JP3408943B2 - Two-frequency measurement method and multi-frequency radar device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-frequency measuring method for performing measurement on a target by using two types of radar transmission frequencies, and further to a multi-frequency radar device suitable for implementing this two-frequency measuring method. .

[0002]

2. Description of the Related Art "Satellite-borne radar" (Kumagaya et al., IEICE Technical Report, SANE 93-52, October 1993, pp. 67-72) shows scattered scatterers (for example, rainfall and cloud particles).
The radar equation when the observation targets in the radar, the target particle formula deformed under the assumption that the size of laser rie scattering holds small enough is marked (although decay Ignore the effect). According to this equation, the radar reception power is inversely proportional to the square of the radar transmission wavelength,
It can be said that the higher the radar transmission frequency, the larger the radar reception power, that is, the higher the sensitivity of target detection / observation. The above paper further examines the effect of attenuation, and states that lower radar transmission frequencies are less susceptible to atmospheric attenuation. In the above paper, these two related to radar transmission frequencies
Based on the knowledge of the types, 2 of 94 GHz and 35 GHz
We propose a dual-frequency measurement that uses different types of radar transmission frequencies. According to the two-frequency radar that performs such two-frequency measurement, high sensitivity can be realized for a cloud having a low density, and clouds having a high density and vertically distributed (for example, cumulonimbus) can be seen from the top of the cloud. Quantitative measurements can be performed over the bottom.

[0003]

However, although it is possible to increase the sensitivity by increasing the radar transmission frequency, it is not possible to obtain sufficient sensitivity by itself, and therefore an observation result with sufficient accuracy is obtained. I can't do it either. This is because noises or errors occur due to various causes such as various clutters that are received together with echoes, receiver noises generated by the receivers, and rounding errors that occur in calculation when measuring two frequencies. In particular, as described in the above-mentioned paper, a meteorological radar targeting a distributed scatterer such as cloud particles may be susceptible to clutter due to the nature of its application.

According to the present invention, various noises or errors such as clutter and other noises generated before the receiver, receiver noises generated by the receiver, rounding error generated by the two-frequency measuring method itself, etc. It is an object of the present invention to realize a method or apparatus that can reduce the influence on the execution result and can perform more accurate dual-frequency measurement than the conventional method.

[0005]

[0006]

According to a first aspect of the present invention, target information relating to the property of a target is obtained based on two types of observation data indicating radar reception power at each of two types of radar transmission frequencies forming a transmission frequency pair. In the two-frequency measurement method including the step of generating the target information, the method includes a compensation step of compensating for the noise component contained in each of the two types of observation data, prior to the generation of the target information. This supplement
The compensation step includes a step of measuring the noise component by a transmission / reception operation in the direction in which the target does not exist .

A second configuration of the present invention has a step of generating target information relating to the property of the target based on two types of observation data indicating the radar reception power at each of the two types of radar transmission frequencies forming a transmission frequency pair. In the two-frequency measurement method, there is a step of setting the distance resolution of the two types of observation data according to the difference of the observation data due to the difference of the distance resolution so that the rounding error generated when generating the target information is relatively small. It is a thing. A third configuration of the present invention has a step of switching the distance resolution in the second configuration so that a plurality of types of observation data having different distance resolutions are generated for each radar transmission frequency. A fourth configuration of the present invention has a step of resampling the observation data in the second configuration so that a plurality of types of observation data having different distance resolutions are generated for each radar transmission frequency.

A fifth configuration of the present invention has a step of generating target information relating to the property of the target based on two types of observation data indicating the radar reception power at each of two types of radar transmission frequencies forming a transmission frequency pair. In the two-frequency measurement method, the step of generating the target information is executed for each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies, and the two-frequency measurement method is A step of combining a plurality of sets of target information with a relatively large weight given to the target information based on the radar transmission frequency having a relatively high signal reception quality. A sixth configuration of the present invention is a two-frequency measurement including a step of generating target information regarding a property of a target based on two types of observation data indicating radar reception powers by two types of radar transmission frequencies forming a transmission frequency pair. In the method, the step of generating the target information is executed corresponding to each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies, and the two-frequency measurement method is relatively It has a step of selecting target information related to a transmission frequency pair including a radar transmission frequency having high signal reception quality. A seventh configuration of the present invention is a transmission frequency pair of 2
In a two-frequency measurement method that generates target information related to the property of a target based on two types of observation data indicating radar reception power at each type of radar transmission frequency, a signal reception is relatively performed from three or more types of radar transmission frequencies. The method further comprises the step of selectively setting the transmission frequency pair including the radar transmission frequency having high quality. An eighth structure of the present invention is the structure of any one of the fifth to seventh structures, which has a step of calculating the signal reception quality based on the information about the temperature of the radar receiver. 9th of this invention
Configuration, in the construction of the fifth to seventh ninth,
The method has a step of measuring the signal reception quality by a transmission / reception operation in a direction in which no target exists. A tenth structure of the present invention is the fifth to seventh structure, wherein:
It has a step of measuring the signal reception quality by an operation of executing reception while transmission is not executed.

The eleventh structure of the present invention is the first to the first
In any one of the configurations of 0 , the step of generating the target information includes a sub-step of obtaining a difference due to the radar transmission frequency of the variation in the distance direction that appears in the two types of observation data, the obtained difference, the radar transmission frequency, and the water vapor. And a sub-step for obtaining the amount of cloud water based on the information on the density and the cloud temperature.

