JPH10303996A - Method and device for frequency shift detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frequency shift detecting method for 8PSK which can be actualized with simple circuit constitution and a frequency shift detecting method which is adaptive to plural kinds of phase modulation. SOLUTION: This method detects delays of equivalent low-frequency signals of I and Q obtained from a 8-phase modulated signal through orthogonal detection between successive symbols, makes an area decision by dividing the delay detected signals into 8 regions of an orthogonal coordinate system with four straight lines y=x.tan(θ/8), y=-x.tan(π/8), y=x.cot(π/8),and y=-x.cot(π/8), and regards in-phase and quadrature components of the delay-detected signals only when the delay detected signals are in regions across an orthogonal coordinate axis among the 8 regions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a phase modulation (PS)
The present invention relates to automatic frequency control (AFC) of K), and to a method and an apparatus for determining whether or not an input signal has a frequency shift.

[0002]

2. Description of the Related Art In recent years, digitalization of video has progressed, and digital broadcasting is being carried out in various countries on satellite, CATV, and terrestrial broadcast media. As a transmission method, phase modulation is mainly used in satellite broadcasting due to the non-linearity of the transmission path. In particular, four-phase phase modulation (QPSK) has been adopted by Digital Video Broadc
This is a modulation method used in CS digital broadcasting using communication satellites in the United States and in Japan as well as asting (DVB-S). In addition, it is considered that multi-valued transmission such as 8PSK and 16PSK will proceed in accordance with a demand for an increase in transmission capacity.

[0003] QPSK demodulation has been put to practical use at the consumer level, and has been introduced in various documents.
Among them, examples of demodulation systems include “Taga, Ishikawa, and Komatsu:“ A study of QPSK demodulation system ”” (Technical Report of the Institute of Television Engineers of Japan, vol. 15, No. 46, CE ').
91-42 (1991.08)) will be briefly described.

FIG. 12 is a diagram showing a configuration of a QPSK demodulation system. In FIG. 12, reference numeral 10 denotes a QPSK modulation signal input terminal, and reference numeral 11 denotes a quasi-synchronous signal for performing quasi-synchronous quadrature detection with a local oscillation signal having a fixed frequency to obtain an equalized low-frequency signal of an in-phase component (I) and a quadrature component (Q). Orthogonal detection means, 12a, 12
b is a low-pass filter for removing aliasing components when AD-converting the I and Q equivalent low-pass signals;
Reference numerals a and 13b denote A / D converters for A / D-converting the equivalent low-frequency signals of I and Q, 14 a complex multiplier used for automatic frequency control, and 15a and 15b for spectrum shaping of QPSK modulated waves. Roll-off filter, 16 is a complex multiplier for carrier recovery, 17 is a data decision circuit, 18
a and 18b are I and Q data output terminals.

The automatic frequency control (AFC) operation of the QPSK demodulation system configured as described above will be mainly described.

[0006] The QPSK modulated signal input from the input terminal 10 is input to the quasi-synchronous quadrature detection means 11. In the quasi-synchronous quadrature detection means 11, a local oscillation signal oscillated by the fixed oscillator 50 at the same frequency as the center frequency of the QPSK modulation wave and a signal obtained by shifting the oscillation signal by 90 ° are supplied to the mixers 11a and 11b, respectively. , QPSK modulated wave, the in-phase component (I) of the QPSK modulated wave,
An equivalent low-frequency signal of the quadrature component (Q) is obtained.

After the I and Q equivalent low-pass signals pass through the aliasing filters 12a and 12b, the A / D converter 1
A / D at the center timing of the modulation symbol in 3a and 13b
Is converted. The digitized equivalent low-pass signal is considered the real and imaginary part of the complex number, respectively. Outputs of the A / D converters 13a and 13b are input to a complex multiplier 14,
QPS input to input terminal 10 due to a frequency shift of a frequency converter (not shown) or the like in the satellite antenna
The frequency deviation between the K modulation signal and the fixed oscillator 50 is corrected.

[0008] The output of the complex multiplier 14 is a roll-off filter 15a, 15 for shaping the spectrum of the QPSK modulated wave.
After being input to b, it is input to the complex multiplier 16 where the carrier is reproduced, and the phase rotation is corrected. The output of the complex multiplier 16 passes through the data determination circuit 17 and is output as I and Q demodulated data from 18a and 18b.

Now, the automatic frequency control (AF
C) is an arctan means 20 for obtaining a phase angle from rectangular coordinates, a frequency error detector 21, an AFC loop filter 4
1. Numerically controlled oscillator 42, sin conversion circuit 43, cos
The frequency error detector 21 includes a conversion circuit 44.
Then, a phase change in one symbol period is obtained from the output of the arctan means 20, and this is used as a frequency error. The frequency error is

[0010]

(Equation 1)

[0011] Then, it is required. The phase state of QPSK is
As shown in FIG. 13A, 45 °, 135 °, −45 °
Since it exists every 90 °, such as ° and -135 °, the phase change (θ _n −θ _n-1 ) in one symbol period can be expressed only from 0 ° to 90 °. Therefore, the frequency error detector 21 changes the phase (θ _n −
θ _n-1 ) is calculated by mod 90 °, and the phase change is 0
When <(θ _n −θ _n−1 ) <45 °, it is regarded as a phase advance and (θ _n −θ _n−1 ) is set as a frequency error, and 45 ° <(θ _n −θ
_n-1 ) <90 °, it is regarded as a phase delay ((θ _n −
θ _n-1 ) -90 °) is output as a frequency error. The output of the frequency error detector is input to a numerical operation oscillator 42 via an AFC loop filter 41, where a sine wave and a cosine wave corresponding to the frequency error are generated, and the frequency error is corrected by the complex multiplier 14a.

As described above, the detection of the frequency error using the arctan means 20 for obtaining the phase angle from the rectangular coordinates can be applied to eight-phase phase modulation (8PSK). The phase state of 8PSK is 0 °, 45 °, 90 °, 135 °, 180 °, −4 as shown in FIG.
Since it exists every 45 ° such as 5 °, −90 °, and −135 °, the phase change in one symbol period (θ _n −θ
_n-1 ) can only be expressed from 0 ° to 45 °. Therefore, the frequency error detector 21 calculates the phase change (θ _n −θ _n−1 ) for one symbol period by mod 45 °, and the phase change is 0 <(θ _n −θ _n−1 ) <22.5 °. In the case of, the phase error is regarded as (θ _n −θ _n-1 ), and
When 2.5 ° <(θ _n −θ _n−1 ) <45 °, the phase delay is regarded as ((θ _n −θ _n−1 ) −45 °) and the frequency error may be output.

However, there is a problem in that the conversion from the rectangular coordinates to the polar coordinates is complicated and the circuit scale becomes large.

[0014]

As described above, in the above-described conventional example, the detection of the frequency shift in the AFC requires a complicated conversion from the rectangular coordinates to the polar coordinates, and therefore the circuit scale becomes large. was there.

Further, in the future, multi-level modulation will advance, and it will be necessary to process a plurality of types of phase modulation.

In view of the above problems, an object of the present invention is to provide a method for detecting a frequency shift in 8PSK, which can be realized with a simple circuit configuration, and a method and apparatus for detecting a frequency shift capable of coping with a plurality of types of phase modulation. .

