JP2811208B2 - Pulse Doppler measurement device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pulse Doppler measuring apparatus, and more particularly to an apparatus for detecting the speed of an object using ultrasonic waves, for example, when measuring the blood flow velocity in a living body in real time. The present invention relates to a pulse Doppler measurement device capable of measuring with a high signal-to-noise ratio.

[Conventional technology]

2. Description of the Related Art Various devices have been known as devices for knowing the flow velocity of an object by the Doppler effect of sound waves. In particular, an apparatus using the pulsed Doppler method (for example,
In Vol. 29, No. 6, 1973 (pp. 351-352), ultrasonic pulses (pulsed continuous wave) are repeatedly transmitted,
It is known that a measurement site can be specified by applying a time gate corresponding to the distance to the measurement site to the received signal.

Conventional ultrasonic Doppler blood flow meters include, for example, JP-A-58-188433, JP-A-60-119929 and JP-A-61-25.
As disclosed in US Pat. No. 527, transmitting ultrasonic waves toward a blood vessel, measuring the Doppler shift frequency of ultrasonic waves reflected by blood in the blood vessel, the direction of blood flow and the ultrasonic transmission direction 2. Description of the Related Art There is known an apparatus for measuring a blood flow by measuring vcos θ when an angle to be formed is θ and a blood flow velocity is v.

[Problems to be solved by the invention]

As described above, by measuring the Doppler frequency, it is possible to know the speed of an object or blood flow. However, in order to measure the blood flow in the human body, MTI (fixed object removal) is used to separate the blood flow from the movement of the blood vessel wall and heart wall.
It is necessary to use a filter. If the blood flow velocity is low due to the MTI filter, the gain of the Doppler signal decreases, causing an error in the Doppler velocity measurement unit, and there is a problem in that the velocity is measured as a velocity different from the true blood velocity.

 Hereinafter, this will be described with reference to the drawings.

FIG. 3 shows the characteristics of various conventional Doppler measuring devices, in which the horizontal axis represents the input phase corresponding to the true blood flow velocity, and the vertical axis represents the output phase corresponding to the measured velocity.
It is a result obtained by simulation. At this time, as a model of the output signal of the phase comparator, which is a Doppler signal, X _n = A _n exp (jω _d t) −B _n (W _n ′ + jW _n ″), where the phase noise is used. W _n ′, W _n ″ is white noise, and uses normal random numbers according to a normal distribution N (0, 1).

W _n ″ is different from W _n ′ by generating an initial value of a random number differently, so that it is uncorrelated. This noise is generated by a reflected signal due to a microscopic fluctuation of blood flow. Consideration is given to the acoustic noise caused by the change every time, the non-uniformity of the tissue in the propagation process of the sound wave, the electric noise in the amplifier used for the signal amplification in the measuring device, etc. W _n ′ is The noise in the real part, W _n ″, represents the noise in the imaginary part. Note that ω _d is the Doppler frequency.

For example, in the conventional pulsed Doppler measurement of the type called autocorrelation method shown in U.S. Pat.No. 4,583,409, there was a problem that an error was generated for a low-speed blood flow, and a speed that was significantly different from the true speed was estimated. This is as described above. The reason is that the autocorrelation method occurs when detecting the phase difference between Doppler signals. That is,
In operation for adding the phase difference vectors obtained by taking the autocorrelation of the Doppler signal comrades obtained through the MTI each pulse repetition period, when the noise amplitude B _n is small (B _n << 1), the phase difference vector In the phase term, the noise has the effect of canceling each other out. Therefore, the phase difference ω _d T (T = t _{n + 1}
−t _n ) is accurately obtained, but the noise amplitude B _n is large (B _n ≫
1) Sometimes, the noise is not canceled in the phase term and the addition increases, so that the phase difference is (N is the number of additions), which is inaccurate. Also, instead of adding the phase difference vector, the Doppler signal phase (angle) is detected to obtain an angle difference Δθ for each measurement iteration, and the angle difference is divided into a cos component and a sin component. Also, in a method called a two-axis component method (Japanese Patent Laid-Open No. 63-84553) for obtaining a phase difference represented by two components after adding and averaging the same, an error exactly the same as that in the above autocorrelation method occurs. FIG. 3 is a curve in which the output phase corresponding to the measurement speed in the autocorrelation method or the two-axis component method is obtained by the above-described simulation with respect to the input phase corresponding to the true blood flow velocity. It has been shown that there are large detection errors.