A multi-frequency radar device according to a twelfth structure of the present invention includes a plurality of radar transmitting / receiving sections for executing a search for a target at different radar transmission frequencies and generating the observation data, and the first through eleventh aspects. And a signal processing unit that executes the two-frequency measurement method according to any one of the configurations.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Embodiment 1. 1 to 3 show a first embodiment of the present invention.
Shows the configuration of. As shown in FIG. 1, the radar device according to this embodiment is provided with n (n is a natural number of 2 or more) transmitting / receiving units 1-1, 1-2, ... 1-n and corresponding thereto. Transmission / reception antennas 2-1 2-2, ... 2-n are provided. Each transmitting / receiving unit 1-i (i is a natural number from 1 to n)
Has a transmitter 3 for transmitting a radar pulse at a predetermined repetition period and a predetermined carrier frequency (radar transmission frequency) fi, and the radar pulse transmitted from the transmitter 3 is shared by the transmission / reception antenna 2-i. It is radiated to the outside from the corresponding transmission / reception antenna 2-i via the transmission / reception switch 4 which is a means for performing. If a target 5 such as a cloud particle exists in the radiation direction, this radar pulse is reflected by the target 5 and received by the transmitting / receiving antenna 2-i. Transmission / reception antenna 2-
The radar pulse received at i, that is, the echo from the target 5 is supplied to the receiver 6 via the duplexer 4, and the receiver 6
It is subjected to amplification and other processing at, converted into digital data at the A / D converter 7, and temporarily stored in the buffer memory 8. This data is data indicating the radar reception power, and when the target 5 is a scatterer such as a cloud, it reflects information on the property of the scatterer, for example, the amount of cloud water. Therefore, in the following description, the digital data stored in the buffer memory 8 will be referred to as observation data Zmi.

Further, the radar transmission frequency in each transmission / reception unit is different from the radar transmission frequency in the other transmission / reception units. Therefore, there is a difference in content due to the difference in radar transmission frequency between the observation data obtained by different transmitting / receiving units. If the radar transmission frequency f1 used in the transmission / reception unit 1-1 is higher than the radar transmission frequency f2 used in the transmission / reception unit 1-2, the transmission / reception unit 1
The observation data Zm1 obtained in -1 has a higher sensitivity (it is less likely to be buried in clutter etc.), and the observation data Zm2 obtained in the transmission / reception unit 1-2 is less susceptible to the influence of atmospheric attenuation. Occurs (see above paper).

The radar device shown in FIG. 1 further includes a signal processing section 9 and a display section 10. The signal processing unit 9
As shown in FIG. 2, it has a two-frequency measurement method execution circuit 11. The dual-frequency measurement method execution circuit 11 includes transmission / reception units 1-1, 1
-2, ... n observation data Zm obtained in 1-n
At least two types of observation data among 1, Zm2, ... Zmn are used to execute the calculation process related to the dual frequency measurement, and the target information regarding the property of the target 5 is derived. For example, if the target 5 is a cloud, the amount of cloud water (or the amount of cloud ice, hereinafter referred to as the amount of cloud water) M is derived. When deriving the cloud water amount M,
The procedure of obtaining the difference between different transmission frequencies of the radar reception power fluctuation amount along the time axis direction (distance direction) and obtaining the cloud water amount M from the relationship between this difference and the propagation loss per unit distance is used.

Here, the principle of dual frequency measurement will be described. Now, when the radar reception power related to the distance r is expressed as Pr (r) and the propagation loss per unit distance is expressed as k (r),
From the radar equation when targeting a scatterer (see above paper),

[Equation 1] Can be derived. Therefore, if the radar received power fluctuation amount along the time axis direction (distance direction) is defined as the ratio (logarithmic difference) of the radar received power between adjacent range bins, the fluctuation amount is

[Equation 2] (However, Δr is distance resolution), the following formula

[Equation 3] Holds approximately. As mentioned above, the observation data Zm
1, Zm2, ... Zmn are radar transmission frequencies f1 and f, respectively.
Since the radar received power at 2, ...
Observation data Zma and Zm selected from two observation data Zm1, Zm2, ... Zmn selected from these n observation data
If the difference δ of the above-mentioned fluctuation amount for b is calculated,

[Equation 4] Becomes

On the other hand, the propagation loss k (r) per unit distance is

[Equation 5] Given by

[Equation 6] Is. The water vapor density g and the cloud temperature T are quantities that can be separately detected or estimated, the observation data Zma and Zmb are obtained from the transmitter / receiver, and the frequencies fa and fb and the distance resolution Δr are quantities that are determined by design. The cloud water amount M can be derived by using the equations 4 and 6. Note that various attenuations Loxy, Lvap, and Lcl in the equation 5 are
d is the following formula

[Equation 7]

[Equation 8]

[Equation 9] You can ask at. In each formula, the unit of frequency is GH
The unit of z, the density and the amount of cloud water is g / m ³ , the unit of temperature is Celsius, and the unit of attenuation is dB / km.

An averaging circuit 12, a propagation loss calculating circuit 13, a radar reflection factor calculating circuit 14 and a meteorological parameter calculating circuit 15 are provided in this order after the dual frequency measuring method executing circuit 11. As shown in FIG. 3, the averaging circuit 12 includes n0 delay circuits 16-1, 16- (n0 is a natural number).
It has a built-in circuit in which 2, ... 16-n0 are connected in cascade.
Therefore, when the amount of cloud water input at a certain point of time is expressed as M (r), each delay circuit 16-1, 16-2,
The outputs of 16-n0 are M (r-Δr) and M (r
−2 × Δr), ... M (r−n0 × Δr) The averaging circuit 12 further has a built-in average calculation circuit 17, and the average calculation circuit 17 includes M (r), M
(R−Δr), M (r−2 × Δr), ... M (r−n0 ×)
By calculating the sum of Δr) and dividing by n0 + 1, n0 +
The average value of the amount of cloud water M for one sample is obtained.