[0017]

In order to solve such a problem, the present invention provides a method of delaying an I and Q equivalent low band signal obtained by quadrature detection of an eight-phase modulated signal between successive symbols. Detection is performed, and the phase of the delayed detection signal is (nπ / 4) ± (π / 8) (n = 0, 1, 2, 3, 3).
A determination is made as to which of the eight regions represented by (4,5,6,7) is present, and the differential detection signal is obtained by comparing the (nπ / 2) ± (π / 8) Area (n = 0, 1,
The present invention relates to a frequency shift detecting method characterized in that the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal only when the signal is in (2) or (3), and as an apparatus for achieving the detection method. A quadrature detection unit for performing quadrature detection on the input 8-phase phase modulated signal, and a delay detection unit for performing delay detection between consecutive symbols using as input the I and Q equivalent low band signals output from the quadrature detection unit; The delay detection signal (in-phase component (x), quadrature component (y)) obtained by the above-mentioned delay detection means is input, and its phase is y = x · tan (π / 8) y = −x in the quadrature coordinate system. Tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) Area determination means for performing area determination by dividing the area into eight areas, and the area determination means Output of the differential detection signal Phases, the eight regions including the orthogonal coordinate axes of the areas (nπ / 2) ± (π / 8) in the region (n = 0, 1,
Selecting means for outputting the in-phase component (x) or the quadrature component (y) of the differential detection output signal as a frequency shift signal only when the delay detection output signal is in (2, 3). The method and apparatus for detecting a frequency shift in the 8PSK AFC have a simple circuit configuration,
That is, it is possible to detect a frequency shift without converting to polar coordinates.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION
I and Q equivalent low-frequency signals obtained by quadrature detection of an 8-phase phase modulated signal are subjected to delay detection between consecutive symbols, and the phase of the delayed detection signal is (nπ / 4) ± (π / 8). ) (N = 0, 1, 2, 3,
A determination is made as to which of the eight regions represented by (4,5,6,7) is present, and the differential detection signal is obtained by comparing the (nπ / 2) ± (π / 8) Area (n = 0, 1,
A frequency shift detection method characterized in that the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal only when the differential detection signal is in (2, 3).

According to a second aspect of the present invention, there is provided a quadrature detection means for quadrature detection of an inputted eight-phase modulated signal, and an I and Q equivalent low band signal output from the quadrature detection means as input signals. And a delay detection means for performing delay detection between the detected symbols, and a delay detection signal (in-phase component (x) and quadrature component (y)) obtained by the delay detection means, and the phase thereof is represented by y = Xtan (π / 8) y = -xtan (π / 8) y = xcot (π / 8) y = -xcot (π / 8) An area determining means for performing an area determination, and a phase of the delayed detection signal based on an output of the area determining means, wherein the phase (nπ / 2) ± (π / 8) of a region (nπ / 2) ± (π / 8) including a rectangular coordinate axis among the eight regions = 0,1,
(2) Only when the signal is in (3), a selecting means for outputting the in-phase component (x) or the quadrature component (y) of the differential detection output signal as a frequency shift signal is provided. is there.

According to the invention of claim 3 of the present invention, the quadrature detection means for quadrature detection of the input eight-phase modulated signal, and the I and Q equivalent low band signals output from the quadrature detection means are continuously input. A delay detection means for performing delay detection between symbols, and a delay detection signal (in-phase component (x), quadrature component (y)) obtained by the delay detection means as inputs, and the phase thereof is represented by y in a quadrature coordinate system. = X · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) An area determining means for performing area determination, and a phase of the delayed detection signal based on an output of the area determining means, wherein the area (nπ / 2) ± (π / 8) in the area (nπ / 2) ± (π / 8) including the orthogonal coordinate axes among the eight areas = 0,1,
The in-phase component (x) or the quadrature component (y) of the differential detection output signal is output as a frequency shift signal only when the differential detection output signal is in (2, 3). A frequency shift detecting device, comprising: a selector for holding a frequency shift signal.

According to a fourth aspect of the present invention, an I and Q equivalent low band signal obtained by quadrature detection of an eight-phase modulated signal is subjected to delay detection between successive symbols, and the delayed detection signal is obtained. For each of the eight regions, the phase is determined as to which of the eight regions represented by (nπ / 4) ± (π / 8) (n = 0,1,2,3,4,5,6,7) When the differential detection signal is in an area (n = 0, 1, 2, 3) within ((π / 4) + (nπ / 2)) ± (π / 8) among the eight areas. Is a frequency shift detection method, wherein a difference between an in-phase component (x) and a quadrature component (y) of the differential detection signal is regarded as a frequency shift signal.

According to a fifth aspect of the present invention, there is provided a quadrature detecting means for quadrature detecting an inputted eight-phase modulated signal, and an I and Q equivalent low band signal output from the quadrature detecting means as an input. And a delay detection means for performing delay detection between the detected symbols, and a delay detection signal (in-phase component (x) and quadrature component (y)) obtained by the delay detection means, and the phase thereof is represented by y = X · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) The phase of the differential detection signal is based on an output of the area determination means for performing area determination and an output of the area determination means, and the phase of the eight areas does not include a rectangular coordinate axis ((π / 4) + (nπ / 2)) ± Only when in the region (n = 0,1,2,3) within (π / 8) Phase component of the serial delay detection signal (x)
And a selection unit that outputs a difference between the frequency component and the orthogonal component (y) as a frequency deviation signal.

According to a sixth aspect of the present invention, there is provided a quadrature detection means for quadrature detection of an inputted eight-phase modulation signal, and an I and Q equivalent low-frequency signal output from the quadrature detection means as inputs. And a delay detection means for performing delay detection between the detected symbols, and a delay detection signal (in-phase component (x) and quadrature component (y)) obtained by the delay detection means, and the phase thereof is represented by y in a quadrature coordinate system. = Xtan (π / 8) y = -xtan (π / 8) y = xcot (π / 8) y = -xcot (π / 8) The phase of the differential detection signal is based on an output of the area determination means for performing area determination and an output of the area determination means, and the phase of the eight areas does not include a rectangular coordinate axis ((π / 4) + (nπ / 2)) ± Only when in the region (n = 0,1,2,3) within (π / 8) Phase component of the serial delay detection signal (x)
Frequency difference detection means for outputting a difference between the frequency shift signal and the orthogonal component (y) as a frequency shift signal, and for other areas, holding a frequency shift signal for which the area determination has been performed before. Device.

According to a seventh aspect of the present invention, an I and Q equivalent low band signal obtained by quadrature detection of an eight-phase modulated signal is subjected to delay detection between successive symbols, and the delayed detection signal is obtained. , The phase is (nπ / 4) ± (π / 8) (n = 0, 1, 2, 3,
A region determination is performed to determine which of the eight regions represented by (4, 5, 6, 7) is located, and a region (n = 0) within (nπ / 2) ± (π / 8) of the eight regions , 1,
2,3), the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal, and ((π / 4) + (nπ / 2)) ± (π / 8) When the differential detection signal is in the region (n = 0, 1, 2, 3), the in-phase or quadrature component of the signal obtained by rotating the differential detection signal by (π / 4) is regarded as a frequency shift signal. Frequency deviation detection method.