On the other hand, the phase difference of the Doppler signal for each measurement
A method of directly adding the value of the phase difference a plurality of times to obtain an averaged phase difference and converting the averaged speed into a speed is disclosed in the 1978 Ultrasonics Symposium Proceedings (Ultrasonics).
s Symposium Proceedings) at pages 348-352. Hereinafter, this is called a phase difference averaging method. In this method, if the phase difference corresponding to the true blood flow velocity is close to π or −π, the detected phase difference may exceed π or −π every time due to the fluctuation of the detected phase difference due to noise. −
Due to the return of the value at π, the addition result becomes a value near zero, and there is a disadvantage that it is erroneously detected as a low-speed blood flow, so that it cannot be used. To explain this with a diagram, as shown in FIG. 4 (a), the blood flow velocity v is a positive value, and the detected phase differences Δθ _{1 to} Δθ ₈ are dispersed near + π. When the phase differences Δθ ₇ and Δθ ₈ exceed + π, Δθ
₇ , Δθ ₈ is considered a negative angle. Therefore, the result of the addition averaging Δθ _S is a positive angle near zero, which is significantly different from the true average phase difference. Blood flow velocity v is the same when is negative, when the eight addition of the phase difference Δθ ₁ ~Δθ _8, the phase difference [Delta] [theta] _1, [Delta] [theta] ₂ is to cross the - [pi], which are positive angle regarded , the result [Delta] [theta] _S of the arithmetic mean is a negative angle in the vicinity of zero (see FIG. 4 (b)).

The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the above-described problems in the conventional pulsed Doppler measurement apparatus based on the phase difference averaging method, thereby enabling measurement with a high signal-to-noise ratio. And a pulse Doppler measuring device.

[Means for solving the problem]

In order to achieve the above object, one feature of the present invention is to detect a phase difference of an ultrasonic pulse reflected by an object, and calculate an average value of a plurality of sequentially obtained phase differences at a transmission interval of the ultrasonic pulse. In the pulse Doppler measurement device that calculates the speed of the object by dividing the frequency fluctuation by dividing, the addition average of the positive phase difference and the addition average of the negative phase difference among the sequentially obtained phase differences are separately performed. And a means for calculating the sum (weighted sum) of the cosine component and the sine component of the angle indicated by the averaging value, and calculating the declination angle indicated by the sum as the entire average phase difference.

Another feature of the present invention is that, as described above, a correction value detection unit that outputs an overall average phase difference obtained from the sum of sine components and cosine components as an angle correction value, and uses the angle correction value as a base axis of coordinates. A phase difference averaging unit that corrects the values of the individual phase differences, adds and averages the corrected phase differences, and converts the added and averaged value into the original coordinate angle to obtain an average value of the phase difference. It is in the point.

Still another feature of the present invention is that a sequentially obtained phase difference is divided into a positive phase difference and a negative phase difference, and a means for calculating each gravity center angle and power, and a sine component and a cosine component of the positive gravity center angle, respectively. The point is that there is provided a means for multiplying the electric power and applying the respective electric power to the sine component and the cosine component of the negative center-of-gravity angle to obtain the declination indicating the sum of the sine components and the sum of the cosine components. This declination is also converted into a speed as an overall average phase difference, or used as a correction value when performing the averaging of the individual phase differences.

