JPS6327781A - Signal discriminating method - Google Patents

Abstract

PURPOSE:To separate and extract only a desired response signal from response signals to a plurality of question devices transmitting question signals at the same cycle, by changing question signal emitting timing by a minute time at random if necessary. CONSTITUTION:External synchronous signal generated at a definite cycle are delayed by a minute time by a random pulse repeated period (PRP) generator 11 to output signals of random cycles. Therefore, the output signals of a timing circuit 4 inputting said signals also become random cycles and, on the basis of the signals of said random cycles, a coder 5 outputs question signals of random cycles to a transmitter 6. Unnecessary synchronous response signals generated by transmitting question signals at the same cycle by a plurality of devices as mentioned above are removed as non-synchronous signals by transmitting question signals at random cycles.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field to which the invention pertains) The present invention relates to a signal identification method 1, for example, a secondary radar (Second radar).
The present invention relates to a method for removing response signals to interrogation signals from other interrogators that are transmitted at the same frequency as the self-interrogator in a dary five-surveillance radar (hereinafter referred to as SSR) system.

(Prior Art) Aircraft accidents are occurring frequently due to current and future aircraft traffic congestion and high speed aircraft, and it is becoming more important to take measures to prevent these accidents.

As one of the prevention systems, ATCRBS (Air Traffic Control System) is installed at major sea route points or major airports.
troll Shisenimo Radar Beacon Sys
tem) has been installed.

ATCRBS is an interrogation signal emitted by an SSH interrogator, which is a ground device, and is received by a device called a transponder mounted on an aircraft, and automatically sends back a response signal containing information about the aircraft.
R receives this response signal and determines the position or altitude of the aircraft.

This is a system that displays flight directions and performs air traffic control based on that information to prevent accidents such as aircraft collisions.

In the following, a case will be considered in which ground stations 1 and 2 equipped with SSR are installed within a close distance as shown in FIG. 3 in A'rCR8B, and an aircraft 3 flies in the vicinity of these stations.

When multiple ground stations are installed close to each other in this way, their interrogation repetition periods are generally different from each other, and in this case, when interrogation signals Q1 and Ql are transmitted, corresponds to these and transmits response signals A1 and A2 that are synchronized with each other, so both ground stations 1 and 20 receive both response signals A1 and A2. At ground station 2, A1 is asynchronous with respect to Ql, so conventionally this person 2 and A
Response signals A1 and A2 corresponding to interrogation signals Q1 and Ql transmitted by ground stations 1 and 2, respectively, were obtained by a circuit for removing asynchronous signals, that is, a deruter circuit.

However, if the ground stations 1 and 2 are
As shown in the timing chart, the ground station 1 transmits an interrogation signal at the same period t.

If we consider the case where the ground station 2 transmits an interrogation signal after a certain period of time, the response signals to both interrogation signals will be synchronized, making it impossible to exclude them by the above-mentioned defruer circuit, resulting in a problem of incorrect display.

To explain this in detail, as shown in FIG. 4, if t2 and t3 are the times required for radio waves to propagate the distances between the aircraft 3 and the ground stations 1 and 2, the aircraft 3 receives the interrogation signal. The timing for transmitting the response signal corresponding to this interrogation signal is generally as shown in the figure (d) after the time t2 has elapsed since the interrogation by ground station 1, and the time t3 has elapsed from the interrogation signal from the ground station 2. As shown in FIG. 3, it is defined as after a predetermined time t4, which includes the time required for switching between transmission and reception of the transponder.

Therefore, the ground station 1 receives two signals, 2 t 2 + t 4 and t. 2t3+ after sending the interrogation signal
After t4 and 12+13+1. Two signals, one after -1o, will be received.

