and y coordinates.

FIG. 4 is a diagram for explaining the operation of the modulation removing section 32. As shown in this figure (a), the modulation removal section 33 determines in which quadrant the received symbol is. As shown in this figure (b), -45 ° when the received symbol is in the first quadrant, -135 ° when it is in the second quadrant,
When it is in the third quadrant, it is rotated by + 135 °, and when it is in the fourth quadrant, it is rotated by + 45 °, and it is rotationally moved to one point on the x axis as shown in FIG. The received symbol rotated and moved in this way should converge to one point on the x-axis, as shown in FIG. 6D, if there is no fluctuation in the local oscillator 7. However, if the oscillation frequency of the local oscillator 7 fluctuates, it does not converge to one point on the x-axis,
For example, the rotationally moved received symbol has a phase shift in the + direction of the y-axis or a phase shift in the-direction of the y-axis.
This means to represent the phase shift of the carrier obtained by removing the modulation component from the carrier modulated to QPSK by the received symbol. If the phase shift of the carrier is PD, and the phase shift PD of the carrier shifts in the + direction of the y-axis,
When the oscillation frequency of the local oscillator 7 is shifted so as to increase, y
If it deviates in the-direction of the axis, it means that the oscillation frequency of the local oscillator 7 is deviated so as to decrease. Therefore, the frequency can be controlled by feeding back to the local oscillator 7 so that the phase shift PD of the carrier is eliminated. That is, by detecting the frequency difference between the main carrier of the broadcast wave and the signal of the local oscillator 7 of the receiver by the phase change, it is possible to reduce the error due to the level change due to multipath, fading, etc. Frequency modulation can be realized.

FIG. 5 is a diagram for explaining the statistical processing unit 33. As shown in the figure, for any arbitrary plurality of carriers i = 1, 2, ..., K (<n), the phase shift PD of the carrier from which the modulation is removed is averaged. in this way,
Carrier phase shift P obtained by removing modulation from a plurality of carriers
By averaging D, even if multipath occurs in the target carrier, its adverse effect can be reduced.

FIG. 6 is a diagram showing a modification of the statistical processing section 33. As shown in this figure (a), the carrier phase shifts PD1, PD2, ..., PDk whose modulation has been removed are stored in a memory (not shown) of the DSP, and these are arranged in order of size, for example, PDm> PDm + 1>. > PDm + k−1, and rearrange them in ascending or descending order.
Then, the one in a predetermined order is adopted for the feedback control.

For example, if the rank is centered, the same effect as averaging can be obtained. In this way, by removing the abnormal value from the carrier phase shift PD from which the modulation components obtained from a plurality of carriers have been removed, good automatic frequency modulation can be realized regardless of the abnormality of the carrier due to multipath. FIG. 7 is a diagram showing another modification of the statistical processing unit 33. As shown in this figure (a), they are arranged in descending order, and as shown in this figure (b), the average of k-2 values excluding the maximum value PDm and the minimum value PDm + k-1 as abnormal values is calculated. It is adopted as the carrier phase shift from which the calculated modulation component is removed. It is also possible to provide a prescribed value with a certain width for the average value of the whole and to set it as an abnormal value when each data exceeds this value. This is because this abnormal value may be affected by multipath fading. Therefore, by removing the abnormal value from the carrier phase shift PD obtained by removing the modulation components obtained from a plurality of carriers, good automatic frequency modulation can be realized regardless of the abnormality of the carrier due to multipath.

Further, the carrier for which an abnormal value is determined, in the above example, the carrier of i = m, m + k-1 may be affected by the multipath fading, so that the reliability of the data will be deteriorated. At the time of sampling, the data of this carrier is not adopted, but the data of another carrier is adopted instead. This is because an abnormal value is detected at a certain timing, which means that multipath is occurring, and this carrier is likely to be in a multipath environment at the next moment. Therefore, if another carrier is used in the next sampling, the possibility that an abnormal value is detected is reduced. Therefore, the reliability of the data is improved.

In the above, the averaging process is performed on any of a plurality of carriers, but selection of any of a plurality of carriers will be described below. FIG. 8 is a diagram showing another modification of the statistical processing unit 33. As shown in the figure, the carrier phase shift PD from which the modulation is removed is divided into a plurality of groups using the one stored in the memory of the DSP as an adopted unit, and one section is determined using the random number table. Select a group with the pointer and use it for averaging.

