JPH0454479A - Radar receiving performance measuring circuit - Google Patents

Abstract

PURPOSE:To measures and inspect a radar reception system without any trouble to operation by inputting a microwave signal as a simulated received signal, which is outputted from a microwave generator only in a set area, to the sent and received signal transmission line of an in-use radar. CONSTITUTION:When an antenna azimuth signal is inputted from the radar in use to a circuit 1 and a trigger signal is inputted to a trigger circuit 3, a circuit 4 supplies a timing gate signal to a signal generator 31 only in the preset area. The generator 31 generates a pulse-modulated microwave only in the time zone of the timing gate signal and the wave is supplied to a mixer preamplifier 35 through a converter 32, a protecting element 5, a coupler 33, and a switch 34. A preamplifier IF signal which is outputted is synchronized with the timing gate signal outputted from the gate circuit 4 to measure and inspect MDS, etc., and also perform inspection as a video signal through a main amplifier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention relates to a radar reception performance measuring circuit for measuring the reception performance of a maritime surveillance radar installed on land, particularly the performance of a radar reception system during operation. It is related to.

[Prior Art] Conventionally, for example, marine surveillance radar systems installed on land require constant (24-hour) operation.
Most radar transceivers are equipped with two radar transceivers, and if a failure occurs in the active one, it is possible to immediately switch to the backup one.

FIG. 2 is a system configuration diagram of a conventional dual-equipment radar. In the figure, 21 is a radar antenna, 22 is a waveguide,
23 is a waveguide switch, 24 is a non-reflection terminator, 25-1 and 25-2 are #1 and #2 radar transceivers, and 26 is a signal switch.

In FIG. 2, the radar transmitter/receiver 25-1 is connected to the radar antenna 21 via the waveguide 22 and waveguide switch 23 and is in operation. Also #Ruda transceiver 2
The received output signal 5-1 is supplied to an indicator (not shown) via a signal switch 26. Also #2 radar transceiver 2
5-2 is in a standby state, and if the transmitter is activated for operation check, its transmission power is consumed by the non-reflection terminator 24 via the waveguide switch 23. When inspecting the receiving system of the standby unit, turn off the power to the transmitter, remove the non-reflection terminator 24, and input the output signal of the microwave signal generator as a pseudo received signal instead. Let's do it.

FIG. 3 is a configuration diagram of a conventional radar reception performance measurement system. In the figure, 22 is a waveguide, and 31 is a microwave signal generator, which oscillates a microwave with the same frequency as the oscillation center frequency of the magnetron of the radar to be measured, and modulates this with a pulse synchronized with the radar trigger signal. It generates modulated microwaves or CW (continuous wave) microwaves and outputs them through a coaxial terminal. 32 is a coaxial/waveguide converter, which is a converter between a microwave coaxial signal transmission line and a waveguide signal transmission line. 33 is a directional coupler, and the vertical and horizontal waveguide signal transmission paths shown in the figure are capable of transmitting signals with almost no signal attenuation due to the high degree of coupling. In the waveguide signal transmission path between the two, signals are transmitted with large signal attenuation (for example, 30 to 50 dB) due to the small degree of coupling. Therefore, the transmitted signal and the received signal are transmitted in both directions between the radar antenna and the transmitter/receiver switch 34 with almost no signal attenuation. Further, most of the microwave signal output from the microwave signal generator 31 and input to the directional coupler 33 via the coaxial/waveguide converter 32 is consumed by the non-reflection terminator 37. However, the - part is 30~
The signal is attenuated by about 50 dB and is supplied to the transmission/reception switching device 34. Reference numeral 34 denotes a transmission/reception switch, which uses a circulator, for example, and connects the transmission line so that the output of the magnetron 36 is transmitted in the direction of the directional coupler 33 at the time of transmission, and the transmission power is not transmitted in the direction of the mixer/preamplifier 35. When receiving, the input signal from the directional coupler is transmitted in the direction of the mixer/preamplifier 35, and the input signal from the magnetron 3 is switched.
The transmission path is switched so that the signal is not transmitted to 6. 35 is a mixer/preamplifier, which includes a mixer that converts a microwave (RF) signal into an intermediate frequency (IF) signal, and a preamplifier for amplifying the IF signal after conversion. A magnetron 36 generates microwaves to be transmitted based on input from a modulator (not shown). 37 is a non-reflection terminator for the microwave signal generator 31.

To measure the radar reception performance using the configuration shown in Figure 3,
First, the power to the magnetron 3B is turned off and placed in a receiving state. That is, the transmission/reception switch 34 switches the signal transmission path so that the input signal from the directional coupler 33 is transmitted to the mixer/preamplifier 35. Next, the output signal of the microwave signal generator 31 is transferred to the coaxial/waveguide converter 82 and the directional coupler 3.
3 and a mixer/preamplifier 35 via a transmission/reception switch 34.
This preamplifier IF output signal, the main amplifier IF output signal (not shown) which is a common part without active/standby switching, and the detected video signal are inspected. For example, measure the value of MDS (minimum detection signal), which indicates radar reception sensitivity, using an IF multiplied signal or a video signal.
(The smaller the S value is, the better the sensitivity of the radar receiver is.) Check whether it is below a predetermined reference value. If this is not the case, replace defective parts (for example, mixer diodes, etc.) and perform maintenance and inspection to ensure that radar reception performance always meets design standards.

[Problem to be solved by the invention] In the conventional radar reception performance measurement system as described above,
There has been a problem in that inspecting the receiving system of a working machine while it is in operation will cause operational problems.

For example, when a pulse modulation signal is input from a microwave signal generator, a ring-shaped image is displayed in all directions on the CRT of the radar display device, and ship echoes and the like are masked. Furthermore, when a CW multiplied signal is input, an image is displayed over the entire surface on the CRT of the radar display device, and ship echoes and the like are all masked.

The present invention has been made in order to solve such problems, and an object of the present invention is to obtain a radar reception performance measurement circuit that can inspect the radar reception system of currently operating aircraft without hindering operation. do.

[Means for Solving the Problems] The radar reception performance measurement circuit according to claim 1 of the present invention sets in advance an azimuth range and a distance range that designate the area in which the radar reception performance is to be measured, and the radar antenna Timing gate signal generation means for generating a timing gate signal within the set azimuth range and at a timing when a received signal can be obtained from within the set distance range by the radar transmission signal, and supplying the timing gate signal to the microwave signal generator. Then, the output signal of a microwave signal generator that generates microwaves during the time period of the timing gate signal is transmitted to the transmission/reception signal transmission path of the radar under test via the microwave signal generator protection element and the directional coupler. and microwave signal input means for inputting the microwave signal.

A radar reception performance measuring circuit according to a second aspect of the present invention includes the timing gate signal generating means according to the first aspect, microwave signal input means, and the microwave signal generator.

[Operation] In the present invention, when the timing gate signal generating means is set in advance with an azimuth range and a distance range specifying the area in which the radar reception performance is to be measured, the radar antenna is set within the set azimuth range. , and generates a timing gate signal at a timing when a received signal is obtained from within the set distance range by the radar transmission signal, and a microwave signal generator generates a microwave signal during the time period of the timing gate signal, and A wave signal input means inputs the output signal of the microwave signal generator to a transmission/reception signal transmission line of the radar to be measured via the microwave signal generator protection element and the directional coupler.

[Example 1] FIG. 1 is a configuration diagram of a radar reception performance measurement system according to the present invention. In the same figure, 22 and 31 to 37 are the same devices as in FIG. 1 is the direction interface (hereinafter referred to as I/
It is a circuit (referred to as
For example, an angle signal measured in the direction of rotation of the radar antenna 11 with north as the reference direction is input and converted into binary angle data of about 12 bits. - For example, if the angle signal is an output signal from a synchro oscillator, synchro/digital (
The circuit can be constructed using a commercially available conversion module called an S/D) converter. 2 is an azimuth gate circuit, and when arbitrary gate start azimuth θ1 and gate end azimuth θ2 are set from the outside, the set azimuth angle range θ1 to θ is
The azimuth gate signal is output only during 2. The specific circuit includes a pair of digital comparators that compare the set azimuth θ1° θ2 and the rotating antenna azimuth and output a matching signal, and a pair of digital comparators that output a matching signal by comparing the set azimuth θ1° θ2 and the azimuth θ2.
It can be constructed from an S/R type flip-flop that is reset by a match signal. 3 is a trigger 1/F and distance gate circuit, and when arbitrary gate start distance R and gate end distance R2 are set externally, each time a radar trigger signal is input,
A timing gate signal is output at a timing when a received signal is obtained from within the set distance range (distance R to R2) by the radar transmission signal. This circuit counts clock signals serving as a time reference (that is, distance reference) after the radar trigger signal is input, and calculates the set distance MR1.
It is only necessary to generate timing gate signals between times t and t2 delayed by an amount corresponding to R2 and R2, respectively.

Therefore, a concrete circuit can be composed of a pair of subtraction counters and an S/R type flip-flop that is set and reset by the counter output (carry signal in this case). 4 is an azimuth/distance gate circuit;
Orientation gate signal from orientation gate circuit 2 and trigger I/F
and a timing gate signal from the distance gate circuit 3. That is, this circuit outputs a timing gate signal whose radar reception distance is from R to R2 only when the azimuth angle of the radar antenna is within the range from θ to 02. (Refer to the timing gate signal of the designated azimuth range concave circle in FIG. 5). Therefore, the designated area based on the set orientations θ, θ and distances R, R2 is P
P I (Plan Po5ition Indicat
or) is shown as a fan-shaped area on the display surface of the indicator (see the hatched area in FIG. 4).

5 is a protection element, and the magnetron 3 of the radar transceiver
6 is oscillating, a part of its transmission power is input from the directional coupler 33 to the microwave signal generator 31 via the coaxial/waveguide converter 32, and if the generator 31 is malfunctioning or It is a protection element to prevent malfunction.
Typically, an isolator (an element that transmits a signal in a specified direction with little attenuation, but causes significant attenuation in the opposite direction) or a signal attenuator is used.

FIG. 4 is a diagram showing the gate designated area on the PPI display screen, where point P is the radar installation position, and the hatched part of the fan-shaped area is the direction θ, θ2, and distance Ri.

It shows the designated area by R2. In Figure 4,
The radar is installed at the tip of a peninsula, and shows an example of a maritime surveillance radar whose azimuth is 0'' due north.

Fig. 5 is a diagram showing a timing gate signal with specified direction and distance, where point P is the radar installation position, and the timing gate signal is a schematic diagram of the signal within the range specified by direction θ, θ2 and distances R and R2. This is what is shown.

The operation of FIG. 1 will be explained with reference to FIGS. 4 and 5.

First, in order to measure the radar reception performance of a current aircraft in operation, the present invention uses a designated area based on the azimuth θ1゜θ and distances R and R2 in Fig. 4 to be reflected in an area that does not hinder operation, such as a flat area on land. Set it in an area where there are few targets. Measurements of the radar reception system are carried out only within this set area, and normal operation is performed in other areas, for example, operation as a radar for maritime surveillance.

The antenna direction signal from the radar during operation is the direction 1/F circuit 1.
In addition, when a trigger signal (master trigger signal synchronized with the transmission pulse) is input to the trigger I/F and distance gate circuit 3, the preset directions θ and θ and distances R and R are specified. The azimuth/distance gate circuit 4 supplies a timing gate signal as shown in FIG. 5 to the microwave signal generator 31 only within the area of the fan-shaped area. The microwave signal generator 31 generates pulse modulated microwaves only during the time period of this timing gate signal, and the coaxial/waveguide converter 32, the protection element 5, and the directional coupler 33
and is supplied to the mixer/preamplifier 35 via the transmission/reception switch 34. The preamplifier IF signal output from the mixer/preamplifier 35 is synchronized with the timing gate signal output from the azimuth/distance gate circuit 4, and
It is also possible to measure and inspect the MDS etc. by displaying it on a scope, or by displaying it on a PPI display as a video signal via the main amplifier.