This is repeated for the two ground stations below, and since the interrogation signal transmission period of each ground station is equal to each other, the response signal for the interrogation signal of the ground station 2 is repeated at the ground station 1, and the response signal for the interrogation signal of the ground station 2 is repeated.
The defect is that the response signals to the interrogation signals received by the receiver are synchronized with the interrogation signals of the telepathic ground station, and cannot be removed by conventional defruter circuits, resulting in incorrect information being obtained due to these unnecessary response signals. was there.

Problems have also arisen in systems that exchange various types of information by sending back response signals.

(Object of the invention) The present invention has been made in view of the above-mentioned circumstances, and includes:
It is an object of the present invention to provide a signal identification method that separates and extracts only a desired response signal from response signals to a plurality of interrogation devices that transmit interrogation signals at the same period.

(Summary of the Invention) In order to achieve the above object, the present invention has the following configuration.

That is, by randomly changing the repetition period of the interrogation signal transmitted by the self-interrogation device, the response signal to the interrogation signal transmitted from another interrogation device is made asynchronous with the interrogation signal of the self-interrogation device, and when receiving the response signal, an asynchronous signal is generated. The filter is configured to be removed by a circuit, for example, a defruter circuit.

;Example) Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

Before proceeding, a conventional signal identification method will be briefly explained in order to facilitate understanding of the present invention.

That is, FIG. 5 is a block diagram showing a conventional SSR, in which an external synchronization signal with a constant period is input to a timing circuit 4 for controlling the interrogation period, and its output is used to generate interrogation pulses corresponding to the required mode. Gouda 5. It is transmitted as an interrogation signal from an antenna 8 via a transmitter 6 and a duplexer 7.

Further, the response signal sent back is received by the antenna 8, and this signal is inputted via the duplexer 7 and the receiver 9 to the defruter circuit 1° which operates according to the timing signal from the KOG 5 to obtain the desired output. It is structured like this.

Conventionally, the timing circuit 4 generates a signal with a fixed period based on the external synchronization signal generated at a constant period, and the interrogation signal is transmitted at a period determined by this signal. When a response signal returned in response to a transmitted interrogation signal is received, as described above, this response signal is synchronous and cannot be removed by the defrouter circuit.

FIG. 1 is a block diagram showing an embodiment of an identification device for implementing the signal identification method of the present invention.

This is a block diagram when used for SSH, in which the external synchronization signal used for conventional SSH is input to the random pulse repetition period (PRP) generator 11, and its output is output from the timing circuit 4. Gouda 5. The interrogation signal is transmitted from the antenna 8 via the transmitter 6 and duplexer 7.

Further, a response signal to the interrogation signal is also received by the antenna 8 as described above, and this signal is inputted via the duplexer 7 and the receiver 9 to the defruter circuit 10 operated by the timing signal from the Korg 5 to obtain the desired output. This is how it was done.

According to this configuration, the random PRP generator 11 outputs a random period signal obtained by delaying the external synchronization signal generated at a constant period by a small amount of time at random, so that the output signal of the timing circuit 4 which receives this signal as input also The signal has a random period, and the Korg 5 outputs a random period interrogation signal to the transmitter 6 using this random period signal.

In addition, the duplexer 7, the antenna 8. The receiver 9 and the defruter circuit 10 operate in the same manner as conventional ones.

In the ground station 1 equipped with the identification device as described above,
Regarding the case where unnecessary response signals due to the interrogation period of this station being equal to that of ground station 2 cannot be removed, the second
This will be explained using the timing chart shown in the figure.

Now, if an unnecessary response signal appears on the radar screen of ground station 1 and it is difficult to determine which one is the response to the question from the own station, 1
For example, the operator generates the random PRP generator 1
1 to randomly change the interrogation signal transmission period from 1 to 16 as shown in FIG. By forming a time difference Δt of Δt, Δt2, etc., the aircraft 3 calculates the respective distances between the aircraft 3 and the ground stations 1 and 2 after each ground station transmits the interrogation signal, as shown in the same figure (cl). The response signal to the interrogation signal from each ground station is received 14 hours after receiving the interrogation signal as shown in the figure (dl) for the reasons mentioned above. Send.

