JPS5973782A - System for automatically selecting receiving output of circular polarized wave - Google Patents

Abstract

PURPOSE:To enable certain and precise selection, in a radar for generating circular polarized wave receiving output and linear polarized receiving output, by selecting only the circular polarized receiving output while comparing both polarized wave receiving outputs with respect to a same partial region. CONSTITUTION:A circular polarized component is guided to a receiver 6 while received by a circular polarized wave antenna 4 while a linear polarized wave component is guided to a receiver 7 while received by a linear polarized wave antenna 5 and both components are sent to a comparator circuit 9 and a selector circuit 10 as video signals. When a region where any object other than a rainfall is absent is selected as the partial region of a partial region signal generating circuit 8, the average value of the video signals in the partial region become high in the linear polarized wave and a selection signal is generated in the comparator circuit 9 while the video signal of the circular polarized signal is selected by the selector circuit 10 and the video signal of the circular polarized wave is outputted from a receiving output terminal 12. By this method, automatic selection with good quality receiving no influence of the reflection from the other object can be performed by the selecting way of the partial region.

Description

[Detailed description of the invention] (Technical field) The present invention relates to an automatic selection method for circularly polarized wave reception output.

(Background Art) In order to reduce reflected waves from rainfall in radar, circularly polarized waves may be used during rainfall.

When using circularly polarized waves, the reception level from normal targets is generally lower than when using linearly polarized waves, so when it is not raining, linear polarized waves are used and sometimes circular polarized waves are used together), and when it is raining, circularly polarized waves are used. The use of In such cases, conventionally, operators have manually selected the polarization by visually observing the rainfall or rainfall reflected waves. However, in recent years, radar data is often automatically processed (such artificial selection methods have become inconvenient).

(Problems to be solved by the invention) In order to improve the drawbacks of such conventional techniques, the present invention
In a radar that generates a circularly polarized wave reception output and a linearly polarized wave reception output, the circularly polarized wave reception output is compared for the same partial area, and only the circularly polarized wave reception output is selected based on the comparison result. The purpose is to provide an automatic circularly polarized wave reception output selection method that enables reliable and fine-grained selection.

(Structure and operation of the invention) The accompanying drawings are block diagrams of embodiments of the invention.

In the figure, 1 is a transmitter, 2 is a transmission/reception switching circuit, 3 is a rotation drive unit,
4 is a circularly polarized antenna, 5 is a linearly polarized antenna, 6.7 is a receiver, 8 is a partial area signal generation circuit, 9 is a comparison circuit, 10 is a selection circuit, 11 is a trigger signal generation circuit, 12 is a reception output The terminal 13 is a part according to the present invention.

Transmitter 1 creates transmission radio waves. The transmission/reception switching circuit 2 operates to guide transmitted radio waves to the antenna side and guide received radio waves from the antenna to the receiver side. The rotation drive unit 3 functions to rotate the circularly polarized antenna 4 and the linearly polarized antenna 5 as one body,
A rotation angle signal is sent to the partial area signal generation circuit 8. Also included inside the rotary drive head 3 are rotary coupling parts for transmission lines (waveguides) that are connected to the transmission/reception switching circuit 2, the circularly polarized antenna 4, and the receiver 7 and the linearly polarized antenna 5, respectively. ing. The circularly polarized antenna 4 emits circularly polarized radio waves to the outside and receives circularly polarized radio waves (circularly polarized waves with the same rotation with respect to the time of emission and the direction of propagation of the radio waves). The linearly polarized antenna 5 receives linearly polarized radio waves. Receivers 6 and 7 perform heterodyne detection and amplification of the received radio waves, perform envelope detection, and output video signals. The partial area signal generation circuit 8 receives a rotation angle signal from the rotation drive unit 3 and a trigger signal from a trigger signal generation circuit 11 that generates a radar trigger signal, and delays the trigger signal to generate a predetermined radar reception signal. A gate-like partial area signal is generated only during the period corresponding to the period when the partial area returns from the received partial area, and this signal is sent to the comparator circuit 9.
Send to. Comparison circuit 9 receives video signal outputs of circularly polarized waves and linearly polarized waves from receivers 6 and 7, and also receives partial area signals from partial area signal generation circuit 9, selects video signals within the partial areas, and outputs the respective video signals. The averaged post-polarized average outputs are compared, and if the linearly polarized average output is greater than the circularly polarized average output by a certain value or more, a selection signal is generated and the circularly polarized antenna 4 and the linearly polarized antenna are selected. It is held for only one rotation period of 5. This selection signal is sent to selection circuit (2)0. The selection circuit 10 receives circularly polarized and linearly polarized video signal outputs from the receivers 6 and 7, and a selection signal from the comparator circuit 9. When this selection signal is valid, it selects the circularly polarized video signal of both video signals. In other cases, linear polarization output is selected and output. The trigger generation circuit 11 is a radar
A trigger signal is generated and sent to the transmitter 1, the receivers 6 and 7, and the partial area signal generation circuit 8.