The propagation loss calculation circuit 13 includes an averaging circuit 12
The average value calculated in 1 is input as the cloud water amount M, and the propagation loss Lenv is obtained from this cloud water amount M. Here, the propagation loss Lenv is 10 “power” appearing on the right side of the radar equation shown in Formula 1, that is, the propagation loss k per unit distance.
It is a quantity defined by the integral of (r), and when the bottom of Napier is adopted as the base

[Equation 10] Is expressed as By using the cloud water amount M obtained by the two-frequency measurement method execution circuit 11 and averaged in the distance direction by the averaging circuit 12, k (r) in the equation 10 can be obtained for each radar transmission frequency. The propagation loss calculation circuit 13 has 2
Based on any of the observation data Zmi input to the frequency measurement method execution circuit 11 and the propagation loss per unit distance ki (r) corresponding to this observation data Zmi, the radar transmission frequency fi is calculated using the above equation. Propagation loss Lenv
Find i.

The radar reflection factor calculation circuit 14 uses the radar reception power Pr in the radar equation when a scatterer is targeted.
Paying attention to the fact that is proportional to the radar reflection factor D, the radar reflection factor D is obtained. Here, in the radar equation when the scatterer is the target, the radar reception power Pr is equal to the transmission frequency fi.
Is proportional to the square of. If this frequency dependence is removed by the processing by the circuit before the radar reflection factor calculation circuit 14, the radar reflection factor Z (this does not depend on frequency) is given by the following equation.

[Equation 11] Can be obtained from Radar reflection factor calculation circuit 14
Is the observation data Zmi and the corresponding propagation loss Le.
Based on nvi, using this equation, the radar reflectivity factor Z
Ask for.

The meteorological parameter calculation circuit 15 calculates a meteorological parameter D such as precipitation based on the cloud water amount M, the propagation loss Lenvi, the radar reflection factor Z, etc., and supplies the meteorological parameter D to the display unit 10. The display unit 10 displays information about weather based on the supplied weather parameter D and the like.

With such a configuration, the amount of cloud water M and the meteorological parameter D in which noise or error is reduced as compared with the conventional case
Can be derived. That is, the averaging circuit 1 for the cloud water amount M
Since the averaging process is performed in 2, the error variance of the cloud water amount M is reduced to n0 ^-1/2 times the value before averaging. Therefore, according to this embodiment, it is possible to mitigate the influence of noise or measurement error generated in the steps up to the dual frequency measurement method execution circuit 11.

Embodiment 2. Embodiment 2 of this invention
Is an embodiment in which the averaging circuit 12 in the first embodiment is modified to have an n0 sample integrating circuit 18 and an average calculating circuit 19 as shown in FIG.
The n0 sample integrating circuit 18 integrates n0 cloud water amounts M,
The average calculation circuit 19 divides the result by n0 to obtain
The average value of the amount of cloud water M over the period of n0 samples is obtained. The difference between the averaging circuit 12 shown in FIG. 3 and the averaging circuit 12 shown in FIG. 4 is that the former is, so to speak, performing a moving average calculation and that the sample period of the cloud water amount M does not change even after the averaging. On the other hand, in the latter case, the cloud water content M for n0 samples is averaged, and the sampling cycle of the cloud water content M after averaging is 1 / n0 before averaging. Therefore, in this embodiment, in addition to obtaining all the effects obtained in the first embodiment, the information processing amount in the circuits after the propagation loss calculation circuit 13 becomes 1 / n0, and the processing load is lightened. You can also get the effect.

Embodiment 3. Embodiment 3 of the present invention
Is to add an observation data averaging function and a distance resolution switching function to the two-frequency measurement method execution circuit 11 in the first or second embodiment so that the averaging circuit 12 in the latter stage of the two-frequency measurement method execution circuit 11 can be eliminated. In addition, it is an embodiment in which the rounding error caused by the two-frequency measurement calculation can be reduced.

FIG. 5 shows the functional configuration of the dual frequency measurement method execution circuit 11 in this embodiment, taking the case of n = 2 as an example. The dual frequency measurement method execution circuit 11 shown in FIG.
Dual frequency measurement method execution unit 20, input circuits 21-1 and 21-
2. Resolution selection circuit 22 and resolution selection control circuit 23
have. The two-frequency measurement method execution unit 20 inputs two types of observation data (Zm1 and Zm2 when n = 2).
Point Hereinafter, for general handling, the cloud water amount M is calculated according to the above-described principle, based on a set of inputs to one dual-frequency measurement method execution circuit, which will be expressed as Zma and Zmb). The input circuits 21-1 and 21-2 perform averaging processing on the observation data Zm1 and Zm2 to be input as Zma and Zmb to the two-frequency measurement method execution unit 20, respectively.
The resolution selection circuit 22 selects the observation data Zma and Zmb related to the required distance resolution Δr and supplies the observation data Zma and Zmb to the two-frequency measurement method execution unit 20. The two-frequency measurement method execution unit 20 executes the two-frequency measurement calculation based on the above-mentioned principle based on the observation data Zma and Zmb, and derives the cloud water amount M.