The timing when the ground stations 1 and 2 receive this transmitted response signal is as shown in tel and (fl) in the figure.

That is, from each interrogation signal transmission, the ground station 1 receives 2 t ,
Two signals are received after +t 4 and after 12+13+14+Δt (or -Δt), and the ground station 2 receives 213+14 signals.
Two signals are received, one after 1, +13+1, and +Δt (or -Δt), and as is clear from these figures, the response signals required for each are synchronized with the interrogation signal transmitted by the home ground station. The signals other than
This is asynchronous because it includes a de-router circuit, so this can be removed by a deruter circuit and only the necessary response signal can be output.

In the above description, an example of SSR has been described, but the present invention is not limited to this, but can be applied to a system that transmits an interrogation signal, sends back a corresponding response signal from another device, and receives the same. It can be applied to any device, and the communication medium with other devices may be wired instead of radio waves, and the period of transmitting the interrogation signal can be randomly changed depending on the configuration of the respective system. What is necessary is to include a device that transmits the interrogation signal to the receiving side and a device that removes signals that are asynchronous with the interrogation signal.

Furthermore, when randomly changing the period of transmitting the interrogation signal, the amount of change in the period should be determined by taking into consideration the time from when the interrogation signal is transmitted until the response signal is returned.
- The period should not be shortened to the extent that the next interrogation signal is transmitted before the response signal to the previous interrogation signal is received. That is, it is sufficient if one corresponding response signal can be received during one cycle of the transmitted interrogation signal.

However, the minimum value of this amount of change depends on the discrimination ability of the defruter circuit, so taking this into consideration, the amount of change should be longer than the time that the deruter circuit can discriminate as a random signal, that is, the sampling period of the deruter circuit. Bye. In the embodiment, only the ground station 1 randomly changes the interrogation signal transmission period, but it is not necessary to do so only on one side, and here, the interrogation signal transmission period of the ground station 2 may also be changed randomly.

As for the specific method of randomly changing the interrogation signal, for example, by adding a minute delay time that changes randomly to the shortest cycle time and sending it out, this can be easily realized using conventional technology, so I will explain it in detail. is omitted.

Furthermore, IFF (Identification) is used to identify allies by transmitting or receiving interrogation signals and response signals between aircraft.
ification of Fr1end or fo
e) Maku is a T that has been proposed and is being put into practical use.
Cp (Traffic Alert and Co1
It is obvious that the method according to the present invention can also be applied to systems such as 1ision avoidance system) and the like.

(Effects of the Invention) As explained above, the present invention eliminates unnecessary synchronous response signals caused by multiple devices transmitting interrogation signals at the same cycle by transmitting interrogation signals at random cycles. This is effective in making the response signal an asynchronous signal and eliminating it.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the identification device according to the present invention, FIGS. 2(a) to (fl are timing chart diagrams for explaining the effects of the identification device shown in FIG. 1),
FIG. 3 illustrates the present invention 1... Ground station 1. 2・・・・・・Ground station 2゜3・・・・・・
...Aircraft, 4...Timing circuit, 5...Korg. 6......Transmitter, 7......
−・Duplexer 8・・・・・・・・・Antenna,
9......Receiver, 10...
...Defruer circuit. 11...Random PRP generator. Patent Applicant: Toyo Tsushinki Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 1 Hiroshi Ward S Drawing Procedure Amendment October 1986 270 61 Patent 1 Application No. 171327 Showa 3. Related: Applicant's mail volume: 253-01 Telephone: 0167-7.
1-1131 (Code 107 Contents of amendment: Figures 1 and 2 are revised by adding them to the attached drawings. Figure 1' tail 2 times

Claims (1)

[Claims] In a device that receives a response signal returned from another device in response to an interrogation signal transmitted at a predetermined period, the interrogation signal sending timing is randomly changed by a minute time as necessary. signal identification method.