JP4488177B2 - Angle measuring method and apparatus - Google Patents

Description

  The present invention relates to an angle measurement method and apparatus for obtaining a radio wave incident angle in a high-speed angle measurement method in which a search angle range is successively narrowed down and set without erroneously setting a search range.

  When a wide search angle range is precisely measured and a plurality of radio waves are separately measured, the calculation load of the angle measurement algorithm increases and the processing time also increases. Therefore, in order to reduce the computation load while satisfying the desired angle measurement accuracy, and to speed up the processing time, the initial process roughly measures the wide search angle range and searches near the obtained angle estimation value. It is conceivable to narrow down the angle range and precisely measure the angle.

  However, with this method, if an incorrect angle estimate is obtained in the initial stage due to the local minimum of the azimuth evaluation function, the setting of the search angle range in the subsequent processing is incorrect, which may cause the incident angle estimation to fail. is there.

  As conventional angle measurement processing, there is a method of performing high-speed angle measurement processing using the maximum likelihood estimation angle measurement method (see, for example, Non-Patent Document 1). However, the calculation load of the maximum likelihood estimation angle measurement method increases with the number of angle points at which the azimuth evaluation function is calculated to the power of incident waves. Therefore, in order to reduce the calculation load while satisfying the desired angle measurement accuracy, the initial processing calculates an azimuth evaluation function using a wide search angle range using rough angle intervals, and the angle estimation value obtained by the azimuth evaluation function It is conceivable that the search angle range of the next stage is narrowed in the vicinity, the angle interval is narrowed, and the azimuth evaluation function is calculated to measure the angle (high-speed maximum likelihood estimation angle measurement method).

  According to this method, the angle mesh interval can be set finely at the time of the final incident angle estimation process, and compared with the case where a fine angle range is set for each incident angle estimation process, the radio wave can be calculated with a low calculation amount. It is possible to precisely measure the incident angle.

Ziskind I., Wax M., "Maximum likelihood localization of multiple sources by alternation projection", IEEE Trans. Acoust., Speech, and Signal Processing, vol.ASSP-36, No. 10, pp. 1553-1560, Oct. 1988.

  However, in this method, in the initial angle measurement processing, there is a possibility that an incorrect angle estimation value by the local minimum of the azimuth evaluation function may be obtained depending on the position of the angle point and the value of the azimuth evaluation function. In this case, the setting of the search angle range in the subsequent process is also incorrect, and the incident angle estimation fails.

  The present invention has been made in view of the above points, and determines whether or not an incident wave actually exists in an angle value estimated by angle measurement processing, and sets a search angle range that is generated by an incorrect angle estimated value. An object of the present invention is to obtain an angle measuring method and apparatus capable of avoiding the failure.

The angle measuring method and apparatus according to the present invention obtains an incident angle estimated value of an incident wave acquired using the maximum likelihood estimated angle measuring method, and is a matrix in which steering vectors corresponding to the obtained incident angle estimated value are arranged. The incident angle information and the incident signal estimation value obtained by reproducing the incident signal by extracting the incident signal by removing the incident angle information from the received signal using the given incident angle information. The evaluation value represented by the incident angle of the received signal and the least square estimation error with respect to the reproduction signal is obtained, and if the obtained evaluation value is larger than the thermal noise power, it is determined that a false value exists in the angle estimation value. is there.

  According to the present invention, it is possible to determine whether an incident wave actually exists in the angle value estimated by the angle measurement processing, and to avoid a search angle range setting failure caused by an incorrect angle estimated value. .

Embodiment 1 FIG.
FIG. 1 is a block diagram for explaining an angle measurement method and apparatus according to Embodiment 1 of the present invention, and shows a configuration for performing high-speed angle measurement using the maximum likelihood angle measurement method. However, for the sake of simplicity, an outline in the case of one-dimensional angle measurement in which only azimuth angle measurement is performed is shown. It is assumed that _K receiving waves 21,..., 2K are incident on M receiving element antennas 11,. Here, it is assumed that the wave number K of the incident wave is smaller than the number M of the element antennas. The outputs of the receiving element antennas 11,..., 1M are A / D converted through M A / D converters 31,..., 3 M and input to the incident angle estimation signal processing unit 4. Thus, the incidence angle is estimated.