[Action]

As described above, the averaging of the positive phase difference and the averaging of the negative phase difference are separately performed, and the declination 角 of the weighted sum of the cosine and sine components of the angle indicated by each averaging is shown. Is close to the true average of the dispersed Δθ _n as shown by the triangle in FIG. 4 (a) or the triangle in FIG. 4 (b), even if each phase difference is dispersed near + π. Indicates a value. Therefore, even if the true velocity is a value close to + π or close to -π in terms of the Doppler phase difference, the average value of the phase difference is indicated by ▲ in FIG. 4 (a) or (b).
There is no large error caused by mutual cancellation of angles as shown by ▼.

However, in the case of the above ▼, the effect of improving the signal-to-noise ratio with respect to the increase in the number of samples is inferior to that of the simple averaging operation of the phase difference. Therefore, according to a configuration in which the above ▲ is used as an angle correction value of each phase difference, the corrected phase difference is added and averaged, and the added and averaged value is corrected again, for example, in FIG. Since the averaging of the angles of the respective phase differences Δθ _n on the new coordinate axis based on the direction is performed, not only a large error due to the mutual cancellation of the angles does not occur, but also the signal An excellent average phase difference of the noise-to-noise ratio is obtained.

Further, in a configuration in which the respective center-of-gravity angles of the positive phase difference and the negative phase difference are employed to obtain the average phase difference or the correction value for the averaging from the weighted sum of the respective sine components and cosine components. , A more accurate average phase difference or correction value can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing a pulse Doppler measuring apparatus according to an embodiment of the present invention. In the figure, 1 is an ultrasonic transducer, 2 is a transmitting circuit, 3 is a receiving circuit, 4 is a phase comparator, 5 is an A / D converter, 6 is an MTI filter, 7 is a speed calculator, 8 is a switch, 9 is a control unit, 10 is a divider and
Reference numeral 11 denotes a display device. FIG. 1 shows details of the speed calculating section 7. This will be described in detail later.

The pulse Doppler measurement apparatus shown in the present embodiment is based on a phase difference averaging method in which the signal-to-noise ratio is improved, and performs the phase difference averaging method after adding the Doppler argument, correcting the Doppler argument. The outline of the operation is as follows.

The ultrasonic pulse transmitted by the transmission circuit 2 is repeatedly transmitted at equal intervals T from the ultrasonic transducer 1 to the reflecting object 14. The ultrasonic pulse reflected by the reflecting object 14 is received by the receiving circuit 3, and the phase comparator 4 compares the phases of the reference signals α = Acosω ₀ t and α ′ = Asinω ₀ t, The respective outputs V _R and V _I are obtained.

Now, _let the output of the phase comparator 4 for the reflector 14 be V _Rn , V
_In (where n = 1, 2,...), V _Rn and V _In can be represented by the following equations.

V _Rn = A _n cos θ _n (1) V _In = A _n sin θ _n (2) For simplicity, the above equations (1) and (2) are summarized as follows:
It shall be described as follows.

V _n ′ = A _n exp (jθ _n ) (3) This is the output of the A / D converter 5.

Then, when the output V _n of the A / D converter 5 'is input to the MTI6, obtain an output V _n of MTI6. When the primary differential circuit MTI, is _{V n = V n '-V'} n-1 ... (4). Hereinafter referred to the V _n and phase vectors.

Next, the operation of the speed calculator 7 shown in FIG. 1 will be described. The speed calculation unit 7 shown in the present embodiment includes a phase difference averaging unit 71
0 and a correction value detection unit 720. First, the phase vector V _n
There phase (argument) of V _n are input to ATAN memory 711 theta _n is outputted. The delay circuit 712 obtains θ _n−1 one time before and obtains a difference from the current θ _n to obtain a phase difference Δθ _n Δθ _n = θ _n −θ _n−1 (5). The phase difference [Delta] [theta] _n is the sign judgment and piece count 721, a positive number K and a negative number L of [Delta] [theta] _n is counted and replaced secretly respectively arranged as [Delta] [theta] _k and [Delta] [theta] _l. That is, In the averaging units 722 and 723, averaging of Δθ _k and Δθ ₁ is performed, respectively. ▲
If they are ▼ and ▲ ▼, they are expressed by the following equations.

At this time, ▲ ▼ indicates the phase difference Δθ in the first and second quadrants.
_{n is} the average value of the phase differences Δθ _n in the third and fourth quadrants. The reason for performing the averaging by dividing in this manner is that the phase difference Δθ
_{Since n} is limited to the range of ± π, the phase difference Δθ _n
This is to eliminate the occurrence of an error in which the average value approaches zero when the phase differences in the vicinity of ± π cancel each other out when the addition is performed. The COS memory 724 and the SIN memory 725 convert the phase difference ▼ into cosine and sine components. The COS memory 726 and the SIN memory 727 similarly convert the phase difference ▼ into cosine and sine components, respectively. C for adders 728 and 729
The output values of the OS memory 724 and the SIN memory 725 are each added K times. Similarly, the adders 730 and 731 add the output values of the COS memory 726 and the SIN memory 727 L times, respectively. The addition result of the COS memories, that is, the addition result of the adders 728 and 730
X _R, if put the addition result of the addition result i.e. the adder 729 and 731 of the SIN memory comrades and X _I, X _R, X _I expressed the as follows.

If X _R and X _I are the real part and the imaginary part of a complex number, they can be expressed as X = X _R + jX ₂ (9). It is. ATAN memory 732 is a memory for outputting the X _R and X _I ▲ ▼. The above is the outline of the correction value detection unit 720. However, it is also possible to use ▲ as the Doppler declination プ ラ to be obtained instead of the correction value.

In the phase difference averaging unit 710 is for adding to correct the phase difference [Delta] [theta] _n. Use the correction value ▲ ▼ to improve S / N. Angle corrector 713 subtracts the correction value ▲ ▼ accordance with the terms of the following from the [Delta] [theta] _n. The corrected phase difference is Δθ
_m , Δθ _m is Can be represented by

Such [Delta] [theta] _m is a correction value ▲ ▼ value obtained by converting the respective phase difference [Delta] [theta] _n to the angle on the new coordinate axis and cornerstone output from the correction value detection unit 720. Such a Δ
The adder / averager 714 performs an addition average on θ _{n according} to the following equation.

Since this averaging operation is the average of the angles around the center of the dispersed values of Δθ _n as the base axis (the angle of zero), an error such as 落 in FIG. 4A or FIG. ) Does not occur. Next, in the adder 715, the following equation was obtained. Is converted to the value ▲ ▼ of the phase difference on the original coordinate axis.

As described above, the "zero drop" phenomenon in the addition operation of the phase difference did not occur, and the average phase difference Δ ▲ with a small error was obtained by the speed calculation unit 7.

In FIG. 2, the switch 8 is switched by a command from the control unit 9. When the mode is switched to the a side, the phase difference ▼ is divided by the divider 10. If the division result is ω _d , ω _d = ▲ ▼ / T (14) ω _d is the Doppler angular frequency. When the switch is switched to the b side, the phase difference ▲ is divided by the divider 10. At this time, the Doppler angular frequency ω _d is expressed by ω _d = ▲ / T (15). The switch 8 is connected to a console via the control unit 9.
The display unit 11 is connected to the display unit 11 by the user of the apparatus and operates the console 12 so that the display unit 11 can simultaneously display either one of ▲ ▼ or ▲ ▼ or simultaneously perform a parallel display.

According to the above embodiment, in the simple addition of the phase difference, N
Signal-to-noise ratio improvement by averaging Has the effect of being done , It is possible to more accurately estimate the Doppler frequency.