The input circuit 21-j (j is a natural number not less than 1 and not more than n) has n0 delay circuits 24-- as shown in FIG.
A circuit in which 1, 24-2, ... 24-n0 are connected in cascade is built in. Therefore, if the observation data Zmj input at a certain point of time is expressed as Zmj (r), the outputs of the delay circuits 24-1, 24-2, ... 24-n0 are Zm (r-Δr), Zm (r-2 × Δr), ... Zm
It can be expressed as (r−n0 × Δr). Averaging circuit 2
1-j further has a built-in average calculation circuit 25, and this average calculation circuit 25 has Zm (r) and Zm (r-Δ
r), Zm (r-2 × Δr), ... Zm (r−n0 × Δ
r) is obtained and divided by n0 + 1 to obtain n0 + 1
The average value of the observation data Zmj for the sample is calculated. The obtained average value is input as observation data Zmj to the two-frequency measurement method execution unit 20 via the resolution selection circuit 22. Therefore, in this embodiment, the variance included in the observation data Zmj, for example, the variance caused by clutter, receiver noise, etc., can be suppressed to n0 ^-1/2 times. The resolution selection circuit 22 is
The distance resolution Δr of the observation data Zma and Zmb is appropriately Δ
While switching among r1, Δr2, ..., Which distance resolution is to minimize the rounding error occurring in the two-frequency measurement method execution unit 20 is determined, and the observation data Zma related to the distance resolution selected according to the determination result is determined. And Zmb to the dual frequency measurement method execution circuit 11. In order to realize such a function, the resolution selection circuit 22 includes switches 26a and 26b provided corresponding to the observation data Zma and Zmb, as shown in FIG. Switch 2
6a is an observation data Zma having a distance resolution Δr1 and a distance resolution Δr based on the input observation data Zma.
A plurality of types of observation data Zma having different distance resolutions are generated, such as observation data Zma having two. The switch 26b relates to the observation data Zmb,
It functions and functions similarly to the switch 26a.

The logarithmic difference calculation circuits 27-1, 27-2, ... At the subsequent stage of the switches 26a and 26b have distance resolutions Δr1 and Δr that the observation data Zma and Zmb can take.
2, observation data Zma and observation data Zm that have corresponding distance resolutions, respectively.
The above-mentioned difference δ is calculated based on b. The comparison circuit 28 provided in the subsequent stage is a logarithmic difference calculation circuit 27-
1, 27-2, ... (δ1 in FIG. 7,
.delta.2, ...) Are compared with each other to determine which is the largest. As is clear from the above-mentioned formula 4, the difference δ
It can be expected that the larger the value of, the smaller the rounding error that occurs in the two-frequency measurement calculation. Therefore, the comparison circuit 28 generates a resolution selection command SELΔr for designating the distance resolution having the largest difference. The generated resolution selection command SELΔr is used for the switches 26a and 26a.
b It is supplied to the selector 29 in the subsequent stage. The selector 29 is
The observation data Zma and Zmb having the distance resolution specified by the resolution selection command SELΔr are selected and supplied to the two-frequency measurement method execution unit 20. Therefore, in this embodiment, it is possible to reduce the rounding error that occurs when measuring two frequencies.

Fourth Embodiment Embodiment 4 of the present invention
Is an embodiment in which the input circuit 21-j in the third embodiment is modified to have an n0 sample integrating circuit 30 and an average calculating circuit 31 as shown in FIG.
The n0 sample integration circuit 30 integrates n0 pieces of observation data Zmj, and the average calculation circuit 31 divides the result by n0 to obtain the observation data Z in the period of n0 samples.
Calculate the average value of mj. The input circuit 21 shown in FIG.
The difference between j and the input circuit 21-j shown in FIG. 8 is that the former is so-called moving average calculation and the sampling period of the observation data Zmj does not change after the averaging, whereas the latter has n0 samples. Minute observation data Zmj are averaged, and the sampling period of the observation data Zmj after averaging is 1 / n0 before averaging. Therefore, in this embodiment, in addition to obtaining all the effects obtained in the third embodiment, the information processing amount in the circuits after the resolution selection circuit 22 becomes 1 / n0, and the processing load is lightened. The effect is also obtained.

Embodiment 5. Embodiment 5 of the present invention
Are the switches 26a and 2 in the third or fourth embodiment.
6b is modified, and as shown in FIG. 9, resampling circuits 32-1a, 32-2a, ... And 32-1b, 3 respectively.
This is an embodiment having a configuration including 2-2b, .... Explaining the switch 26a as an example, the observation data Zma input to the switch 26a is directly given to the selector 29, while the resampling circuits 32-1a, 3-1
.. are resampled at rates different from each other, whereby observation data Zma having a distance resolution different from that of the observation data Zma given to the selector 29 as it is is generated. Switch 26b
Has the same operation and function as the switch 26a with respect to the observation data Zmb. Therefore, in this embodiment, it is possible to obtain the same function and effect as the switching of the distance resolution without switching the distance resolution. That is, since the distance resolution is not switched during observation, the observation time can be shortened.

