Double-frequency-point locomotive signal ground equipment detector

Abstract

The utility model discloses a double frequency point type locomotive signal ground equipment detector, comprising a power supply, an MCU, a sine generator, a power amplification circuit and a current indication circuit, the MCU is connected with the power supply, the sine generator is connected with the MCU and is used for generating a sine signal source, an input end of the power amplification circuit is connected with the sine generator, and an output end of the power amplification circuit is connected with the power amplification circuit. The output end is connected with to-be-tested ground equipment in an electromagnetic coupling mode; the current indication circuit is connected with the power amplification circuit and is used for displaying the coupling condition of the ground equipment to be tested. The detector monitors and visually displays the coupling condition of the ground equipment inductor in an electromagnetic coupling mode, and can directly check the tuning condition and the acting capacity of the inductor under the condition that a ground inductor circuit is not cut off.

Description

Technical Field

[0001] This utility model relates to the field of locomotive signal ground equipment testing technology, specifically to a dual-frequency point-type locomotive signal ground equipment testing instrument. Background Technology

[0002] Locomotive signals consist of ground equipment and onboard equipment. The ground equipment transmits the display of the ground signal ahead to the locomotive via encoding. The onboard equipment decodes the signal and displays it on the locomotive, allowing the driver to confirm the information and take appropriate action in advance.

[0003] The ground equipment includes ground sensors and tuning boxes. The ground sensors and tuning boxes can form two passive resonant circuits at 1200Hz and 1700Hz. Depending on the display status of the ground signal, the two circuits can be formed simultaneously or one of the circuits can be formed alone to transmit information to the locomotive sensors.

[0004] Dual-frequency point-type locomotive signals are transmitted through mutual sensing between locomotive sensors and ground sensors. Two frequencies (1200Hz and 1700Hz) and two coupling operations are used to form a single signal transmission. The installation of ground sensors on the line is as follows... Figure 8 As shown. Each action point has two sensors. When a locomotive passes through an action point, it needs to receive two signals to correctly display a signal. The first sensor at each action point is equipped with a single-frequency tuner (resonating at 1200Hz or 1700Hz), and the second sensor is equipped with a dual-frequency tuner (it can resonate at 1200Hz or 1700Hz, or simultaneously form a resonance of 1200Hz and 1700Hz). Each station has three action points in each direction. The first action point is located 900 meters from the entrance signal, and the second action point is located 400 meters from the entrance signal; the first and second action points repeat the entrance signal display. The third action point is located inside the entrance signal and repeats the exit signal display. When a locomotive passes over the ground sensor, electromagnetic coupling occurs between the locomotive sensor and the ground sensor, reducing the resonant current in the corresponding circuit of the locomotive sensor and decreasing the voltage output. By detecting this voltage value, the information on the ground can be obtained.

[0005] However, dual-frequency point-type locomotive signals are only used on some meter-gauge railways, and manufacturers have stopped production for many years. The contradiction between use and maintenance is prominent. In order to maintain the operation of the equipment, there is an urgent need for a ground equipment testing instrument to test the ground equipment and play a positive role in ensuring safe train operation. Utility Model Content

[0006] To address the aforementioned problems, this utility model provides a dual-frequency point-type locomotive signal ground equipment detector. It generates a sine wave signal through a sine generator and monitors the ground equipment through electromagnetic coupling, enabling the detection of dual-frequency point-type locomotive signal ground equipment.

[0007] Specifically, this utility model is implemented as follows:

[0008] A dual-frequency point-type locomotive signal ground equipment detector includes:

[0009] power supply;

[0010] The MCU is connected to the power supply.

[0011] A sine wave generator, connected to an MCU, is used to generate a sine wave signal source;

[0012] The power amplifier circuit has its input terminal connected to a sine generator, and its output terminal connected to the ground device under test via electromagnetic coupling.

[0013] A current indicator circuit, connected to the power amplifier circuit, is used to display the coupling status of the ground equipment under test.

[0014] Furthermore, the power amplifier circuit includes:

[0015] An amplifier is connected to a sine generator at its input and to a capacitor C3 and a coil Lj at its output. The coil Lj forms an electromagnetic coupling circuit with the ground sensor coil Ld of the ground device under test.

[0016] Furthermore, the amplifier is an LM386 chip, with pin 2 grounded, pin 3 connected to the sine generator, pin 4 grounded, pin 5 connected to capacitor C3, pin 6 connected to the power supply, and pin 7 grounded via capacitor C1.

[0017] Furthermore, the power amplifier circuit also includes a capacitor C3 and a resistor R1, with the capacitor C2 and resistor R1 located between pin 5 and ground.

[0018] Furthermore, a potentiometer is provided between the sine generator and pin 3.

[0019] Furthermore, the current indicating circuit includes:

[0020] Coil Lq is connected in series with coil Lj;

[0021] An ammeter, connected to coil Lq, is used to measure the current in coil Lq.

[0022] Furthermore, the current indication circuit also includes a diode D, a current-limiting resistor R2, and a filter capacitor C4. The diode D is connected to the current-limiting resistor R2, and the other end of the current-limiting resistor R2 is grounded after passing through an ammeter. The filter capacitor C4 is connected in series with the current-limiting resistor R2. The resistor R1 and the current-limiting resistor R2 together set the midpoint voltage.

[0023] Furthermore, the dual-frequency point-type locomotive signal ground equipment detector also includes:

[0024] The power supply, MCU, sine generator, power amplifier circuit and current indicator circuit are all housed inside the housing, and the ammeter is mounted on the housing.

[0025] Furthermore, a frequency switch is provided on the housing, which is connected to the MCU and used to switch between 1200Hz and 1700Hz sine wave signal sources.

[0026] Furthermore, the sine generator includes: a phase accumulator, a waveform memory, a digital-to-analog converter, and a low-pass filter connected in sequence.

[0027] The working principle of this invention is as follows: The MCU provides working pulses to the sine generator, which generates a sine signal. This signal is transmitted to a power amplifier for power amplification to obtain a sufficiently large power output. The amplified signal generates a current I1 in the loop. I1 flows through coil Lj and forms a magnetic field. This magnetic field acts on the ground sensor coil Ld of the ground device under test, creating a changing magnetic flux in coil Ld, thereby inducing a voltage in coil Ld. Since the ground sensor forms a loop, this induced voltage will generate a current I2. The magnetic flux generated by I2 opposes the change in the magnetic flux of the ground sensor, weakening the magnetic flux in coil Lj.

[0028] This function is equivalent to adding a reflective impedance to the ground equipment detector circuit from the ground sensor circuit, which reduces the current in the ground equipment detector circuit and the voltage across the coil of the ground equipment detector. Since the coil Lq of the current indicator circuit is wound around the coil Lj, the voltage across the coil Lj decreases, which in turn reduces the voltage across the coil Lq, thereby reducing the current and causing the ammeter pointer to deflect to the left. Thus, without disconnecting the ground sensor circuit, the deflection of the ammeter pointer can be used to directly reflect the tuning status and operational capability of the ground equipment sensor.

[0029] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0030] (1) The dual-frequency point-type locomotive signal ground equipment detector provided by this utility model can directly check the tuning status and function of the sensor without cutting off the ground sensor circuit.

[0031] (2) Monitoring is carried out by electromagnetic coupling, and an ammeter is connected at the same time. The ammeter can intuitively display the coupling status of the ground equipment sensor.

[0032] (3) The amplifier circuit adopts the OTL power amplifier circuit, which can make the detector work with a single 3.7V battery, making the detector smaller and lighter. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the dual-frequency point-type locomotive signal ground equipment detector in Example 1;

[0034] Figure 2 This is a side view of the dual-frequency point-type locomotive signal ground equipment detector in Example 1;

[0035] Figure 3 This is an internal schematic diagram of the dual-frequency point-type locomotive signal ground equipment detector in Example 1;

[0036] Figure 4 This is a structural block diagram of the dual-frequency point-type locomotive signal ground equipment detector in Example 1;

[0037] Figure 5 This is a structural block diagram of the sine generator in Example 1;

[0038] Figure 6 This is a circuit diagram of the power amplifier circuit in Example 1;

[0039] Figure 7 This is a usage status diagram of the dual-frequency point-type locomotive signal ground equipment detector in Example 1;

[0040] Figure 8 This is a layout diagram of the existing dual-frequency point-type locomotive signal ground equipment.

[0041] Figure label:

[0042] 1-Housing; 11-Battery compartment; 2-Frequency switch; 3-Circuit board; 4-Power display module; A-Ammeter. Detailed Implementation

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] like Figure 1-4As shown, this embodiment provides a dual-frequency locomotive signal ground equipment detector, including: a housing 1 and a power supply, MCU, sine generator, power amplifier circuit, and ammeter A disposed within the housing 1. The housing 1 consists of a cover and a body. The power supply, MCU, sine generator, and power amplifier circuit are located inside the body, while ammeter A is located on the surface of the cover. The body has a built-in battery compartment 11 for holding a single 3.7V battery. The MCU uses a PIC18LF4520 microcontroller, which has a CPU and a CCP module. The CCP module can generate two PWM pulses with adjustable frequency and duty cycle to generate a 500kHz square wave signal. The input terminal of the MCU is connected to a frequency switch 2 on the surface of the cover, and the CCP module is connected to the sine generator. The frequency of the signal generated by the sine generator can be switched via the frequency switch 2.

[0046] Specifically, the sine wave generator uses the AD9833 DDS signal generator module as the chip for generating sine waves. It adopts DDS (Direc Digital Synthesis) technology and selects the AD9833 from Analog Devices (ANALOG DEVICES) as the chip for generating sine waves. The 500kHz square wave signal output by the microcontroller MCU is controlled by the program to generate 1200Hz and 1700Hz sine wave signal sources by the AD9833. After being amplified by the LM386, the signal drives a series resonant circuit composed of capacitors and inductors. By coupling this circuit with the ground circuit, the condition of the ground equipment can be determined, providing technical support for the maintenance work in the signal work area.

