JPH06138198A - Automatic antenna switching device - Google Patents

Abstract

PURPOSE:To secure stable azimuth and distance information by forcing a selection antenna to be switched to a lower side antenna before the azimuth and distance information become unstable when an upper antenna of the body of an aircraft is selected and a reception signal level is reduced in an in-flight TACAN device. CONSTITUTION:The lock state of azimuth and distance is judged by a lock criterion equipment 1, a counter 2 determines a switching timing according to the output, and an antenna switching signal generator 3 outputs an antenna switching drive signal at the switching timing for switching an antenna automatically. When an upper antenna is selected, a memory signal MB or MD of azimuth or distance retaining the output information before a reception level becomes unstable for a certain amount of time is input art OR circuit 4, its output and a selection antenna monitoring signal are input to an AND circuit 5, and then the antenna switching signal generator 3 is forced to be reset by the output for switching to a lower antenna.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic antenna switching device, and more particularly to an on-board tacan (TACAN;
The present invention relates to an antenna automatic switching device that automatically switches an antenna of an Air Navigation device.

[0002]

2. Description of the Related Art As shown in FIG. 3, a conventional automatic antenna switching device for an on-board takan device has an azimuth unlock signal L _B.
And a distance unlock signal L _D to input a counter drive signal S _D and a counter reset signal S _R , a clock determiner 1, a counter drive signal S _D and a counter reset signal S
Counter 2 which inputs _R and outputs a timing signal S _T
And an antenna switching signal generator 3 for receiving the timing signal S _T and outputting the antenna switching device drive signal S _S.

Next, the operation of the conventional automatic antenna switching device of the on-board takan device will be described with reference to the waveform diagram of FIG.

The on-board takan device measures the azimuth and distance with respect to the ground takan device by transmitting and receiving a tacan signal to and from the ground takan device. The normal measurement state is locked and the received signal is received. Unlocking is a state in which normal azimuth and distance cannot be measured due to a decrease in the level of.

In the on-board takan device, there are cases where antennas for transmission and reception are arranged at two positions above and below the airframe of the deployed aircraft, and these two antennas are automatically or manually switched and used. There is. Hereinafter, the automatic antenna switching operation of the conventional onboard takan device will be described.

In FIG. 3, the lock determiner 1 inputs the azimuth unlock signal L _B and the distance unlock signal L _D ,
The counter drive signal S _D is output only when both unlock signals are in the unlocked state. The counter 2 operates while the counter drive signal S _D is input, and outputs the timing signal ST at regular time intervals (conventional device example: about 6 seconds).

The antenna switching signal generator 3 to which the timing signal S _T is input outputs the antenna switching device driving signal S _S , and the state of the antennas of the upper and lower two systems is switched by this signal.

Further, when either one of the azimuth and the distance is in the clock state and either the distance unlock signal L _D or the azimuth unlock signal L _B is not input,
The counter reset signal S _R is output and the counter drive signal S _D is not output.

The counter 2 is reset by the counter reset signal S _{R, the} operation is stopped because the counter drive signal S _D is not input, and the timing signal S _T is not output. Therefore, since the antenna switching signal generation circuit 3 does not generate the antenna switching device drive signal S _S , the antenna selection state when the lock state is achieved is held.

[0010]

As described above, this automatic antenna switching device stops its operation when either the azimuth or the distance is locked, and the antenna selection state at that time is changed. Retained.

As described above, the antennas of these two systems may be connected to two locations above and below the body of the aircraft. In this case, the onboard takan device transmits and receives the tacan signal to and from the ground takan device. If an antenna located on the upper side of the antenna is used, this antenna enters the airframe above the ground takan device, and the level of the received signal decreases as the elevation angle from the ground surface increases.

As described above, in the normal flight mode,
The upper antenna of the aircraft often has a lower received signal level than the lower antenna, and a level difference of 30 dB may occur depending on the aircraft.

Therefore, when the upper antenna is selected, even if the lower antenna is in a good reception state, the level of the received signal is lowered, and when the sensitivity becomes lower than the specified sensitivity, the azimuth and distance information is obtained. May become unstable, and if the level further decreases, the bearing and distance may become unlocked.

As described above, in the conventional automatic antenna switching device, the azimuth and distance information is not switched to the lower antenna until both the azimuth and the distance are in the unlocked state, which is the worst state. There is a problem that the air space in the state becomes larger than that when the lower antenna is selected.

The object of the present invention is to solve the above-mentioned problems,
Even if the reception level drops when the upper antenna is selected and used in the onboard takan device, the lower antenna is switched to the stable orientation and distance before the orientation and distance become unlocked. An object is to provide an automatic antenna switching device capable of ensuring information.

[0016]

SUMMARY OF THE INVENTION An automatic antenna switching device of the present invention is a takan onboard device having two systems of antennas arranged on an upper side and a lower side of an aircraft to be connected to a takan onboard device provided in the aircraft. An automatic antenna switching device that automatically switches the connection between the antenna and the takan onboard device when the onboard device is connected to the upper antenna installed on the upper side of the aircraft. It has a configuration that automatically switches to the lower antenna disposed on the side to continuously secure stable azimuth and distance information.