Sixth Embodiment Embodiment 6 of the present invention
Is an embodiment in which the input circuit 21-j in Embodiments 3 to 5 is modified to compensate the receiver noise included in the observation data Zmj as shown in FIG. That is, the input circuit 21-j corresponds to the corresponding receiver 6
It has a receiver noise detection circuit 32 for detecting the receiver noise Nj. The input circuit 28-j receives the receiver noise Nj.
And the observation data Zmj are respectively provided with Fourier transform circuits 33 and 34 for the region of time t (that is, the region of distance) to the region of frequency f. Fourier transform circuit 3
Receiver noise Nj in the frequency domain obtained from 3 and 34
(F) and the observation data Zmj (f) are input to the subtraction circuit 35. The subtraction circuit 35 compensates the component of the receiver noise Nj (f) in the observation data Zmj (f) by subtracting the receiver noise Nj (f) from the observation data Zmj (f), and the resulting frequency domain is obtained. Is supplied to the inverse Fourier transform circuit 36 as observation data Zmj (f). The inverse Fourier transform circuit 36 uses the observation data Zmj.
(F) is converted from the frequency domain to the observation data Zmj (r) in the time domain, that is, the distance domain, and is output to the resolution selection circuit 22 and other subsequent circuits. Therefore, according to this embodiment, the receiver noise component N included in the observation data Zmj
Since j can be suppressed and the S / N ratio of the observation data Zmj can be improved, the accuracy of the two-frequency measurement executed based on the observation data Zmj can be improved.

FIG. 11 shows an example of the operation of the receiver noise detection circuit 32 in this embodiment. In the operation shown in this figure, the receiver noise detection circuit 32 first detects the temperature Tj of the receiver 6 by the temperature sensor 37 attached to the corresponding receiver 6 (100). next,
The receiver noise detection circuit 32 has the following equation.

[Equation 12] The receiver noise Nj is calculated in accordance with (101) and the result is output to the Fourier transform circuit 33 (102). In the above equation, Nmj is the noise figure, hj is the transmission pulse spatial tone, k is the Boltzmann constant, c is the speed of light, and temperature Tj is expressed in absolute temperature. By adopting such a procedure, in this embodiment, the receiver noise Nj can be evaluated in advance without waiting for the input of the observation data Zmj. This can be compensated for in stages. Note that this embodiment can be combined with Embodiment 1 or 2.

Embodiment 7. Embodiment 7 of the present invention
Is a modification of the operation procedure of the receiver noise detection circuit 32 in the sixth embodiment, and detects the receiver noise Nj using the observation data Zmj in the direction in which the echo from the target 5 does not exist as shown in FIG. It is an embodiment that adopts the procedure. That is, the receiver noise detection circuit 32 first inputs the observation data Zmj (103), and the observation data Zmj is input.
When it can be considered that the target 5 does not exist in the observation direction obtained from the observation data Zmj as viewed from j (10
4), the observation data Zmj is stored as noise (1
05). The receiver noise detection circuit 32 outputs the stored observation data Zmj as receiver noise Nj (10
6). Therefore, also in this embodiment, the same operational effect as that of the sixth embodiment can be realized. Further, in this embodiment, although the observation data Zmj is required to be input, the observation data Zmj applied in the direction in which the target 5 does not exist is used. Not only this, it is possible to cancel out the influence of noise components, such as clutter, which occur in the stage before the receiver 6. Note that this embodiment can also be combined with Embodiment 1 or 2.

Embodiment 8. Embodiment 8 of the present invention
Is a modification of the operation procedure of the receiver noise detection circuit 32 according to the sixth embodiment, intentionally generating a timing at which transmission is not executed as shown in FIG. 13, and observation data obtained in a state where transmission is not executed. In this embodiment, Zmj is regarded as noise Nj. That is, the receiver noise detection circuit 3
2 is (10) when a predetermined transmission non-execution condition is satisfied, such as when a predetermined time has elapsed from the previous transmission non-execution timing.
7) Then, the corresponding transmitter 3 is instructed to cut off the transmission pulse (108), and as a result, the observation data Zmj obtained while the transmission is not executed is input / stored (109). The observation data Zmj when not transmitting is related to noise generated in the receiver 6 or the like, that is, the above-mentioned receiver noise Nj and unnecessary radiation incident on the corresponding transmitting / receiving antenna 2-j, and thus these Can be regarded as noise.
Therefore, the receiver noise detection circuit 32 executes step 106. With such a configuration, in this embodiment, it is possible to obtain the same operational effects as those of the above-described sixth or seventh embodiment. However, this embodiment is superior to the sixth embodiment in that it can compensate the unwanted radiation incident on the transmission / reception antenna 2-j, but on the other hand, it cannot compensate the clutter because the transmission is not performed. It is inferior to 7. Also, this embodiment can be combined with the first or second embodiment as in the sixth and seventh embodiments.

Ninth Embodiment In describing each of the above-described embodiments, particularly Embodiments 3 to 8, two types of observation data Zm1 and Zm2 were assumed for convenience of explanation, but the present invention has three or more types of observation data Zm1, Zm2,
It can also be realized as a circuit that inputs Zm3, ... And executes two-frequency measurement based on it. The ninth embodiment of the present invention is a modification of the configuration of the so-called dual frequency measurement method execution circuit 11 in the first to eighth embodiments, and has three or more kinds of observation data relating to mutually different radar transmission frequencies f1, f2, f3, .... Several pairs of observation data are set from Zm1, Zm2, Zm3, ..., Two-frequency measurement is executed for each observation data pair, and the average of a plurality of cloud water amounts obtained as a result is weighted and added. The cloud water amount M to be supplied to the propagation loss calculation circuit 13 via the circuit 12 or directly,
It is intended to be derived.

