JPH01307687A - Precise distance measuring instrument - Google Patents

Abstract

PURPOSE:To reduce a reflecting signal from a building, etc., in the periphery and to raise the distance measuring accuracy by an on-board instrument by suppressing a radiation of a response signal of a final approach (FA) mode of a precise distance measuring instrument (DME/P), in the outside of a microwave landing system (MIS) azimuth covered area. CONSTITUTION:In this instrument, a high frequency switch 9 is connected between a transmitter 8 and a diplexer 2. In case when a question signal is an initial approach (IA) mode, the high frequency switch 9 supplies an output of the transmitter 8 to a horizontal surface non-directional antenna 11 through the diplexer 2 by a control signal 42 from a decoding circuit 4 which has discriminated said signal, and transmits a response signal to the whole peripheral direction. On the other hand, in case when a question of an FA mode, the high frequency switch 9 supplies the output of the transmitter 8 to a horizontal surface directional antenna 10 by the control signal 42 and radiates it. That is, the radiation to the outside of the MIS azimuth covered area is suppressed and a reflecting signal by a building, etc., being outside of the MIS azimuth covered area is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a vI close distance measurement device for use with microwave landing gear in navigation systems.

(Prior art) This type of precision distance measuring device (hereinafter referred to as DME/P)
is a distance measuring element in the microwave '4 land system (hereinafter referred to as MLS), and is a high-precision distance measuring device that is compatible with DME (distance measuring device) used for general aviation navigation aids. be.

The ground device (transponder) of the DME/P has a configuration as shown in FIG. The receiving unit 3 generates a video signal (narrowband video signal) 31 having a bandwidth similar to that of a normal DME and a video signal 32 in a wide I2 band, and each of them is connected to a decoding circuit 4 and a delay comparison circuit (DAC).
Supply to 5.

As shown in FIG. 6, the decoding circuit 4 detects the time of 50% amplitude of the video signal waveform, measures the bare pulse interval (not shown), and decodes the normal DME or DME.
/P initial approach mode (IA mode) and D M E
/ Determine which mode is POI & final approach mode (FA mode).

IA mode and FA mode are operated by the onboard DME monitoring the distance measurement value and switching the bare pulse interval between 7 nautical miles or more and 7 nautical miles or less.

The wideband video signal 32 maintains a steeply rising pulse waveform, and the delay comparison circuit 5 compares the delayed wideband video signal 33 and the amplitude-attenuated wideband video signal 34 as shown in FIG. Measure the time when the amplitude is about 10% at the early point of the pulse rise. Decode circuit 4
The pulse time output 41 of the delay comparison circuit 5 and the pulse time output 51 of the delay comparison circuit 5 are respectively supplied to the gate circuit 6. The gate circuit 6 selects one of these pulse time signals based on the control signal 42 for distinguishing between IA mode and FA mode obtained by measuring the bare pulse interval in the decoding circuit 4, and delays the selected signal. Supplied to circuit 7. The delay control circuit 7 generates a reference signal for pulse modulation to which a delay time prescribed for each of the IA mode and the FA mode is added based on the control signal 42 and supplies it to the transmitter 8. The transmitter 8 adjusts the transmission timing using this pulse modulation reference signal, generates a high frequency paired pulse signal, and supplies it to the antenna 1 through the diplexer 2. The horizontal plane directivity of the antenna 1 is omnidirectional or MLS direction guidance angle coverage (±40° to ±
60°) or more.

(Problems to be Solved by the Invention) The conventional DME/P using such an antenna has the following drawbacks. That is, in a device using a horizontal omnidirectional antenna, the azimuth guidance F2jil of MLS
l! D for aircraft that require high-precision ranging during flight.
The response signal to the M E/P interrogator may be mixed with reflected signals from surrounding buildings, etc., and the il!
II Degrades distance accuracy. On the other hand, when using a horizontal plane directional antenna limited to the azimuth guidance coverage area of MLS, it is possible to reduce reflected signals from surrounding buildings and prevent deterioration of aF+range accuracy. However, normal D outside the MLS coverage area
There is a drawback that questions and responses from the ME and DME/P intercogators cannot be made.