Alternatively, a single carrier may be selected from a plurality of random number tables and used for feedback. When a plurality of carriers are adopted, a fixed carrier is adopted, but it is more averaged and good automatic frequency modulation can be realized when adopted randomly. FIG. 9 is a diagram illustrating the feedback amount control unit 34. As shown in the figure, the feedback amount control unit 3
In 4, the feedback control amount proportional to the magnitude of the carrier phase shift PD from which the modulation component is removed (proportional coefficient = k ″) is obtained, and when the shift PD becomes larger than the predetermined value ± a, a large proportional coefficient k ′ ( > K ″) is used. In this way, by weighting the feedback control amount,
Convergence is improved, and stability at the time of convergence is also improved.

FIG. 10 shows the feedback amount control unit 3 of FIG.
It is a figure which shows the modification of No. 4. As shown in the figure, the magnitude of the carrier phase shift PD after removing the modulation component is a constant value ± b
If (<± a) or less, the proportional coefficient is set to zero and no feedback is performed. Once the automatic frequency control is once stable, it does not change unless a considerable time elapses and the environment of the receiver (in particular, the change of the oscillation frequency of the local oscillator 7 due to the temperature change) changes. For this reason, a stable oscillation frequency can be obtained rather than an unreasonable control. Clogged up and good automatic frequency control is possible.

Next, when the automatic frequency control (AFC) is performed by removing the phase information or the modulation component, the problem is that the phase change occurs such that the amount of the modulation component removed is erroneous. This means that the tracking range is narrow. Therefore, first, by comparing the levels of the two conventional carriers A and B, a certain degree (to the extent that the modulation component is not mistaken) is pulled in,
After that, automatic frequency modulation may be performed based on the phase information.

The conventional automatic frequency modulation by level detection has the advantage that the tracking range (pull-in range) is wide, and by combining this with the stable invention, the detection method is switched, so that the pull-in range is wide and stable. Good automatic frequency control can be realized. FIG. 11 is a diagram showing another example of the automatic frequency control unit 30 of the multicarrier type receiver according to the present invention. As shown in the figure, the automatic frequency control unit 30 is different from the phase modulation removal unit 4 in comparison with the example of FIG.
2 is different as follows.

FIG. 12 is a diagram showing the obtained Lissajous waveform of in-phase and quadrature-phase changes. As shown in this figure, when expressed by a Lissajous waveform, since it is QPSK modulation, the phase change Δ
γ _i is the change of the phase modulation component ± 45 °, ± 135
° is required. The fluctuation of the phase change Δγ _i shown in this figure is
This is due to fluctuations in the oscillation of the local oscillator 7. FIG. 13 is a diagram showing an example of the in-phase component sin Δγ _i of the phase change.
As shown in the figure, the signal waveform of the in-phase component sin Δγ _i changes in symbol units, and the sampling period t
It changes in _s units.

FIG. 14 shows the in-phase component sin Δγ _i of the phase change.
It is a figure which shows the frequency component of the signal waveform of. Since the phase modulation component changes at random, as shown in the figure, most of the phase components change at the frequency 1 / t _s and the frequency 2 / t
_s , frequency 3 / t _s , frequency 4 / t _s , decreasing in that order. Low-pass filter constituting the phase modulation removal unit 42 is set to the cutoff frequency f <4 / t _s, to remove the modulation component.

FIG. 15 is a diagram for explaining the Lissajous waveform in the output of the phase modulation removing section 42. As shown in this figure, since the phase modulation component is removed, the phase change Δ
γ _i converges on the origin and fluctuates near the origin. FIG. 16 is a diagram for explaining the relationship between the frequency shift of the local oscillator 7 and the phase change Δγ _i . The deviation of the frequency of the local oscillator 7 is obtained as a phase change per unit time. As shown in the figure, in the direction of frequency shift, when there is a phase change Δγ _{i in} the Lissajous waveform, for example, 0 to 180 °,
It is determined that the frequency has shifted to the positive side, and if there is a phase change Δγ _i between 180 and 360 °, it is determined that the frequency has shifted to the negative side.

Thus, rather than detecting the frequency shift from the level difference between the two carriers near the center of the multicarrier as in the conventional case, the frequency shift is detected by detecting the phase change of any one of the multicarriers. Because it detects
The effects of multipath and fading are reduced. In addition,
The coarse adjustment of the automatic frequency control unit 30 according to the present invention is shown in FIG.
The automatic frequency control unit 21 shown in 9 may be used for fine adjustment. This is to realize stable automatic frequency control with a wide pull-in range.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an automatic frequency control unit 30 of a multi-carrier type receiver according to the present invention.

FIG. 2 is a diagram illustrating a phase change detection unit 31 of FIG.

FIG. 3 is a diagram showing an in-phase component I ′ and a quadrature component of a phase change in a Lissajous waveform.

FIG. 4 is a diagram illustrating an operation of a phase modulation removing section 32.