If the value ▲ ▼ obtained from the correction value detection unit 720 is a value close to zero, the “zero drop” phenomenon in the averaging operation is unlikely to occur without performing correction by ▲ ▼.
In this case, the configuration may be such that ▲ ▼ = 0.

FIG. 5 shows a speed calculator according to another embodiment of the present invention. The speed calculation unit in FIG. 5 is also used as the block 7 in the configuration in FIG.

5, the same parts as those in FIG. 1 are denoted by the same reference numerals. Differs from the speed calculation portion of FIG. 1, the origin of a new coordinate for the phase difference average calculation ▲ ▼ (correction value ▲ ▼) power of each phase vector V _n for obtaining the (power) In consideration of the above, the barycentric angle of each phase difference of the first and second phenomena and the barycentric angle of each phase difference of the third and fourth quadrants are calculated, respectively, so that even when noises having greatly different phase differences are mixed, the true value is obtained. In that a correction value ▲ ▼ close to the average phase value is obtained. The power calculator 736 calculates the power P _n from the real part I _n and the imaginary part R _{n of the} phase vector V _n sequentially obtained from the MTI filter of FIG.

P _n = R _n ² + I _n ² (15) The configurations of the ATAN memory 711, delay circuit 712, positive / negative judgment and number counter 721 are the same as those in FIG. 1, and the phase difference Δθ _n between the phase vectors is sequentially calculated. Then, the sign is discriminated and classified into Δθ _k (positive) and Δθ ₁ (negative). Adder 737 is a power calculator 736 only when 721 determines positive.
Add the outputs of The output is Can be expressed as On the other hand, the adder 738 adds the output of the power calculator 736 only when 721 is determined to be negative. The output is Can be expressed as The center-of-gravity calculator 742 uses the positive phase difference Δθ _k distributed in 721, the output P _k of the power calculator 736 corresponding thereto, and the output of the adder 737 to form the first and second quadrants by the following equation. The center-of-gravity angle ▲ ▼ of a certain phase point Δθ _k is _obtained .

On the other hand, the center-of-gravity arithmetic unit 743 has the third and fourth phenomena by using the negative phase difference Δθ ₁ , the output P ₁ of the power arithmetic unit 736 corresponding thereto, and the output of the adder 738 according to the following equation. Phase difference Δ
Obtain the center of gravity angle θ of θ _l .

The memory 724 and the SIN memory 725 convert the center of gravity angle ▼ into a cosine component and a sine component, respectively. COS memory 726, S
The IN memory 727 similarly converts the center of gravity angle ▼ into a cosine component and a sine component, respectively. C for multipliers 728 and 729
Output value of adder 737 to output value of OS memory 724 and SIN memory 725 That is, the power is multiplied. Similarly, in multipliers 730 and 731, C
Power to the output value of OS memory 726 and SIN memory 727 (The output of the adder 738). Sum of COS memory comrades i.e., the addition result of the multiplier 728 and 730 X _R, if put the addition result of the addition result i.e. the multiplier 729 and 731 of the SIN memory comrades and X _I, X _R, X _I is It can be expressed as follows.

Configuration of ATAN memory 732 is also similar to Figure 1, therefore a plurality of polarization of the real part X _R represented by the place in (18) to the aforementioned (8), the imaginary part X _I component from 732 Corner ▲ ▼
Is obtained. The above is the outline of the operation of the correction value detection unit 720 'in the speed calculation unit in FIG.

The configuration and operation of the phase difference averaging unit 710 are the same as those in FIG. That is, in order to prevent an error that occurs when the average of the individual phase differences Δθ _n is directly added,
Is corrected using equation (11), and the phase difference Δθ _m when the origin on the new coordinate axis is set to ▲ ▼ is averaged, and the average phase difference on the original coordinate axis is calculated by equation (13). Convert to get ▲ ▼. Further, the above correction value ▲ ▼ instead of ▲ ▼ may be adopted as the average phase difference and converted into the speed.

〔The invention's effect〕

As described above, according to the present invention, an ultrasonic pulse reflected by an object is received, the phase difference between the ultrasonic pulses is detected, the phase difference is averaged, and then the angle of the phase difference vector is detected. Then, the pulse Doppler measurement apparatus for calculating the speed of the object performs the averaging of the phase difference by dividing the averaging phase difference (angle) by the transmission interval of the ultrasonic pulse to obtain a frequency variation. Since the angle correction means for correcting the angle difference is provided at this time, there is an effect that a pulse doubler measurement apparatus capable of measuring with a high signal-to-noise ratio can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of a speed detector, which is a main part of a pulse Doppler measuring apparatus according to an embodiment of the present invention, FIG. 2 is an overall view of the pulse Doppler measuring apparatus of the embodiment, and FIG. FIG. 4 is a diagram showing characteristics of a measuring device, FIG. 4 is a diagram for explaining a problem of the prior art, and FIG. 5 is a block diagram showing another embodiment of the present invention. 711,732 …… ATAN memory, 712 …… Delay device, 713 …… Angle corrector, 714,722,723 …… Average averaging device, 721 …… Positive / negative discrimination and counting device, 724,726 …… COS memory, 725,727
... SIN memory, 715,728,729,730,731 ... Adder, 2
…… Transmission circuit, 3… Reception circuit, 4 is phase comparator, 5…
... A / D converter, 6 ... MTI filter, 7 ... Speed detector,
8 switch, 9 control unit, 10 divider, 11
Display, 12 ... Operation console.

Continuation of the front page (56) References JP-A-1-320048 (JP, A) JP-A-1-212541 (JP, A) JP-A-64-37936 (JP, A) JP-A-61-25527 (JP) , A) Patent 2704414 (JP, B2) Patent 2714042 (JP, B2) Patent 2714067 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01S 15/00-15/96 G01S 7 / 52-7/66 A61B 8/06

Claims (6)