The radar transmission pulse is triggered by the trigger generation circuit 11.

Next, the operation will be explained. Transmission radio waves generated by the transmitter 1 are transmitted via the transmission/reception switching circuit 2 and the rotary drive section 3 to the circularly polarized antenna 4 and are emitted to the outside as circularly polarized radio waves. Of the radio waves that have hit the target and been reflected, circularly polarized components with the same rotation in terms of the radio wave traveling direction as at the time of emission are received by the circularly polarized antenna 5, and the received radio waves are transmitted to the rotation drive unit 3 and the transmission/reception switching circuit 2.
It is guided to the receiver 6 via the receiver 6, where it is converted into a video signal, and is sent to the comparator circuit 9 and the selection circuit lO as a circularly polarized video signal.
sent to. On the other hand, among the radio waves that have hit the target and been reflected, linearly polarized components having the same polarization as the polarization direction of the linearly polarized antenna 5 are received by the linearly polarized antenna 5, and the received radio waves are passed through the rotary drive unit 3. The signal is then guided to the receiver 7, where it is made into a video signal, and similarly sent to the comparator circuit 9 and the selection circuit 10 as a linearly polarized video signal. The selection signal described above is created by the comparison circuit 9, and the selection circuit 10 selects either the circularly polarized video signal or the linearly polarized video signal based on this selection signal, and outputs it to the reception output terminal 12 as a reception output. Sent.

If we think about the operation during rain, most of the reflected waves from rain will be circularly polarized waves with the direction of radio wave propagation reversed compared to when circularly polarized waves are emitted, so only a small amount will be received by the circularly polarized antenna 4. (The video signal level of the receivers 6 and 7 is considerably higher for the linearly polarized video signal.) Therefore, the partial area signal generating circuit 80 selects an area where there are no targets other than rain as the partial area. Since the average value of the video signal in this partial area is higher for the linearly polarized wave, the comparator circuit 9 generates a selection signal. The video signal is selected, and a circularly polarized video signal is output to the receiving output terminal 12.Except when it is raining, both video signals in the partial area are only receiver noise, and the main noise level is set to be equal in advance. If the selection signal is set so that the selection signal is not generated, the selection circuit 10 selects the linearly polarized video signal, and the linearly polarized video signal is output to the reception output terminal.

(Effects of the Invention) As explained above, in the above embodiment, the received outputs of circularly polarized waves and linearly polarized waves are compared for partial areas, so depending on how the partial areas are selected, reflections from other targets may be affected. It becomes possible to make judgments for reliable selection that are not affected by waves, and high-quality automatic selection is performed.

The above embodiment is for the case where only one partial area is provided, but the required observation range of the radar is divided into multiple areas, a partial area is provided inside each area, and the above is described for each partial area. Compare the received outputs of circularly polarized waves and linearly polarized waves as in the embodiment, and select the received outputs of circularly polarized waves and linearly polarized waves in the area to which the partial area belongs based on the selection signal of this partial area. It is also possible to do this. In this way, fine-grained automatic selection for each area is possible.
This method is particularly effective when rainfall intensity is uneven in a region.

In addition, in the above embodiment, the circularly polarized reception output is selected to be obtained when it is raining, and the linearly polarized reception output is selected to be obtained when it is not raining.
In a radar that uses both side wave reception outputs when it is not raining, selection is made to obtain circularly polarized wave reception outputs when it is raining, and to obtain both side wave reception outputs when it is not raining.

As described above, according to the present invention, it is possible to reliably and precisely perform automatic selection to obtain only the circularly polarized wave reception output during rain, so it can be applied to various search radars such as harbor radar. It is extremely effective.

[Brief explanation of the drawing]

The accompanying drawings are block diagrams of embodiments of the invention. ■=Transmitter, 2: Transmission/reception switching circuit, 3: Rotary drive section, 4: Circularly polarized antenna, 5: Linearly polarized antenna, 6
, 7: receiver, 8 partial area signal generation circuit, 9: comparison circuit, 10: selection circuit, 11: )! J signal generation circuit, 12: reception output terminal, ]3: part related to the present invention. Patent applicant Oki Electric Industry Co., Ltd. Patent application agent Megumi Yamamoto - 435-

Claims (1)

[Claims] In a radar that generates a circularly polarized received output and a linearly polarized received output, the radar received signal is generated in a predetermined partial area by a partial area signal obtained by delaying the trigger signal of the transmitted signal at a specific rotation angle of the antenna. Decide the period during which the circularly polarized wave is reflected (), compare the reception level of the circularly polarized wave during that period, and select the circularly polarized wave reception output if the reception level of the circularly polarized wave is higher than the reception level of the linearly polarized wave by a predetermined value or more. An automatic circularly polarized wave reception output selection method characterized by selecting and outputting a linearly polarized wave reception output in other cases.