JPH01173889A - Atc transponder equipped with interference signal removing circuit - Google Patents

Abstract

PURPOSE:To prevent the title transponder from malfunctioning by inputting a reference level signal outputted from an OR circuit and a received signal to a comparator for comparison, and outputting a reception signal component exceeding the reference level signal to a processing circuit. CONSTITUTION:When the interference signal removing circuit 20 is added to the ATC transponder, a white noise component and a low frequency component are amplified by a wide-band amplifier 21, then DC-amplified to a prescribed voltage value, and inputted to the OR circuit 25 if the amplitude level of the white noise varies or if the low frequency component is contained in the receiver output 12a. The comparator 14 compares the voltage of the reference level signal 20a from the OR circuit 25 with the receiver output 13a to extract and output only the component exceeding the reference level signal 20a to the processing circuit 17. Consequently, the noise component contained in the output signal 13a is not outputted from the comparator 14.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is an ATC/IF system for identifying aircraft, ships, etc.
AT that is equipped with an interference signal removal circuit that makes it possible to prevent malfunctions caused by interference signals in F transponders.
Regarding C transponders.

(Prior art) Information regarding identification objects such as aircraft, ships, etc., such as nationality,
ATC (^ir Tr
afic ConLrol ) / I F F (Id
entiricaLion of Fr1end or
There is a type of transponder (automatic response device) shown in FIG.

In the two-way communication between this ATC/lFF transponder and an identification interrogation device installed at a base station, encoded pulse train signal radio waves from the transponder are received and diffracted by the interrogation device, and information about the target aircraft, etc. An identification is made.

In the current system, I030 MHz is used for sending the interrogation signal by the interrogator, and 1090 M11Z is used for the response signal from the ATC/IFF transponder.

The ATC/1FF transponder in Figure 3 has antenna 1.
a digital delay line 3 that delays the phase of the output pulse from the receiver 2 by a predetermined width and outputs it to a comparator 6 (described later); and a receiver output signal ( A variable reference voltage setter 4 inputs a demodulated signal (demodulated signal) and changes the level of a reference voltage according to the level of the inputted demodulated signal, and uses the output signal from the variable reference voltage setter 4 as one human power and has a sensitivity of 1lIII. @ No. 13 and AOC (＾utow+aLic 0verload
Adder 5 has the control signal as the other input, and the reference voltage B output from adder 5 is input to the receiver output signal input via the digital delay line 3 to calculate the component of signal A. The voltage value of reference signal B (
A comparator 6 outputs a component exceeding the threshold value as a comparator output signal C to a processing circuit 7. The effective component in the signal A extracted by the reference signal B is subjected to predetermined processing in the processing circuit 7 for response.

However, in conventional transponders, signal components that do not exceed the threshold level obtained by adding the output of the variable reference voltage setter 4, the sensitivity control signal, and the AOC control signal are removed; It was impossible to remove reception noise exceeding .

That is, such conventional ATC/IFT? In the transponder, CW (Continuous Vlave) or 8M (＾mpliLude ModulaL) corresponding to the reception frequency (1030M IfZ)
ion) When an interference signal such as a signal wave is input, the interference signal increases the inherent noise included in the output of the receiver 2, or the noise is superimposed on the low frequency component, so the noise component becomes random. This pulse train is manually inputted to the processing circuit 7 of the transponder, which causes the transponder to malfunction. As a result of malfunction, the transponder sends out useless response signals and the like.

Most of these interference signals are mixed in from other communication equipment mounted on the aircraft, etc.

In addition, FIGS. 4(a), 4(b), and 4(c) show the correspondence of each signal A%B, C in FIG.
), when there is a regular input pulse A in a normal state with no interference signal, if the voltage value of the regular signal A from the receiver is greater than the voltage value of the reference signal B, the signal C will be regular. Output.

If there is CW interference with other signals and there is interference with the regular input signal, a large amount of noise (white noise) will be generated in addition to the regular output signal C of the comparator 6, as shown in (b), so the processing This may cause the circuit 7 to malfunction.

Furthermore, if there is interference from the AM signal (low frequency component), white noise higher than the level of signal B will be input to the processing circuit 7 as the comparator output even if there is no regular input signal A, as shown in cl. be done.