According to an eighth aspect of the present invention, there is provided a quadrature detection means for quadrature detection of an inputted eight-phase modulated signal, and an I and Q equivalent low band signal output from the quadrature detection means as an input. Delay detecting means for performing delay detection between the symbols detected, phase rotating means for performing the (π / 4) phase rotation of the delayed detection signal by using the output of the delay detecting means as input, and delay detecting means obtained by the delay detecting means. Signal (in-phase component (x),
With the quadrature component (y)) as input, the phase is calculated in the orthogonal coordinate system as follows: y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8), a region determination unit that performs region determination by dividing the region into eight regions, and the phase of the differential detection signal is orthogonal from the eight regions based on the output of the region determination unit. Area (n = 0/2, 1) within the area (nπ / 2) ± (π / 8) including the coordinate axes
2,3), the in-phase component (x) or the quadrature component (y) of the differential detection output signal is output as a frequency shift signal, and the region ((π / 4) + (nπ / 2)) ± (π / 8), the range (n = 0, 1, 2, 3) is satisfied.
/ 4), and a selecting means for outputting an in-phase component (x) or a quadrature component (y) of the signal whose phase has been rotated by / 4) as a frequency shift signal.

According to a ninth aspect of the present invention, an I and Q equivalent low band signal obtained by quadrature detection of an eight-phase modulated signal is subjected to delay detection between consecutive symbols, and the delay detection signal is obtained. For (nπ / 4) ± (π / 8) (n = 0,1,2,3,
Region determination is performed on eight regions of (4, 5, 6, 7), and a region (n = 0) within ((π / 4) + (nπ / 2)) ± (π / 8) among the eight regions , 1, 2, 3), the difference between the in-phase component and the quadrature component of the differential detection signal is regarded as a frequency shift signal, and the region (n = 0) within (nπ / 2) ± (π / 8) , 1,
2,3), the difference between the in-phase component and the quadrature component of the signal obtained by rotating the differential detection signal by (π / 4) is regarded as a frequency shift signal. is there.

According to a tenth aspect of the present invention, there is provided a quadrature detection means for quadrature detection of an inputted eight-phase modulated signal, and an I and Q equivalent low-pass signal output from the quadrature detection means as inputs. Delay detection means for performing delay detection between the selected symbols, phase rotation means for performing (π / 4) phase rotation of the differential detection signal by using an output of the delay detection means as an input,
The delay detection signal (in-phase component (x), quadrature component (y)) obtained by the above-mentioned delay detection means is input, and its phase is y = x · tan (π / 8) y = −x in the quadrature coordinate system. Tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) Area determination means for performing area determination by dividing the area into eight areas, and the area determination means From the output of the above, the delayed detection signal is a region within the region ((π / 4 + nπ / 2)) ± (π / 8) which does not include the orthogonal coordinate axis among the eight regions.
When (n = 0, 1, 2, 3), the difference between the in-phase component (x) and the quadrature component (y) of the differential detection signal is output as a frequency shift signal, and the region including the quadrature coordinate axis (nπ / 2 Area within ± π / 8: n = 0,
1, 2, 3), the difference between the in-phase component (x) and the quadrature component (y) of the signal rotated in phase by the delayed detection signal (π / 4) by the phase rotation means is used as a frequency shift signal. And a selecting means for outputting the frequency deviation.

According to an eleventh aspect of the present invention, in the area determination of the differential detection signal in the orthogonal coordinate system, the area determination straight line is switched according to the type of phase modulation, and the differential detection output is determined by the area determination. A frequency shift detection method is characterized in that when in an area including a coordinate axis, an in-phase or quadrature component of a differential detection signal is regarded as a frequency shift signal.

According to a twelfth aspect of the present invention, the area detection means of the quadrature coordinate system of the differential detection signal includes a determination area switching means for switching the determination area according to the type of phase modulation. Selection means for outputting the in-phase component (x) or the quadrature component (y) of the differential detection signal as a frequency shift signal only when the differential detection signal is in a region including the coordinate axes of the rectangular coordinates. Is a frequency shift detecting device.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 shows a configuration diagram of a frequency shift detecting apparatus according to a first embodiment of the present invention.
1b is an equivalent low-band signal input terminal for an in-phase component (I) and a quadrature component (Q) obtained by quadrature detection of an 8PSK signal, 2 is a 1-symbol delay unit, 3 is a complex conjugate generation unit, 4 is a complex multiplication unit Numeral 5 is a region determining means, 6a and 6b are sign inverting means, 7 is a selecting means, and 8 is a frequency shift signal output terminal. The operation will be described below.

The equivalent low-frequency signals of the in-phase component (I) and the quadrature component (Q) obtained by quadrature detection of the 8PSK signal are 1a, 1
is input to the input terminal b. The I and Q equivalent low band signals are digitized, and the equivalent low band signals are regarded as a real part and an imaginary part of a complex number, respectively. This equivalent low-frequency signal includes a frequency shift caused by a frequency converter (not shown) in the satellite antenna or the like.

The I and Q equivalent low-frequency signals including the frequency shift are subjected to delay detection in one symbol period. The differential detection is constituted by one-symbol delay means 2, complex conjugate generation means 3, and complex multiplication means 4, and performs complex multiplication of the current equivalent low band signal and the complex conjugate signal of the equivalent low band signal one symbol before. Is done. This can be expressed as

[0033]

(Equation 2)

Is as follows. From this (Equation 2), if there is no frequency shift in the equivalent low-frequency signal, the phase state of the differential detection output becomes π / π as shown by ● in the phase state diagram of FIG.
There are eight points of 4 · n (n = 0 to 7). However, if there is a frequency shift (Δf), the phase shifts by 2π · Δf · Ts from the position of ●.

Now, in order to obtain a frequency shift from the delayed detection output without converting the rectangular coordinates into polar coordinates, it is necessary to select a value substantially proportional to the frequency shift on the rectangular coordinates. Therefore, as shown in FIG. 2A, the delay detection output result is expressed as nπ / 4 ± π / 8 (n = 0, 1, 2, 3, 4, 5,
6,7) to divide into eight areas, of which the area (nπ / 2) ± (π / 8) including the coordinate axes (n = 0,1,
2, 3)) That is, in each of the area a, the area b, the area c, and the area d,
When the phase of the differential detection output enters, the in-phase component (x) and the quadrature component (y) of the differential detection output can be regarded as values proportional to the frequency shift.

For example, considering the region a (region within (0) ± (π / 8)), the frequency is advanced from (0) to (+ π / 8), and the quadrature component (y ) Becomes positive, and the value increases as the frequency advance increases. On the other hand, the frequency is delayed from (0) to (−π / 8), the quadrature component (y) of the differential detection output becomes negative, and the value of the frequency delay increases and the value decreases.

As shown in FIG. 2B, in the case of the regions a, b, c, and d in FIG. 2, y (quadrature component) and −x (in-phase It is a feature of the present invention to output the component, −y (quadrature component), and x (in-phase component) as frequency shift signals, and not output them at other times.

For this purpose, the differential detection output is input to the area determining means 5, and as shown in FIGS. 2 (a) and 2 (b),
Y = x · tan (π / 8) in a rectangular coordinate system, y = −x ·
tan (π / 8), y = x · cot (π / 8), and y
It detects where the phase of the differential detection signal is included in a region delimited by a straight line of = −x · cot (π / 8), that is, performs region determination in eight regions. The selection means 7 determines y = x · tan (π / 8) of the eight areas of the differential detection signal based on the area determination result of the area determination means 5.
And y = −x · tan (π / 8), the region a and the region c, when the region a (y <x · tan (π / 8) and y> −x · tan (π / 8)), the quadrature component (y) of the differential detection signal is used as the frequency shift signal, and in the region c (y> xtan (π / 8) and y <-xtan)
(When π / 8)) is the orthogonal component (y) ·
(-1) is a frequency shift signal, and y = x · cot
(Π / 8) and y = −x · cot (π / 8), among the regions b and d, when region b (y> x · cot)
(Π / 8) and y> -x · cot (π / 8)
Is the in-phase component (x) · (−1) of the differential detection signal as a frequency shift signal, and in a region d (y <x · cot (π / 8)
When y <−x · cot (π / 8)), the in-phase component (x) of the differential detection signal is output as a frequency shift signal.