(57) [Claims] A transmitting / receiving means for transmitting an ultrasonic pulse repeatedly to a test object at a predetermined interval, receiving a reflected wave from the test object, and generating a reception signal from the received reflected wave; Each time a wave signal is generated, a phase detecting means for generating a phase vector representing the phase of the received signal, and each time the phase vector is generated, the previously generated phase vector and the current phase A phase difference detection means for generating a phase difference value between the vector, a plurality of the phase difference values output from the phase difference detection means, a first group having a positive value, and a negative value Means for classifying into the second group;
A phase difference value belonging to the county, a means for obtaining a first total average value from the phase difference values belonging to the second group, and means for converting the first total average value into a flow velocity. Pulse Doppler measurement device. 2. A pulse Doppler measuring apparatus according to claim 1, wherein a phase difference value output from said phase difference detecting means is converted into an angle in a new polar coordinate system in which a direction of said first total average value is regarded as a reference axis. Means for calculating, based on the angle in the new polar coordinates, means for calculating a second total average value of the phase difference values output from the phase difference detection means, wherein the means for converting to the flow velocity is at least A pulse Doppler measuring apparatus, wherein one of the first and second total average values is converted into a flow velocity. 3. Transmitter / receiver means for repeatedly transmitting an ultrasonic pulse to a test object at predetermined intervals, receiving a reflected wave from the test object, and generating a reception signal from the received reflected wave;
Each time the received signal is generated, a phase detecting means for generating a phase vector representing the phase of the received signal, and each time the phase vector is generated, the previously generated phase vector and the current A phase difference detecting means for generating a phase difference value between the phase vector and a plurality of the phase difference values output from the phase difference detecting means, a first group having a positive value, and a negative value Means for classifying into the second group having
Calculating a first average angle from the phase difference values belonging to the group;
Means for calculating a cosine value and a sine value of an average angle of the second group, means for obtaining a second average angle from the phase difference values belonging to the second group, and obtaining a cosine value and a sine value of the second average angle; The first product, which is the product of the cosine value of the first average angle and the first load coefficient equal to the number of the phase difference values belonging to the first group, is calculated as the cosine value of the second average angle and the second product. Means for adding to a second product which is a product of a second load coefficient equal to the number of phase difference values belonging to the second group to obtain a load sum of the cosine values of the first and second average angles; , A third product that is the product of the sine value of the first average angle and the first load coefficient,
Means for adding to a fourth product that is a product of the sine value of the second average angle and the second load coefficient to obtain a load sum of the sine values of the first and second average angles; , The declination of a vector having a real part equal to the load sum of the cosine value and an imaginary part equal to the load sum of the sine value, and a first total of the phase difference values output from the phase difference detection means. A pulse Doppler measuring apparatus comprising: means for calculating an average value; and means for converting the first total average value into a flow velocity. 4. The pulse Doppler measuring apparatus according to claim 3, wherein the phase difference value output from the phase difference detecting means is converted into an angle in a new polar coordinate system in which the direction of the first total average value is regarded as a reference axis. Means, an averaging means for adding and averaging angles in the new polar coordinates, and an output from the averaging means being a second total average value of the phase difference values output from the phase difference detecting means. Means for converting the phase difference value output from the phase difference detection means into an angle in the original polar coordinates, wherein the means for converting into the flow velocity is at least one of the first and second total average values. A pulse Doppler measuring device that converts one into a flow velocity. 5. A transmission / reception means for repeatedly transmitting an ultrasonic pulse to a test object at predetermined intervals, receiving a reflected wave from the test object, and generating a reception signal from the received reflected wave; A phase detector that generates a phase vector representing the phase of the received signal each time a wave signal is generated, and detects a power value that represents the power of the received signal each time the phase vector is generated Means, a phase difference detecting means for generating a phase difference value between the previously generated phase vector and the current phase vector each time the phase vector is generated, and an output from the phase difference detecting means. Means for classifying the plurality of phase difference values into a first group having a positive value and a second group having a negative value, and applying the power value to the phase difference value belonging to the first group. Corresponding to the power value output from the detecting means. Means for obtaining a first average angle by weighting, for obtaining a cosine value and a sine value of the first average angle, and for outputting the power value to a phase difference value belonging to the second group. Means for obtaining a second average angle by weighting in correspondence with the power value, obtaining a cosine value and a sine value of the second average angle, belonging to the first group, and a cosine value of the first average angle A first product corresponding to a phase difference value, which is a product of a first sum equal to a sum of the power values output from the power value detecting means, is calculated by the second product.
And the second sum equal to the sum of the power values output from the power value detecting means, corresponding to the phase difference values belonging to the second group, Means for obtaining the load sum of the cosine values of the first and second average angles, and a third product which is the product of the sine value of the first average angle and the first sum. Is added to a fourth product that is the product of the sine value of the second average angle and the second sum, and the load sum of the sine values of the first and second average angles is calculated. Means for determining, a declination of a vector having a real part equal to the load sum of the cosine value and an imaginary part equal to the load sum of the sine value, 1. A pulse Doppler comprising: means for obtaining a total average value of the first parameter; and means for converting the first total average value into a flow velocity. Measuring apparatus. 6. A pulse Doppler measuring apparatus according to claim 5, wherein a phase difference value output from said phase difference detecting means is converted into an angle in a new polar coordinate system in which a direction of said first total average value is regarded as a reference axis. Means for adding and averaging angles in the new polar coordinates; and outputting the output of the means for adding and averaging the phase difference as a second total average value of the phase difference values output from the phase difference detecting means. Means for converting the phase difference output from the detection means into a value in the original polar coordinates, wherein the means for converting into the flow velocity comprises at least one of the first and second total average values. A pulse Doppler measurement device characterized in that the measurement is converted into a pulse Doppler.