Transponder transmission unit sixth order bandpass filter circuit

Abstract

The application is suitable for the field of communication related technology, and provides a transponder transmission unit six-order band-pass filter circuit, which comprises a first-order circuit, a second-order circuit, a third-order circuit, a fourth-order circuit, a fifth-order circuit and a sixth-order circuit; and the multiple-order circuits in the filter circuit are connected in series in sequence. Compared with the original filter circuit, the above filter circuit has a narrower passband bandwidth of 3.8MHz~4.7MHz, effectively filters out interference signals, and has a better suppression degree with a stopband attenuation of about-100dB. The center frequency of the BTM device uplink signal is 4.234MHz±175KHz, and the frequency deviation is ±282KHz. After the interference signals are filtered out by the six-order band-pass filter circuit, the signal with a frequency range of 3.8MHz~4.7MHz is obtained, which is convenient for the transponder transmission unit to better demodulate the FSK signal.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of communication, and particularly relates to a transponder transmission unit six-order band-pass filter circuit. BACKGROUND

[0002] With the deepening of the construction of a traffic power, the contribution of high-speed railway to the development of national economy gradually highlights. The CTCS-3 level train control system of Chinese high-speed rail is praised as the "brain" and "nerve center" of high-speed rail, is one of the three key technologies of high-speed rail, and is key technical equipment for ensuring safe operation of trains and improving transportation efficiency, which is composed of ground equipment and on-board equipment. The on-board equipment transponder transmission unit is used for data transmission between ground and train, processes uplink signals and messages between transponders, and communicates with the on-board host unit equipment.

[0003] The transponder transmission device is composed of a transponder transmission host and an antenna unit, and the transponder transmission host includes a power board, a sending board, a receiving board, a decoding board, a communication board and a recording board. The sending board is connected with the antenna unit through a D cable, and is connected with the receiving board by means of a pull handle wire. The receiving board receives FSK modulated information transmitted from the sending board, and amplifies and demodulates the information. The center frequency of the uplink signal of the transponder transmission device is 4.234 MHz ± 175 KHz, and the frequency deviation is ± 282 KHz. A filter circuit is needed to filter out interference signals so as to better demodulate the FSK signal and avoid interference with the normal operation of the device, which constitutes a hidden danger to the safe operation of the train.

[0004] At present, the existing filter circuit has the following disadvantages: the passband bandwidth is wide, the stopband suppression degree is low, and the insertion loss is large. The interference signals cannot be effectively filtered out, which will introduce electromagnetic interference and have an adverse effect on the demodulation of the FSK signal of the transponder transmission unit. SUMMARY

[0005] In view of the above problems, on the one hand, the application discloses a transponder transmission unit six-order band-pass filter circuit, which comprises:

[0006] A first-order circuit for filtering out interference signals outside a specified frequency range;

[0007] A second-order circuit, one end of the second-order circuit being connected with one end of the first-order circuit, for increasing the steepness of the passband and the stopband suppression degree;

[0008] A third-order circuit, one end of the third-order circuit being connected with the other end of the second-order circuit, for increasing the steepness of the passband and the stopband suppression degree, and also for increasing the passband flatness;

[0009] A fourth-order circuit, one end of the fourth-order circuit being connected to the other end of the third-order circuit, for narrowing the passband bandwidth, and for increasing the steepness of the transition band and the stopband rejection;

[0010] A fifth-order circuit, one end of the fifth-order circuit being connected to the other end of the fourth-order circuit, for further modifying the steepness of the transition band, and for increasing the stopband rejection; and

[0011] A sixth-order circuit, one end of the sixth-order circuit being connected to the other end of the fifth-order circuit, for outputting a signal meeting the set requirements.

[0012] The multi-order circuits in the filter circuit are connected in series.

[0013] Further, the first-order circuit comprises a first capacitor assembly and a first inductor assembly connected in series; one end of the first capacitor assembly is connected to the signal input end, and the other end of the first capacitor assembly is connected to the first inductor assembly.

[0014] Further, the first capacitor assembly comprises a capacitor C1, a capacitor C2 and a capacitor C3 connected in parallel with each other; and the first inductor assembly comprises an inductor L1 and an inductor L2 connected in series with each other.

[0015] The inductor L1 is arranged between the first capacitor assembly and the inductor L2, and one end of the inductor L2 is connected to the second-order circuit.

[0016] Further, the second-order circuit comprises a capacitor C4 and a second inductor assembly, and the capacitor C4 is connected in parallel with the second inductor assembly.

[0017] Further, the second inductor assembly comprises an inductor L3 and an inductor L4 connected in series.

[0018] One end of the capacitor C4 and one end of the inductor L3 are connected to a common point, and the capacitor C4 and the second-order circuit and the first-order circuit are connected at the common point; the other end of the capacitor C4 and one end of the inductor L4 are both grounded.

[0019] Further, the third-order circuit comprises a second capacitor assembly and a third inductor assembly connected in series with each other.

[0020] Further, the second capacitor assembly comprises a capacitor C5 and a capacitor C6 connected in series with each other, and the third inductor assembly comprises an inductor L5 and an inductor L6 connected in series with each other.

[0021] The inductor L5 and the inductor L6 are connected to one end of the second capacitor assembly and one end of the inductor L6, respectively, one end of the second capacitor assembly is connected to the second-order circuit, and the other end of the inductor L6 is connected to the fourth-order circuit.

[0022] Further, the fourth-order circuit comprises a third capacitor component and a fourth inductor component connected in parallel with each other.

[0023] Further, the third capacitor component comprises a capacitor C7, a capacitor C9 and a capacitor C8 connected in parallel with each other, and the fourth inductor component comprises an inductor L7 and an inductor L8 connected in series with each other.

[0024] One end of the capacitor C7, one end of the capacitor C9, one end of the capacitor C8 and one end of the inductor L7 are connected at a common point, and are connected to the third-order circuit and the fifth-order circuit at the common point; the other end of the capacitor C7, the other end of the capacitor C9, the other end of the capacitor C8 and the other end of the inductor L8 are grounded.

[0025] Further, the fifth-order circuit comprises a fourth capacitor component and a fifth inductor component connected in series with each other.

[0026] Further, the fourth capacitor component comprises an inductor C10 and an inductor C11 connected in parallel with each other; and the fifth inductor component comprises an inductor L9 and an inductor L10 connected in series with each other.

[0027] Two ends of the inductor L9 are connected to one end of the fourth capacitor component and one end of the inductor L10, respectively; the other end of the fourth capacitor component is connected to the fourth-order circuit; and the other end of the inductor L10 is connected to the sixth-order circuit.

[0028] Further, the sixth-order circuit comprises an inductor L11, a capacitor C12 and a capacitor C13 connected in parallel with each other.

[0029] One end of the inductor L11, one end of the capacitor C12 and one end of the capacitor C13 are connected at a common point, and are connected to the fifth-order circuit and an output terminal at the common point; the other end of the inductor L11, the other end of the capacitor C12 and the other end of the capacitor C13 are grounded.

[0030] Compared with the prior art, the application has the following beneficial effects:

[0031] The six-order band-pass filter circuit for the transponder transmission unit has a narrower passband bandwidth, effectively filters out interference signals, and has a better suppression degree, because the passband bandwidth of the original filter circuit is 3.8MHz-4.7MHz, the stopband attenuation is about -100dB, and the center frequency of the BTM device uplink signal is 4.234MHz±175KHz, and the frequency deviation is ±282KHz. After the interference signals are filtered out by the six-order band-pass filter circuit, the signal with a frequency range of 3.8MHz-4.7MHz is obtained, which is convenient for the transponder transmission unit to better demodulate the FSK signal.

[0032] Additional features and advantages of the present application will be set forth in the description that follows, and in part will be apparent from the description, or can be learned by practice of the application. The objectives and other advantages of the present application will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and the ordinary skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0034] Figure 1 A six-order band-pass filter circuit diagram of an embodiment of the present application is shown;

[0035] Figure 2 A six-order band-pass filter circuit diagram of an embodiment of the present application is shown; DETAILED DESCRIPTION

[0036] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the ordinary skilled in the art without any creative effort are within the protection scope of the present application.

[0037] The present application is designed to solve the above-mentioned background art problems, and a six-order band-pass filter circuit is provided. In an embodiment of the present application, as shown in Figure 1 and Figure 2 The filter circuit comprises:

[0038] A first-order circuit for filtering out interference signals outside a specified frequency range;

[0039] A second-order circuit, one end of which is connected to one end of the first-order circuit, for increasing the steepness of the passband and the stopband rejection;

[0040] A third-order circuit, one end of which is connected to the other end of the second-order circuit, for increasing the steepness of the passband and the stopband rejection, and for increasing the passband flatness;

[0041] A fourth-order circuit, one end of which is connected to the other end of the third-order circuit, for narrowing the passband bandwidth, and for increasing the steepness of the passband and the stopband rejection;

[0042] a fifth-order circuit, one end of the fifth-order circuit being connected with the other end of the fourth-order circuit, for further modifying the steepness of the transition band and increasing the stopband attenuation;

[0043] a sixth-order circuit, one end of the sixth-order circuit being connected with the other end of the fifth-order circuit, for outputting a signal meeting the set requirements;

[0044] The multi-order circuits in the filter circuit are connected in series.

[0045] In actual application, compared with the original filter circuit, the above filter circuit has a narrower passband bandwidth of 3.8MHz~4.7MHz, effectively filters out interference signals, and has a better suppression degree with a stopband attenuation of about -100dB. The BTM device uplink signal center frequency is 4.234MHz±175KHz, and the frequency deviation is ±282KHz. After the interference signals are filtered out by the sixth-order band-pass filter circuit, a signal with a frequency range of 3.8MHz~4.7MHz is obtained, which is convenient for the transponder transmission unit to better demodulate the FSK signal.

[0046] In an embodiment of the present application, as shown in Figure 1 and Figure 2 the first-order circuit comprises a first capacitor component and a first inductor component connected in series; one end of the first capacitor component is connected with the signal input end, and the other end of the first capacitor component is connected with the first inductor component.

[0047] In a case of the present embodiment, the first capacitor component comprises capacitors C1, C2 and C3 connected in parallel with each other; and the first inductor component comprises inductors L1 and L2 connected in series with each other.

[0048] The inductor L1 is arranged between the first capacitor component and the inductor L2, and one end of the inductor L2 is connected with the second-order circuit.

[0049] As an exemplary selection scheme of the present embodiment, the selection of each component in the first-order circuit is as follows: the capacitance of the capacitor C1 is 160pF, the capacitance of the capacitor C2 is 160pF, the capacitance of the capacitor C3 is 3pF, the inductance of the inductor L1 is 3.3μH, and the inductance of the inductor L2 is 1μH. The series connection of the capacitors in the first-order circuit and the parallel connection of the inductors interact with each other to roughly obtain a single passband with a center frequency of 4.271MHz. The signal passes through the first-order circuit to roughly filter out the signals near 4.271MHz, and the filtering effect is relatively poor.

[0050] In an embodiment of the present application, as shown in Figure 1 and Figure 2 the second-order circuit comprises a capacitor C4 and a second inductor component, and the capacitor C4 and the second inductor component are connected in parallel.

[0051] In one case of the embodiment, the second inductive component comprises inductance L3 and inductance L4 connected in series.

[0052] One end of the capacitor C4 is connected to one end of the inductance L3 at a common point, and is connected to the first-order circuit and the second-order circuit at the common point; the other end of the capacitor C4 and one end of the inductance L4 are both grounded.

[0053] As an exemplary selection scheme of the embodiment, in the second-order circuit, the selection of each component is as follows: the capacitance of the capacitor C4 is 4.7 nF, the inductance of the inductance L3 is 270 nH, and the inductance of the inductance L4 is 27 nH. The inductance in series in the second-order circuit interacts with the capacitor in parallel, so that the stopband suppression degree is increased, the change amplitude of the transition band is changed, and the noise in the signal passing through the first-order circuit can be effectively filtered out.

[0054] In one embodiment of the application, as shown in Figure 1 and Figure 2 The third-order circuit comprises a second capacitive component and a third inductive component connected in series.

[0055] In one case of the embodiment, the second capacitive component comprises capacitor C5 and capacitor C6 connected in series, and the third inductive component comprises inductance L5 and inductance L6 connected in series.

[0056] The inductance L5 is connected to one end of the second capacitive component and one end of the inductance L6, respectively, the other end of the second capacitive component is connected to the second-order circuit, and the other end of the inductance L6 is connected to the fourth-order circuit.

[0057] As an exemplary selection scheme of the embodiment, in the third-order circuit, the selection of each component is as follows: the capacitance of the capacitor C5 is 43 pF, the capacitance of the capacitor C6 is 43 pF, the inductance of the inductance L5 is 15 μH, and the inductance of the inductance L6 is 1 μH. The capacitor in parallel in the third-order circuit interacts with the inductance in series, so that the stopband suppression degree and the steepness of the transition band are increased, the passband flatness is increased, the interference signal in the signal passing through the third-order circuit can be effectively suppressed, the interference signal in the transition band frequency range can also be filtered out, and the signal passing through the passband is reduced in attenuation.

[0058] In one embodiment of the application, as shown in Figure 1 and Figure 2 The fourth-order circuit comprises a third capacitive component and a fourth inductive component connected in parallel.

[0059] In one case of the embodiment, the third capacitive component comprises capacitor C7, capacitor C9, and capacitor C8 connected in parallel, and the fourth inductive component comprises inductance L7 and inductance L8 connected in series.

[0060] One end of the capacitor C7, one end of the capacitor C9, one end of the capacitor C8 and one end of the inductor L7 are connected at a common point, and are connected to the three-order circuit and the five-order circuit at the common point; the other end of the capacitor C7, the other end of the capacitor C9, the other end of the capacitor C8 and one end of the inductor L8 are grounded.

[0061] As an exemplary selection scheme of the embodiment, in the four-order circuit, the selection of each component is as follows: the capacitance of the capacitor C7 is 1nF, the capacitance of the capacitor C9 is 2.2nF, the capacitance of the capacitor C8 is 3.3nF, the inductance of the inductor L7 is 150nH, and the inductance of the inductor L8 is 68nH. The series-parallel connection of the capacitors and the inductors in the four-order circuit narrows the passband bandwidth, and can increase the steepness of the transition band and the stopband rejection degree. The interference signals in the signal passing through the four-order circuit can be effectively suppressed, the interference signals in the transition band are also filtered out, and the narrow passband bandwidth can more effectively filter out the interference signals.

[0062] In an embodiment of the application, as shown in Figure 1 and Figure 2 the five-order circuit comprises a fourth capacitor component and a fifth inductor component connected in series.

[0063] In a case of the embodiment, the fourth capacitor component comprises an inductor C10 and an inductor C11 connected in parallel; the fifth inductor component comprises an inductor L9 and an inductor L10 connected in series.

[0064] The inductor L9 is connected to one end of the fourth capacitor component and one end of the inductor L10, the other end of the fourth capacitor component is connected to the four-order circuit, and the other end of the inductor L10 is connected to the six-order circuit.

[0065] As an exemplary selection scheme of the embodiment, in the five-order circuit, the selection of each component is as follows: the capacitance of the capacitor C10 is 56pF, the capacitance of the capacitor C11 is 62pF, the inductance of the inductor L9 is 10μH, and the inductance of the inductor L10 is 1.8μH. The parallel connection of the capacitors and the series connection of the inductors in the five-order circuit increase the stopband rejection degree, the steepness of the transition band and the passband flatness, so that the interference signals in the signal passing through the five-order circuit can be effectively suppressed, the interference signals in the transition band are also filtered out, and the signal passing through the passband is reduced in attenuation.

[0066] In an embodiment of the application, as shown in Figure 1 and Figure 2 the six-order circuit comprises an inductor L11, a capacitor C12 and a capacitor C13 connected in parallel.

[0067] One end of the inductor L11, one end of the capacitor C12 and one end of the capacitor C13 are connected at a common point, and are connected to a five-stage circuit and an output terminal at the common point; the other end of the inductor L11, the other end of the capacitor C12 and the other end of the capacitor C13 are all grounded.

[0068] As an exemplary selection scheme of the present embodiment, in the six-stage circuit, the inductance of the inductor L11 is 820nH, the capacitance of the capacitor C12 is 1.5nF, and the capacitance of the capacitor C13 is 220nF. The capacitors and inductors in the six-stage circuit interact in parallel, increasing the stopband suppression degree and the change range of the transition band, so that the interference signals in the signal passing through the six-stage circuit can be effectively suppressed, and the interference signals in the transition band frequency range can also be filtered out.

[0069] The six-stage filter circuit filters out the interference signals in other frequency ranges except the signals in the passband range with respect to the input signal. The filter circuit can be used in a transponder transmission unit to filter out the interference components of the uplink signal of the transponder device, so that the transponder transmission unit can better demodulate the FSK signal.