In areas other than the areas a, b, c and d, no signal is output or the previous frequency shift signal is held.

As described above, it is possible to detect a frequency shift without performing a complicated conversion from the rectangular coordinates to the polar coordinates in order to obtain the frequency shift.

The resulting frequency shift signal is
As shown in FIG. 16, as a digital AFC, a loop filter 41, a numerical operation oscillation circuit (NCO) 42, si
n conversion means 43, cos conversion means 44, complex multiplier 14
The frequency can be controlled through the
As shown in (1), the local oscillation circuit of the quasi-synchronous quadrature detection is a voltage controlled oscillator (VCO), so that the loop filter 41, the D / A converter 70, and the AF through the quasi-synchronous quadrature detection
C becomes possible.

In the area judgment by the area judgment means 5, the absolute value of the differential detection output is taken, and in the first quadrant (x ≧ 0 and y ≧ 0) of the orthogonal coordinates, y = x · tan (π
/ 8), y = x · cot (π / 8) on a straight line from 0 to π /
It is needless to say that eight regions can be determined by determining the region of up to 2 and determining the coordinate representation using the signs of the differential detection outputs x and y.

Also, tan (π / 8) used for area determination
It goes without saying that there is no problem even if the values of and cot (π / 8) are finite.

(Embodiment 2) FIG. 3 shows a second embodiment of the present invention, wherein 1a and 1b denote in-phase components (I) and quadrature components obtained by quadrature detection of an 8PSK signal. (Q) Equivalent low band signal input terminal, 2 is one symbol delay means, 3 is complex conjugate generation means, 4 is complex multiplication means, 5 is area determination means, 106a and 106b are absolute value generation means, 1
07 is a subtraction means, 108 is a sign inversion means, 7 is a selection means, and 8 is a frequency shift signal output terminal. The operation will be described below.

The equivalent low band signals of the in-phase component (I) and the quadrature component (Q) obtained by quadrature detection of the 8PSK signal are 1a, 1
is input to the input terminal b. The I and Q equivalent low band signals are digitized, and the equivalent low band signals are regarded as a real part and an imaginary part of a complex number, respectively. This equivalent low-frequency signal includes a frequency shift caused by a frequency converter (not shown) in the satellite antenna or the like.

The I and Q equivalent low-frequency signals including the frequency shift are subjected to differential detection in one symbol period. The delay detection is composed of a one-symbol delay means 2, a complex conjugate generation means 3, and a complex multiplication means 4, and is a complex conjugate signal of the current equivalent low-band signal and the equivalent low-band signal of one symbol before. And are complex multiplied. When this is expressed by an equation, it becomes as shown in (Equation 2).

From this (Equation 2), if there is no frequency shift in the equivalent low band signal, the phase state of the differential detection output is π / 4 · n (n = 0 to 7) as shown by ● in the phase diagram of FIG. )It is in. However, if there is a frequency shift Δf, 2π · Δf · Ts
, The phase is shifted from ●.

Now, in order to obtain the frequency shift from the delayed detection output without converting from the rectangular coordinates to the polar coordinates, it is necessary to select a value substantially proportional to the frequency shift on the rectangular coordinates. Therefore, as shown in the phase diagram of FIG. 4A, the delay detection output result is expressed as (nπ / 4) ± (π / 8) (n = 0, 1, 2, 3, 4, 4).
5,6,7) to divide into 8 areas, of which area does not include coordinate axes,
That is, the region (n) within (π / 4) + (nπ / 2) ± (π / 8)
= 0, 1, 2, 3) When entering each of the regions e, f, g and h, the in-phase component (x) of the differential detection output and the quadrature The difference from the component (y) can be regarded as a signal substantially proportional to the frequency shift.

For example, in the e region (region within π / 4 ± π / 8), the frequency advances from π / 4 to π / 4 + π / 8, and the in-phase component (x ) And the orthogonal component (y) become positive (| y | − | x |), and the value increases as the frequency advance increases.
On the other hand, the frequency is delayed from π / 4 to π / 4−π / 8 at the boundary of π / 4, and the difference (| y | − | x |) between the in-phase component (x) of the differential detection output and the quadrature component (y) is delayed. ) Becomes negative, the value of which becomes smaller as the frequency lag increases.

As described above, in the case of the region e, the region f, the region g, and the region h, a value proportional to the frequency shift is shown in FIG.
As shown in (c), (| y |-| x |),-(| y |-| x |), (| y |-| x |) and-(| y |-| x |) It is a feature of the present invention that the signal is output as a frequency shift signal and is not output at other times. .

For this purpose, the differential detection output is input to the area determining means 5, and as shown in FIGS. 4 (a) and 4 (c),
Delayed in a rectangular coordinate system by a straight line of y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) The detection signal is subjected to area determination in eight areas, and the delayed detection outputs (x) and (y) are calculated by the absolute value generation means 106a and 106b, the subtraction means 107, and the sign inversion means 108 by (π / 4) + The region (n) within (nπ / 2) ± (π / 8)
= 0, 1, 2, 3) (| y |-| x |) and-(| y |-| x |), which are values proportional to the frequency shift at (= 0, 1, 2, 3).

Based on the area judgment result of the area judgment means 5, the selection means 7 determines that the delayed detection signal is y = x · t out of the eight areas.
In the region e sandwiched between an (π / 8) and y = x · cot (π / 8), ie, y> x · tan (π / 8)
And y <x · cot (π / 8) and the region g
, That is, y <x · tan (π / 8) and y>
When x · cot (π / 8), (| y |
− | X |) as a frequency shift signal, and y = −x · t
When the region f is sandwiched between an (π / 8) and y = −x · cot (π / 8), that is, y> −x · tan (π / 8)
And when y <−x · cot (π / 8) and in the region h, that is, when y <−x · tan (π / 8) and y> −x · cot (π / 8), differential detection is performed. The signal-(| y |-| x |) is output as a frequency shift signal.

In a region other than the regions e, f, g and h, nothing is output or the previous frequency shift signal is held.

With the above configuration, it is possible to detect a frequency shift without performing a complicated conversion from a rectangular coordinate to a polar coordinate to obtain the frequency shift.

The frequency shift signal obtained in this way is converted into a digital AFC as shown in FIG. 16 as a loop filter 41, a numerical operation oscillator (NCO) 42,
The frequency control is possible via the conversion means 43, the cos conversion means 44, and the complex multiplier, and the local oscillation circuit for quasi-synchronous quadrature detection is connected to a voltage controlled oscillator (VC) as shown in FIG.
By setting O), AFC through a loop filter, a D / A converter, and quasi-synchronous quadrature detection becomes possible.

In the area judgment by the area judgment means 5, the absolute value of the delay detection output is taken and y = x · tan (π) in the first quadrant (x ≧ 0 and y ≧ 0) of the orthogonal coordinates.
/ 8), y = x · cot (π / 8) on a straight line from 0 to π /
It is needless to say that eight regions can be determined by determining the region of up to 2 and determining the coordinate representation using the signs of the differential detection outputs x and y.