These interference signals are generated, for example, by IJ HF radios used in the aircraft on which the transponder is mounted. In other words, when the transmission frequency of the LJ)lFNila machine is set to about 255MHz to 346MHz, the spurious components (102ON10
40 MHz) may be applied as an interference signal to the receiver 2 of the transponder via the LI HF antenna and the transponder antenna l. This UHF radio is
Generates interference signals that can cause transponder malfunctions (erroneous responses,
On the other hand, this causes a problem of lowering the response rate of the transponder during transmission from the UHF radio.

Further, in addition to the above, f-interference Q occurs due to direct interference between various devices related to the equipment inside the aircraft, interference between antenna cables, and the like.

(Object of the invention) The present invention has been made in view of the
An object of the present invention is to provide an ATC transformer bong equipped with an interference No. 43 removal circuit that does not malfunction even when the No. 43 signal is manually operated.

(Summary of the Invention) In order to achieve the above object, an ATC transponder equipped with an interference signal removal circuit according to the present invention has the following characteristics: J,
From the signal components included in the A signal, extract the components exceeding the threshold level of the first reference level ('A') as the effective signal components. In an ATC transponder S configured to output a valid signal component to a processing circuit, this A'rC transponder is provided with an interference signal removal circuit.

Due to the interference fij, the transfer (3) is amplified and superimposed on the noise component, and the second level is obtained by changing the thresh-t hold level nl according to the level of the noise component. It has an OR circuit that manually outputs the higher level of both reference level signals (No. 4) by manually inputting No. a and the first reference signal/bell signal of 1iiJ, and outputs No. 4 from this OR circuit. The third reference level signal and the received signal are input to a comparator and compared, and the received 4g signal component having a level exceeding the third reference level A is outputted to the processing circuit. It is a feature.

(First Embodiment) Hereinafter, an ATC transponder equipped with an interference signal removal circuit of the present invention will be described in detail with reference to the drawings.

Figure 1 shows a transponder equipped with the malfunction prevention circuit of the present invention;
This is an explanatory diagram of the configuration of the transponder, which includes an antenna 11, a receiver (31112) that receives an interrogation signal from the base station via the antenna 1.1, and a receiver delayed by a digital delay line 1:3. A comparator 14 which receives the machine output signal +3a as one input, and a sensitivity control which inputs the receiver output, the sensitivity control signal and the A OCu control signal and outputs a reference signal (first reference level signal) +5a at a predetermined level. circuit] 5 and the output signal 15a from the sensitivity control circuit 15
It has an interference signal removal circuit 20 which inputs the signal and outputs it to the other input terminal of the comparator 14, and a processing circuit 17 which inputs the output signal +4a from the comparator 14 and performs response and display.

The sensitivity control circuit 15 includes a variable reference voltage setter 18 and an adder 19.

Note that the sensitivity control signal and AOC (Automatic
The 0vcrload Control control signal is
This is a signal that sets a reference level for eliminating noise superimposed on the receiver output signal and for reducing a human input signal to the processing circuit 17 to within the processing capacity of the processing circuit 17.

The comparator 14 compares the receiver output signal 13a and the third reference level signal 20a output from the interference signal removal circuit 20, so that the level of the receiver output signal 13a is the level of the third reference level signal 20a. When the comparator output signal 14a is larger than the processing circuit! Output to 7.

Processing circuit +7 performs processing required for displaying response 1.

The interference signal removal circuit 20 includes a wideband amplifier 21 for inputting the receiver output signal 12a and amplifying white noise and low frequency components, and a wideband amplifier 2! AC/D that converts the receiver output signal 12a amplified by
A C converter 22, a DC amplifier 23 that amplifies the DC signal from the converter 22, and a voltage that sets the voltage from the DC amplifier 23 to a predetermined set value and outputs the set value as a second reference level signal 24a. The regulator 24 and the output signal 15a from the sensitivity control circuit 15 are used as one input, and the voltage 31? ! ! second reference level signal 2 from device 24;
4a as the other input, and an OR circuit 25 which outputs a signal with a higher level.

In the above configuration, if the interference signal removal circuit 20 does not exist, when the amplitude level of white noise superimposed on a received signal such as an interrogation signal or a video signal becomes high, the amplitude level of the white noise is adjusted by the sensitivity control circuit 15. Since the voltage exceeds the set reference voltage (-) of the comparator 14, the white noise component is randomly supplied to the processing circuit as the output signal of the comparator 14. This causes malfunctions.

On the other hand, when the interference signal removal circuit 20 is added, if the amplitude level of white noise fluctuates or low frequency components are included in the receiver output 12a, the white noise components and low frequency components will be removed. After being amplified by the broadband amplifier 21, it is converted to DC and amplified, and then the voltage regulator 2
After the voltage is set to a predetermined voltage value in step 4, it is manually input to the OR circuit 25. In the 011 circuit 25, the signal with the higher level of the voltage output from the sensitivity control circuit 15 and the output voltage from the voltage regulator 24 is converted into a third reference level signal 20a.
It is output to the comparator 14 as . The comparator 14 compares the voltage of the third reference level signal 20a from the OR circuit 25 with the received delta machine output +3a via the delay line 13, and extracts only the component exceeding the third reference level signal 20a from the output +3a. The signal is extracted and outputted to the processing circuit 17 as a regular signal. Therefore, the output signal 13a from the delay line 13
Noise components included in are not output from the comparator 14.

According to the experimental results, it was possible to completely eliminate malfunctions during response.

Next, FIG. 2 shows a second embodiment of the present invention, which is an embodiment in which the interference signal removal circuit of the present invention is applied to a diversity type transponder equipped with two receiver systems. In addition,
The same parts as in FIG. 1 are denoted by the same reference numerals, and redundant explanation will be omitted.

In this embodiment, the interference signal cancellation circuit 20 includes receiver output signals 12a, 12' from each receiver 12.12°.
a and outputs the receiver output signal with a higher signal level (including noise level) to the wideband amplifier 21.
Two voltage systems that input the output signals from the R circuit 30 and the I) C amplifier 23, respectively! 11s! li vessel 24.24°
The second embodiment differs from the first embodiment in that it has a 25.25° shifter OR circuit and a processing circuit 14.14° corresponding to each system.

Originally, it would be preferable to separately provide the interference signal removal circuit 20 for each system as shown in FIG. The configuration in which the removal circuit 20 is shared also has sufficient significance.

In the above configuration, the interference signal received by each receiver 12.12° is suppressed by the two systems of voltage regulators 24.24°. Therefore, interference signal removal can be performed accurately regardless of which receiving system the interference signal is applied to.

In addition, as a modification of the present invention, the voltage regulator 24.24°
The output voltage of each sensitivity control circuit 15.15° may be fed back to each sensitivity control circuit 15.15° so that the setting level of the sensitivity control circuit 15.15° itself can be obtained from the voltage regulator 24.24°. For example, since the sensitivity control signal and the ΔOC control signal can be omitted, the circuit configuration can be simplified.

(Effects of the Invention) As described above, the ATC equipped with the interference signal removal circuit of the present invention
According to the transponder, malfunction of the transponder can be prevented even when noise generated by interference signals increases.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a transponder equipped with the malfunction prevention circuit of the present invention, Fig. 2 is an explanatory diagram of the configuration of a second embodiment of the invention, Fig. 3 is an explanatory diagram of a conventional example, and Fig. 4 ( a) (
b) (c) is a waveform diagram showing the correspondence of each output signal in FIG. 3. 1.11...Antenna 2.12.12"...Receiver 3.13...Digital delay line 4
．． 14... Comparator 5... Adder 6... Comparator
7... Processing circuit 15... Sensitivity control circuit 15
a... First reference level signal 17... Processing circuit 19... Adder 20a... Third reference level signal 20... Interference signal removal circuit 21... Wideband amplifier 22... AC/DC converter 23 --- DC amplifier 24... Voltage regulator 24a... Second reference level signal 25.25°... OR circuit 30...
OR circuit patent applicant Toyo Tsushinki Co., Ltd.

Claims (2)

[Claims] (1) Based on a first reference level signal generated based on the signal level of the received signal output from the receiver, extract an effective signal component included in the received signal, and output this effective signal component to a processing circuit. In the ATC transponder, the ATC transponder includes an interference signal removal circuit,
The interference signal removal circuit generates a second reference level signal obtained by varying a threshold level according to the level of a noise component amplified and superimposed on the received signal due to the interference signal, and the first reference level signal. and a third reference level signal output from the OR circuit, the third reference level signal outputted from the OR circuit and the received signal are An ATC transponder equipped with an interference signal removal circuit, characterized in that the signal is input to a comparator for comparison, and received signal components having a level exceeding the third reference level signal are output to a processing circuit. (2) An ATC transponder equipped with an interference signal cancellation circuit according to claim 1, wherein the single interference signal cancellation circuit is applied to a plurality of receiving systems.