FIG. 2 shows partial steps in the incident angle estimation signal processing unit 4. First, the incident wave number K is determined (step 81), and the received signal x is observed to obtain the correlation matrix R (step 82). In step 82, the following processing is performed. The reception signal x (t) output from each element antenna 11,..., 1M has a steering vector a (θ _K ), an M × K matrix A in which the steering vectors are arranged, an incident signal vector s (t), When the noise vector n (t) is used, it is expressed by the following equation (1).

ついで、受信信号ベクトルｘについてのＭ×Ｍ次元の共分散行列Ｒを次式（２）で求める。

Next, an M × M dimensional covariance matrix R for the received signal vector x is obtained by the following equation (2).

ここで、Ｈは複素共役転置、Ｒ_０は入射信号ベクトルs(t)の共分散行列を表す。σ^２はノイズの電力、Ｉは単位行列である。

Here, H represents a complex conjugate transpose, and R ₀ represents a covariance matrix of the incident signal vector s (t). σ ² is noise power, and I is a unit matrix.

  Next, in step 83, the angle range in which the angle measurement process is performed is set at an arbitrary angle interval.

の組み合わせ全てに対し

For all combinations

を求める。ついで、最尤推定測角法の方位評価関数Ｐ_ＭＬ

Ask for. Next, the azimuth evaluation function P _{ML of} the maximum likelihood angle measurement method

を求める。ここで、

Ask for. here,

を示す。

Indicates.

  In step 84, the orientation evaluation function

が最大となる

Is maximized

をＫ波の電波の入射角度推定値とする。

Is the estimated angle of incidence of K-wave radio waves.

  However, the computational load of the maximum likelihood angle measurement method is the bearing evaluation function

を計算する角度ポイント個数の入射波数乗で増大する。そこで、所望の測角精度を満たしつつ演算負荷の低減を図るため、初期の処理では広い探索角度範囲を荒い角度間隔を用いて方位評価関数を計算する。この方位評価関数により得られた角度推定値付近に、次段の探索角度範囲を絞り込み、角度間隔を細かくして方位評価関数を計算し測角することが考えられる。この方法を以下では高速型最尤推定測角法と呼ぶ。

It increases with the number of incident wave powers of the number of angle points. Therefore, in order to reduce the calculation load while satisfying the desired angle measurement accuracy, in the initial processing, the azimuth evaluation function is calculated using a wide search angle range and rough angle intervals. It is conceivable that the search angle range of the next stage is narrowed near the estimated angle value obtained by this azimuth evaluation function, the azimuth evaluation function is calculated and the angle is measured with finer angular intervals. This method is hereinafter referred to as a high-speed maximum likelihood estimation angle measurement method.

  FIG. 3 shows the steps of the fast maximum likelihood angle measurement method. In step 91, a covariance matrix R is obtained from the received signal x (t). In step 92, the entire search area is combined with all angles of K incident waves at rough angular mesh intervals.

について

about

を求める。ついで、方位評価関数

Ask for. Next, orientation evaluation function

を全ての

All

について求める。

Ask for.

  In step 93, the next search area is set in an angle range equal to or greater than a certain threshold value. Further, the angle mesh interval is set finer than the angle mesh interval used in step 92. The next process is performed using the newly set search range and angular mesh interval (return to step 91 in the next process).

  In step 94, an estimated incident angle estimated value in this series of processing is obtained. Thereafter, steps 91-93 are repeated.

  According to this method, the angle mesh interval can be set finely during the final incident angle estimation process. Thereby, compared with the case where a fine angle range is set for each incident angle estimation process, it is possible to precisely measure the incident angle of the radio wave with a small amount of calculation.