In view of these drawbacks, the technical problem of the present invention is to solve the problem of horizontal plane omnidirectionality and ML according to the questions of IA mode and FA mode, respectively.
It is possible to transmit response signals with directivity that has strong radiation characteristics in the S direction guidance coverage area, and provides the all-around coverage area required in IA mode.
The objective is to achieve high-precision distance measurement in FA mode.

(Means for Solving the Problems) The precision distance measuring device according to the present invention has an initial approach mode (IA mode) and a final approach mode (FA mode) of the interrogation signal.
and means for emitting a response signal with different directivity characteristics depending on each of the modes. The radiation means includes two antennas with different horizontal directivity or an antenna with variable directivity.

(Embodiment) FIG. 1 shows an embodiment of the present invention, in which 9 is a high frequency switch, 10
11 is a horizontal plane directional antenna, 11 is a horizontal plane omnidirectional antenna, and the others are conventional DME/P shown in FIG.
This is the same as the ground equipment.

In this embodiment, a high frequency switch 9 is connected between the transmitter R8 and the diplexer 2. When the interrogation signal is in IA mode, the high frequency switch 9 supplies the output of the transmitter R8 to the horizontal omnidirectional antenna 11 through the diplexer 2 according to the control signal 42 from the decoding circuit 4 that discriminates it, and responds in all circumferential directions. Send a signal. On the other hand, when the FA mode inquiry 18 is received, the high frequency switch 9 supplies the output of the transmitter 8 to the horizontal plane directional antenna 10 and emits it q·t according to the control signal 42. That is, as shown by the broken line in FIG. 2, radiation outside the MLS azimuth coverage area is suppressed, and reflected signals from buildings, etc. outside the MLS azimuth coverage area are suppressed.

In addition to the above-mentioned embodiments, the antenna may have a configuration as shown in FIG. 3. In other words, three planar directional antennas 101, 102, and 103 are combined to perform reception in an omnidirectional state and IA mode. Sends a response signal. On the other hand, the signal 92 (see Fig. 1) from the high frequency switch 9 is supplied to the circulator 13, and the response signal/signal of the FA mode is sent to the MLS.
It is possible to emit light from only one directional antenna 102 having directivity in the azimuth coverage area. In this example, element antennas with three planes of the same directivity are used, but the directivity of the component antennas may be different, or the number of element antennas used may be two or four or more. It is also possible.

(Effects of the Invention) As explained above, in the present invention, reflected signals from surrounding buildings, etc. are reduced by suppressing the emission of the FA mode response signal of the DME/P ground equipment outside the MLS azimuth coverage area. This has the advantage of increasing the distance measurement accuracy of the on-board device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a diagram for explaining the antenna radiation characteristics, Fig. 3 is a block diagram of an antenna in another embodiment, and Fig. 4 is the antenna of Fig. 3. FIG. 5 is a configuration diagram of a conventional DME/P ground device, and FIGS. 6 and 7 are signal waveform diagrams for explaining a conventional DME/P distance measurement method. DESCRIPTION OF SYMBOLS 1... Antenna, 2... Diplexer, 3... Receiving part, 4... Decoding circuit, 5... DAC16...
Gate circuit, 7... Delay control circuit, 8... Transmitter,
9...High frequency switch, 10...Directional antenna, 1
1... Omnidirectional antenna, 12... Power divider, 13
...Circulator, 101-103...Directional antenna. Figure 3 q ri Figure 4 H Go to page
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Claims (1)

[Claims] 1. In a ground device that receives an interrogation signal from an onboard device of an aircraft precision distance measuring device and transmits a response signal, an initial approach mode (IA mode) and a final approach mode (FA mode) of the interrogation signal are set. A precision distance measuring device comprising: means for determining; and means for emitting the response signal with different directivity characteristics depending on each of the modes.