Also, tan (π / 8) used for area determination
It goes without saying that there is no problem even if the values of and cot (π / 8) are finite.

(Embodiment 3) FIG. 5 shows a third embodiment of the present invention, wherein 1a and 1b show an in-phase component (I) and a quadrature component obtained by quadrature detection of an 8PSK signal. (Q) Equivalent low band signal input terminal, 2 is one symbol delay means, 3 is complex conjugate generation means, 4 is complex multiplication means, 5 is area determination means, 6a, 6b, 6c and 6d are sign inversion means,
7 is a selection means, 110 is a π / 4 phase shift means, and 8 is a frequency shift signal output terminal. The operation will be described below.

The equivalent low-frequency signals of the in-phase component (I) and the quadrature component (Q) obtained by quadrature detection of the 8PSK signal are 1a, 1
is input to the input terminal b. The I and Q equivalent low band signals are digitized, and the equivalent low band signals are regarded as a real part and an imaginary part of a complex number, respectively. This equivalent low-frequency signal includes a frequency shift caused by a frequency converter (not shown) in the satellite antenna or the like.

The I and Q equivalent low-frequency signals including the frequency shift are subjected to delay detection in one symbol period. The delay detection is composed of a one-symbol delay means 2, a complex conjugate generation means 3, and a complex multiplication means 4, and is a complex conjugate signal of the current equivalent low-band signal and the equivalent low-band signal of one symbol before. And are complex multiplied. When this is expressed by an equation, it becomes as shown in (Equation 2).

From this (Equation 2), if there is no frequency shift in the equivalent low band signal, the phase state of the differential detection output is π / 4 · n (n = 0 to 7) as shown by ● in the phase state diagram of FIG. )It is in. However, if there is a frequency shift Δf, 2π · Δf · Ts
, The phase is shifted from ●.

In order to determine the frequency shift from the delayed detection output without converting the rectangular coordinates to the polar coordinates, it is necessary to select a value substantially proportional to the frequency shift on the rectangular coordinates. Therefore, as shown in the phase diagram of FIG. 6A, the delay detection output result is expressed as (nπ / 4) ± (π / 8) (n = 0, 1, 2, 3, 3).
4,5,6,7) to divide into eight regions, of which a region including the coordinate axes, that is, a region (n = 0,1,) within (nπ / 2) ± (π / 8)
2, 3)) When entering each of the regions a, b, c and d, the in-phase component (x) or the quadrature component (y) of the differential detection output is regarded as a signal proportional to the frequency shift. I can do it.

For example, in the area a (area within 0 ± π / 8), the frequency is advanced from (0) to (+ π / 8), and the quadrature component (y) of the differential detection output is positive. That is, as the advance of the frequency increases, the value also increases. On the other hand, the frequency is delayed from (0) to (−π / 8),
The quadrature component (y) of the differential detection output becomes negative, and as the frequency delay increases, its value also decreases.

As described above, in the case of the region a, the region b, the region c, and the region d, a value proportional to the frequency shift is shown in FIG.
As shown in (a), y, -x, -y, x are output as frequency shift signals.

On the other hand, of the eight regions, a region not including the coordinate axis, that is, a region (n) within (π / 4) + (nπ / 2) ± (π / 8)
= 0, 1, 2, 3) When the differential detection signal is in each of the regions e, f, g and h, the phase of the differential detection signal is rotated by π / 4 as shown in FIG. The in-phase component (x) and the quadrature component (y) of the signal can also be regarded as signals proportional to the frequency shift.

For this purpose, the delay detection output is input to the area determining means 5, and as shown in FIG. 6A, y = x · tan (π / 8) y = −x · tan (π) in the rectangular coordinate system. / 8) y = x · cot (π / 8) y = −x · cot (π / 8) The area of the differential detection signal is determined in eight areas, and the differential detection output (x), (x In y), the phase is rotated by π / 4 by the phase rotation means 110.

The phase rotation of π / 4 is

[0068]

(Equation 3)

Can be represented by Phase rotation means 110
However, as shown in FIG. 8, complex multiplication is unnecessary, and can be realized by addition, subtraction, and constant multiplication. The outputs of the complex multiplication means 4 and the phase rotation means 110 are input to the selection means 7 and, based on the area determination result of the area determination means 5, as shown in FIG.
When the differential detection signal is in the area a among the eight areas, that is, y <x · tan (π / 8) and y> −x · ta
When n (π / 8), the quadrature component (y) of the differential detection signal is used as a frequency shift signal, and in the region b, that is, y> x · cot (π / 8) and y> −x · cot
(Π / 8), the in-phase component (x) of the differential detection signal
(-1) is a frequency shift signal, and in a region c, that is, y> x · tan (π / 8) and y <−x · ta
When n (π / 8), the quadrature component (y) · (−1) of the differential detection signal is used as a frequency shift signal, and in the region d, that is, y <x · cot (π / 8) and y <−.
In the case of x · cot (π / 8), the in-phase component (x) of the differential detection signal is used as a frequency shift signal, and in the region e, that is, y> x · tan (π / 8) and y <x · cot
In the case of (π / 8), the in-phase component (x) · (−1) of the delayed detection signal after the π / 4 phase rotation is used as a frequency shift signal,
In the case of the area f, that is, y> −x · tan (π / 8)
And when y <−x · cot (π / 8), π / 4
Quadrature component (y) · (−1) of differential detection signal after phase rotation
Is a frequency shift signal, and in a region g, that is, y <x
Tan (π / 8) and y> x · cot (π / 8)
In the case of, the in-phase component (x) of the delayed detection signal after the π / 4 phase rotation is used as a frequency shift signal, and in a region h, that is, y <−x · tan (π / 8) and y> −x · co
At t (π / 8), the in-phase component (y) of the delayed detection signal after the π / 4 phase rotation is output as a frequency shift signal.

As described above, it is possible to detect a frequency shift without performing a complicated conversion from the rectangular coordinates to the polar coordinates in order to obtain the frequency shift.

The frequency shift signal obtained in this way is converted into a digital AFC as shown in FIG. 16 as a loop filter 41, a numerical operation oscillator (NCO) 42, a sin
The frequency can be controlled via the conversion means 43, the cos conversion means 44, and the complex multiplier 14, and the local oscillation circuit for quasi-synchronous quadrature detection is connected to a voltage controlled oscillator (V
CO), the loop filter 41, D / A
The converter 70 enables AFC via quasi-synchronous quadrature detection.

In the area judgment by the area judgment means 5, the absolute value of the delay detection output is taken, and y = x · tan (π) in the first quadrant (x ≧ 0 and y ≧ 0) of the orthogonal coordinates.
/ 8), y = x · cot (π / 8) on a straight line from 0 to π /
It is needless to say that eight regions can be determined by determining the region of up to 2 and determining the coordinate representation using the signs of the differential detection outputs x and y.

Also, tan (π / 8) used for area determination
It goes without saying that there is no problem even if the values of and cot (π / 8) are finite.

(Embodiment 4) FIG. 9 shows a fourth embodiment of the present invention, wherein 1a and 1b show an in-phase component (I) and a quadrature component obtained by quadrature detection of an 8PSK signal. (Q) Equivalent low band signal input terminal, 2 is one symbol delay means, 3 is complex conjugate generation means, 4 is complex multiplication means, 5 is area determination means, 106a, 106b, 116a, 116b
Are absolute value generation means, 107 and 117 are subtraction means, 10
8, 118 are sign inversion means, 7 is selection means, 110 is π
A / 4 phase rotation means 8 is a frequency shift signal output terminal. The operation will be described below.

The equivalent low-frequency signals of the in-phase component (I) and the quadrature component (Q) obtained by quadrature detection of the 8PSK signal are 1a, 1
is input to the input terminal b. The I and Q equivalent low band signals are digitized, and the equivalent low band signals are regarded as a real part and an imaginary part of a complex number, respectively. This equivalent low-frequency signal includes a frequency shift caused by a frequency converter (not shown) in the satellite antenna or the like.

The I and Q equivalent low-frequency signals including the frequency shift are subjected to delay detection in one symbol period. The delay detection is composed of a one-symbol delay means 2, a complex conjugate generation means 3, and a complex multiplication means 4, and is a complex conjugate signal of the current equivalent low-band signal and the equivalent low-band signal of one symbol before. And are complex multiplied. When this is expressed by an equation, it becomes as shown in (Equation 2).

From this (Equation 2), if there is no frequency shift in the equivalent low-frequency signal, the phase state of the differential detection output is π / 4 · n (n = 0 to 7) as shown by ● in the phase diagram of FIG. )It is in. However, if there is a frequency shift Δf, 2π · Δf · Ts
, The phase is shifted from ●.

Now, in order to obtain the frequency shift from the delayed detection output without converting from the rectangular coordinates to the polar coordinates, it is necessary to select a value substantially proportional to the frequency shift on the rectangular coordinates.

Therefore, as shown in FIG. 9A, the delay detection output result is expressed as (nπ / 4) ± (π / 8) (n = 0, 1, 2, 3, 4,
5,6,7) to divide into 8 areas, of which area does not include coordinate axes,
That is, the region (n = (n / 4) + (nπ / 2) ± π / 8)
0, 1, 2, 3)), when entering each of the regions e, f, g, and h, as shown in FIG. 4B, the in-phase component (x) of the differential detection output, The difference from the orthogonal component (y) can be regarded as a signal substantially proportional to the frequency shift.

For example, in the e region (region within π / 4 ± π / 8), the frequency is advanced from (π / 4) to (π / 8) at the boundary of π / 4, and the delay detection is performed. The difference (| y |-| x |) between the in-phase component (x) and the quadrature component (y) of the output becomes positive, and the value increases as the frequency advance increases. On the other hand, at the boundary of π / 4, (π / 4) − (π /
The frequency is delayed up to 8), and the difference (| y | − | x |) between the in-phase component (x) and the quadrature component (y) of the differential detection output
Becomes negative, and its value decreases as the frequency delay increases.

As described above, in the case of the region e, the region f, the region g, and the region h, the value proportional to the frequency shift is shown in FIG.
As shown in (a), (| y |-| x |),-(| y |-| x |), (| y |-| x |) and-(| y |-| x |) Output as a frequency shift signal.

On the other hand, of the eight regions, a region including the coordinate axis, that is, a region (n = 0, 1, 1) within (nπ / 2) ± (π / 8)
2, 3) When in the regions a, b, c and d, the differential detection signal is rotated by π / 4 as shown in FIG. The difference between (x) and the orthogonal component (y) can also be regarded as a signal substantially proportional to the frequency shift.

For this purpose, the differential detection output is input to the area determining means 5, and as shown in FIG. 10A, y = x · tan (π / 8) y = −x · tan (π) in the rectangular coordinate system. / 8) y = x · cot (π / 8) y = −x · cot (π / 8) The area of the differential detection signal is determined in eight areas, and the differential detection output (x), (x y) is calculated by the absolute value generating means 106a and 106b, the subtracting means 107, and the sign inverting means 108 in the area (n) within (π / 4) + (nπ / 2) ± (π / 8).
= 0, 1, 2, 3), and becomes a value proportional to the frequency deviation (| y |-| x
|) And-(| y |-| x |), and
The phases of the differential detection outputs (x) and (y) are rotated by π / 4 by the phase rotation means 110, and the outputs are (nπ) by the absolute value generation means 116a and 116b, the subtraction means 117, and the sign inversion means 118. / 2) region (n = 0, 1, ±) within ± (π / 8)
2,3) becomes a value proportional to the frequency shift (| y | − | x
|) And-(| y |-| x |), and the selecting unit 7
Is input to

By the way, the phase rotation of π / 4 can be expressed by (Equation 3). As shown in FIG. 8, the phase rotation means 110 does not require complex multiplication, and is realized by addition, subtraction, and constant multiplication. it can.

As shown in FIG. 11, the selecting means 7 determines, based on the area determination result of the area determining means 5, when the differential detection signal is in the area e among eight areas, ie, y> xtan.
(Π / 8) and y <x · cot (π / 8) and in the region g, ie, y <x · tan (π
/ 8) and y> x · cot (π / 8),
(| Y |-| x |) of the differential detection signal is used as a frequency shift signal, and in the region f, that is, y> −x · tan (π /
8) and y <−x · cot (π / 8) and in the region h, ie, y <−x · tan (π /
8) And when y> −x · cot (π / 8), − (| y | − | x |) of the differential detection signal is used as a frequency shift signal, and in the region a, that is, y <x · tan (π). / 8)
When y> −x · tan (π / 8) and in the region c, that is, when y> x · tan (π / 8) and y <−x · tan (π / 8), π / (| Y |-| x |) of the differential detection signal after the four-phase rotation is used as a frequency shift signal, and in a region b, that is, y> x · cot
(Π / 8) and y> −x · cot (π / 8) and in the region d, ie, y <x · cot (π /
8) And when y <−x · cot (π / 8),
-of the delayed detection signal of the delayed detection signal after the π / 4 phase rotation
(| Y |-| x |) is output as a frequency shift signal.

As described above, it is possible to detect a frequency shift without performing a complicated conversion from orthogonal coordinates to polar coordinates in order to obtain the frequency shift.

The frequency shift signal obtained as described above is converted into a digital AFC as shown in FIG. 16 as a loop filter 41, a numerical operation oscillation circuit (NCO) 42,
The frequency can be controlled via the conversion means 43, the cos conversion means 44, and the complex multiplier 14, and the local oscillation circuit for quasi-synchronous quadrature detection is connected to a voltage controlled oscillator (V
CO), the loop filter 41, D / A
The converter 70 enables AFC via quasi-synchronous quadrature detection.

In the area judgment by the area judgment means 5, the absolute value of the differential detection output is taken, and y = x · tan (π) in the first quadrant (x ≧ 0 and y ≧ 0) of the orthogonal coordinates.
/ 8), y = x · cot (π / 8) on a straight line from 0 to π /
It is needless to say that eight regions can be determined by determining the region of up to 2 and determining the coordinate representation using the signs of the differential detection outputs x and y.

Also, tan (π / 8) used for area determination
It goes without saying that there is no problem even if the values of and cot (π / 8) are finite.

(Embodiment 5) FIG. 13 shows a fifth embodiment of the present invention. Reference numerals 1a and 1b denote I and Q equivalent low-frequency signal input terminals including a frequency shift, and 2 denotes a terminal. 1 symbol delay means, 3 is a complex conjugate generating means, 4 is a complex multiplying means, 5 is a region determining means, 6a and 6b are sign inverting means, 7
Is a selection means, 8 is a frequency shift signal output terminal, and 9 is a judgment condition switching means.