Further, in the automatic antenna switching device of the present invention, the takan onboard device keeps the output information before being unstable so as to prevent the bearing or distance information from being destabilized due to a decrease in reception level for a short time. The configuration is such that automatic switching to the lower antenna is performed based on the direction memory signal or the distance memory signal held for time.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the function of one embodiment of the present invention.

In the embodiment shown in FIG. 1, a clock discriminator 1 which inputs a direction unlock signal L _B and a distance unlock signal L _D and outputs a counter drive signal S _D and a counter reset signal S _R. , A counter ₂ which inputs the counter drive signal S _D and the counter reset signal S _R and outputs a timing signal S _T , and a memory signal which inputs the direction memory signal M _B and the distance memory signal M _D. An OR circuit 4 that outputs S _M , an AND circuit 5 that inputs the memory signal S _M and the selected antenna monitoring signal S _K, and outputs a lower antenna forced selection signal S _L ,
The antenna switching signal generator 3 receives the timing signal S _T and the lower antenna forced selection signal S _L and outputs the antenna switching device drive signal S _S.

Next, the operation of this embodiment will be described.

FIG. 2 is a main waveform diagram of each part in the embodiment of FIG. 1, and the operation of the embodiment of FIG. 1 will be described below with reference to FIG.

The lock determiner 1 inputs the azimuth unlock signal L _B and the distance unlock signal L _D shown in FIG. 2, and only when both are in the unlocked state, the counter drive signal S
Output _D.

The counter 2 operates while the counter drive signal S _D is being input, and outputs the timing signal S _T at regular time intervals, for example, about every 6 seconds.

The antenna switching signal generating circuit 3 to which the timing signal S _T is input outputs the antenna switching device drive signal S _S , and the connection between the upper and lower antennas is switched by this signal.

Usually, the on-board takan device is used before the azimuth and distance are unlocked in order to prevent the azimuth or distance information from becoming unstable due to a decrease in the level of the received signal for a short time before the azimuth and the distance become unlocked. The memory operation is performed to hold the output information of the above for a certain period of time. When the upper antenna is selected in the normal flight mode, the received signal level is lower than that of the lower antenna, the azimuth and distance information becomes unstable, and the azimuth or distance memory operation may be performed. Will increase.

Therefore, in this embodiment, by using the azimuth memory signal M _B and the distance memory M _D indicating that the azimuth and distance are in memory operation, the lower antenna is forcibly selected as follows. Switch to.

That is, in FIG. 1, the OR circuit 4 outputs the memory signal S _M when either the azimuth memory signal M _B or the distance memory signal M _D is input.

The AND circuit 5 has a selection antenna monitoring signal S.
_{When the} memory signal S _M is input under the condition that _K is input, that is, the upper antenna is selected in this embodiment, the lower antenna forced selection signal S _L is output, and this signal causes the antenna The switching signal generator 3 is forcibly reset and outputs the antenna switching device drive signal S _S ,
The lower antenna is selected by this signal.

When either the azimuth or the distance is locked and either the distance unlock signal L _D or the azimuth unlock signal L _B is not input, the counter reset signal S _R is output and counting is performed. The drive signal SD is no longer output.

The counter 2 is reset by the counter reset signal S _R , and the counter drive signal S _D is not input, so that the operation is stopped and the timing signal S _T is not output.

Therefore, since the antenna switching signal generator 3 does not generate the antenna switching driving signal S _S , the antenna selection state when the lock state is achieved is held.

In this way, stable azimuth and distance information can always be secured even when the upper antenna is selected.

[0034]

As described above, according to the present invention, when the upper antenna is selected in the on-board takan device, if the azimuth and distance enter the memory operation due to the level price of the received signal, the selected antenna is forced. And by automatically switching to the lower antenna, the antenna is switched to the lower antenna before the worst state of both azimuth and distance is unlocked, maintaining a stable and good reception state at all times, and stable azimuth. And, it has an effect that the distance information can be secured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an automatic antenna switching apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a waveform chart of each part of FIG.

FIG. 3 is a block diagram showing a configuration of a conventional antenna automatic switching device.

FIG. 4 is a waveform chart of each part of FIG.

[Explanation of symbols]

 1 lock determiner 2 counter 3 antenna switching signal generator 4 OR 5 AND circuit

Claims (2)

[Claims] 1. An automatic antenna switching device for automatically switching connection between two systems of antennas installed on an upper side and a lower side of an aircraft to be connected to an on-board device of a takan installed in an aircraft. So, when the takan onboard device is connected to the upper antenna installed on the upper side of the aircraft, the antenna is automatically switched to the lower antenna installed on the lower side of the aircraft in response to the decrease in the reception level. An automatic antenna switching device characterized by continuously securing stable and stable direction and distance information. 2. An orientation memory signal or distance in which the takan onboard device holds output information before being unstable for a certain period of time in order to prevent the orientation or distance information from becoming unstable due to a decrease in reception level for a short time. The automatic antenna switching device according to claim 1, wherein the automatic switching to the lower antenna is performed based on a memory signal.