That is, the two-frequency measurement method execution circuit 11 in this embodiment, as shown in FIG. 14, corresponds to three or more kinds of observation data Zm1, Zm2, Zm3, ... 21-2, 21-3, ... Are given. Input circuits 21-1, 21-2, 21-
.. have the structure as shown in FIG. 6 or FIG. Further, the input circuits 21-1, 21-2,
21-3, ... In the latter stage, resolution selection circuits 22-1, 2
2-2, 22-3, ... Are provided. Each of the resolution selection circuits 22-1, 22-2, 22-3, ... Has a configuration as shown in FIG. 7 or FIG.
You have entered different observation data pairs. For example, the resolution selection circuit 22-1 sets the observation data Zm1 and Zm2, and the resolution selection circuit 22-2 sets the observation data Zm2 and Zm3.
The resolution selection circuit 22-3 uses observation data Zm1 and Zm3.
The input is different, such as. The outputs of the resolution selection circuits 22-1, 22-2, 22-3, ...
Dual frequency measurement method execution circuit 20-
1, 20-2, 20-3, ..., And the two-frequency measurement method execution circuits 20-1, 20-2, 20- are provided.
3 ... Derives a cloud water amount M12 based on the observation data Zm1 and Zm2, a cloud water amount M23 based on the observation data Zm2 and Zm3, a cloud water amount M13 based on the observation data Zm1 and Zm3, and supplies them to the combination / selection circuit 38. To do. The combination / selection circuit 38, under the control of the combination / selection control circuit 39, supplies these cloud water amounts M12, M23, M13 ,.
Is weighted and added, and the resulting data is output as the amount of cloud water M.

FIG. 15 shows the combination / connection in this embodiment.
The internal configurations of the selection circuit 38 and the combination / selection control circuit 39 are shown. The coupling / selection control circuit 39 includes receiver noise detection circuits 40-1 and 40- provided corresponding to each receiver 6.
2, 40-3, ..., These receiver noise detection circuits 40-1, 40-2, 40-3 are shown in FIGS.
3 and the like, noise components N1 included in the corresponding observation data Zm1, Zm2, Zm3, ...
N2, N3, ... Are detected. Receiver noise detection circuit 40-
S / N ratio calculation circuits 41-1, 41-2, 41-3, ... Are provided at the subsequent stages of 1, 40-2, 40-3 ,. , 41-2, 41
-3, ... is the following formula

[Equation 13] Corresponding observation data Zm1, Zm2, Zm3, ...
S / N ratios SNR1, SNR2, SNR3, ... Of are calculated. The weight determining circuit 42 uses the S / N ratios SNR1 and SNR.
Based on NR2, SNR3, ... Weights w1, w2, w3,
... is determined and the weighted addition circuit 43 in the combination / selection circuit 38 is determined.
Give to. The weighted addition circuit 43 determines the determined weight w1,
The amount of cloud water M12, M23, M1 using w2, w3, ...
The cloud water amount M is derived by weighted addition of 3, ...
Here, the weight determination circuit 42 determines the weight so that the cloud water amount based on the observation data having a good S / N ratio is given a relatively large weight. Therefore, the cloud water amount M obtained from the weighted addition circuit 43 is the cloud water amount M whose error is reduced by utilizing the observation data having a good S / N ratio. Therefore,
As a result, the accuracy of the cloud water amount M output from the dual frequency measurement method execution circuit 11 is increased.

Embodiment 10. Embodiment 1 of the present invention
0 is a modification of the configurations of the coupling / selection circuit 38 and the coupling / selection control circuit 39 in the ninth embodiment, and as shown in FIG. 16, one of the cloud water amounts M12, M23, M13, ... This is an embodiment in which the configuration is selected according to. That is, the combination / selection control circuit 3 shown in FIG.
9 has a comparison circuit 44 for selecting the best value from among the S / N ratios SNR, SNR2, SNR3 ,.
The comparison circuit 44 generates a cloud water content selection command SELM based on the result of this comparison. The selector 45 of the coupling / selection circuit 38 responds to this cloud water amount selection command by selecting the cloud water amounts M12 and M2.
Of M3, M13, ..., the one calculated based on the observation data relating to the best S / N ratio is selected, and the selected amount of cloud water is output to the subsequent stage as the amount of cloud water M. Even with this configuration, the same operational effects as those of the above-described ninth embodiment can be obtained.

Eleventh Embodiment Embodiment 1 of the present invention
1 is a two-frequency measurement method execution circuit 1 according to the tenth embodiment.
It is an embodiment according to a configuration in which the selection process is executed before performing the two-frequency measurement method instead of after performing the modification to No. 1. That is, as shown in FIG. 17, the two-frequency measurement method execution circuit 11 in this embodiment is used.
Is a selection circuit 46 that selects any two of the observation data Zm1, Zm2, Zm3, ... Input by the input circuits 21-1, 21-2, 21-3 ,. The selection control circuit 47 for controlling Further, the resolution selection circuit 22 is one, and the two-frequency measurement method execution unit 20 is also one. Such a configuration has an advantage that the number of dual-frequency measurement method execution units 20 and the like can be reduced as compared with the tenth embodiment, and therefore the circuit scale can be reduced.

The selection circuit 46 and the selection control circuit 47 shown in FIG. 17 have an internal configuration as shown in FIG. 18, for example. As shown in this figure, the selection control circuit 47 is
It has an internal configuration similar to that of coupling / selection control circuit 39 shown in FIG. However, the command output from the comparison circuit 44 is not the cloud water amount selection command SELM but the observation data selection command SELZm. Selector 45 in selection circuit 46
Selects any two of the observation data Zm1, Zm2, Zm3, ... According to the observation data selection command SELZm, and selects the two observation data Zma and Zm.
b is the resolution selection circuit 22 and the two-frequency measurement method execution unit 2
Supply to 0. Here, the comparison circuit 44 instructs the observation data selection command SE to instruct observation data with a good S / N ratio.
It emits LZm. Therefore, it can be expected that the measurement accuracy of the cloud water amount M obtained from the so-called two-frequency measurement method execution unit 20 becomes relatively good.

