JPH062332Y2 - Modulation signal generation circuit - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a modulation signal generation circuit, and more particularly to a modulation signal for controlling a modulator for forming a radiation pattern in an electronic scanning antenna of a Takan navigation assistance device. Regarding the generation circuit.

[Conventional technology]

The electronic scanning antenna has V = 1 + ACOS10 ° N-BCOS90 ° N (V: amplitude, A :) on each of the 36 antenna elements arranged on the circumference.
15 Hz modulation degree, B: 135 Hz modulation degree, N: antenna element number) is given to the tacan radiation pattern as shown in FIG. Make up.

Conventionally, this type of modulation signal generation circuit has the system shown in FIG. The modulation signal for controlling the modulator is stored in the ROM, the data in the ROM in the modulation signal generation circuit is read by the address signal from the address generation circuit, the data is D / A converted, and then the data is passed through the buffer. Being sent to the modulator. This system has 18 systems corresponding to 18 modulators. Each modulator simultaneously generates two amplitude-modulated signals with different phases by 180 °, and 180 ° out of 36 antenna elements arranged all around.
Are supplied to two antenna elements having a positional relationship of. Therefore, the modulation signal generating circuit of each system includes two ROMs as shown in FIG. 2, and these two ROMs store the data of the amplitude modulation signals having different phases by 180 °. The modulator modulates the carrier signal with two modulation signals to generate a high frequency signal to be supplied to the two radiators. ROM
The amplitude value data corresponding to the above-mentioned V is stored in 2 and the phase of that of the ROM 3 differs from the data stored in the ROM 2 by 180 °.

In FIG. 2, since the address signals for reading ROMs of 18 systems are common, each ROM needs to store different data in order to make the radiation pattern shown in FIG. 3 as the data to be stored. Data is 10 °
Are set to have a phase shift of.

[Problems to be solved by the invention]

Since the modulation waveform stored in the ROM in the above-described conventional modulation signal generation circuit includes the information of the modulation phase corresponding to only the specific modulator and the antenna element fed by the modulator. , If one of the 18 modulators fails and needs to be replaced with a spare modulator, it is necessary to prepare 36 kinds of ROMs for the modulation signal generation circuit.
There is a drawback that the maintainability and economical efficiency of the device are poor.

[Means for solving problems]

In order to solve such a drawback, the modulation signal generating circuit of the present invention utilizes the characteristic that one modulator feeds two antenna elements different by 180 °, and the modulation signal for controlling one modulator is used. The data stored in the two ROMs in the generation circuit are modulated by 180 ° out of phase with each other, and the data stored in the ROMs corresponding to the other 17 modulators also have the same phase. The circuit has a modulation waveform and a circuit configuration in which the phase of the modulation waveform that differs every 10 ° corresponding to each antenna element can be freely set by a switch.

〔Example〕

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram of an embodiment of the present invention. In the figure, ROMs 6 and 7 store the data of modulated signals having different phases by 180 ° similarly to the data stored in the ROMs 2 and 3 of FIG. In the present invention, this data is 18
Is common to all systems. Since the tacan radiation pattern is obtained by outputting high frequency signals having different phases from 18 systems, the phase difference is stored in the ROM in the present invention.
The configurations described below are arranged and given before 6 and 7. In the figure, the address from the address generation circuit 1 input to the modulation signal generation circuit changes from 0 to 359 when expressed in decimal (hereinafter, the address signal is a 9-bit binary number, but all are expressed in decimal). In the adder, the address signal is added to the values of 0 to 359 of the phase setting switch, and the address signal becomes +. Since the data area stored in the ROM is 0 to 359, it is determined whether the address signal is 360 or more, and if the subtractor in the next stage has 360 or more,
Subtract 360 to get =-=-360, 36
When it is smaller than 0, it is set to =-=-0. The ROM that stores the modulation waveform is accessed by the address signal, outputs 8-bit data, is D / A converted, and is then sent to the modulator via the buffer.

The modulation signal generation circuit corresponds to the modulator and has a modulation waveform of 1
1 consisting of two ROMs that store data that differ by 80 °
It is possible to freely set the phase of the control signal sent to the modulator in eight systems by the eighteen phase setting switches.

[Effect of device]

As described above, according to the present invention, the address signal for accessing the data of the modulation waveform of the same phase stored in each of the two ROMs corresponding to the eighteen modulators is provided with eighteen phase setting switches and eighteen phase setting switches. Adder and 18 comparators and 18
The phase of the signal waveform for controlling the modulator can be freely set by this subtractor.

Therefore, even if any of the 18 modulators fails, the phase of the modulation waveform stored in the ROM is the same, and the phase of the signal waveform controlling the modulator can be freely set. Two ROMs that store waveforms,
It is possible to replace two ROMs corresponding to the failure modulator, and there is an effect that maintainability and economic efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention. 1 ... Address generation circuit, 2 ... adder, 3 ... phase setting switch, 4 ... comparator, 5 ... subtractor, 6,7 ...
ROM, 8, 9 ... D / A converter, 10, 11 ... Buffer, 12 ... Modulator FIG. 2 is a system diagram of a conventional technique. 1 ... Address generation circuit, 2, 3 ... ROM, 4, 5 ...
... D / A converter, 6,7 ... buffer, 8 ... modulator. FIG. 3 is a diagram showing a tacan radiation pattern.

Claims (1)

[Scope of utility model registration request] 1. A modulation signal generation circuit for controlling a modulator according to a modulation waveform stored in a ROM, wherein the phases of the modulation waveforms stored in two ROMs each corresponding to 18 modulators feeding an antenna element. And the circuit configuration that can change the phase of the control signal of the modulator required to form the radiation pattern to a predetermined phase by using the phase setting switch, the adder, the comparator, and the subtractor. Characteristic modulation signal generation circuit.