FIG. 5 is a diagram illustrating a statistical processing unit 33.

FIG. 6 is a diagram showing a modification of the statistical processing unit 33.

FIG. 7 is a diagram showing another modification of the statistical processing unit 33.

FIG. 8 is a diagram showing another modification of the statistical processing unit 33.

FIG. 9 is a diagram illustrating a feedback amount control unit 34.

10 is a diagram showing a modified example of the feedback amount control unit 34 of FIG.

FIG. 11 is a diagram showing another example of the automatic frequency control unit 30 of the multi-carrier type receiver according to the present invention.

FIG. 12 is a diagram showing Lissajous waveforms of the obtained in-phase and quadrature-phase changes.

FIG. 13 is a diagram showing an example of an in-phase component sin Δγ _i of phase change.

FIG. 14 is a diagram showing frequency components of a signal waveform of an in-phase component sin Δγ _i of phase change.

FIG. 15 is a diagram illustrating a Lissajous waveform in the output of the modulation removing unit 22.

16 is a frequency shift and phase change Δγ of the local oscillator 7. FIG.
It is a figure explaining the relationship of _i .

FIG. 17 is a diagram illustrating an example of a statistical processing unit 33 in FIG. 1 that obtains and averages phase changes for a plurality of carriers.

FIG. 18 is a diagram showing an outline of a receiver of a multicarrier system adopting a conventional orthogonal frequency division multiplexing system.

19 is a diagram illustrating the automatic frequency control unit 21 of FIG.

20 is a diagram illustrating control characteristics of the automatic frequency control unit 21 of FIG.

[Explanation of symbols]

 19 ... FFT 21, 30 ... Automatic frequency control section 31 ... Phase change detection section 32, 42 ... Phase modulation removal section 33 ... Statistical processing section 34 ... Feedback amount control section

Claims (11)

[Claims] 1. A multi-carrier type receiver for receiving phase-modulated multi-carriers, comprising: a phase change detection unit for detecting a phase change from the in-phase and quadrature phase components of the multi-carrier; A phase modulation removal unit that removes the phase modulation component from the quadrature component to detect the shift of the phase change, a statistical processing unit that statistically processes the shift of the phase change for a plurality of carriers, and a statistically processed unit. A multi-carrier type receiver comprising: a feedback amount control unit for performing automatic frequency modulation by feeding back time differential of phase shift as frequency shift to a local oscillator. 2. The phase modulation removing unit represents the detected phase change by a Lissajous waveform, and moves to one point by rotation to remove the phase modulation component to detect the shift of the phase change. Item 2. A multi-carrier type receiver according to item 1. 3. The phase modulation removing unit removes a phase modulation component from the in-phase and quadrature components of the detected phase change using a low-pass filter, and displays the removed in-phase and quadrature components in a Lissajous waveform. The multi-carrier type receiver according to claim 1, wherein a shift in phase change is detected. 4. The multi-processor according to claim 1, wherein the statistical processing unit averages the phase change deviations of an arbitrary plurality of carriers out of the multi-carriers and outputs the average to the feedback amount control unit. Carrier type receiver. 5. The statistical processing unit obtains the shifts in the phase change of an arbitrary plurality of carriers out of the multi-carriers, arranges them in order of magnitude, and outputs those in a predetermined order. The multi-carrier type receiver according to claim 1, which is characterized in that. 6. The statistical processing unit obtains deviations of the phase change for an arbitrary plurality of carriers out of the multi-carriers, and averages residuals after removing abnormal values from them. 1. The multi-carrier type receiver described in 1. 7. The multi-carrier reception according to claim 6, wherein instead of the carrier generating the abnormal value, a phase change shift of a carrier different from this is used at the next sampling. Machine. 8. The statistical processing unit divides the multi-carrier into a plurality of groups, and randomly selects a plurality of carriers out of the multi-carriers from the plurality of groups. Item 2. A multi-carrier type receiver according to item 1. 9. The multi-carrier type receiver according to claim 1, wherein the feedback amount control unit weights the carrier according to a shift amount of a phase change of the carrier. 10. The multi-carrier receiver according to claim 1, wherein the feedback amount control unit stops the feedback when the deviation of the phase change of the carrier is small. 11. A first automatic frequency control unit is constituted by the phase change detection unit, the phase modulation removal unit, the feedback amount control unit, and the statistical processing unit, and is further located at the center of the multicarrier. And a second automatic frequency control unit that feeds back the detected level bias to the local oscillator by comparing the levels of the two carriers. The multi-carrier type receiver according to claim 1, wherein the automatic frequency control unit is used for fine adjustment.