[0038]

[0039]

According to the first configuration of the present invention, the noise component contained in each of the two types of observation data obtained by the two-frequency measurement is compensated prior to the generation of the target information based on the observation data. Therefore, it is possible to reduce the influence of various noises generated before compensation, including clutter, receiver noise, and the like, and it is possible to obtain weather information in which the influence of noise is reduced as compared with the conventional case. In particular, in addition to being able to reduce the effects of clutter not only receiver noise in the order to measure the noise component by the transmitting and receiving operation according to the direction in which there are no targets, transmission operations such to execute a received while transmission not run need to run the control is not name.

According to the second configuration of the present invention, since the distance resolution is set according to the difference in observation data due to the difference in distance resolution, it is possible to reduce the rounding error that occurs in the dual frequency measurement method. It is possible to obtain target information with a smaller error than in the past. According to the third configuration of the present invention, since the distance resolution is switched so that a plurality of types of observation data having different distance resolutions are generated for each radar transmission frequency, a difference in observation data due to a difference in distance resolution, for example, The difference value between different frequencies of the received power fluctuation along the time axis direction (distance direction) can be accurately and reliably evaluated. According to the fourth configuration of the present invention, the observation data is resampled so that plural kinds of observation data having different distance resolutions are generated for each radar transmission frequency. Can be realized without switching, and therefore the observation time can be shortened.

According to the fifth aspect of the present invention, two-frequency measurement is executed for each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies (target information is generated). ) And the target information based on the radar transmission frequency having a relatively high signal reception quality (for example, S / N ratio) is combined with a plurality of types of target information with a relatively large weight, so that clutter and receiver noise are combined. It is possible to reduce the influence of noise generated before the target information is combined with each other including the target information on the target information. According to the sixth configuration of the present invention, two-frequency measurement is executed (target information is generated) corresponding to each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies, and , Since the target information related to the transmission frequency pair including the radar transmission frequency with relatively high signal reception quality is selected, the noise generated before selecting the target information including the clutter and receiver noise affects the target information. The impact can be minimized. According to the seventh configuration of the present invention, among three or more types of radar transmission frequencies,
Since the transmission frequency pair including the radar transmission frequency, which has a relatively high signal reception quality, is selected and set, the influence of noise generated before selecting the transmission frequency pair including clutter and receiver noise on the target information is minimized. both to be able to suppress the limit, the order selection is made at an earlier stage 6
The number of circuits for two-frequency measurement can be reduced as compared with the above configuration. According to the eighth configuration of the present invention, since the signal reception quality is calculated based on the information about the temperature of the radar receiver, the receiver noise can be reduced with respect to the fifth to seventh configurations.
It can be suppressed appropriately . According to the ninth configuration of the present invention, the signal reception quality is measured by the transmission / reception operation in the direction in which the target does not exist, and therefore the same effects as the first configuration can be realized with respect to the fifth to seventh configurations. . This invention
According to the configuration of 10, since the signal reception quality is measured by the operation of executing the reception while the transmission is not executed,
Regarding the fifth to seventh configurations, not only the receiver noise but also the
It is possible to reduce the influence of data .

According to the eleventh configuration of the present invention, the difference in the distance direction variation appearing in the two types of observation data is obtained by the radar transmission frequency, and the obtained difference and information on the radar transmission frequency, the water vapor density and the cloud temperature are stored. Since the target information is generated by obtaining the amount of cloud water based on the above, the effects of the first to tenth configurations can be obtained in the weather radar that generates the target information such as the amount of cloud water.

According to the twelfth structure of the multi-frequency radar device of the present invention, a plurality of radar transmitting / receiving sections are caused to execute a target search at different radar transmission frequencies, and the observation data obtained as a result are used as the first data. Since the processing is performed by the two-frequency measuring method according to any one of the eleventh to eleventh configurations, it is possible to provide a multi-frequency radar device suitable for implementing the two-frequency measuring method according to the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a radar device according to first to eleventh embodiments of the present invention.

FIG. 2 is a block diagram showing a configuration of a signal processing unit according to the first to eleventh embodiments of the present invention.

FIG. 3 is a block diagram showing a configuration of an averaging circuit according to the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an averaging circuit according to a second embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a dual frequency measurement method execution circuit according to a third embodiment of the present invention.

FIG. 6 is a block diagram showing a configuration of an input circuit according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of a resolution selection circuit according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of an input circuit according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a resolution selection circuit according to a fifth embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of an input circuit according to a sixth embodiment of the present invention.

FIG. 11 is a flowchart showing an operation procedure of a receiver noise detection circuit according to the sixth embodiment of the present invention.

FIG. 12 is a flowchart showing an operation procedure of a receiver noise detection circuit according to the seventh embodiment of the present invention.

FIG. 13 is a flowchart showing an operation procedure of a receiver noise detection circuit according to the eighth embodiment of the present invention.

FIG. 14 is a block diagram showing a configuration of a dual frequency measurement method execution circuit according to a ninth embodiment of the present invention.

FIG. 15 is a block diagram showing configurations of a combination / selection circuit and a combination / selection control circuit according to a ninth embodiment of the present invention.

FIG. 16 is a view showing a combination / embodiment of the tenth embodiment of the present invention
It is a block diagram which shows the structure of a selection circuit and a coupling / selection control circuit.

FIG. 17 is a block diagram showing a configuration of a dual frequency measurement execution method circuit according to an eleventh embodiment of the present invention.

FIG. 18 is a block diagram showing configurations of a selection circuit and a selection control circuit according to an eleventh embodiment of the present invention.

[Explanation of symbols]

1-1, 1-2, ... 1-n Transmission / reception unit, 2-1, 2-
2, ... 2-n transmitting / receiving antenna, 3 transmitter, 5 target, 6 receiver, 9 signal processing unit, 10 display unit, 11
2 frequency measurement method execution circuit, 12 averaging circuit, 13 propagation loss calculation circuit, 14 radar reflection factor calculation circuit, 15
Meteorological parameter calculation circuit, 16-1, 16-2, 16
-N0, 24-1, 24-2, 24-n0 delay circuit,
17, 19, 25, 31 Average calculation circuit, 18, 30,
n0 sample integrating circuit, 20, 20-1, 20-2,
20-3, ... 2 frequency measurement method execution unit, 21-1, 21-
2, 21-3, ... Input circuit, 22, 22-1, 22
2, 22-3 resolution selection circuit, 26a, 26b switch, 27-1, 27-2, 27-3 logarithmic difference calculation circuit, 28,44 comparison circuit, 29,45 selector, 3
2, 40-1, 40-2, 40-3 receiver noise detection circuit, 33, 34 Fourier transform circuit, 35 subtraction circuit,
36 Fourier inverse transform circuit, 38 combination / selection circuit, 3
9 coupling / selection control circuit, 41-1, 41-2, 41-
3 S / N ratio calculation circuit, 42 weight determination circuit, 43 weighted addition circuit, 46 selection circuit, 47 selection control circuit.

─────────────────────────────────────────────────── --- Continuation of front page (56) References JP-A-6-242218 (JP, A) JP-A-5-107351 (JP, A) JP-A-62-104226 (JP, A) JP-A-50- 120292 (JP, A) JP 53-80194 (JP, A) JP 5-87924 (JP, A) JP 50-62083 (JP, A) JP 60-257380 (JP, A) Special table HEI 5-507148 (JP, A) Special table HEI 7-505222 (JP, A) Special table HEI 6-506537 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01S 7/00-7/42 G01S 13/00-13/95

Claims (12)

(57) [Claims] 1. A two-frequency measuring method comprising the step of generating target information regarding the properties of a target based on two types of observation data indicating radar received powers by two types of radar transmission frequencies forming a pair of transmission frequencies. prior to the generation of target information, it has a compensation step of compensating a noise component included in the two types of observation data each, the compensation
The step is for sending and receiving operations related to the direction in which the target does not exist.
A two-frequency measuring method, which further comprises a step of measuring the noise component . 2. A two-frequency measurement method comprising the step of generating target information regarding the property of a target based on two types of observation data indicating radar received powers by two types of radar transmission frequencies forming a pair of transmission frequencies. A two-frequency wave characterized by including the step of setting the distance resolution of the above-mentioned two types of observation data according to the difference in observation data due to the difference in distance resolution so that the rounding error that occurs when generating target information is relatively small. Measuring method. 3. The two-frequency measuring method according to claim 2 , further comprising a step of switching the distance resolution of the observation data so that plural kinds of observation data having different distance resolutions are generated for each radar transmission frequency. . 4. The two-frequency measurement method according to claim 2, further comprising a step of resampling the observation data so that plural kinds of observation data having different distance resolutions are generated for each radar transmission frequency. . 5. A two-frequency measuring method comprising the step of generating target information regarding the property of a target based on two types of observation data indicating radar received powers by two types of radar transmission frequencies forming a pair of transmission frequencies. The step of generating target information is executed corresponding to each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies, and the above-mentioned two-frequency measurement method has a relatively low signal reception quality. A two-frequency measurement method comprising a step of combining a plurality of sets of target information with a relatively large weight given to the target information based on a high radar transmission frequency. 6. A two-frequency measurement method comprising the step of generating target information regarding the property of a target based on two types of observation data indicating radar received powers by two types of radar transmission frequencies forming a pair of transmission frequencies. The step of generating target information is executed corresponding to each of a plurality of transmission frequency pairs obtained by combining three or more types of radar transmission frequencies, and the above-mentioned two-frequency measurement method has a relatively low signal reception quality. A two-frequency measurement method comprising the step of selecting target information relating to a transmission frequency pair including a high radar transmission frequency. 7. A two-frequency measurement method for generating target information on the property of a target based on two kinds of observation data indicating radar received powers by two kinds of radar transmission frequencies forming a pair of transmission frequencies A two-frequency measuring method comprising the step of selectively setting the transmission frequency pair including a radar transmission frequency having a relatively high signal reception quality from among the radar transmission frequencies. 8. 2-frequency measurement method according to any one of claims 5 to 7, characterized by the step of calculating the signal reception quality on the basis of the information about the temperature of the radar receiver. 9. 2-frequency measurement method according to any one of claims 5 to 7 by the transmitting and receiving operation according to the direction in which the target is not present, characterized by the step of measuring the signal reception quality. 10. 2-frequency measurement method according to any one of claims 5 to 7, characterized by the step of measuring the signal reception quality by the operation to execute the received while the transmission non-execution. 11. The step of generating the target information comprises:
It has a substep of obtaining a difference due to a radar transmission frequency of a variation in the distance direction appearing in the above two kinds of observation data, and a substep of obtaining a cloud water amount based on the obtained difference and information on the radar transmission frequency, water vapor density and cloud temperature. The two-frequency measurement method according to any one of claims 1 to 10 , characterized in that. 12. A plurality of radar transmission / reception units that perform target searches at different radar transmission frequencies to generate the observation data, and a two-frequency measurement method according to any one of claims 1 to 11. A multi-frequency radar device, comprising: