JPS6322121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a limiter circuit in a variable frequency automatic train stopping device, which is inserted between an amplifier circuit and a phase circuit constituting the oscillation section of a receiver. It consists of a resistor and a capacitor connected in series, and when the input from the amplifier circuit is above a certain value, it is suppressed to a certain value and output, and when the input from the amplifier circuit is below a certain value. The gist is that the resistance value of the resistor and the capacitance of the capacitor are set so that the output is output as is.

Variable frequency automatic train stopping system (hereinafter referred to as "variable frequency ATS")
Information transmission between the ground and the vehicle is carried out in the manner described below with reference to FIGS. 1 and 2.

In Fig. 1, the part surrounded by the dotted line V indicates the on-board receiver of the frequency-variable ATS, where 1 is the on-board receiver, OSC is the oscillator, ATT is the resistive attenuator, and F ₀ to F _o
are wave transmitters that pass only frequencies ₀ to _o , respectively, and Sch
is a Schmitt trigger circuit, A is an amplifier circuit, Rec is a rectifier, and MRo to nR are relays that are activated by inputs of frequencies ₀ to _o , respectively. At a predetermined position on the track on the ground, a ground coil 2 consisting of an L/C ₁ circuit capable of receiving information through electromagnetic coupling with an onboard coil 1 provided on the vehicle is laid. The oscillator OSC is the second
Phase circuit PH ₁ ~ _{PH 3} and amplifier circuit as shown in figure a
After connecting A ₁ and A ₂ alternately, connect it to the amplifier circuit.
Consists of connecting A ₃ and power amplifier circuit A ₄ ,
A so-called feedback oscillation circuit is configured in which a part of the output is positively fed back to the input side via the onboard element 1 consisting of two loosely coupled coils. in this case,
Accurate reception of information cannot be guaranteed unless the amplification degree and phase shift of the oscillation circuit OSC, the attenuation degree of the feedback circuit, and the phase characteristics are kept constant.

When the amplification degree of the oscillation circuit OSC is μ and the attenuation degree of the feedback circuit is β, the oscillation conditions are as follows: Gain |μβ|≧1 Phase φ=2πn (n=0, 1, 2...).

In other words, in order to satisfy the oscillation condition μβ=1, the absolute value of the product of the oscillation circuit's amplification μ and the feedback circuit's attenuation β must be 1 or more, and the phase difference between the two must be 0. It is.

Feedback oscillation circuits are basically designed to have |μβ|>1, but when looking at the actual loop gain,
The feedback voltage does not amplify infinitely, but saturates at a constant value, and at this point |μβ|=1.

If it is an oscillation circuit that aims to oscillate at a normal single frequency, it is sufficient to satisfy these conditions, but in a variable frequency ATS, even when the onboard coil 1 is coupled with the ground coil 2, it is reliable. It is required to oscillate at a frequency near the resonance frequency of the ground element 2.
That is, when coupled with a ground element having a resonance frequency _{of 1} to _o , it is required to satisfy the condition μβ=1 for any of the frequencies ₁ to _o .

Let's look at this point regarding the conventional variable frequency ATS.

Inductance L where onboard coil 1 is installed on the track
The oscillation circuit is connected to the ground element ₂ , which has a resonance frequency determined by
A part of the oscillation frequency ₀ , which is unique to the OSC, flows to the oscillation feedback circuit, and the oscillation force of ₀ is passed through the resistor attenuator ATT, the bandpass filter Fo that passes only _{the 0} frequency, the Schmitt trigger circuit Sch, and the amplifier circuit A, and then to the rectifier.
Rec, is rectified into DC by rectifier Rec, is given to master relay MRo, and is sent to master relay MRo.
Keep MRo operational. This indicates that information from the ground is not being received. In this case, there is no problem since the setting is made to satisfy the oscillation condition (μβ=1) for feedback circuit ₀ . As the train progresses, when the onboard coil 1 comes close to the berm 2 with resonance frequency ₁ and the onboard coil 1 and the berm 2 are electrically coupled, a positive feedback oscillation circuit including the onboard coil 1 is activated. The characteristics of are changed, and in addition to the feedback circuit ₀ , a feedback circuit ₁ is formed whose path is from the primary coil of the onboard coil 1 to the ground coil 2 to the secondary coil of the coil coil 1. As the onboard element 1 approaches the ground element, the amount of return of the onboard element ₁ gradually increases, and
With a phase change of ₁ , μβ = 1 is also satisfied for ₁ , and as shown in Figure 2b, two frequencies of ₀ and ₁ oscillate and beat B is generated, but the oscillation Due to the non-linearity of the circuit OSC, as the feedback amount of ₁ increases and the oscillation level becomes stronger, the oscillation level of ₀ is suppressed, and the oscillation condition no longer satisfies μβ = ₁ , and oscillation stops. Oscillation begins to occur. In other words, the frequency is changed from ₀ to ₁ . As a result, master relay MRo falls,
₁ is a resistance attenuator ATT ₁ , a bandpass filter F ₁ that passes only ₁ , a Schmitt circuit Sch, an amplifier circuit A,
As the relay ₁ R operates through the rectifier Rec, ₁
Represents receiving information. When the onboard shelving element 1 moves away from the beacon 2, a phenomenon opposite to the above-mentioned phenomenon occurs between the onboard shelving element and the beacon element. Onboard child 1 has a resonant frequency
The same applies to the passage of ground elements ₁ to _o .

In the above case, as the onboard coil 1 approaches the center of the berm 2, the coupling between them becomes stronger, so the input level of _one frequency to the feedback circuit increases, and as the onboard coil 1 approaches the center of the berm 2. When it reaches the vicinity, the input level will exceed a certain tolerance value, and the oscillation frequency of ₁ will also increase to the 2nd oscillation frequency.
Since a tendency as shown in FIG. b is exhibited, there is a possibility that the output of the amplifier circuit constituting the feedback circuit will be saturated. Since a phase circuit can maintain a sine wave and obtain effective phase characteristics only within a level range that does not saturate, if there is a saturated stage before or after the phase circuit, normal phase characteristics cannot be obtained. , the variable frequency characteristics themselves will be adversely affected.

On the other hand, as the range of frequency fluctuation per piece of information increases, the number of information that can be used within a predetermined frequency range decreases. In order to allocate more information in a limited frequency range, it is necessary to reduce the range of variation per piece of information as much as possible.

In order to solve the problems that exist in such a variable frequency ATS, the present invention has been developed, for example, by using an amplifier A ₂ at the input stage of the oscillation unit and a phase circuit PH at the subsequent stage, which constitutes the oscillation unit OSC, as shown in FIG. ₃ , a limiter circuit is inserted, for example, in which a resistor R and a capacitor _C2 are connected in series to a rectifier made up of diodes connected in parallel in opposite directions. In this case, the resistance value of resistor R and capacitor C ₂
When the input from the amplifier circuit A ₂ is above a certain value, the capacitance is kept below a certain value, and when it is below a certain value, the capacitance is kept as it is in each phase circuit.
Each is set to output to PH ₃ . That is, the purpose is achieved by lowering the impedance of the phase circuit _PH3 by the resistor R and by cutting off the DC component by the capacitor C.
More specifically, if the resistance value of the resistor R is set to about half of the impedance of the phase circuit _PH3 , and the capacitance of the capacitor C is set to 10 times or more the impedance of the subsequent circuit, the above-mentioned objective can be sufficiently achieved. By doing this, the phase circuit PH will not be adversely affected by the saturation of the amplifier circuit in the subsequent stage, so the variable frequency characteristics will be improved compared to the conventional method, and the frequency level will always be within a certain range. Therefore, it is possible to realize a significant improvement in the equal frequency variable ATS, which can increase the amount of information that can be used for a predetermined section, compared to the conventional method. In addition, in the above embodiment, the limiter circuit is connected to the amplifier circuit _A2 and the phase circuit.
Although we have described the case where it is inserted between the PH ₃ and the PH 3, the insertion location is determined by the level relationship of the amplifier circuit, etc.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an example of the ground element and onboard receiver of a variable frequency ATS, Figure 2 a is a circuit diagram showing details of the oscillation section in Figure 1, and Figure 2 b is a variable frequency ATS.
A diagram showing an example of frequency variation in ATS, and FIG. 3 is a circuit diagram showing an embodiment of the present invention. A ₁ to _{A 4} ... Amplifier circuit, C ₂ ... Capacitor, D ₁
~D ₂ ... Rectifier, PH ₁ ~ _{PH 3} ... Phase circuit,
OSC...Receiver oscillation section, R...Resistance, V...
receiver.

Claims (1)

[Claims] 1. In the oscillation section that constitutes the feedback oscillation circuit of the on-board receiver and consists of a phase circuit and an amplifier circuit connected in series alternately and an amplifier circuit and a power amplifier circuit connected to the latter stage, either of the amplifier circuits and A circuit in which a resistor and a capacitor are connected in series is inserted into a rectifier consisting of diodes connected in parallel in the opposite direction between it and the phase circuit in the next stage, and the resistance value of the resistor and the capacitance of the capacitor in the previous stage are When the input from the amplifier circuit in the previous stage is above a certain value, it is set to be suppressed to a certain value and output, and when the input from the previous stage amplifier circuit is below a certain value, it is set to be output as is. A limiter circuit in a variable frequency automatic train stopping device.