  However, as shown in FIG. 4, in this method, in the initial angle measurement processing, there is a possibility of obtaining an incorrect angle estimation value by the local minimum of the direction evaluation function depending on the position of the angle point and the value of the direction evaluation function. is there. In this case, the setting of the search angle range in the subsequent process is also incorrect, and the incident angle estimation fails.

  In the configuration according to the first embodiment shown in FIG. 1, it is determined whether an incident wave actually exists in the angle value estimated by the angle measurement process, and the search angle range setting generated by the incorrect angle estimated value is set. In order to avoid failure, the true / false determination unit 6 based on the evaluation function Jeva determines whether the incident angle estimated value is true or false, and the search angle range setting unit 5 sets the search angle range used in the subsequent processing.

  Processing for determining the authenticity of the incident angle estimation value in the authenticity determination unit 6 will be described below. Incident angle estimated value of incident wave by angle measurement process

が決定されると、それに対応するステアリングベクトルを並べた行列

Is determined, a matrix of corresponding steering vectors

が決定される。

Is determined.

  Now, the received signal x (t) output from each element antenna can be described by equation (1).

とすると、次式が成り立つ。

Then, the following equation holds.

  This least squares solution

は入射信号ベクトルs(t)の最尤推定値となる。

Is the maximum likelihood estimate of the incident signal vector s (t).

  Specific estimated value of incident signal

は次式で与えられる。

Is given by:

が入射角度真値の組み合わせであれば、

Is a combination of true incident angles,

は真の入射信号ベクトルs(t)を再生することが可能である。さらに、評価関数として受信信号の最小二乗推定誤差を考える。これは、

Can reproduce the true incident signal vector s (t). Further, the least square estimation error of the received signal is considered as an evaluation function. this is,

で表される。

It is represented by

  Equation (5) is the estimated incident angle.

が真の入射角度と合致している場合、評価関数Jevaは熱雑音電力の総和

If is matched with the true angle of incidence, the evaluation function Jeva is the sum of the thermal noise power

に近い値をとる。

It takes a value close to.

On the other hand, when the estimated incident angle value is different from the true incident angle, the estimation of the incident signal vector of Equation (4) fails, and the signal power of the incident wave remains in the evaluation function Jeva, so the value is larger than the sum of the thermal noise power. It becomes. Since the sum of the thermal noise power can be acquired in an environment where no signal is incident in advance, it can be used as a true / false judgment criterion. From this, the authenticity of the incident angle estimated value can be confirmed using the least square estimation error of the received signal as an evaluation function. That is, using a matrix based on the incident angle estimate of the incident wave, an incident signal estimate obtained by reproducing the incident signal is obtained as shown in Equation (4), and then the reproduced incident signal estimate and the incident angle are obtained. using based on the estimated value matrix and the received signal x (t) obtains the evaluation value J _eva of formula (5), compares the evaluation obtained value J _eva and thermal noise power || n || ^2, evaluation value If J _eva is greater than the thermal noise power || n || ² , it can be determined that a false value exists in the incident angle estimated value.

  Fig. 5 shows angle combination values for searching the horizontal axis.

、縦軸を評価関数Jevaとしたグラフである。これによると、図４に示した誤った探索範囲を設定するような入射角度組み合わせでは評価関数の値は熱雑音電力の総和より大きくなる。これにより、例えば測角アルゴリズムが前述の高速型最尤推定測角法である場合、図４でみられたような誤った角度推定値によって発生する探索角度範囲設定の失敗を回避することが可能であると考えられる。

The vertical axis represents the evaluation function Jeva. According to this, the value of the evaluation function becomes larger than the total sum of the thermal noise power in the incident angle combination that sets the erroneous search range shown in FIG. As a result, for example, when the angle measurement algorithm is the above-described high-speed maximum likelihood estimation angle measurement method, it is possible to avoid a search angle range setting failure caused by an incorrect angle estimation value as seen in FIG. It is thought that.