Note that the microwave signal generator 31 according to the present invention may be either a general-purpose commercial product or a dedicated built-in device. In the case of general-purpose commercial products, they are used as general measuring instruments, so
Many microwave frequencies can be set variably over a wide range. However, in order to use the output signal of this microwave signal generator as a pseudo reception signal of the radar, it is necessary to adjust the frequency of the generated microwave to the oscillation center frequency of the magnetron of the radar to be measured. In addition, general-purpose microwave signal generators are generally large in size and are used by connecting to other equipment via coaxial cables, so they are often configured as a separate device from this measuring device. On the other hand, a microwave signal generator as a dedicated built-in device only needs to generate the oscillation frequency of the magnetron of the radar under test, so the range of the oscillation frequency is limited, and the output signal is transmitted through a protection element. It can also be output directly using a waveguide. Therefore, it can be manufactured using small equipment and can be combined with other equipment.
A measurement system can be configured with units. Therefore, it is possible to improve work efficiency by reducing the number of connection points and adjustment points for equipment.

[Effects of the Invention] As explained in detail above, according to the present invention, as the area for measuring the radar reception performance in advance, an area that does not hinder the operation of the active radar during operation is determined based on the azimuth range and distance range of the radar. Since the microwave signal as a pseudo reception signal output from the microwave signal generator is input to the transmitting/receiving signal transmission path of the working radar only within the set area, the working radar This has the effect of making it possible to measure and inspect the radar receiving system without hindrance to operation.

By configuring a single-unit radar reception performance measuring circuit incorporating a dedicated microwave signal generator, it is possible to improve work efficiency by reducing the number of equipment connection points and adjustment points.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a radar reception performance measurement system according to the present invention, FIG. 2 is a system configuration diagram of a conventional dual-equipment radar,
Figure 3 is a configuration diagram of a conventional radar reception performance measurement system, Figure 4 is a diagram showing the gate designated area on the PPI display screen, and Figure 5 is a diagram showing the gate designated area on the PPI display screen.
The figure shows a timing gate signal with direction and distance specified. In the figure, 1 is a direction/IF circuit, 2 is a direction gate circuit, 3 is a trigger I/F and distance gate circuit, 4 is a direction/distance gate circuit, 5 is a protection element, 21 is a radar antenna, 2
2 is a waveguide, 23 is a waveguide switch, 24 and 37 are non-reflection terminators, 25-1 and 25-2 are #1 and #2 radar transceivers, 26 is a signal switch, and 31 is a microwave a signal generator, 32 a coaxial/waveguide converter, 33 a directional coupler,
34 is a transmission/reception switch, 35 is a mixer/preamplifier, and 36 is a magnetron. Patent applicant Oki Electric Industry Co., Ltd./L Song Dynasty's 2nd Emperor's death letter 0 site Z keynote 2nd person P letter customer moxibustion t4 note 11 ♂ pp+S exhibitor's boot wing V red kusuke and shown Concave part 4 Figure 22 Tohakan Regu history, Moko to 0 Ji soft Retar Doi Mei I Timing → Book title number ΣH length diagram Figure 5

Claims (2)

[Claims] (1) Set an azimuth range and a distance range in advance to specify the area where radar reception performance is to be measured, and ensure that the radar antenna is within the set azimuth range and that the radar transmission signal is within the set distance range. a timing gate signal generating means for generating a timing gate signal at a timing when a received signal is obtained from the timing gate signal and supplying the timing gate signal to a microwave signal generator; and a microwave signal generator for generating a microwave signal during a time period of the timing gate signal. A radar reception performance measuring circuit comprising: microwave signal input means for inputting an output signal to a transmitting/receiving signal transmission path of a radar to be measured via the microwave signal generator protection element and a directional coupler. . (2) A radar reception performance measuring circuit comprising: the timing gate signal generating means according to claim 1; microwave signal input means; and the microwave signal generator.