JP3948907B2 - Phase detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a phase detection device for detecting a reference carrier for synchronous detection used for demodulating an 8-level (8-phase) PSK signal from a received signal, and more particularly to a 4-phase phase for a QPSK demodulator having a simple circuit configuration. The present invention relates to a carrier phase detector that converts a carrier phase value from a carrier phase value output from a comparator and a position of a signal point on a phase plane of a received signal so as to correspond to an 8-phase PSK signal.
[0002]
[Prior art]
In recent digital information communication and broadcasting, or a position measurement system, a phase shift keying (PSK) method for shifting a phase is used as a modulation method for placing a signal on a reference carrier wave. . The PSK system includes a BPSK (Binary PSK) system that shifts 2 phases, a QPSK (Quadrature PSK) system that shifts 4 phases, an 8-phase PSK system that shifts 8 phases, and a 16 phase shift. There is a 16PSK system.
[0003]
If the number of phases is increased in the PSK method, the amount of information transmitted at a time can be increased, but the phase difference between signals is reduced, so that it is difficult for the receiving side to discriminate signals. Therefore, when the number of phases used for communication is increased from 2 phases to 4 phases, or from 4 phases to 8 phases, etc., if the wireless service area is set to be the same, the output on the transmission side is increased. Or improve the capabilities of the receiver. In other words, when the signal transmission speed is improved by increasing the number of phases, the noise resistance characteristics and the like deteriorate.
[0004]
Therefore, depending on the communication application, for example, when it is desired to immediately transmit a large amount of data to a device having a large-screen high-quality display, there is a QPSK method capable of high-speed signal transmission even if the transmission quality is low. Since the amount of data used for communication is small in a device having a small display such as a small-sized terminal, a BPSK method or the like having a high transmission quality may be used even if the signal transmission speed is low.
[0005]
In general, when demodulating a phase shift keying reception signal, a harmonic baseband signal is extracted by a low-pass filter after the reception signal is multiplied by a synchronized reference carrier wave. Also, the PSK system has a carrier recovery circuit that recovers a reference carrier synchronized with the received signal from the received signal. As a reference carrier wave reproducing method, a frequency multiplication method, a Costas loop method, or the like is known.
[0006]
The frequency multiplication method matches each phase of the modulated signal multiplied by N times (N is an integer phase number greater than or equal to 2) by multiplying the received signal being modulated, and in the vicinity of the reference carrier frequency N times that signal. Only a component (a sine wave whose phase does not change) is extracted by using a narrow band filter, and a reference carrier wave is obtained by dividing the N-fold sine wave component by a 1 / N frequency dividing circuit.
[0007]
On the other hand, the Costas loop method is a method in which N multiplication and 1 / N frequency division performed by the frequency multiplication system are equivalently performed by addition / subtraction and multiplication in the baseband band. The Costas loop circuit has a relatively simple circuit configuration and can reproduce a carrier wave with high accuracy, and thus is used in a demodulation circuit for a BPSK signal or a QPSK signal.
[0008]
By the way, the Costas loop method has a relatively simple circuit configuration as described above, and can reproduce a carrier wave with high accuracy, so that it is frequently used in the two-phase and four-phase PSK methods. However, the Costas loop method is not used because the phase difference between signals becomes small in the 8-phase PSK method and the signal cannot be discriminated on the receiving side, and the frequency multiplication method is generally used. That is, in the carrier recovery of the received signal of the 8-phase PSK system, the carrier wave is recovered using a nonlinear circuit such as an eighth power circuit for the received wave.
[0009]
FIG. 15 is a block diagram of a configuration in the case where a recovered carrier wave is obtained by demodulating a phase shift keying reception signal using a frequency multiplication method. For example, P24-P25 of “Next Generation Digital Modulation / Demodulation Technology Supervised by Jun Hirose Trikes” This is shown in “Carrier regeneration by frequency multiplication method”.
[0010]
In FIG. 15, reference numeral 200 denotes a conventional phase detector using a frequency multiplication method, and reference numeral 19 denotes a quadrature detector that outputs an in-phase signal I and a quadrature signal Q as a demodulated signal DM using a carrier recovered from a received signal. Reference numeral 20 denotes a phase conversion circuit that generates a quadrature signal orthogonal to the carrier wave (rotated by 90 °) from the regenerated reference carrier wave.
[0011]
In the phase detector 200, reference numeral 16 denotes an N multiplier (8 multiplier in the case of 8-phase PSK) that multiplies the received signal, and 17 denotes a band-pass filter that passes only the N-multiplier frequency band of the carrier wave. And 18 is an N frequency divider (in the case of 8-phase PSK, an 8 frequency divider) that outputs a reference carrier signal that is obtained by dividing the received signal multiplied by N by N.
[0012]
Next, an operation for obtaining a reproduced carrier wave in the conventional carrier reproducing apparatus for 8-phase PSK signal shown in FIG. 15 will be described.
The received signal (modulated signal) of the 8-phase PSK system is multiplied by 8 (in the case of 8-phase PSK) by the N multiplier 16 so that the phases of the modulated signals coincide. The received signal multiplied by 8 having the same phase passes through the band-pass filter 17, so that only the frequency component multiplied by 8, that is, only a component in the vicinity of the frequency 8 times the carrier frequency is extracted. The frequency component that is eight times the carrier frequency is a sine wave whose phase does not change.
[0013]
Next, the frequency component of 8 times becomes a frequency of 1/8 by passing through the 8 frequency divider and becomes the frequency of the reference carrier wave. Therefore, the 8-phase PSK carrier recovery device shown in FIG. 15 degenerates the eight phase states of the received signal (modulated signal) of the 8-phase PSK system to zero, and an unmodulated sine wave is obtained. This unmodulated sine wave becomes the regenerated reference carrier wave.
[0014]
[Problems to be solved by the invention]
However, since the above-described conventional 8-phase PSK signal carrier recovery apparatus uses an 8-multiplier, a band-pass filter, and an 8-divider, there is a problem that the circuit scale as the carrier recovery apparatus increases. .
[0015]
Further, the conventional carrier recovery device for 8-phase PSK signal obtains a reference carrier wave by multiplying the received wave by 8 and dividing it by 8, so that a noise component in the received wave or a fluctuation component due to the influence of fading, etc. Is included, the noise components and fluctuation components that could not be suppressed by the bandpass filter remain in the reference carrier as they are, and there is a problem that a highly accurate reference carrier cannot be obtained.
[0016]
Furthermore, the conventional 8-phase PSK signal carrier recovery apparatus has eight stable phase points, and therefore, the reception line quality is poor (low C / N: signal power pair) compared to a QPSK signal having four stable phase points. There is a problem in that the phase of the recovered carrier is likely to cause a phase slip, that is, the operation stability is poor.
[0017]
The present invention has been made to solve the above-described problems, and provides an 8-phase PSK carrier phase detector that operates with high accuracy and a stable reference carrier wave by using a relatively simple circuit configuration. With the goal.
[0018]
[Means for Solving the Problems]
  The phase detection apparatus according to the first aspect of the present invention regenerates a reference carrier wave used for synchronous detection and demodulation of a digital signal phase-modulated by an 8-phase modulation (8-phase PSK: Phase Shift Keying) method. A phase detection device for outputting a reference carrier for a four-phase modulation scheme as a temporary phase value from an in-phase signal and a quadrature signal of a received signal, and an eight-phase modulation scheme used for transmission and reception Calculate the value obtained by adding the absolute value of the ideal signal point at the temporary phase value to the temporary phase value, calculate the value obtained by subtracting the absolute value from the temporary phase value, and set the counterclockwise direction on the phase plane as the positive direction. The polarity is discriminated from the temporary phase value, and when the polarity is positive, the added value is output, and when the polarity is negative, the subtracted value is output as the converted phase value.Temporary phase value conversion circuitAnd an in-phase signal and a quadrature signal input to the 4-phase phase comparator, or output from the 4-phase phase comparatorTemporary phase valueBased on the phase plane, a phase area discriminating circuit for discriminating the existence area of the received signal point on the phase plane and outputting an area signal indicating the existence area, and based on the area signalTemporary phase valueAnd a selection circuit for switching and outputting the conversion phase value.
[0019]
According to a second aspect of the present invention, in the phase detection device according to the first aspect, the phase region discriminating circuit divides the angle between adjacent ideal signal points on the phase plane of the eight-phase modulation system into two equal parts. It is characterized by discriminating each area.
[0020]
  According to a third aspect of the present invention, there is provided the phase detector according to the second aspect, wherein the selection circuit is configured such that the region signal determined by the phase region determination circuit is an ideal common to the four-phase modulation method and the eight-phase modulation method. When the signal indicates that it is the region closer to the signal pointTemporary phase valueAnd a conversion phase value is selected when the signal indicates that the region is closer to the ideal signal point of the 8-phase modulation method only.
[0021]
  According to a fourth aspect of the present invention, in the phase detection device according to the second aspect, the selection circuit is configured such that the region signal determined by the phase region determination circuit has a polarity in the phase control direction of the four-phase modulation system and an eight-phase signal. To indicate that the polarity of the phase control direction of the modulation method is the sameTemporary phase valueAnd the conversion phase value is selected when it indicates that the polarity of the phase control direction of the four-phase modulation method and the polarity of the phase control direction of the eight-phase modulation method are opposite to each other.
[0022]
According to a fifth aspect of the present invention, in the phase detection device according to any one of the first to fourth aspects, the phase region discrimination circuit compares the provisional phase value output from the four-phase phase comparator with a predetermined value. A comparison circuit is included, and a region where a reception signal point exists is determined based on a comparison result of the circuit.
[0023]
According to a sixth aspect of the present invention, in the phase detection device according to any one of the first to fourth aspects, the phase region discriminating circuit is a ratio of the values of the in-phase signal and the quadrature signal input to the four-phase phase comparator. A division circuit for obtaining the received signal point is determined based on a division result of the circuit.
[0024]
  According to a seventh aspect of the present invention, in the phase detection device according to any one of the first to fourth aspects, the phase region discriminating circuit detects arc tangents of the in-phase signal and the quadrature signal input to the four-phase phase comparator. Find valueSignal point angle discrimination circuitAnd the existence area of the reception signal point is determined based on the calculation result of the circuit.
[0025]
  The phase detection apparatus according to the present invention described in claim 8 is a phase detection apparatus for reproducing a reference carrier wave used when synchronously detecting and demodulating a digital signal phase-modulated by the 8-phase modulation method. A phase region discriminating circuit for discriminating the existence region of the reception signal point on the phase plane from the in-phase signal and the quadrature signal of the reception signal, and outputting a region signal indicating the existence region of the reception signal point, and based on the region signal A numerically controlled oscillator that generates sine waves and cosine waves with different fixed angles for each region, a product of fixed angle sine waves for in-phase and quadrature signals, and a product of fixed angle cosine waves for in-phase and quadrature signals A complex multiplier that adds a phase rotation to an in-phase signal and a quadrature signal by adding products whose phases are orthogonal to each other, andComplex multiplierFor in-phase and quadrature signals with phase rotation output fromPhase valueAnd a four-phase phase comparator.
[0026]
According to a ninth aspect of the present invention, in the phase detection device according to the eighth aspect, the phase region discriminating circuit is configured to divide the angle between adjacent ideal signal points on the phase plane of the eight-phase modulation system into two equal parts. It is characterized in that the area of the received signal is determined every time.
[0027]
According to a tenth aspect of the present invention, in the phase detection device according to the ninth aspect, the phase region discriminating circuit determines the region of the received signal as an angle between adjacent ideal signal points on the phase plane of the eight-phase modulation system. In addition to the angle divided into two equal parts, the angle between adjacent ideal signal points on the phase plane of the four-phase modulation method is also determined for each angle divided into two equal parts, and the complex multiplier is detected by the phase region determination circuit The phase for the in-phase signal and the quadrature signal is such that the ideal signal point of the 8-phase modulation method closest to the region signal overlapped with the ideal signal point of the 4-phase method closest to the ideal signal point of the 8-phase method. It is characterized by giving rotation.
[0028]
Further, the present invention of claim 11 is the phase detection device according to claim 9, wherein the phase region discriminating circuit sets the counterclockwise direction of the phase plane to the positive direction and receives the received signal of the four-phase modulation system. The polarity of the phase control direction is discriminated for each region, and when the polarity is positive, the complex multiplier determines that the ideal signal point of the 8-phase modulation method in the region is the most ideal signal point of the 8-phase method. It is characterized in that phase rotation is applied to the in-phase signal and the quadrature signal so as to overlap with the ideal signal point of the near 4-phase system.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0030]
Embodiment 1 FIG.
FIG. 1 is a view showing ideal signal points of 4 phases and 8 phases on the phase plane for the purpose of explaining the present invention, and ideal signal points of 8 phases are replaced with ideal signal points of 4 phases every other one. Since they overlap, ideal signal points B, D, F, and H common to the four and eight phases and ideal signal points A, C, E, and G of only the eight phases are shown to be alternately adjacent. On the phase plane, the line connecting ideal signal points A and E is the I axis, and the line connecting ideal signal points C and G is the Q axis.
[0031]
Further, in FIG. 1, the I axis and the Q axis are orthogonal coordinate axes, a region where both the I axis and the Q axis are positive is the first quadrant, and a region where the I axis is negative and the Q axis is positive is the second quadrant. The region where both the I axis and the Q axis are negative is the third quadrant, and the region where the I axis is positive and the Q axis is negative is the fourth quadrant. The ideal signal point B common to the four and eight phases is disposed at 45 ° with respect to the I axis, the ideal signal point D is disposed at 135 ° with respect to the I axis, and the ideal signal point H is defined as the I axis. The ideal signal point F is arranged at −135 ° with respect to the I axis.
[0032]
  In addition, the IQ orthogonal coordinates in FIG. 1 are arbitrary received signals.Signal point OP (not shown)Is the angle θ, the coordinate position of the signal point OP can be expressed as (cos θ, sin θ) using the angle θ, the sin function, and the cos function.
[0033]
  The four-phase modulation reception signal in the first quadrant is phase-controlled and drawn into the ideal signal point B, and the four-phase modulation reception signal in the second quadrant is phase-controlled and drawn into the ideal signal point D, and the third The received signal of the four-phase modulation in the quadrant is phase-controlled and drawn into the ideal signal point F, and the received signal of the four-phase modulation in the fourth quadrant is phase-controlled.Ideal signal point HBe drawn into.
[0034]
In the phase control, in the first quadrant and the third quadrant, the phase value (or phase error) is output by the calculation of IQ, and in the second quadrant and the fourth quadrant, the phase value is output by the calculation of Q-I.
[0035]
  However, even within the first quadrant, received signals up to 45 ° with respect to the I axis are phase-controlled in the positive direction when the counterclockwise direction is set as the positive direction, and are drawn into the ideal signal point B. The received signal from 45 ° to Q axis is controlled in phase in the negative direction.Ideal signal point BWill be drawn into. Similarly, in the second quadrant, received signals up to 45 ° with respect to the Q axis are phase-controlled in the positive direction and drawn into the ideal signal point D, but from 45 ° to the I axis with respect to the Q axis. The received signal is phase-controlled in the negative direction and drawn into the ideal signal point D.
[0036]
  In the fourth quadrant, received signals up to -45 ° with respect to the I axis are phase-controlled in the negative direction and drawn into the ideal signal point H, but with the I axis as the reference.-45 °To the Q axis are phase-controlled in the positive direction and drawn into the ideal signal point H. In the third quadrant,I Axis to Q axisBased on135 °The received signals up to are phase-controlled in the positive direction and drawn into the ideal signal point F.135 °To the Q axis are phase-controlled in the negative direction and drawn into the ideal signal point F.
[0037]
As described above, in the case of four phases, the ideal signal point changes every 90 °, and the direction (phase controlled polarity) drawn into the ideal signal point differs every 45 °. In this case, the ideal signal point changes every 45 °, and the direction drawn into the ideal signal point changes every 22.5 °.
[0038]
In FIG. 1, in order to classify the received signals of the 8-phase modulation every 22.5 °, an area of 22.5 ° is provided for the I axis. In the first quadrant, four regions a1, b1, c1, and d1 are provided. Similarly, four areas of areas a2, b2, c2, and d2 are provided in the second quadrant, and four areas of areas a3, b3, c3, and d3 are provided in the third quadrant, The fourth quadrant is provided with four regions a4, b4, c4, and d4.
[0039]
For example, in the first quadrant, the reception signal in the region a1 is phase-controlled in the negative direction and drawn into the ideal signal point A, and the reception signal in the region b1 is phase-controlled in the positive direction and drawn into the ideal signal point B. The reception signal in the region c1 is phase-controlled in the negative direction and drawn into the ideal signal point B, and the reception signal in the region d1 is phase-controlled in the positive direction and drawn into the ideal signal point C.
[0040]
From the above, it can be seen that for the 8-phase modulation reception signal in the first quadrant, the reception signals in the regions b1 and c1 can be drawn into the ideal signal point using the same phase control as the 4-phase modulation reception signal. For the received signals in the regions a1 and d1, a means for drawing in the ideal signal point using phase control in the opposite direction (reverse polarity) to the received signal of the four-phase modulation is required.
[0041]
FIG. 2 is a block diagram showing the configuration of the 8-phase PSK phase detection apparatus according to Embodiment 1 of the present invention. FIG. 3 is a diagram showing an example of phase values detected by the 8-phase PSK phase detector of FIG. 2 on the IQ orthogonal coordinate axis, and FIG. 4 shows various phases in the first quadrant of the IQ orthogonal coordinate axis. It is the figure which showed the example of the value.
[0042]
In FIG. 2, reference numeral 1 denotes a quadrature detector that outputs an in-phase signal I and a quadrature signal Q as a demodulated signal DM using a cosine wave and a sine wave of a carrier recovered from a received signal, and 2 is a modified Costas circuit. The four-phase phase comparator is configured to output a phase value when the received signal has four phases (QPSK). In the present embodiment, the phase value is output as a temporary phase value TPV. 3 is a first phase region discriminating circuit that discriminates the phase region of the received signal of eight phases from the temporary phase value TPV, and 5 is a converted phase value CTPV obtained by converting the control direction (polarity) of the temporary phase value TPV in reverse. A temporary phase value conversion circuit for output, and 6 is a first selection circuit for selecting one of the temporary phase value TPV and the conversion phase value CTPV according to the output of the first phase region discrimination circuit 3 and outputting it as the phase value PV. , 7 is a loop filter that removes noise from the phase value PV, and 8 is a numerically controlled oscillator (NCO) that generates a cosine wave and a sine wave of a carrier wave based on the phase value PV. In addition, the phase detection apparatus 101 of the present embodiment includes a four-phase phase comparator 2, a first phase region determination circuit 3, a provisional phase value conversion circuit 5, and a first selection circuit 6.
[0043]
The 4-phase comparator 2 further includes a first polarity discriminating circuit 21 that discriminates the polarity of the in-phase signal I, a second polarity discriminating circuit 22 that discriminates the polarity of the quadrature signal Q, and the quadrature signal Q having the first polarity. A first multiplier 23 that multiplies and outputs the polarity discrimination result by the discrimination circuit 21; a second multiplier 24 that multiplies the polarity discrimination result by the second polarity discrimination circuit 22 and outputs the same signal I; A first subtracter 25 that subtracts the multiplication result of the first multiplier 23 from the multiplication result of the multiplier 24 and outputs the result.
[0044]
The first phase region discriminating circuit 3 is further compared with an absolute value calculating circuit 51 that takes the absolute value of the temporary phase value TPV output from the four-phase phase comparator 2 and a first value that is compared with the absolute value of the temporary phase value TPV. The first fixed value storage unit 52 that stores the fixed value F1 and the absolute value of the temporary phase value TPV and the first fixed value F1 are compared, and the comparison result is output to the first selection circuit 6 as a control signal (binary). And a comparison circuit 53. The first fixed value F1 can be expressed as R · cos 22.5 ° −R · sin 22.5 °, where R is the radius of each ideal signal point in IQ orthogonal coordinates, for example.
[0045]
The temporary phase value conversion circuit 5 further includes a third polarity determination circuit 31 that determines the polarity of the temporary phase value TPV, and a second fixed value storage that stores a second fixed value F2 that is added to or subtracted from the temporary phase value TPV. Unit 32, first adder 33 that adds second fixed value F2 to provisional phase value TPV and outputs it as a candidate for converted phase value CTPV, and subtracts second fixed value F2 from provisional phase value TPV to convert phase The second subtractor 34 that is output as a candidate for the value CTPV, and the output of the first adder 33 and the output of the second subtractor 34 are selected by the output of the third polarity discriminating circuit 31 and the converted phase value CTPV is output. And a second selection circuit 35.
[0046]
The operation of the 8-phase PSK phase detection apparatus of the first embodiment configured as described above will be described below.
When the in-phase signal (I signal) and the quadrature signal (Q signal) of the 8-phase PSK received signal are input from the quadrature detector 1 to the four-phase phase comparator 2, the four-phase phase comparator 2 By multiplying the polarity of the signal on the side different from that signal and subtracting the result of the other from the result of the multiplication, the signal is proportional to the phase value based on the arrangement of signal points used in the four-phase QPSK system. A value to be calculated is calculated, and the value is output as a temporary phase value TPV.
[0047]
Here, the arrangement and phase control range of the signal points of the four-phase QPSK scheme and the arrangement and phase control range of the signal points of the eight-phase PSK scheme used in the first embodiment will be described using actual examples.
[0048]
  As shown in FIG. 3, when the received signal is the signal point T in the first quadrant indicated by (I≈0.87, Q = 0.5) on the IQ orthogonal coordinate axis, the temporary phase value TPV is The phase control direction (polarity) is (+), and the phase region is b1. Since the temporary phase value TPV is an output of the four-phase phase comparator 2, it can be obtained by calculating {I × (Q polarity) −Q × (I polarity)}. The polarity of I and Q is “1” when positive (+),Negative (-)In the case of "-1". Therefore, the output (provisional phase value TPV) of the four-phase phase comparator 2 formed of the modified Costas circuit can be obtained by the following calculation in IQ orthogonal coordinates.
[0049]
TPV is in the first quadrant: TPV = I × (1) −Q × (1) = I−Q
TPV is in the second quadrant: TPV = −I × (1) −Q × (−1) = Q−I
TPV is in the third quadrant: TPV = −I × (−1) − (− Q) × (−1) = I−Q
TPV is in the fourth quadrant: TPV = I × (−1) − (− Q) × (1) = Q−I
[0050]
In the case of FIG. 3, since the signal point T is in the first quadrant, the temporary phase value TPV = 0.87 × 1−0.5 × 1 = 0.37.
When the received signal is a signal point U in the fourth quadrant indicated by (I≈0.87, Q = −0.5) on the IQ orthogonal coordinate axis, the phase control direction (polarity) of the temporary phase value TPV ) Is (-), and the phase region is c4. In this case, the temporary phase value TPV of the signal point U is 0.87 × (−1) − (− 0.5) × 1 = −0.37.
[0051]
In the present embodiment, the phase region to which the signal point belongs is determined by the first phase region determination circuit based on the value of the provisional phase value TPV, and the phase control of the four-phase QPSK method can be used as it is. It is determined whether or not the region requires control in the opposite direction to the phase control of the four-phase QPSK method.
[0052]
Further, the provisional phase value conversion circuit 5 generates a conversion phase value used when control in the opposite direction to the phase control of the four-phase QPSK method is necessary. For example, the temporary phase value conversion circuit 5 generates the conversion phase value in the first quadrant. The signal points are the same in that the control in the opposite direction to the four-phase QPSK phase control is necessary, but the original four-phase QPSK phase control is in the opposite direction. Therefore, it is necessary to obtain the opposite direction for the converted phase value CTPV, the converted phase value CTPV obtained by adding the radius R of the ideal signal point on the IQ orthogonal coordinate axis to the temporary phase value TPV, and the radius of the ideal signal point from the temporary phase value TPV. The converted phase value CTPV obtained by subtracting R is used by selecting the polarity of the signal point from the temporary phase value TPV.
[0053]
FIG. 4 is a diagram showing an example different from FIG. 3 regarding the arrangement of signal points and the phase control range of the 4-phase QPSK system and 8-phase PSK system. In the figure, only the first quadrant is shown on behalf of the first to fourth quadrants.
[0054]
In FIG. 4, the range of arrows indicated by QA1 and QA2 is a phase control range based on the arrangement of the signal point B used in the QPSK system. In the first embodiment, the range of the provisional phase value TPV is Become.
[0055]
The provisional phase value TPV detected by the four-phase phase comparator 2 from the in-phase signal I and the quadrature signal Q is a value that increases as it approaches the I-axis or Q-axis that is a quadrature coordinate axis. Becomes zero.
[0056]
Here, in the 8-phase PSK system, the signal points are arranged at the point A on the I axis and the point C on the Q axis in addition to the point B. , It is necessary to control the phase at point A or point C.
In the present embodiment, the temporary phase value TPV is compared with the first fixed value F1 by the comparison circuit 53, and a point on the orthogonal coordinates of the temporary phase value TPV detected from the received signal exists in the area a1 in FIG. Whether it exists in d1, or exists in region b1 or c1.
[0057]
On the other hand, the provisional phase value conversion circuit 5 discriminates the polarity of the provisional phase value TPV by the third polarity discriminating circuit 31, and from the provisional phase value TPV when the counterclockwise direction is positive in FIG. The second fixed value F2 is subtracted, and if the polarity is negative, the second fixed value F2 is added to the temporary phase value TPV. That is, for the temporary phase value TPV having a positive polarity, the second fixed value F2 is subtracted so that the value becomes zero at the point A, and for the temporary phase value TPV having a negative polarity, the value is obtained at the point C. The second fixed value F2 is added so as to be zero.
[0058]
These subtraction results or addition results are selected by the second selection circuit 35 using the discrimination result of the third polarity discrimination circuit 31 as a control signal and output from the temporary phase value conversion circuit 5. The subtraction result or the addition result is not output as a phase value as it is, but the first selection circuit 6 to be described later includes the region a1 and the region d1 in FIG. Is selected and output only.
[0059]
The first selection circuit 6 outputs a result selected from the temporary phase value TPV and the output of the temporary phase value conversion circuit 5 using the comparison result of the comparison circuit 53 as a control signal (binary). When the provisional phase value TPV is present in the region a1 and the region d1 in FIG. 4, the output of the provisional phase value conversion circuit 5 is selected. When the provisional phase value TPV is present in the region b1 and the region c1 in FIG. TPV is selected.
[0060]
By calculating in this way, for example, the temporary phase value TPV when the signal point P or the signal point S of the received signal exists in the area a1 or d1 as shown in FIG. Is converted into a phase value PV corresponding to the signal point arrangement of the 8-phase PSK method, and the temporary phase value when the signal point Q or the signal point R of the received signal exists in the region b1 or c1 as shown in FIG. Since the TPV corresponds to the signal point arrangement based on the B point common to the 8-phase PSK system and the QPSK system, it is not necessary to convert the temporary phase value TPV. Therefore, the first selection circuit 6 outputs the temporary phase value TPV as it is as the phase value PV by the control signal of the comparison circuit 53. When there are signal points of the received signal in the areas a1 and d1, the first selection circuit 6 selects and outputs the conversion phase value CTPV that is the output of the temporary phase value conversion circuit 5.
[0061]
Specifically, in FIG. 4, when a1 to d1 are each 22.5 ° and sa1 to sd2 are each 11.25 °, the provisional phase value of each signal point output from the four-phase phase comparator 2 The TPV value (I-Q) is as follows.
[0062]
(I−Q) of signal point A = cos 0 ° −sin 0 ° = 1
(IQ) of signal point P = cos 11.25 ° -sin 11.25 ° ≈0.786
(I−Q) of signal point M = cos 22.5 ° −sin 22.5 ° ≈0.541
(I−Q) of signal point Q = cos 33.75 ° −sin 33.75 ° ≈0.275
(IQ) of signal point B = cos 45 ° −sin 45 ° = 0
(I−Q) of signal point R = cos 56.25 ° −sin 56.25 ° ≈−0.275
(I−Q) of signal point N = cos 67.5 ° −sin 67.5 ° ≈−0.541
(I−Q) of signal point S = cos 78.75 ° −sin 78.75 ° ≈−0.786
(I−Q) of signal point C = cos 90 ° −sin 90 ° = −1
[0063]
  Further, the value (conversion phase value CTPV) output from the temporary phase value conversion circuit 5 is:Third polarity discrimination circuit 31When the polarity of (IQ) is detected and the polarity is (+), the value obtained by subtracting the radius of the ideal signal point = 1 in the IQ orthogonal coordinates is selected by the second selection circuit 35, and the polarity is If (−), the value obtained by adding 1 is selected by the second selection circuit 35 and output to the first selection circuit 6. Specifically, the output value for each signal point of the temporary phase value conversion circuit 5 is as follows.
[0064]
Conversion phase value CTPV of signal point A = (I−Q) −1 = 0
Conversion phase value CTPV of signal point P = (I−Q) −1≈−0.214
Conversion phase value CTPV of signal point M = (I−Q) −1≈−0.459
Conversion phase value CTPV of signal point Q = (I−Q) −1≈−0.725
Conversion phase value CTPV of signal point B = (I−Q) ± 1 = ± 1
Conversion phase value CTPV of signal point R = (I−Q) + 1≈0.725
Conversion phase value CTPV of signal point N = (I−Q) + 1≈0.459
Conversion phase value CTPV of signal point S = (I−Q) + 1≈0.214
Conversion phase value CTPV of signal point C = (I−Q) + 1 = 0
[0065]
When control for 8 phases is required, the region a1 is closer to the signal point A than the signal point M and the region d1 is closer to the signal point C than the signal point N. ) Is larger than 0.541. The value of 0.541 is stored as the first fixed value F1 in the first fixed value storage unit 52 in the first phase region determination circuit 3. In the first phase region discriminating circuit 3, the temporary phase value TPV that has become an absolute value by the absolute value calculating circuit 51 and the first fixed value F1 (0.541) are compared by the comparison circuit 53, For example, control signals having different binary values are output to the first selection circuit 6 depending on whether the temporary phase value TPV of the absolute value is larger or smaller than the fixed value F1. The first selection circuit 6 selects the converted phase value CTPV when the absolute temporary phase value TPV is larger than the first fixed value F1, and the absolute temporary phase value TPV is higher than the first fixed value F1. If it is smaller, the temporary phase value TPV is selected, and the selection result is output to the loop filter 7 as the phase value PV.
[0066]
Similarly, in the second quadrant, when the absolute value of (Q−I) is greater than 0.541, in the third quadrant, the absolute value of (I−Q) is greater than 0.541 as in the first quadrant. In the fourth quadrant, as in the second quadrant, when the absolute value of (Q-I) is larger than 0.541, control for eight phases is performed, and the conversion phase value CTPV is selected. The selection result is output to the loop filter 7 as the phase value PV.
[0067]
FIG. 5 is a diagram showing the relationship between the phase angle and the region where the absolute value of the provisional phase value TPV in IQ orthogonal coordinates is larger than the first fixed value F1 (0.541).
In the first quadrant, regions where the absolute value of the temporary phase value TPV is larger than 0.541 are a region ma1 and a region md1. For example, in the 8-phase PSK system, when the amplitude radius of each signal point and the amplitude radius of the ideal signal point are substantially the same, the arc drawn with the radius of the ideal signal point in the region ma1 is the ideal signal point in the region a1. Thus, it can be shown that the absolute value of the temporary phase value TPV is larger than 0.541. If the amplitude radius R of each signal point is different from the amplitude radius R0 of the ideal signal point, the region ma1 may be different from the region a1, but this implementation is performed under a situation where there is not much influence of the amplitude of the received signal. The form is effective.
[0068]
Similarly, the region md1 can also indicate that the absolute value of the provisional phase value TPV is larger than 0.541. Similarly, in the second quadrant areas ma2 and md2, the third quadrant areas ma3 and md3, and the fourth quadrant areas ma4 and md4, the absolute value of the temporary phase value TPV may be larger than 0.541. it can.
[0069]
6 is selected by the output of the four-phase phase comparator 2 (provisional phase value TPV), the output of the temporary phase value conversion circuit 5 (conversion phase value CTPV), and the first selection circuit 6 in the present embodiment. It is a figure which shows the output (phase value PV).
[0070]
Since the temporary phase value TPV output from the four-phase phase comparator 2 is the same as the output of the conventional QPSK, for example, in the first quadrant, the ideal signal from the ideal signal point A (1, 0) on the I axis. The point between points B (cos 45 °, sin 45 °) is (+) polarity, and between ideal signal point C (0, 1) on the Q axis and ideal signal point B (cos 45 °, sin 45 °) Becomes (−) polarity, that is, is drawn to the ideal signal point B.
[0071]
On the other hand, the converted phase value CTPV output from the provisional phase value converting circuit 5 is output in the opposite direction (reverse polarity) to the output of the conventional QPSK. For example, in the first quadrant, on the I axis The signal between the ideal signal point A (1, 0) and the ideal signal point B (cos 45 °, sin 45 °) is (−) polarity, and the ideal signal from the ideal signal point C (0, 1) on the Q axis A point between points B (cos 45 °, sin 45 °) has a (+) polarity, that is, a point between ideal signal point A and ideal signal point B is drawn into ideal signal point A, and ideal signal point C and ideal signal point C are ideal. Things between signal points B are drawn into ideal signal points C.
[0072]
The first selection circuit 6 outputs the temporary phase value TPV output from the four-phase phase comparator 2 and the converted phase value CTPV output from the temporary phase value conversion circuit 5 as 22.5 from the I axis. Switch at an angle of ° and 67.5 ° and output. For example, in the first quadrant, when the signal point of the received signal is a region a1 between 22.5 ° from the I axis, the conversion phase value CTPV is selected. Similarly, when the signal point of the received signal is in the regions b1 and c1, the temporary phase value TPV is selected, and when the signal point of the received signal is in the region d1, the converted phase value CTPV is selected again. The
[0073]
In the second quadrant, similarly, the conversion phase value CTPV is selected in the region a2 and the region d2, and the temporary phase value TPV is selected in the region b2 and the region c2. Similarly, in the third quadrant and the fourth quadrant, the conversion phase value CTPV is selected in the region a3, the region a4, the region d3, and the region d4, and the temporary phase value TPV is selected in the region b3, the region b4, the region c3, and the region c4. Selected.
[0074]
As described above, the 8-phase PSK phase detection apparatus 101 of the phase detection apparatus according to the first embodiment compares the magnitude of the provisional phase value TPV that is the output of the QPSK demodulation 4-phase phase comparator 2. Compared with the first fixed value F1 at the time 53, the temporary phase value is output as TPV as it is depending on the region where the received signal in IQ orthogonal coordinates exists, or the temporary phase value conversion circuit 5 converts the temporary phase value to the temporary phase value TPV. Since whether or not to output the converted phase value CTPV obtained by adding or subtracting F2 is output to the loop filter 7 as the phase value PV, the carrier wave corresponding to the signal point arrangement of the 8-phase PSK system can be obtained with a relatively simple circuit configuration. The phase can be detected.
[0075]
  The four-phase phase comparator 2 according to the present embodiment includes a modified Costas circuit and is used in a conventional phase detector.8 multiplierThe modified Costas circuit is a relatively simple and small-scale circuit when compared to a band-pass filter, an eighth divider, and the like. Also, the first phase region discriminating circuit 3 and the provisional phase value converting circuit 5 are simple and small in scale as compared with the conventional 8-multiplier, band-pass filter, 8-divider, and the like. Therefore, in this embodiment, it is possible to obtain a reference carrier wave for 8-phase PSK that operates with high accuracy and stability using a relatively simple and small circuit configuration.
[0076]
In this embodiment, since the modified Costas circuit is used as described above, in the conventional 8-phase PSK signal carrier recovery device, the received carrier wave is multiplied by 8 and divided by 8 to obtain a reference carrier wave. Therefore, even if the received wave contains noise components or fluctuation components due to the effects of fading, those noise components and fluctuation components that could not be suppressed by the bandpass filter are used as a reference. No carrier wave remains, and a highly accurate reference carrier wave can be obtained.
[0077]
Further, in this embodiment, since the accuracy of the reference carrier is improved as described above, a phase slip occurs in which the phase of the recovered carrier is drawn to the wrong phase when the reception channel quality is poor (low C / N). It becomes difficult and operational stability can be improved.
[0078]
Embodiment 2. FIG.
In the first embodiment described above, the phase region where the signal point exists is determined based on whether or not the absolute value of the temporary phase value TPV is larger than the first fixed value F1 (0.54). When the amplitude radius R of the signal point is different from the amplitude radius R0 of the ideal signal point, that is, in a situation where the influence of the amplitude of the received signal is large, the region ma1 is different from the region a1, and the region may not be accurately identified. Conceivable. Therefore, in the second embodiment, the phase region where the signal point exists is discriminated by the ratio of the I signal and the Q signal, so that the region is accurately discriminated even under a situation where the influence of the amplitude of the received signal is large, and the discrimination result Is used to select the temporary phase value TPV and the converted phase value CTPV.
[0079]
FIG. 7 is a block diagram showing the configuration of the phase detection apparatus 102 according to the second embodiment of the present invention. In FIG. 7, parts having the same functions as those of the phase detection apparatus 101 of the first embodiment shown in FIG. FIG. 8 is a diagram showing the phase value of the phase detection device of FIG. 7 on the IQ orthogonal coordinate axis.
[0080]
The phase detection apparatus 102 for obtaining the 8-phase PSK reference carrier wave of FIG. 7 is mainly different from the phase detection apparatus 101 of the first embodiment shown in FIG. The ratio of the Q signal to the signal (Q / I) is calculated, and the second phase region discriminating circuit 10 discriminates the region where the signal point on the IQ orthogonal coordinate axis exists from the ratio (Q / I), and outputs the control signal. It is a point which outputs and controls the 1st selection circuit 6. FIG. Other configurations are the same as those of the first embodiment. The second phase region discriminating circuit 10 is a circuit that outputs, for example, a binary control signal by comparing the input value with a predetermined value in the same manner as the first phase region discriminating circuit 3. Since the value is Q / I, the predetermined value is also different from that of the first embodiment. The predetermined value used in this embodiment will be described later.
[0081]
In the present embodiment, for example, regions a1, b1, c1, and d1 divided every 22.5 ° are set in advance for a region where signal points in the first quadrant exist, and the ratio (Q / In step I), it is determined to which region the signal point of the received signal belongs.
[0082]
Hereinafter, the operation of the phase detection apparatus according to the second embodiment will be described.
The temporary phase value TPV, which is the output of the four-phase phase comparator 2, is converted into the converted phase value CTPV by the temporary phase value conversion circuit 5, and is selected from the temporary phase value TPV and the converted phase value CTPV by the first selection circuit 6. The operation until the obtained value is output as the phase value PV is the same as that of the first embodiment. In the present embodiment, the control signal generation method for controlling the first selection circuit 6 is different from the first embodiment, and the second phase region discrimination circuit 10 generates the control signal based on the above ratio (Q / I). To do.
[0083]
  Q / I division circuit 9Calculates the value of the ratio of the I and Q signals. The second phase region discriminating circuit 10 uses this ratio (Q / I) to discriminate which one of a1 to d1 is a region where the received signal exists. Specifically, since the ratio of the I signal to the Q signal (Q / I) is used, for example, the signal areas in the first quadrant are areas a1, b1, c1, d1 as shown in FIG. The region is divided as follows according to the value of / I.
[0084]
Area a1: 0 <Q / I <sin 22.5 ° / cos 22.5 ° ≈0.414
Area b1: sin22.5 ° / cos22.5 ° ≈0.414 <Q / I <sin45 ° / cos45 ° = 1
Region c1: sin45 ° / cos45 ° = 1 <Q / I <sin67.5 ° / cos67.5 ° ≈2.414
Area d1: sin67.5 ° / cos67.5 ° ≈2.414 <Q / I <∞
The above values 0.414, 1, and 2.414 are used by the second phase region discriminating circuit 10 to discriminate the region.
[0085]
For example, if the signal point of the received signal in FIG. 8 is T, the ratio (Q / I) is 0.5 / 0.87 = 0.575, which is in the range of 0.414 <Q / I <1. Since it is a value, it is understood that the signal point of the received signal exists in the region b1.
[0086]
Then, as in the first embodiment, when there is a signal in the regions b1 and c1, it is not necessary to convert the provisional phase value TPV, so the first selection circuit 6 controls the second phase region determination circuit 10. The temporary phase value TPV is output as it is based on the signal. On the other hand, when a signal exists in the region a1 or d1, the first selection circuit 6 selects and outputs the conversion phase value CTPV output from the temporary phase value conversion circuit 5.
[0087]
As described above, the phase detection apparatus 102 for obtaining the 8-phase PSK reference carrier wave according to the second embodiment divides and sets the regions a1, b1, c1, d1, etc. where the signals exist according to the angles. The Q / I division circuit 9 calculates the ratio of the I signal and the Q signal, and the second phase region discrimination circuit 10 discriminates the region where the signal point exists from the ratio to control the first selection circuit 6. Since it is configured, it is possible to accurately determine a region even under a situation where the influence of the amplitude of the received signal is large, and to suppress the influence of the amplitude of the received signal as compared with the first embodiment, so that the operation can be stabilized. .
[0088]
Embodiment 3 FIG.
  FIG. 9 is a block diagram showing a configuration of the phase detection device 103 according to the third embodiment of the present invention. In FIG. 9, parts having the same functions as those of the phase detection apparatus according to the second embodiment shown in FIG.Also,FIG. 10 is a diagram showing the phase value of the phase detection device of FIG. 9 on the IQ orthogonal coordinate axes.
[0089]
The phase detection apparatus 103 for obtaining the 8-phase PSK reference carrier wave in FIG. 9 is mainly different from the phase detection apparatus 102 in the second embodiment shown in FIG. Instead of the Q / I dividing circuit 9 for calculating the ratio (Q / I) of the Q signal, the signal point angle discriminating circuit 11 calculates the signal point angle θ1 from the I signal and the Q signal, and the third phase region discriminating circuit 12 Thus, the region where the signal point on the IQ orthogonal coordinate axis exists is determined from the angle θ1, the control signal is output, and the first selection circuit 6 is controlled. Other configurations are the same as those of the second embodiment.
[0090]
  Third phase region discrimination circuit 12IsSecond phase region discrimination circuit 10In this embodiment, for example, a binary control signal is output by comparing the input value with a predetermined value. However, in this embodiment, the input value becomes the angle θ1 of the signal point. Unlike the first and second embodiments, the angles are different. The predetermined value used in this embodiment will be described later.
[0091]
Also in the third embodiment, for example, areas a1, b1, c1, and d1 divided every 22.5 ° are set in advance, and the signal point of the received signal is set to any area depending on the angle θ1 of the signal point described above. To belong to.
[0092]
Further, the method of detecting the angle of the signal point in the third embodiment is based on the arc tangent (TAN^{− 1}) Is detected to detect the angle θ1. Arc Tangent (TAN^{− 1}) May be read (detected) from the angle θ1 corresponding to the I and Q signals stored in the read-only memory (ROM). By determining whether the detected angle θ1 is one of the above-described regions a1, b1, c1, and d1, a selection is made from the temporary phase value TPV and the converted phase value CTPV.
[0093]
Hereinafter, the operation of the phase detection device 103 according to the third embodiment will be described.
The temporary phase value TPV, which is the output of the four-phase phase comparator 2, is converted into the converted phase value CTPV by the temporary phase value conversion circuit 5, and is selected from the temporary phase value TPV and the converted phase value CTPV by the first selection circuit 6. The operation until the obtained value is output as the phase value PV is the same as in the first embodiment. In the present embodiment, the method for generating the control signal for controlling the first selection circuit 6 is different from that in the first embodiment. As described above, the arc tangent (TAN) is obtained from the I signal and the Q signal.^{− 1}The third phase region discriminating circuit 12 generates a control signal using the angle θ1 obtained by calculating
[0094]
(TAN^{− 1} ROM) and the like signal point angle discriminating circuit 11 detects the angle θ1 of the signal point from the I signal and Q signal, and the third phase region discriminating circuit 12 determines the region where the signal point of the received signal exists from the angle θ1 It is determined which of the areas a1, b1, c1, and d1. Specifically, since the angle θ1 of the signal point of the received signal is used, for example, as shown in FIG. 10, the signal area in the first quadrant is an area a1, b1, The same angle as c1 and d1 is a predetermined value, and the region is divided as follows according to the angle.
[0095]
θ1 = TAN^{− 1}(Q / I)
Area a1: 0 <θ1 <22.5 °
Region b1: 22.5 ° <θ1 <45 °
Area c1: 45 ° <θ1 <67.5 °
Region d1: 67.5 ° <θ1 <90 °
[0096]
In the case of the first quadrant, the above values 22.5 °, 45 °, 67.5 °, and 90 ° are used by the third phase region determination circuit 12 to determine the region.
[0097]
For example, if the signal point of the received signal is T in FIG.^{− 1}Since (0.5 / 0.87) = 30 °, which is a value in the range of 22.5 ° <θ1 <45 °, it can be seen that the signal point of the received signal exists in the region b1.
[0098]
Then, as in the first embodiment, when there is a signal in the regions b1 and c1, it is not necessary to convert the temporary phase value TPV, so the first selection circuit 6 controls the third phase region determination circuit 12. The temporary phase value TPV is output as it is based on the signal. On the other hand, when a signal exists in the region a1 or d1, the first selection circuit 6 selects and outputs the conversion phase value CTPV output from the temporary phase value conversion circuit 5.
[0099]
  As described above, the phase detection apparatus 103 for obtaining the 8-phase PSK reference carrier wave according to the third embodiment divides the regions a1, b1, c1, d1, etc. where the signal points of the received signal exist by the angle. TAN^{− 1} The signal point angle discriminating circuit 11 such as a ROM detects the angle θ1 of the signal point of the received signal, and the third phase region discriminating circuit 12 discriminates the region where the signal point exists from the angle θ1, and the first selection circuit 6 Since the region where the signal point of the received signal exists can be divided according to the angle, the region can be accurately identified even under a situation where the influence of the amplitude of the received signal is large.Influence of amplitudeBy suppressing this, it is possible to operate more stably than in the first embodiment, and it is possible to make the circuit configuration simpler than in the second embodiment including the Q / I division circuit 9.
[0100]
Embodiment 4 FIG.
  FIG. 11 is a diagram showing ideal signal points of eight phases on the phase plane in an arrangement different from that in FIG. 1 for explaining the fourth embodiment of the present invention. The four-phase ideal signal points are arranged in the middle of any adjacent eight-phase ideal signal points. Specifically, in the first quadrant of the IQ orthogonal coordinate axis, the 4-phase ideal signal point K is arranged at an angle of 45 ° with the I-axis as in FIG. 1, but the 8-phase ideal signal point J is Arranged at an angle of 22.5 ° with the I axis,Ideal signal point LIs arranged at an angle of 67.5 ° with the I axis.
[0101]
The received signal of the four-phase modulation in the first quadrant is phase-controlled in the same manner as in the first to third embodiments and is drawn into the ideal signal point K. Assuming that the 8-phase received signal remains as shown in FIG. 11, the received signal in which the signal point is detected in the region a1 and the region b1 is drawn into the 8-phase ideal signal point J, and the region c1 and the region d1. The received signal from which the signal point is detected needs to be drawn into the eight-phase ideal signal point L. However, when a four-phase phase comparator is used, it is drawn into the four-phase ideal signal point K. .
[0102]
Therefore, unlike the first to third embodiments described above, the phase detection device according to the present embodiment does not convert the output of the four-phase phase comparator, but the common-mode signal I input to the four-phase phase comparator. 8 phase ideal signal points by discriminating the phase region from the quadrature signal Q in advance and performing phase rotation at a fixed angle with respect to the in-phase signal I and quadrature signal Q and inputting them to the four-phase phase comparator. Are matched with the 4-phase ideal signal points to detect the 8-phase phase value. Note that the above fixed angle means that the IQ orthogonal coordinate axes are rotated so that the 8-phase ideal signal points covering the phase region where the signal points of the received signal are detected overlap the arrangement of the 4-phase ideal signal points. Is an angle.
[0103]
FIG. 12 is a block diagram showing the configuration of the phase detection device 104 according to the fourth embodiment of the present invention. 13 and 14 are diagrams showing the phase values of the phase detection device 104 of FIG. 12 on the IQ orthogonal coordinate axes.
[0104]
The phase detector 104 for obtaining the 8-phase PSK reference carrier wave in FIG. 12 is mainly different from the phase detector 103 in the third embodiment shown in FIG. The complex multiplier 13 that rotates the in-phase signal I and the quadrature signal Q is provided in the previous stage of the comparator 2, and the temporary phase value conversion circuit 5 and the first selection circuit 6 in the subsequent stage of the 4-phase phase comparator 2. Therefore, the third phase region discriminating circuit 12 that outputs the control signal to the first selection circuit 6 and the signal point angle discriminating circuit 11 are also eliminated, and sine waves and cos waves are generated for the complex multiplier 13. The numerically controlled oscillator 15 is provided, and the numerically controlled oscillator 15 is provided with a fourth phase region discriminating circuit 14 that outputs a control signal that discriminates the phase region of the received signal. Other configurations are the same as those of the third embodiment.
[0105]
In the present embodiment, the output of the four-phase phase comparator 2 is directly input to the loop filter 7 as the phase value PV instead of the provisional phase value TPV because there is no subsequent circuit.
[0106]
The complex multiplier 13 includes three to sixth multipliers 41 to 44, a third subtractor 45, and a second adder 46. The third multiplier 41 receives the in-phase signal I and the cos wave from the numerically controlled oscillator 15 and outputs a multiplication result. The fourth multiplier 42 receives the quadrature signal Q and the cos wave from the numerically controlled oscillator 15 and outputs a multiplication result. The fifth multiplier 43 receives the in-phase signal I and the sin wave from the numerically controlled oscillator 15 and outputs a multiplication result. The sixth multiplier 44 receives the quadrature signal Q and the sin wave from the numerically controlled oscillator 15 and outputs a multiplication result.
[0107]
The third subtracter 45 subtracts the output of the sixth multiplier 44 from the output of the third multiplier 41 and outputs it as a rotation in-phase signal I ′. The second adder 46 outputs the output of the fourth multiplier 42. And the output of the fifth multiplier 43 are added and output as a rotation orthogonal signal Q ′.
[0108]
Hereinafter, the operation of the phase detection device 104 according to the fourth embodiment will be described.
For example, the fourth phase region discriminating circuit 14 discriminates the phase region of the received signal in the same manner as the third phase region discriminating circuit 12 of the third embodiment, but the input signal is an in-phase signal (I signal) and a quadrature signal ( Q signal), the determination method is different from that of the third embodiment. For example, as in the second embodiment, the region where the received signal exists is determined by comparing the magnitudes in consideration of the polarities of the I signal and the Q signal. The regions to be determined are the region a1 and the region in FIG. It is only necessary to determine whether the region is a region (a1 + b1) to which b1 is added or a region (c1 + d1) to which the region c1 and the region d1 are added.
[0109]
When the received signal exists in the area (a1 + b1), the fourth phase area determination circuit 8 outputs a fixed value of 22.5 degrees. Then, a fixed value of cos (22.5 °) and sin (22.5 °) is output from the numerically controlled oscillator 15. On the other hand, when the received signal exists in the region (c1 + d1), the fourth phase region determination circuit 8 outputs a fixed value of −22.5 degrees. Then, fixed values of cos (−22.5 °) and sin (−22.5 °) are output from the numerically controlled oscillator 15.
[0110]
When the received signal exists in the region (a1 + b1), the complex multiplier 13 performs +22.5 degree fixed phase rotation on the in-phase signal (I signal) and the quadrature signal (Q signal). If it exists in the region (c1 + d1), a fixed phase rotation of −22.5 degrees is performed.
[0111]
FIG. 13 is a diagram illustrating IQ orthogonal coordinate axes when +22.5 degrees fixed phase rotation is performed on the I signal and the Q signal.
The 8-phase ideal signal point J shown in FIG. 11 is subjected to a fixed phase rotation of +22.5 degrees. As a result, the signal point arrangement of the ideal signal point J output from the complex multiplier 13 is a 4-phase ideal signal. It coincides with point K. The rotation in-phase signal I ′ and the rotation quadrature signal Q ′ output from the complex multiplier 13 are input to the four-phase comparator 2, and the 8-phase reference carrier wave when the received signal exists in the region (a1 + b1). Are detected.
[0112]
FIG. 14 is a diagram illustrating IQ orthogonal coordinate axes when a fixed phase rotation of −22.5 degrees is performed on the I signal and the Q signal.
The ideal signal point L of 8 phases shown in FIG. 11 is subjected to a fixed phase rotation of −22.5 degrees. As a result, the signal point arrangement of the ideal signal point L output from the complex multiplier 13 is the ideal signal point of 4 phases. Matches K. The rotation in-phase signal I ′ and the rotation quadrature signal Q ′ output from the complex multiplier 13 are input to the four-phase comparator 2, and the 8-phase reference carrier wave when the received signal exists in the region (c1 + d1). Are detected.
[0113]
Although the above description has been given only for the first quadrant, the phase of the 8-phase reference carrier can be detected in the same manner for the second to fourth quadrants.
[0114]
As described above, the phase detection apparatus 104 for obtaining the 8-phase PSK reference carrier wave according to the fourth embodiment discriminates the area where the received signal exists by the fourth phase area discriminating circuit 14, and Correspondingly, the complex multiplier 13 applies a fixed phase rotation of +22.5 degrees or −22.5 degrees to the received signal, converts the signal point arrangement of the 8-phase PSK system into the signal point arrangement of the QPSK system, and uses for QPSK. Since the 4-phase phase comparator 2 is configured to be used as it is, the phase of the carrier wave corresponding to the 8-phase PSK signal point arrangement can be detected with a relatively simple circuit configuration as in the first embodiment. Can do.
[0115]
Further, since the four-phase phase comparator 2 is composed of a modified Costas circuit, it is possible to obtain a reference carrier for 8-phase PSK that operates with high accuracy and stability using a relatively simple and small circuit configuration. Therefore, the noise component and the fluctuation component do not remain in the reference carrier as they are, and a highly accurate reference carrier can be obtained.
[0116]
Further, in the first embodiment, the second embodiment, and the third embodiment, since there are eight phase stable points, it is easy to cause a slip to an adjacent phase stable point at low C / N. In the fourth embodiment, since there are four phase stable points, the operational stability can be improved.
[0117]
Each of the above embodiments is applied to a phase detector for generating a reference carrier wave when demodulating an 8-phase PSK modulated wave. For example, a demodulator such as a digital television receiver is used. You may incorporate in the one part circuit of a part.
[0118]
Further, the types of various circuits constituting the phase detection device, the connection state, the types of main signal units connected to the phase detection device, the control method, and the like are not limited to the above-described embodiments.
[0119]
【The invention's effect】
According to the first to fifth aspects of the present invention, the magnitude of the temporary phase value by the four-phase phase comparator for QPSK demodulation is compared with a fixed value, thereby determining the area where the received signal exists, and the temporary area value is determined according to the area. Since it is selected whether to output the phase value as it is, or to output a value obtained by adding or subtracting a fixed value to the provisional phase value, the carrier wave phase detector corresponding to the 8-phase PSK signal point arrangement is configured. There is an effect that the phase of the reference carrier wave corresponding to the signal point arrangement of the 8-phase PSK system can be detected with a simple and small circuit configuration.
Furthermore, even when the received line quality is poor (low C / N) such that the received wave includes a noise component or a fluctuation component due to the influence of fading or the like, the noise component and the fluctuation component are directly used as a reference. Since the reference carrier wave that does not remain in the carrier wave and that operates with high accuracy and stability can be obtained, the phase slip of the reproduced reference carrier wave is less likely to occur in the wrong phase, and the reception operation is stable. It has the effect that can be improved.
[0120]
Further, in the present invention of claim 6, since the ratio of the I signal and the Q signal is calculated and the region where the received signal exists is determined from the ratio, in addition to the above effect, the presence of the received signal Area can be divided according to the angle, and even under the situation where the influence of the amplitude of the received signal is large, the area can be accurately identified and the influence of the amplitude of the received signal can be suppressed, so that the operation is stabilized. Has the effect of being able to.
[0121]
  In the present invention of claim 7, the region where the signal point of the received signal exists is set by dividing by the angle, and the TAN is obtained from the I signal and the Q signal.^{− 1}In addition to the above effects, the signal point of the received signal exists with a simple circuit configuration. Area can be divided according to the angle, and the area can be accurately determined even under the influence of the amplitude of the received signalInfluence of amplitudeIt has the effect that it can be made to operate stably by suppressing.
[0122]
According to the eighth to eleventh aspects of the present invention, a region where a received signal exists is determined, a fixed phase rotation is given to the received signal in correspondence with the region, and the signal point arrangement of the 8-phase PSK system is changed to the signal point of the QPSK system. Since the four-phase phase comparator for QPSK can be used by converting to the arrangement, the phase stable point is reduced from 8 points to 4 points. In addition to the effects of claims 1 to 5, low C / Even at N o'clock, it is difficult to cause slip to the adjacent phase stabilization point, and the operational stability can be improved.
[Brief description of the drawings]
FIG. 1 is a diagram showing ideal signal points of 4 phases and 8 phases on a phase plane for explaining the present invention.
FIG. 2 is a block diagram showing a configuration of an 8-phase PSK phase detection apparatus according to Embodiment 1 of the present invention.
FIG. 3 is a diagram showing an example of phase values detected by the 8-phase PSK phase detection device of FIG. 2 on IQ orthogonal coordinate axes.
FIG. 4 is a diagram showing examples of various phase values in the first quadrant of IQ orthogonal coordinate axes.
FIG. 5 is a diagram showing a relationship between a region where an absolute value of a temporary phase value in IQ orthogonal coordinates is larger than a fixed value and a phase angle.
FIG. 6 is a diagram illustrating an output selected by a selection circuit and an output of a four-phase phase comparator, an output of a provisional phase value conversion circuit, and the like in the present embodiment;
FIG. 7 is a block diagram showing a configuration of a phase detection device according to a second embodiment of the present invention.
8 is a diagram showing phase values of the phase detection device of FIG. 7 on IQ orthogonal coordinate axes.
FIG. 9 is a block diagram showing a configuration of a phase detection device according to a third embodiment of the present invention.
10 is a diagram showing phase values of the phase detection device of FIG. 9 on IQ orthogonal coordinate axes.
FIG. 11 is a diagram showing ideal signal points of 8 phases on a phase plane in an arrangement different from that in FIG. 1 for the explanation of Embodiment 4 of the present invention.
FIG. 12 is a block diagram showing a configuration of a phase detection device according to a fourth embodiment of the present invention.
13 is a diagram illustrating one state of the phase value of the phase detection device of FIG. 12 on an IQ orthogonal coordinate axis.
14 is a diagram showing a state different from that of FIG. 13 of the phase value of the phase detection device of FIG. 12 on an IQ orthogonal coordinate axis.
FIG. 15 is a block diagram showing a configuration in which a reproduction carrier wave is obtained by demodulating a phase shift keying reception signal using a frequency multiplication method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Quadrature detector, 2 4-phase phase comparator, 3 1st phase area discrimination circuit, 5 Temporary phase value conversion circuit, 6 1st selection circuit, 7 Loop filter, 8 Numerically controlled oscillator, 21 1st polarity discrimination circuit, 22 2nd polarity discriminating circuit, 23 1st multiplier, 24 2nd multiplier, 25 1st subtractor, 31 3rd polarity discriminating circuit, 32 2nd fixed value memory | storage part, 33 1st adder, 34 2nd subtractor , 35 second selection circuit, 51 absolute value calculation circuit, 52 first fixed value storage unit, 53 comparison circuit, 101 phase detector, I in-phase signal, Q quadrature signal, TPV temporary phase value, CTPV conversion phase value, PV Phase value, RC received signal.

Claims (11)

A phase detection device for reproducing a reference carrier wave used for synchronous detection and demodulation of a digital signal phase-modulated by an 8-phase modulation (8-phase PSK) method,
A four-phase phase comparator that outputs a reference carrier for a quadrature phase shift keying (QPSK) system as a temporary phase value from an in-phase (I) signal and a quadrature (Q) signal of the received signal;
A value obtained by adding the absolute value of an ideal signal point in the 8-phase modulation method used for transmission / reception to the temporary phase value is calculated, and a value obtained by subtracting the absolute value from the temporary phase value is also calculated. The counterclockwise direction in is set as a positive direction, and the polarity is determined from the provisional phase value. When the polarity is positive, the added value is output, and when the polarity is negative, the subtracted value is output. A temporary phase value conversion circuit that outputs a converted phase value;
Based on the in-phase signal and the quadrature signal input to the four-phase phase comparator, or the provisional phase value output from the four-phase phase comparator, the presence area of the received signal point on the phase plane is determined, A phase region discrimination circuit that outputs a region signal indicating the presence region;
A phase detection device comprising: a selection circuit that switches and outputs the temporary phase value and the converted phase value based on the region signal.   The phase detection device according to claim 1, wherein the phase region determination circuit determines a region for each angle that bisects an angle between adjacent ideal signal points on a phase plane of an eight-phase modulation system. . The selection circuit, the phase region domain signal is discriminated by discriminating circuit, four-phase modulation scheme and 8-phase when a signal indicative of the region closer to a common ideal signal point in a modulation scheme the temporary select the phase value, the phase detector of claim 2 for a signal indicative of the region closer to the ideal signal points of only eight-phase modulation method, characterized by selecting the conversion phase value apparatus. When the selection signal indicates that the region signal determined by the phase region determination circuit indicates that the polarity of the phase control direction of the four-phase modulation method is the same as the polarity of the phase control direction of the eight-phase modulation method, The provisional phase value is selected, and when the polarity of the phase control direction of the four-phase modulation method and the polarity of the phase control direction of the eight-phase modulation method are reversed, the conversion phase value is selected. The phase detection device according to claim 2.   The phase region discriminating circuit has a comparison circuit that compares a temporary phase value output from the four-phase phase comparator with a predetermined value, and discriminates an existing region of a reception signal point based on a comparison result of the circuit. The phase detection device according to claim 1.   The phase region discrimination circuit has a division circuit for obtaining a ratio between the values of the in-phase signal and the quadrature signal input to the four-phase phase comparator, and discriminates the existence region of the reception signal point based on the division result of the circuit. The phase detection device according to any one of claims 1 to 4. The phase region discriminating circuit has a signal point angle discriminating circuit for obtaining arc tangent values of the in-phase signal and the quadrature signal to be input to the four-phase phase comparator, and a reception signal point existing region is calculated based on the calculation result of the circuit The phase detection device according to claim 1, wherein: A phase detection device for reproducing a reference carrier wave used for synchronous detection and demodulation of a digital signal phase-modulated by an 8-phase modulation method,
A phase region discriminating circuit that discriminates an existence region of a reception signal point on a phase plane from an in-phase signal and a quadrature signal of the reception signal, and outputs a region signal indicating the existence region of the reception signal point;
A numerically controlled oscillator that generates a sine wave and a cosine wave at different fixed angles for each region based on the region signal;
The product of the fixed angle sine wave with respect to the in-phase signal and the quadrature signal and the product of the fixed angle cosine wave with respect to the in-phase signal and the quadrature signal, by adding the products whose phases are orthogonal to each other, A complex multiplier for outputting a phase rotation to the in-phase signal and the quadrature signal;
A four-phase phase comparator that outputs a phase value for a carrier wave of a four-phase modulation scheme with respect to an in-phase signal and a quadrature signal to which a phase rotation is output from the complex multiplier ;
A phase detector.   The said phase area | region discrimination circuit discriminate | determines the area | region of a received signal for every angle which divides the angle between the adjacent ideal signal points on the phase plane of an 8-phase modulation system into two equal parts. Phase detector. The phase region discriminating circuit adds the region of the received signal to each angle that divides the angle between adjacent ideal signal points on the phase plane of the eight-phase modulation scheme into two equal parts, and is adjacent to the phase plane of the four-phase modulation scheme. The angle between matching ideal signal points is also determined for each angle that is divided into two equal parts,
In the complex multiplier, the ideal signal point of the 8-phase modulation system closest to the domain signal detected by the phase domain discrimination circuit overlaps the ideal signal point of the 4-phase system closest to the ideal signal point of the 8-phase system. The phase detection apparatus according to claim 9, wherein phase rotation is applied to the in-phase signal and the quadrature signal. The phase region determination circuit sets the counterclockwise direction of the phase plane as a positive direction, determines the polarity of the phase control direction for each region of the reception signal of the four-phase modulation method,
In the complex multiplier, when the polarity is positive, the ideal signal point of the 8-phase modulation system in the region overlaps with the ideal signal point of the 4-phase system closest to the ideal signal point of the 8-phase system. The phase detection apparatus according to claim 9, wherein phase rotation is applied to the in-phase signal and the quadrature signal.

Images