  That is, according to the first embodiment, the incident angle estimation signal processing unit 4 obtains an incident angle estimated value of the incident wave, and the authenticity judgment unit 6 reproduces the incident signal using the obtained incident angle estimation. To obtain an evaluation value that is a sum of squares of values obtained by subtracting the reproduced incident signal from the received signal based on the reproduced incident signal, and to determine whether the angle estimation value is true or false based on the obtained evaluation value. Therefore, it can be determined whether or not an incident wave actually exists in the angle value estimated by the angle measurement process, and a failure in setting a search angle range caused by an incorrect angle estimated value can be avoided.

Embodiment 2. FIG.
FIG. 6 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 2 of the present invention. In the second embodiment shown in FIG. 6, as the evaluation value of the authenticity determination unit 6, the reproduction signal represented by the expression (4) is used.

の電力値を算出することによって求め、入射角度推定値の真偽を判定するよう構成したものである。

This is obtained by calculating the power value of, and configured to determine whether the incident angle estimated value is true or false.

  According to this, the true incident signal vector

が既知である場合、

の信号波形、電力値等を基準に用いて、評価関数Jevaを算出することなく、

の真偽を判断することが可能である。

If is known,

Using the signal waveform, power value, etc. as a reference, without calculating the evaluation function Jeva,

Can be determined.

  Therefore, according to the second embodiment, it is generated by an erroneous angle estimation value as in the first embodiment by determining the authenticity of the incident angle estimation value using the power value of the reproduction signal as the evaluation value. It is possible to avoid failure in setting the search angle range.

Embodiment 3 FIG.
FIG. 7 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 3 of the present invention. In the third embodiment shown in FIG. 7, the authenticity determination unit 6 is based on an evaluation function calculation unit 60 that calculates the value of the evaluation function Jeva, and a comparison between the calculated evaluation value and a preset threshold value. And a true / false determination unit 61 based on a threshold value for determining true / false.

  The evaluation function calculation unit 60 calculates the value of the evaluation function Jeva, and the authenticity determination unit 61 determines that the obtained value is equal to or larger than the threshold value, and determines that the sum of the thermal noise power is greater than the estimated incident angle. It is assumed that no signal is incident in the vicinity of the combination value.

  In this case, the process of narrowing down the search range at the next stage is not performed. In the next angle measurement process, the past search range is used, the angle interval of the angle point is changed, the angle point is shifted without changing the angle interval, and the number of snapshots is increased. Perform corner processing.

  Therefore, according to the third embodiment, the authenticity of the incident angle estimated value is determined based on the comparison between the calculated evaluation value and a preset threshold value. Failure to set the search angle range can be avoided.

Embodiment 4 FIG.
FIG. 8 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 4 of the present invention. In the fourth embodiment shown in FIG. 8, as the true / false determination unit 6, an evaluation function calculation unit 60 that calculates the value of the evaluation function Jeva, and the calculated evaluation value and the previous evaluation function value, that is, past processing, It includes a true / false determination unit 62 based on comparison with the evaluation function value in the previous stage by comparison with the obtained evaluation value.

  The evaluation function calculation unit 60 calculates the value of the evaluation function Jeva, and the true / false determination unit 62 determines that the obtained value is equal to or greater than the past evaluation function value and is greater than the sum of the thermal noise power, and this estimation. It is determined that no signal is incident in the vicinity of the incident angle combination value.

  In this case, the process of narrowing down the search range at the next stage is not performed. In the next angle measurement process, the past search range is used, the angle interval of the angle point is changed, the angle point is shifted without changing the angle interval, and the number of snapshots is increased. Perform corner processing.

  Therefore, according to the fourth embodiment, since the authenticity of the incident angle estimated value is determined based on the comparison between the calculated evaluation value and the evaluation value obtained in the past processing, an erroneous angle estimation is performed. A failure in setting the search angle range that occurs depending on the value can be avoided.

Embodiment 5 FIG.
FIG. 9 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 5 of the present invention. In the fifth embodiment shown in FIG. 9, as the true / false determination unit 6, an evaluation function calculation unit 60 that calculates the value of the evaluation function Jeva, and the true / false based on the comparison between the calculated evaluation value and the previous evaluation function value A true / false determination unit 63 that performs determination and true / false determination by comparing the calculated evaluation value and a threshold value is provided.

  That is, in the fifth embodiment, as the reference value for the true / false determination, the true / false determination based on the threshold value as in the third embodiment and the true / false determination based on the past evaluation function value as in the fourth embodiment. Is what you do. The threshold value is set to be larger than the sum of the assumed thermal noise power.

  According to this method, the evaluation function calculation unit 60 calculates the evaluation function Jeva, and when the obtained value is equal to or greater than the threshold value, the estimated incident angle value is significantly different from the true incident angle value. The process of narrowing down the search range is not performed. In the next angle measurement process, the past search range and angle interval are used in the next angle measurement process, and the angle is measured again by increasing the number of snapshots.

  When the value obtained by the evaluation function Jeva is less than the threshold value and greater than or equal to the past evaluation function value, the error is smaller than the estimated value that is greater than or equal to the threshold value. In this case, in the angle measurement process at the next stage, the search range is not narrowed down, the angle interval of the angle points is changed, and the angle points are shifted without changing the angle interval, and the angle measurement is performed again.

  Therefore, according to the fifth embodiment, authenticity determination is performed by comparing the calculated evaluation value with the evaluation function value of the previous stage, and authenticity determination is performed by comparing the calculated evaluation value and the threshold value. Therefore, it is possible to avoid a failure in setting the search angle range that occurs due to an incorrect angle estimation value.

Embodiment 6 FIG.
FIG. 10 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 6 of the present invention. In the sixth embodiment shown in FIG. 10, the authenticity determination unit 6 is based on a power value calculation unit 64 that calculates the power of the reproduction signal and a comparison between the calculated power value and a preset threshold value. And a true / false determination unit 61 based on a threshold value for determining true / false. Here, since the determination is made using the signal power, the upper and lower limits are given as threshold values.

  The power value calculation unit 64 reproduces the incident signal, calculates the signal power value, and if the authenticity determination unit 61 determines that the signal power value is outside the threshold value range, the reproduction of the incident signal fails. Suppose that no signal is incident in the vicinity of the value of the estimated incident angle combination.

  In this case, the process of narrowing down the search range at the next stage is not performed. In the next angle measurement process, the past search range is used, the angle interval of the angle point is changed, the angle point is shifted without changing the angle interval, and the number of snapshots is increased. Perform corner processing.

  Therefore, according to the sixth embodiment, the authenticity of the incident angle estimated value is determined based on the comparison between the calculated power value and a preset threshold value. Failure to set the search angle range can be avoided.

Embodiment 7 FIG.
FIG. 11 is a block diagram for explaining an angle measuring method and apparatus according to Embodiment 7 of the present invention. In the seventh embodiment shown in FIG. 11, the authenticity determination unit 6 includes a power value calculation unit 64 that calculates the power of the reproduction signal, and a true / false determination by comparing the calculated power value and the evaluation function value of the previous stage And a true / false determination unit 65 that performs true / false determination by comparing the calculated power value with a threshold value. Here, since the determination is made using the signal power, the upper limit and the lower limit of the past signal power value are given as threshold values.

  If the reproduced signal power value is outside the range given by the past signal power value and threshold value, it is determined that the reproduction of the incident signal has failed, and no signal is incident in the vicinity of this estimated incident angle combination value. And

  In this case, the process of narrowing down the search range at the next stage is not performed. In the next angle measurement process, the past search range is used, the angle interval of the angle point is changed, the angle point is shifted without changing the angle interval, and the number of snapshots is increased. Perform corner processing.