Blocks having the same reference numerals as those shown in the configuration described in the first embodiment perform the same operations, and thus description thereof will be omitted. Now, in order to obtain the frequency shift from the delayed detection output without converting the rectangular coordinates to the polar coordinates, a value substantially proportional to the frequency shift on the rectangular coordinates may be selected. In the case of 8PSK according to the first embodiment, when the detection output result is divided into eight regions as shown in FIG. 2, when the detection output result enters each of regions a, b, c, and d including the coordinate axes. Is a variable proportional to the frequency shift, and sets the quadrature component or the in-phase component of the detection output, y, -x, -y, x, as the frequency shift signal, and does not output the signal at other times. In order to make this correspond to a plurality of phase modulations, first, the area determination switching means 9 switches the area determination straight line. For example, QP
At the time of SK reception, it is divided into four regions by a straight line of y = x, y = −x, and at the time of 8PSK reception, y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) The differential detection signal is divided into eight regions by a straight line of y = −x · cot (π / 8). Then, as shown in FIG. 13 (b), the in-phase component (x) of the delayed detection signal is obtained only when the delayed detection signal is located in the area including the coordinate axes of the rectangular coordinates, based on the output of the area determination means among the respective areas. , Or a quadrature component (y) as an amount proportional to the frequency shift and outputting the same with the frequency shift and the polarity, thereby performing a complex conversion for converting a plurality of phase modulations from orthogonal coordinates to polar coordinates. Frequency deviation can be detected.

The frequency shift signal obtained in this way is converted into a digital AFC as shown in FIG. 16 as a loop filter 41, a numerical operation oscillator (NCO) 42, a sin
The frequency can be controlled via the conversion means 43, the cos conversion means 44, and the complex multiplier 14, and the local oscillation circuit for quasi-synchronous quadrature detection is connected to a voltage controlled oscillator (V
CO), the loop filter 41, D / A
The converter 70 enables AFC via quasi-synchronous quadrature detection.

In the area judgment by the area judgment means 5, the absolute value of the delayed detection output is taken and y = x · tan (π) in the first quadrant (x ≧ 0 and y ≧ 0) of the orthogonal coordinates.
/ 8), y = x · cot (π / 8) on a straight line from 0 to π /
It is needless to say that eight regions can be determined by determining the region of up to 2 and determining the coordinate representation using the signs of the differential detection outputs x and y.

Also, tan (π / 8) used for area determination
It goes without saying that there is no problem even if the values of and cot (π / 8) are finite.

[0095]

According to the frequency shift detecting method and the frequency shift detecting apparatus of the present invention, the frequency shift detection in the 8PSK AFC can be performed by a simple method and a simple circuit configuration without performing conversion from rectangular coordinates to polar coordinates. realizable.

Further, in the frequency shift detecting method and the frequency shift detecting apparatus according to the present invention, the frequency shift detecting method and apparatus which can cope with a plurality of types of phase modulation can be realized by a circuit configuration.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a frequency shift detecting device according to a first embodiment of the present invention;

FIG. 2 is a diagram showing an area determination and an output of a selection means accompanying the area determination in the frequency shift detecting apparatus.

FIG. 3 is a configuration diagram of a frequency shift detecting device according to a second embodiment of the present invention;

FIG. 4 is a diagram showing an area determination and an output of a selection means accompanying the area determination in the frequency shift detecting apparatus.

FIG. 5 is a configuration diagram of a frequency shift detecting device according to a third embodiment of the present invention;

FIG. 6 is a phase state diagram showing a region determination in the frequency shift detecting device.

FIG. 7 is a diagram showing an output of a selection unit based on a region determination in the frequency shift detection device.

FIG. 8 is a configuration diagram of a π / 4 phase rotation unit of the frequency deviation detection device of the present invention.

FIG. 9 is a configuration diagram of a frequency shift detecting device according to a fourth embodiment of the present invention.

FIG. 10 is a phase state diagram showing area determination in the frequency shift detecting device.

FIG. 11 is a diagram showing an output of a selection unit based on area determination in the frequency shift detecting apparatus.

FIG. 12 is a diagram illustrating a phase state of an 8PSK differential detection output signal.

FIG. 13 is a configuration diagram of a frequency shift detecting device according to a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of a conventional QPSK demodulation system.

FIG. 15 is a diagram showing phase states of QPSK and 8PSK.

FIG. 16 is a configuration diagram of automatic frequency control using the frequency deviation detecting device of the present invention.

FIG. 17 is a configuration diagram of automatic frequency control using the frequency deviation detection device of the present invention.

[Explanation of symbols]

1a, 1b Equivalent low-frequency signal input terminal 2 1 symbol delay means 3 Complex conjugate generation means 4 Complex multiplication means 5 Area determination means 6a, 6b, 6c, 6d, 108, 118 Sign inversion means 7 Selection means 8 Frequency shift signal output terminal Reference Signs List 9 decision area switching means 10 QPSK modulation signal input terminal 11 quasi-synchronous quadrature detection means 12a, 12b low-pass filter 13a, 13b A / D converter 14 complex multiplier for AFC 15a, 15b roll-off filter 16 for carrier wave reproduction 17 Multiplier 17 Data decision circuit, 18a, 18b I, Q data output terminal 20 Cartesian coordinate-polar coordinate conversion means 21 Frequency error detection means 106a, 106b, 116a, 116b Absolute value generation means 107, 117 Subtraction means

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Noriaki Omoto 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (12)

[Claims] An I and Q equivalent low band signal obtained by quadrature detection of an 8-phase phase modulated signal is subjected to delay detection between successive symbols, and the phase of the delayed detection signal is (nπ / 4). ± (π / 8) (n = 0, 1, 2, 3,
A determination is made as to which of the eight regions represented by (4,5,6,7) is present, and the differential detection signal is obtained by comparing the (nπ / 2) ± (π / 8) Area (n = 0, 1,
A frequency shift detection method, wherein the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal only when the signal is in (2) or (3). 2. Quadrature detection means for performing quadrature detection on an inputted eight-phase modulation signal, and I, which is an output of the quadrature detection means,
A delay detection means for performing delay detection between consecutive symbols using an equivalent low-frequency signal of Q as an input, and a delay detection signal (in-phase component (x), quadrature component (y)) obtained by the delay detection means
, And y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot ( area determining means for performing area determination by dividing the area into eight areas using a straight line of (π / 8), and a phase (nπ / 2) Region within ± (π / 8) (n = 0, 1,
2. A frequency shift detecting apparatus, comprising: a selector that outputs an in-phase component (x) or a quadrature component (y) of the differential detection output signal as a frequency shift signal only when the signal is in the second or third mode. 3. A quadrature detection means for quadrature detection of an inputted eight-phase modulation signal, and a delay detection for performing a delay detection between consecutive symbols by inputting I and Q equivalent low band signals output from the quadrature detection means. Means and the delayed detection signal (in-phase component (x), quadrature component (y)) obtained by the delay detection means, and the phase thereof is expressed in a quadrature coordinate system as: y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) Area determination means for performing area determination by dividing the area into eight areas, From the output of the area determination means, the phase of the differential detection signal is set to an area (nπ / 2) ± (π / 8) including an orthogonal coordinate axis among the eight areas (n = 0, 1,
The in-phase component (x) or the quadrature component (y) of the differential detection output signal is output as a frequency shift signal only when the differential detection output signal is in (2, 3). A frequency deviation detection device, comprising: a selection unit for holding a frequency deviation signal. 4. An I and Q equivalent low band signal obtained by quadrature detection of an 8-phase phase modulated signal is subjected to delay detection between successive symbols, and the phase of the delayed detection signal is (nπ / 4). An area determination is made as to which of the eight areas represented by ± (π / 8) (n = 0, 1, 2, 3, 4, 5, 6, 7), and the differential detection signal In the two regions, ((π / 4) + (nπ / 2)) ± (π / 8) the region (n = 0,1,2,3), the in-phase component of the differential detection signal A frequency shift detection method, wherein a difference between (x) and the orthogonal component (y) is regarded as a frequency shift signal. 5. A quadrature detection means for quadrature detection of an inputted eight-phase modulation signal, and I, which is an output of said quadrature detection means,
A delay detection means for performing delay detection between consecutive symbols using an equivalent low-frequency signal of Q as an input, and a delay detection signal (in-phase component (x), quadrature component (y)) obtained by the delay detection means
, And y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot ( area determining means for performing area determination by dividing the area into eight areas by a straight line of (π / 8), and an area in which the phase of the differential detection signal is based on an output of the area determining means and which does not include a rectangular coordinate axis among the eight areas. (Π / 4) + (nπ / 2)) ± (π / 8) Only in the region (n = 0, 1, 2, 3), the in-phase component (x) of the differential detection signal
A frequency deviation detection device for outputting a difference between the frequency component and the orthogonal component (y) as a frequency deviation signal. 6. A quadrature detecting means for quadrature detecting the input 8-phase phase modulated signal, and I, which is an output of the quadrature detecting means,
A delay detection means for performing delay detection between consecutive symbols using an equivalent low-frequency signal of Q as an input, and a delay detection signal (in-phase component (x), quadrature component (y)) obtained by the delay detection means
, And y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot ( area determining means for performing area determination by dividing the area into eight areas by a straight line of (π / 8), and an area in which the phase of the differential detection signal is based on an output of the area determining means and which does not include a rectangular coordinate axis among the eight areas. (Π / 4) + (nπ / 2)) ± (π / 8) Only in the region (n = 0, 1, 2, 3), the in-phase component (x) of the differential detection signal
Frequency difference detection means for outputting a difference between the frequency shift signal and the orthogonal component (y) as a frequency shift signal, and for other areas, holding a frequency shift signal for which the area determination has been performed before. apparatus. 7. An I and Q equivalent low band signal obtained by quadrature detection of an 8-phase phase modulated signal is subjected to delay detection between successive symbols, and the phase of the delayed detection signal is (nπ / 4). ± (π / 8) (n = 0, 1, 2, 3,
A region determination is performed to determine which of the eight regions represented by (4, 5, 6, 7) is located, and a region (n = 0) within (nπ / 2) ± (π / 8) of the eight regions , 1,
2,3), the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal, and ((π / 4) + (nπ / 2)) ± (π / 8) When the differential detection signal is in the region (n = 0, 1, 2, 3), the in-phase or quadrature component of the signal obtained by rotating the differential detection signal by (π / 4) is regarded as a frequency shift signal. Frequency shift detection method. 8. A quadrature detecting means for quadrature detecting the input eight-phase modulated signal, and I, which is an output of the quadrature detecting means,
Delay detection means for performing delay detection between successive symbols by using an equivalent low-frequency signal of Q as input, phase rotation means for performing (π / 4) phase rotation of the delay detection signal by using an output of the delay detection means as input, The delay detection signal (in-phase component (x), quadrature component (y)) obtained by the above-mentioned delay detection means is input, and its phase is y = x · tan (π / 8) y = −x in the quadrature coordinate system. Tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8) Area determination means for performing area determination by dividing the area into eight areas, and the area determination means From the output of the above, the phase of the differential detection signal is a region (nπ / 2) ± (π / 8) of the eight regions including the orthogonal coordinate axes (n = 0, 1,
2,3), the in-phase component (x) or the quadrature component (y) of the differential detection output signal is output as a frequency shift signal, and the region ((π / 4) + (nπ / 2)) ± (π / 8), the range (n = 0, 1, 2, 3) is satisfied.
/ 4) a selecting means for outputting an in-phase component (x) or a quadrature component (y) of a signal rotated by a phase as a frequency shift signal as a frequency shift signal. 9. An I and Q equivalent low band signal obtained by quadrature detection of an 8-phase phase modulated signal is subjected to delay detection between consecutive symbols, and the (nπ / 4) ± (nπ / 4) ± ( π / 8) (n = 0, 1, 2, 3,
Region determination is performed on eight regions of (4, 5, 6, 7), and a region (n = 0) within ((π / 4) + (nπ / 2)) ± (π / 8) among the eight regions , 1, 2, 3), the difference between the in-phase component and the quadrature component of the differential detection signal is regarded as a frequency shift signal, and the region (n = 0) within (nπ / 2) ± (π / 8) , 1,
2. A frequency shift detection method according to claim 1, wherein a difference between an in-phase component and a quadrature component of the signal obtained by rotating the differential detection signal by (π / 4) is regarded as a frequency shift signal. 10. A quadrature detector for performing quadrature detection on an input 8-phase phase modulated signal, and a delay for performing delay detection between consecutive symbols using I and Q equivalent low-frequency signals output from the quadrature detector as inputs. Detection means, phase rotation means for performing the (π / 4) phase rotation of the delayed detection signal by using the output of the delay detection means as an input, and a delayed detection signal (in-phase component (x), With the quadrature component (y)) as input, the phase is calculated in the orthogonal coordinate system as follows: y = x · tan (π / 8) y = −x · tan (π / 8) y = x · cot (π / 8) y = −x · cot (π / 8), a region determination unit that performs region determination by dividing the region into eight regions, and a delayed detection signal from the output of the region determination unit that does not include the orthogonal coordinate axis among the eight regions. Within the area ((π / 4 + nπ / 2)) ± (π / 8) Area
When (n = 0, 1, 2, 3), the difference between the in-phase component (x) and the quadrature component (y) of the differential detection signal is output as a frequency shift signal, and the region including the quadrature coordinate axis ((nπ / 2) Region within ± (π / 8) (n = 0,
1, 2, 3), the difference between the in-phase component (x) and the quadrature component (y) of the signal whose phase has been rotated by the delayed detection signal (π / 4) by the phase rotation means is a frequency shift signal. A frequency deviation detecting device, comprising: selecting means for outputting the frequency deviation. 11. The method according to claim 1, wherein the area detection line is switched in accordance with the type of the phase modulation in the area detection of the differential detection signal in the orthogonal coordinate system, and the area detection causes the differential detection output to include the coordinate axes of the orthogonal coordinates. 2. The frequency shift detecting method according to claim 1, wherein the in-phase or quadrature component of the differential detection signal is regarded as a frequency shift signal. 12. The area determining means according to claim 2, wherein the area determining means of the orthogonal coordinate system of the differential detection signal includes a determination area switching means for switching the determination area according to the type of phase modulation. Selecting means for outputting the in-phase component (x) or the quadrature component (y) of the differential detection signal as a frequency shift signal only when the differential detection signal is in a region including the coordinate axes of the rectangular coordinates. The frequency deviation detecting device according to claim 2 or 3, wherein: