JP2016010034A - Angle detection device and angle detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angle detection device which reduces circuit scale and is capable of performing high-speed operation.SOLUTION: An angle detection device 10 includes: a conversion section 100 for calculating a sine value (sinθ) and a cosine value (cosθ) corresponding to a phase angle θ of an inputted baseband signal; a comparison section 110 which outputs a result of comparing magnitudes of an absolute value of the sine wave and a predetermined fixed value; a ROM 130 which outputs an inverse sine value θ(in) to the inputted value; and a multiplexer 120 which outputs an absolute value of the sine value, a code of the sine value and a code of the cosine value and further outputs not-greater one of the absolute value of the sine value and the absolute value of the cosine value to the ROM on the basis of a comparison result. On the basis of the absolute value of the sine value, the code of the sine value and the code of the cosine value, the inverse sine value θ(in) inputted from the ROM is converted into a phase angle θ(out) within a range of -π≤θ(out)≤π and outputted. By making one of input of the comparison section 110 into the predetermined fixed value, a circuit scale is reduced and high-speed operation can be performed.

Description

  The present invention relates to an angle detection device and an angle detection method, and more particularly to an angle detection device and an angle detection method for obtaining a phase angle of an input signal.

  In digital communication using the quadrature modulation method, the baseband signal after demodulation is subjected to phase compensation processing such as compensation of carrier frequency difference and phase difference between transmitters and receivers, and compensation of carrier frequency deviation by Doppler shift. Applied. When the amplitude of the baseband signal is expressed in the orthogonal format x + ji (j is a complex unit), the calculation for directly obtaining the phase angle of the baseband signal from the orthogonal format is complicated. For this reason, it is difficult to mount a circuit that performs phase compensation by directly processing an orthogonal signal in a receiver.

  In order to alleviate such difficulties, a technique is known in which the representation of a signal is converted from an orthogonal format to a phase format, and a phase angle is obtained from the signal expressed in the phase format using an inverse trigonometric function. Inverse trigonometric functions for obtaining the phase angle include arc sine (inverse sine), arc cosine (inverse cosine), and arc tangent (inverse tangent).

  In relation to the present invention, Patent Document 1 describes a phase discriminator that performs phase correction by calculating an arc sine. FIG. 9 is a block diagram showing the configuration of the phase discriminator described in Patent Document 1 and related to the present invention. An input signal input from the input terminal 480 is converted into a digital signal by an A / D (analog-digital converter) 450, and a 90 degree phase shifter 460 adds a sine component signal to a cosine signal. Component signals are generated. The amplitudes of the sine component signal and the cosine component signal are normalized by the level detector 400 and the multipliers 401 and 402. The two normalized amplitudes are compared by a comparison circuit (MIN) 410, and based on the value of the smaller signal of the sine component and the cosine component and a table held in the ROM 430, a 90 degree corrector 440 and a differentiator 470. Is used to calculate the phase angle. The calculated phase angle is output from the output terminal 490.

Japanese Patent Laid-Open No. 05-276201 (paragraph [0010])

  In the phase discriminator described in FIG. 9, the comparison circuit 410 compares the sine value (sine value) and cosine value (cosine value) of the input signal. The comparison circuit 410 needs to compare the sine component and the cosine component of the input signal that have different values for each comparison.

  On the other hand, when the comparison circuit 410 is configured by hardware of a digital circuit, a look-up table (LUT) that covers combinations of numerical values (signal amplitudes) to be compared is required. However, in order to compare two variable variables, a large-scale lookup table is required. For this reason, in the configuration for comparing the sine value and the cosine value, there is a problem that the configuration of the comparison circuit is complicated, and the operation frequency of the comparison circuit is difficult to improve due to the complexity of the circuit.

(Object of invention)
An object of the present invention is to provide an angle detection device that has a small circuit scale and can operate at high speed.

  The angle detection device of the present invention includes a conversion means for obtaining a sine value (sinθ) and a cosine value (cosθ) corresponding to the phase angle θ of an input baseband signal, an absolute value of the sine value, and a predetermined fixed value. A comparison means for outputting a comparison result of the magnitude of the signal, a ROM (read only memory) for outputting an inverse sine value θ (in) for the input value, an absolute value of the sine value, a sign of the sine value A multiplexer that outputs a sign of the cosine value, and further outputs, based on the comparison result, an absolute value of the sine value and an absolute value of the cosine value that is not larger to the ROM; and the sine Based on the absolute value of the value, the sign of the sine value, and the sign of the cosine value, the inverse sine value θ (in) input from the ROM is a phase in a range of −π ≦ θ (out) ≦ π. Data processing means for converting to an angle θ (out) and outputting.

  The angle detection method of the present invention obtains a sine value (sinθ) and a cosine value (cosθ) corresponding to the phase angle θ of an input baseband signal, and calculates the magnitude of the absolute value of the sine value and a predetermined fixed value. The comparison result is output, and based on the comparison result, the lesser of the absolute value of the sine value and the absolute value of the cosine value is selected, and the selected absolute value of the sine value or The inverse sine value θ (in) corresponding to the absolute value of the cosine value is obtained, and the inverse sine value θ (in) is calculated based on the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value. The phase angle θ (out) in the range of −π ≦ θ (out) ≦ π is converted and output.

  The angle detection device of the present invention has an effect that the circuit scale is small and high-speed operation is possible.

It is a block diagram which shows the structure of the angle detection apparatus of 1st Embodiment. It is a flowchart which shows the operation | movement procedure of the angle detection apparatus of 1st Embodiment. It is a block diagram which shows the structure of the angle detection apparatus of 2nd Embodiment. It is a block diagram which shows the structure of the AND part of 2nd Embodiment. It is a figure which shows the truth table of an AND part. It is a flowchart which shows the operation | movement procedure of the angle detection apparatus of 2nd Embodiment. It is a graph which shows the relationship between a sine value and a cosine value. It is a graph which shows the relationship between the sine value and cosine value in 2nd Embodiment. It is a block diagram which shows the structure of the phase discriminator relevant to this invention.

(Outline of the embodiment)
FIG. 7 is a diagram showing the relationship between sin θ and cos θ for a certain angle θ (0 ≦ θ ≦ π / 2). When cos θ = sin θ, θ = π / 4 (rad), and the value of cos θ is 1/2 of the square root of 2 (≈0.707). In FIG. 7 and the embodiment of the present specification, the value of cosθ when cosθ = sinθ is described as 0.707.

  Referring to FIG. 7, cos θ> sin θ is satisfied in the range of 0 ≦ sin θ <0.707, and cos θ <sin θ is satisfied in the range of 0.707 <sin θ ≦ 1. Therefore, the magnitude relationship between sin θ and cos θ can be compared by comparing sin θ and a fixed value instead of comparing sin θ and cos θ at the angle θ.

  In the first embodiment, a configuration of an angle detection device including a configuration for comparing the value of cos θ (0.707) where sin θ = cos θ and the absolute value of sin θ will be described.

  In the second embodiment, an angle detection device having a configuration in which the value of sin θ is the upper 3 bits of fixed-point representation and the magnitude relationship between sin θ and 0.75 is evaluated will be described. In the second embodiment, it is always used that cos θ <sin θ when sin θ is 0.75 or more. In the second embodiment, a logical operation is performed on a bit indicating 0.5 and a bit indicating 0.25 in the data indicating the value of sin θ, and the magnitude relationship between sin θ and cos θ is determined based on the logical operation result.

  In the third embodiment, an angle detection device having the same effect as the angle detection device of the first embodiment will be described.

(First embodiment)
(Description of configuration)
The angle detection apparatus according to the first embodiment of the present invention is applied to, for example, a frequency offset detection circuit in digital baseband processing. FIG. 1 is a block diagram showing a configuration of an angle detection apparatus 10 according to the first embodiment of the present invention. The angle detection apparatus 10 includes a conversion unit 100, a comparison unit 110, a multiplexer 120, a ROM (read only memory) 130, and a data processing unit 140.

  The conversion unit 100 includes a power calculation unit 101 that calculates the power of an input signal, a norm calculation unit 102 that calculates the reciprocal of the norm based on the calculated power, and a trigonometric function calculation unit 103 that calculates a trigonometric function. including.

  The conversion unit 100 converts a sine wave component (sinθ, hereinafter “sinusoidal value”) in a phase format from a baseband signal expressed in an orthogonal format x + jy separated into an I (inphase) component and a Q (quadrature) component. And a cosine wave component (cosθ, hereinafter referred to as “cosine value”) are calculated and output as a digital signal. x is the amplitude of the I component, and y is the amplitude of the Q component. θ is the phase angle (−π ≦ θ ≦ π) of the input baseband signal.

  The comparison unit 110 compares the absolute value of the sine value calculated by the conversion unit 100 with a fixed value. The fixed value may be stored in the comparison unit 110 in a form that can be rewritten from the outside. By being configured to compare the absolute value of the sine value with the fixed value, the comparison unit 110 increases the scale of the circuit and the lookup table as compared with the configuration for comparing the sine value and the cosine value. Can be small.

  The multiplexer 120 selects one of the absolute value of the sine value and the absolute value of the cosine value based on the comparison result of the comparison unit 110 and inputs the selected value to the ROM 130. Further, the multiplexer 120 outputs the sign of the sine value and the cosine value and the absolute value of the sine value to the data processing unit 140.

  The ROM 130 stores an arc sine (inverse sine function) lookup table having an arc sine value (angle) range of 0 to π / 4. The range of values input to the lookup table for obtaining the arc sine value is 0 or more and a fixed value or less. The function of the ROM 130 is to obtain an arc sine value corresponding to the sine value or cosine value input from the multiplexer 120 using a lookup table, and output the obtained arc sine value to the data processing unit 140 as θ (in). Is included. The range of the angle θ (in) output from the ROM 130 is 0 ≦ θ (in) ≦ π / 4. On the other hand, the range of the actual phase angle θ (out) of the baseband signal is −π ≦ θ (out) ≦ π. Therefore, θ (in) is converted to θ (out) in the data processing unit 140.

  The data processing unit 140 obtains θ (out) (−π ≦ θ (out) ≦ π) from the angle θ (in) input from the ROM 130 based on the sine value and cosine value input from the multiplexer 120. Θ (out) output from the data processing unit 140 is the phase angle of the input baseband signal.

First, the power calculation unit 101 of the conversion unit 100 is the power of the baseband signal expressed in the orthogonal format x + ji.

Calculate

The norm calculation unit 102 calculates the square root (norm) of the power (pow) obtained by the power calculation unit 101, and is the reciprocal thereof.

Calculate

The trigonometric function calculation unit 103 multiplies the reciprocal of the norm calculated by the norm calculation unit 102 and the baseband signal to calculate the following sine value (sinθ) and cosine value (cosθ).

  The conversion unit 100 can obtain the sine value sinθ and the cosine value cosθ from the baseband signal expressed in the orthogonal format by these calculations.

  The data processing unit 140 includes a determination unit 141 and a conversion unit 142. The determination unit 141 determines a region where the phase angle θ (out) of the baseband signal exists based on the sign of the sine value, the sign of the cosine value, and the comparison result of the comparison unit 110. Specifically, the determination unit 141 determines whether the angle θ (in) output from the ROM 130 corresponds to any angle range of the following expressions (1) to (8). Based on the determination result of the determination unit 141, the conversion unit 142 performs the calculation of any one of the expressions (1) to (8) corresponding to the determination result of the determination unit 141 with respect to the input angle θ (in). The result is output as the phase angle θ (out).

  By executing these processes, the data processing unit 140 sets the angle θ (in) (0 ≦ θ (in) ≦ π / 4) obtained from the arcsine lookup table included in the ROM 130 to −π˜ The phase angle θ (out) corresponding to the range of π is converted.

(Description of operation)
With reference to FIG.1 and FIG.2, operation | movement of the angle detection apparatus 10 of 1st Embodiment is demonstrated in detail. FIG. 2 is a flowchart illustrating an example of an operation procedure of the angle detection device 10 according to the first embodiment.

  First, the power calculator 101 calculates the power (pow) of the baseband signal (step S101 in FIG. 2). Next, the norm calculation unit 102 calculates a norm (Norm) which is a square root of power, and further calculates an inverse of the norm (S102). Then, the trigonometric function calculation unit 103 multiplies the reciprocal of the norm, the y component and the x component of the baseband signal, respectively, to obtain a sine value sin θ (SIN) and a cosine value cos θ (COS) (S103).

  The absolute value (| SIN |) of the sine value calculated in step S103 is compared with the fixed value 0.707 in the comparison unit 110 (S104). The magnitude relationship between the sine value and the cosine value is reversed at 0.707. Therefore, when the absolute value of the sine value is less than 0.707, the multiplexer 120 inputs the absolute value (| SIN |) of the sine value to the ROM 130 (S104: NO to S106). Alternatively, when the absolute value of the sine value is 0.707 or more, the multiplexer 120 inputs the absolute value (| COS |) of the cosine value to the ROM 130 (S104: YES to S105). In other words, the smaller value of the absolute value of the sine value and the absolute value of the cosine value is input to the ROM 130. As a result, a value less than the fixed value is input to the ROM 130.

  The ROM 130 receives the absolute value of the sine value or the absolute value of the cosine value selected by the multiplexer 120. ROM (in) in FIG. 2 indicates a value input to the ROM 130. The ROM 130 obtains an angle θ (in) (0 ≦ θ (in) ≦ π / 4) by drawing a look-up table of an inverse sine function with the input ROM (in) value (S107).

  The data processing unit 140 performs conversion according to the equations (1) to (8) with respect to the angle θ (in) output from the ROM unit 130 to obtain the actual phase angle θ (out) of the baseband signal. Output (S108-S123).

  The determination unit 141 uses the absolute value of the sine value input from the multiplexer 120 and the sign of the sine value and cosine value to determine the angle θ (in) input from the ROM 130 in the region where the actual phase angle θ (out) exists ( -Π ≦ θ (out) ≦ π) is obtained. The conversion unit 142 converts the angle θ (in) into the angle of the region obtained by the determination unit 141, and outputs it as the phase angle θ (out).

The following equations (1) to (8) represent equations for converting the angle θ (in) into the phase angle θ (out). The parentheses in the expressions (1) to (8) indicate the range of the absolute value of the sine value and the sign of the sine value and the cosine value to which each expression is applied. Further, the equations (1) to (8) show the corresponding steps (S111, S113, S115-S116, S119-S120, S122-S123) in FIG.
θ (out) = θ (in): (| sinθ | <0.707, sinθ ≧ 0, cosθ ≧ 0), S119 (1)
θ (out) =-θ (in): (| sinθ | <0.707, sinθ <0, cosθ ≧ 0), S122 (2)
θ (out) = π−θ (in): (| sinθ | <0.707, sinθ ≧ 0, cosθ <0), S120 (3)
θ (out) =-π + θ (in): (| sinθ | <0.707, sinθ <0, cosθ <0), S123 (4)
θ (out) = π / 2−θ (in): (| sinθ | ≧ 0.707, sinθ ≧ 0, cosθ ≧ 0), S111 (5)
θ (out) = − π / 2 + θ (in): (| sinθ | ≧ 0.707, sinθ <0, cosθ ≧ 0), S115 (6)
θ (out) = π / 2 + θ (in): (| sinθ | ≧ 0.707, sinθ ≧ 0, cosθ <0), S113 (7)
θ (out) = − π / 2−θ (in): (| sinθ | ≧ 0.707, sinθ <0, cosθ <0), S116 (8)
From the equations (1) to (8), the phase angle θ (out) of the baseband signal input to the angle detection device 10 is obtained as a value in the range of −π ≦ θ (out) ≦ π (S112). .

  As described above, the angle detection device 10 according to the first embodiment compares the absolute value of the sine value with a fixed value instead of comparing the sine value with the cosine value. Then, the angle detection device 10 obtains the phase angle of the baseband signal based on the comparison result between the sine value and the fixed value, using any one of the equations (1) to (8).

(Explanation of effect)
Since the angle detection device 10 according to the first embodiment having such a configuration can compare one of the comparison targets as a fixed value as compared with the configuration that compares the sine value and the cosine value, the scale of the angle detection device can be compared. Can be made small and simple. As a result, the angle detection apparatus 10 of the first embodiment has an effect that the circuit scale can be easily reduced and the speed can be increased.

(Second Embodiment)
(Description of configuration)
Next, an angle detection apparatus according to a second embodiment of the present invention will be described in detail with reference to FIGS. The angle detection device 20 of the present invention shown in FIG. 3 includes a conversion unit 200, an AND unit 210, a multiplexer 220, a ROM 230, and a data processing unit 240.

  The conversion unit 200 calculates a sine value and a cosine value from the baseband signal expressed in the orthogonal format x + ji, and outputs it as digital data. The calculation procedure of the sine value and the cosine value is the same as that of the conversion unit 100 of the first embodiment.

  The AND unit 210 extracts 3 bits from the sine value output from the conversion unit 200 and performs an AND operation. The configuration and operation of the AND unit 210 will be described later.

  The multiplexer 220 selects one of the absolute values of the sine value and the cosine value input from the conversion unit 200, outputs the selected value to the ROM 230, and also adds the sign of the sine value and the cosine value and the absolute value of the sine value. The value is output to the data processing unit 240.

  The ROM 230 stores a look-up table of arc sine (inverse sine function) corresponding to a range in which an input value is 0 or more and less than 0.75. The ROM 230 outputs an arc sine value (angle) corresponding to the value input from the multiplexer 220 as θ (in). That is, the range of θ (in) output from the ROM 230 with respect to an input having a value of 0 or more and less than 0.75 is 0 ≦ θ (in) ≦ Arcsin (0.75) (rad). Here, Arcsin (0.75) ≈0.848 (rad). Further, the function of the ROM 230 is to obtain an arc sine value corresponding to the sine value or cosine value input from the multiplexer 220 using a lookup table, and output the obtained arc sine value to the data processing unit 240 as θ (in). Functions to be included.

  The data processing unit 240 includes a determination unit 241 that determines a region where the actual phase angle of the baseband signal exists, and a conversion unit 242 that converts the angle. Based on the sign of the sine value and the cosine value input from the multiplexer 220 and the absolute value of the sine value, the determination unit 241 determines the angle θ (in) input from the ROM 230 as described later in Expressions (9) to (16). It is determined which area is described in the formula. The conversion unit 242 performs an operation corresponding to the determination result of the determination unit 241 on the input angle θ (in) according to the equations (9) to (16), and sets the result as the phase angle θ (out). Output.

  The data processing unit 240 converts the angle θ (in) input from the ROM 230 into θ (out) (−π ≦ θ (out) ≦ π) by sequentially executing these procedures. Θ (out) output from the data processing unit 240 is the phase angle of the input baseband signal.

  FIG. 4 is a diagram illustrating a configuration of the AND unit 210. The AND unit 210 includes XOR (exclusive OR) gates 300 and 310 and an AND gate 320. The XOR gate 300 outputs an exclusive OR of a bit (sign bit) indicating a sign of a sine value expressed in a fixed point and a bit indicating 0.5 of the sine value, and one input of the AND gate 320 To enter. The XOR gate 310 outputs an exclusive OR of the sign bit and the bit indicating the sine value 0.25, and inputs the exclusive OR to the other input of the AND gate 320. The AND gate 320 outputs a logical product of the outputs of the XOR gates 300 and 310 to the multiplexer 220 as a comparison result.

  FIG. 5 is a truth table of the AND unit 210. In this embodiment, the sine value is expressed in 2's complement format. 4 and 5, the “sign bit” is “0” when the sine value is non-negative, and is “1” when the sine value is negative. The “bit indicating 0.5” is 1 when the sine value sinθ is sinθ ≧ 0.5 or −0.5 ≦ sinθ <0, and is 0 otherwise. “Bit indicating 0.25” is 1 when the sine value sinθ is 0.25 ≦ sinθ <0.5, 0.75 ≦ sinθ <1, −0.25 <sinθ <0 or −0.75 <sinθ ≦ −0.5, and otherwise. 0.

  When the output of the AND unit 210 is false (“0”), the multiplexer 220 considers that the sine value is smaller than the cosine value, and outputs the absolute value of the sine value to the ROM 230. When the output of the AND unit 210 is true (“1”), the multiplexer 220 considers that the sine value is larger than the cosine value, and outputs the absolute value of the cosine value to the ROM 230.

  Thus, the fixed value that was 0.707 in the first embodiment is 0.75 in the second embodiment.

(Description of operation)
Next, the operation of the angle detection device 20 of the second embodiment will be described in detail. FIG. 6 is a flowchart illustrating an operation procedure of the angle detection apparatus according to the second embodiment.

  First, the conversion unit 200 obtains a sine value and a cosine value of the input signal by the same processing as the conversion unit 100 of the first embodiment (S201 to S203). Next, the AND unit 210 performs the procedure described with reference to FIGS. 4 and 5, the sign bit of the sine value sin θ (SIN) expressed in the binary fixed point, the bit indicating the sine value 0.5, and the sine value. The bit (upper 3 bits) indicating 0.25 is evaluated (S204).

  When the output of the AND unit 210 is false (“0”), the upper 3 bits of the sine value are other than “100” and “011”. In this case, the multiplexer 220 outputs the absolute value (| SIN |) of the sine value to the ROM 230 (S205). When the output of the AND unit 210 is true (“1”), the upper 3 bits of the sine value are “100” or “011”. In this case, the multiplexer 220 outputs the absolute value of the cosine value (| COS |) to the ROM 230 (S206).

  The ROM 230 uses the value input from the multiplexer 220 to draw an inverse sine function look-up table and converts it into an angle θ (in) (S207). Here, 0 ≦ θ (in) ≦ 0.848 (rad).

  FIG. 8 is a graph showing the relationship between the sine value sinθ and the cosine value cosθ in the second embodiment. In the second embodiment, when the absolute value (| SIN |) of the sine value is 0.707 or more and less than 0.75, the sine value is selected (step S206). In this case, as shown in FIG. 8, unlike the first embodiment, the absolute value of the sine value exceeds 0.707. However, the input range of the lookup table provided in the ROM 230 of the second embodiment is 0 or more and 0.75 or less. Therefore, even when the sine value is selected (S206), the arc sine value with respect to the absolute value of the input sine value can be output as θ (in) (0 ≦ θ (in) ≦ 0.848 (rad)).

  Note that the ROM 230 may include a lookup table having an input range of 0 or more and 0.707 or less, similar to the lookup table of the ROM 130 of the first embodiment. When a lookup table similar to that of the first embodiment is used, and the absolute value of the selected sine value is 0.707 or more and less than 0.75, the ROM 230 does not depend on the lookup table. A predetermined angle (for example, π / 4) may be output as θ (in).