[0070] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalent features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A transponder transmission unit sixth order bandpass filter circuit, characterized by, The filter circuit comprises: a first-order circuit for filtering out interference signals outside a specified frequency range; a second-order circuit connected to one end of the first-order circuit, for increasing the steepness of the transition band and the stopband rejection; the second-order circuit comprises a capacitor C4 and a second inductive component, and the capacitor C4 is connected in parallel with the second inductive component; the second inductive component comprises an inductor L3 and an inductor L4 connected in series; one end of the capacitor C4 and one end of the inductor L3 are connected at a common point, and the capacitor C4 and the inductor L4 are connected to the first-order circuit and the second-order circuit at the common point; the other end of the capacitor C4 and one end of the inductor L4 are grounded; a third-order circuit connected to the other end of the second-order circuit, for increasing the steepness of the transition band and the stopband rejection, and for increasing the passband flatness; the third-order circuit comprises a second capacitor component and a third inductive component connected in series; the second capacitor component comprises a capacitor C5 and a capacitor C6 connected in series, and the third inductive component comprises an inductor L5 and an inductor L6 connected in series; the inductor L5 and the inductor L6 are connected to one end of the second capacitor component and the other end of the second capacitor component respectively, and the other end of the inductor L6 is connected to a fourth-order circuit; a fourth-order circuit connected to the other end of the third-order circuit, for narrowing the passband bandwidth, and for increasing the steepness of the transition band and the stopband rejection; a fifth-order circuit connected to the other end of the fourth-order circuit, for further adjusting the steepness of the transition band, and for increasing the stopband rejection; and a sixth-order circuit connected to the other end of the fifth-order circuit, for outputting a signal meeting the set requirements; the multiple-order circuits in the filter circuit are connected in series.

2. The transponder transmission unit sixth order band pass filter circuit of claim 1, wherein, The first-order circuit comprises a first capacitor component and a first inductive component connected in series; one end of the first capacitor component is connected to a signal input end, and the other end of the first capacitor component is connected to the first inductive component.

3. The transponder transmission unit sixth order band pass filter circuit of claim 2, wherein, The first capacitor component comprises a capacitor C1, a capacitor C2 and a capacitor C3 connected in parallel, and the first inductive component comprises an inductor L1 and an inductor L2 connected in series; the inductor L1 is arranged between the first capacitor component and the inductor L2, and one end of the inductor L2 is connected to a second-order circuit.

4. The transponder transmission unit sixth order band pass filter circuit of claim 1, wherein, The fourth-order circuit comprises a third capacitor component and a fourth inductive component connected in parallel.

5. The transponder transmission unit sixth order band pass filter circuit of claim 4, wherein, The third capacitor component comprises a capacitor C7, a capacitor C9 and a capacitor C8 connected in parallel, and the fourth inductive component comprises an inductor L7 and an inductor L8 connected in series; one end of the capacitor C7, one end of the capacitor C9, one end of the capacitor C8 and one end of the inductor L7 are connected at a common point, and the capacitor C7, the capacitor C9, the capacitor C8 and the inductor L8 are connected to the third-order circuit and the fifth-order circuit at the common point; the other end of the capacitor C7, the other end of the capacitor C9, the other end of the capacitor C8 and one end of the inductor L8 are grounded.

6. The transponder transmission unit sixth order band pass filter circuit of claim 1, wherein, The fifth-order circuit comprises a fourth capacitor component and a fifth inductive component connected in series.

7. The transponder transmission unit sixth order band pass filter circuit of claim 6, wherein, The fourth capacitor component comprises an inductor C10 and an inductor C11 connected in parallel, and the fifth inductive component comprises an inductor L9 and an inductor L10 connected in series; The two ends of the inductor L9 are connected with one end of a fourth capacitor assembly and one end of an inductor L10 respectively, the other end of the fourth capacitor assembly is connected with a four-stage circuit, and the other end of the inductor L10 is connected with a six-stage circuit.

8. The transponder transmission unit sixth order band pass filter circuit according to any one of claims 1-7, characterized by, The six-stage circuit comprises an inductor L11, a capacitor C12 and a capacitor C13 which are connected in parallel with each other; One end of the inductor L11, one end of the capacitor C12 and one end of the capacitor C13 are connected at a common point, and the common point is connected with a five-stage circuit and an output terminal; the other end of the inductor L11, the other end of the capacitor C12 and the other end of the capacitor C13 are grounded.

Images