  Therefore, according to the seventh embodiment, the authenticity determination is performed by comparing the calculated power value with the power value of the past reproduction signal, and the authenticity determination is performed by comparing the calculated power value and the threshold value. Therefore, it is possible to avoid a failure in setting the search angle range that occurs due to an incorrect angle estimation value. It is also possible to determine whether the incident angle estimated value is true or false based only on the comparison between the calculated power value and the power value obtained in the past process.

It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 1 of this invention. It is a flowchart explaining the maximum likelihood estimation angle measuring method. It is a flowchart explaining a high-speed maximum likelihood estimation angle measuring method. It is explanatory drawing of the principle of mismeasurement angle generation | occurrence | production in a high-speed maximum likelihood estimation angle measurement method. It is a figure explaining the principle of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 2 of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 3 of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 4 of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 5 of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 6 of this invention. It is a block diagram for demonstrating the angle measuring method and apparatus which concern on Embodiment 7 of this invention.

Explanation of symbols

  11, ..., 1M receiving element antenna, 21, ..., 2K incident wave, 31, ..., 3M A / D converter, 4 incident angle estimation signal processing unit, 5 search angle range setting unit, 6 incident angle estimated value authenticity determination unit, 60 evaluation function calculation unit, 61, 62, 63, 65 authenticity determination unit, 64 power value calculation unit.

Claims (9)

Find the incident angle estimate of the incident wave obtained using the maximum likelihood angle measurement method,
Incident signal estimation that reproduces the incident signal by extracting the incident signal by removing the incident angle information from the received signal using the incident angle information given by a matrix in which steering vectors corresponding to the obtained incident angle estimated values are arranged. And obtaining an evaluation value represented by the least square estimation error with respect to the incident angle of the received signal and the reproduction signal using the incident angle information and the estimated incident signal, and the obtained estimated value is obtained from the thermal noise power. If it is larger, it is determined that a false value exists in the angle estimation value. The angle measuring method according to claim 1,
The evaluation value is a sum of squares of values obtained by subtracting the reproduced incident signal from the received signal. The angle measuring method according to claim 1,
The evaluation value is a power value of a reproduced incident signal. A signal processing unit for obtaining an incident angle estimation value of an incident wave obtained using the maximum likelihood estimation angle measurement method;
The incident signal is extracted by removing the incident angle information from the received signal using the incident angle information given by a matrix in which steering vectors corresponding to the estimated incident angle values obtained by the signal processing unit are arranged. Obtaining the reproduced incident signal estimated value, using the incident angle information and the incident signal estimated value, obtaining an evaluation value represented by an incident angle of the received signal and a least square estimation error with respect to the reproduced signal , and obtaining the evaluated value An angle measuring apparatus comprising: a true / false determination unit that determines that a false value exists in the angle estimation value if is greater than thermal noise power. The angle measuring device according to claim 4,
The angle determination device, wherein the authenticity determination unit uses a sum of squares of values obtained by subtracting the reproduced incident signal from the received signal as an evaluation value. The angle measuring device according to claim 4,
The authenticity determination unit uses the power value of the reproduced incident signal as an evaluation value. The angle measuring device according to any one of claims 4 to 6,
The authenticity determination unit compares the obtained evaluation value with a preset threshold value, and based on the comparison result, a search range, angle points, angle points of angle points in the next stage incident angle estimation process, or An angle measuring device characterized by changing the number of snapshots. The angle measuring device according to any one of claims 4 to 6,
The authenticity determination unit compares the obtained evaluation value with the evaluation value obtained in the past process, and based on the comparison result, the search range, angle point, angle point of the angle point in the next stage incident angle estimation process Angle measuring device characterized by changing interval or number of snapshots. The angle measuring device according to any one of claims 4 to 6,
The authenticity determination unit compares the obtained evaluation value with a preset threshold value, compares the obtained evaluation value with an evaluation value obtained in the past process, and based on both comparison results An angle measuring device characterized by changing a search range, angle points, angle intervals of angle points, or the number of snapshots in an incident angle estimation process in the next stage.

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