  Based on the angle θ (in) output from the ROM 230, the absolute value of the sine value, and the signs of the sine value and the cosine value, the data processing unit 240 performs the phase angle according to the following equations (9) to (16). θ (out) is obtained and output (S208 to S223).

The following formulas (9) to (16) represent formulas for converting the angle θ (in) into the phase angle θ (out). The parentheses in the expressions (9) to (16) indicate the range of the absolute value of the sine value and the sign of the sine value and the cosine value to which each expression is applied. Also, the equations (9) to (16) show the corresponding steps (S211, S213, S215-S216, S219-S220, S222-S223) of FIG.
θ (out) = θ (in): (| sinθ | <0.75, sinθ ≧ 0, cosθ ≧ 0), S219 (9)
θ (out) = − θ (in): (| sinθ | <0.75, sinθ <0, cosθ ≧ 0), S222 (10)
θ (out) = π−θ (in): (| sinθ | <0.75, sinθ ≧ 0, cosθ <0), S220 (11)
θ (out) = − π + θ (in): (| sinθ | <0.75, sinθ <0, cosθ <0), S223 (12)
θ (out) = π / 2−θ (in): (| sinθ | ≧ 0.75, sinθ ≧ 0, cosθ ≧ 0), S211 (13)
θ (out) = − π / 2 + θ (in): (| sinθ | ≧ 0.75, sinθ <0, cosθ ≧ 0), S215 (14)
θ (out) = π / 2 + θ (in): (| sinθ | ≧ 0.75, sinθ ≧ 0, cosθ <0), S213 (15)
θ (out) = − π / 2−θ (in): (| sinθ | ≧ 0.75, sinθ <0, cosθ <0), S216 (16)
(Explanation of effect)
As described above, the angle detection device 20 according to the second embodiment that obtains the phase angle of the baseband signal compares the sine value with the fixed value using a 3-bit value. For this reason, the angle detection device 20 according to the second embodiment can compare the sine value and the fixed value with a simple circuit of two XOR gates and one AND gate. As a result, the angle detection device 20 of the second embodiment also has an effect that the circuit configuration of the angle detection device can be reduced and the operation frequency can be easily improved.

(Third embodiment)
The configuration of the angle detection device 10 described in the first embodiment can also be described as the angle detection device of the following third embodiment. The angle detection apparatus according to the third embodiment includes a conversion unit, a comparison unit, a multiplexer, a ROM, and a data processing unit.

  The function of each part of the angle detection device of the third embodiment is the same as that of the angle detection device 10 described in the first embodiment. That is, the conversion unit obtains a sine value (sin θ) and a cosine value (cos θ) corresponding to the phase angle θ of the input baseband signal. The comparison unit outputs a comparison result between the absolute value of the sine value obtained by the data processing unit and a predetermined fixed value. The multiplexer outputs the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value, and further, based on the comparison result, calculates the smaller value of the absolute value of the sine value and the absolute value of the cosine value. Output to ROM.

  The ROM outputs an inverse sine value θ (in) with respect to the input value. Based on the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value generated by the conversion unit, the data processing unit converts the inverse sine value θ (in) input from the ROM to −π ≦ θ (out ) ≦ π is converted into a phase angle θ (out) in the range and output.

  The angle detection apparatus according to the third embodiment having such a configuration and function can also reduce the scale of the comparison circuit and obtain a simple configuration by obtaining a comparison result between the sine value and the fixed value. it can. The data processing unit converts the inverse sine value θ (in) input from the ROM into a phase angle θ (out) in the range of −π ≦ θ (out) ≦ π and outputs the phase angle θ (out). Here, the region where the phase angle θ (out) exists is determined based on the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value generated by the conversion unit.

  As a result, the angle detection apparatus according to the third embodiment also has an effect that the scale and speed of the circuit of the angle detection apparatus can be easily reduced.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  The present invention can be applied to uses such as calculation of a rotation angle of a servo device in addition to phase detection of digital baseband signal processing.

10, 20 Angle detection device 100, 200 Conversion unit 101 Power calculation unit 102 Norm calculation unit 103 Trigonometric function calculation unit 110 Comparison unit 120, 220 Multiplexer 130, 230 ROM
140, 240 Data processing unit 141, 241 Judgment unit 142, 242 Conversion unit 210 AND unit 300, 310 XOR gate 320 AND gate 400 Level detector 401, 402 Multiplier 410 Comparison circuit 430 ROM
440 90 degree corrector 450 A / D (analog-digital converter)
460 90 degree phase shifter 470 Differentiator 480 Input terminal 490 Output terminal

Claims (6)

Conversion means for obtaining a sine value (sinθ) and a cosine value (cosθ) corresponding to the phase angle θ of the input baseband signal;
A comparison means for outputting a comparison result of the magnitude of the absolute value of the sine value and a predetermined fixed value;
ROM (read only memory) that outputs the inverse sine value θ (in) for the input value;
The absolute value of the sine value, the sign of the sine value, and the sign of the cosine value are output, and based on the comparison result, the absolute value of the sine value and the absolute value of the cosine value that is not greater A multiplexer that outputs the value of
Based on the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value, the inverse sine value θ (in) input from the ROM is in a range of −π ≦ θ (out) ≦ π. Data processing means for converting to a certain phase angle θ (out) and outputting;
An angle detection device comprising: The fixed value is a value of sinθ where cosθ = sinθ,
The ROM has a look-up table for obtaining the inverse sine value θ (in) in the range of 0 ≦ θ (in) ≦ π / 4 corresponding to the input value not less than 0 and not more than the fixed value. Prepared,
The multiplexer is
If the comparison result indicates that the absolute value of the sine value is less than the fixed value, the absolute value of the sine value is output to the ROM;
If the comparison result indicates that the absolute value of the sine value is greater than or equal to the fixed value, the absolute value of the cosine value is output to the ROM;
The angle detection device according to claim 1, wherein:   The angle detection device according to claim 2, wherein the fixed value is 0.707. The fixed value is 0.75,
The comparison means outputs the comparison result based on a bit indicating a sign, a bit indicating 0.5, and a bit indicating 0.25 of the fixed-point data indicating the sine value,
The ROM includes a lookup table for obtaining the inverse sine value θ (in) corresponding to the input value of 0 or more and 0.75 or less,
The multiplexer is
If the comparison result indicates that the absolute value of the sine value is less than 0.75, the absolute value of the sine value is output to the ROM;
When the comparison result indicates that the absolute value of the sine value is 0.75 or more, the absolute value of the cosine value is output to the ROM.
The angle detection device according to claim 1, wherein: The baseband signal is a signal that is separated into an I (inphase) component and a Q (quadrature) component and whose amplitude is expressed in an orthogonal format of x + ji with j as an imaginary unit,
The converting means includes a power calculation unit that calculates the power of the baseband signal as x ² + y ² , a norm calculation unit that calculates a norm of the power as a square root of the power, and calculates an inverse of the norm, A trigonometric function calculation unit for obtaining a product of an inverse number and x as the cosine value, and obtaining a product of the inverse of the norm and y as the sine value;
The angle detection device according to claim 1, further comprising: Find the sine value (sinθ) and cosine value (cosθ) corresponding to the phase angle θ of the input baseband signal,
Output a comparison result of the magnitude of the absolute value of the sine value and a predetermined fixed value,
Based on the comparison result, select the lesser of the absolute value of the sine value and the absolute value of the cosine value,
Find the inverse sine value θ (in) corresponding to one of the absolute value of the selected sine value and the cosine value,
Based on the absolute value of the sine value, the sign of the sine value, and the sign of the cosine value, the inverse sine value θ (in) is set to a phase angle θ (out) in a range of −π ≦ θ (out) ≦ π. Convert and output,
An angle detection method characterized by the above.

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