[0047] like Figure 5 As shown, it includes: a phase accumulator, a waveform memory, a digital-to-analog converter, and a low-pass filter connected in sequence. The method by which a DDS signal generator generates a signal is existing technology. Its principle is based on the sampling theorem. First, the waveform to be generated is sampled, the sampled values ​​are digitized and stored in the memory as a lookup table, then the data is read from the lookup table, converted to an analog quantity by a D / A converter, and the stored waveform is reconstructed.

[0048] The phase accumulator, composed of an N-bit adder and an N-bit accumulator, is a crucial component of the DDS module. Driven by the reference frequency clock, the DDS module begins operation. With each incoming reference clock, the accumulator adds the frequency control word (FW) to the value output from the register, inputting the sum back into the register. The accumulator register, in turn, feeds back the data generated during the previous reference clock cycle. This continuous accumulation of the frequency control word, driven by the clock, allows for the conversion between phase and amplitude. Using the data output from the phase accumulator as an address, the waveform memory can be used to look up the corresponding amplitude table, thus converting the phase to amplitude. The waveform memory is a programmable read-only memory (PROM) that stores the sampled coded values ​​of a one-cycle sine wave signal, addressed by phase. It contains the digital amplitude information of a one-cycle sine wave, with each address corresponding to a phase point within the 0°-360° range of the sine wave. The output of the N-bit register is added to the frequency control word to obtain the data, which is used as an address to address the waveform memory. The waveform memory maps the input address phase information into a sine wave amplitude signal to drive the DAC to output an analog signal. The low-pass filter filters out abrupt high-frequency signals and outputs a spectrally pure sine wave signal.

[0049] In the DDS module, the formula for the output frequency is:

[0050]

[0051] The frequency resolution of the output signal is

[0052]

[0053] As can be seen from the above two equations, when the reference signal and the number of bits in the adder or register are given, the final output frequency of the signal is mainly determined by the frequency control word. Therefore, when the frequency control word changes, the output frequency also changes, thus realizing the basic function of frequency modulation.

[0054] like Figure 6As shown, the power amplifier circuit uses an OTL circuit, which includes: an amplifier, capacitor C3, and resistor R1. The amplifier uses an LM386 chip, with pin 2 as the inverting input, pin 3 as the non-inverting input, and pin 5 as the output. Pin 2 is grounded, and pin 3 is connected to a sine wave generator. The sine wave signal generated by the sine wave generator is divided by a 10K potentiometer and then input from pin 3. Pin 4 is grounded, and pin 5 is connected to an external capacitor C3, which is then connected to the coil Lj. Pin 6 is connected to the power supply, and a capacitor C2 and resistor R1 are placed between pin 5 and ground. Pin 7 is grounded via capacitor C1. Pins 1 and 8 are voltage gain setting terminals. When pins 1 and 8 are open, the negative feedback is strongest, and the voltage amplification factor of the entire circuit is 20 times. Alternatively, an external RC series circuit can be connected between pins 1 and 8 to increase the voltage amplification factor to 200.

[0055] The current indication circuit includes: diode D, current-limiting resistor R2, filter capacitor C4, coil Lq and ammeter A. Coil Lq is wound around coil Lj. Diode D is connected to current-limiting resistor R2. The other end of current-limiting resistor R2 is grounded through ammeter A. Filter capacitor C4 is connected in series with current-limiting resistor R2.

[0056] like Figure 7 As shown, the working principle of this detector is as follows: The MCU provides working pulses to the sine generator, which generates a sine signal. The signal is transmitted to the power amplifier for power amplification. The amplified signal generates a current I1 in the loop. I1 flows through coil Lj and forms a magnetic field. This magnetic field acts on the ground sensor coil Ld of the ground device under test, forming a changing magnetic flux in coil Ld, thereby generating an induced voltage in coil Ld. Since the ground sensor forms a loop, this induced voltage will generate a current I2. The magnetic flux generated by I2 opposes the change in the magnetic flux of the ground sensor, weakening the magnetic flux in coil Lj. This function is equivalent to adding a reflective impedance to the ground equipment detector circuit from the ground sensor circuit, reducing the current in the ground equipment detector circuit and the voltage across the ground equipment detector coil. Since the coil Lq of the current indicator circuit is wound around the coil Lj, the voltage across coil Lj decreases, which in turn reduces the voltage across coil Lq, thus reducing the current and causing the ammeter pointer to deflect to the left. Therefore, without disconnecting the ground sensor circuit, the deflection of the ammeter pointer can be used to directly reflect the tuning status and operational capability of the ground equipment sensor.

[0057] The above-described specific examples are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art to which this invention pertains can make various simple deductions, modifications, or substitutions based on the concept of this invention.

Claims

1. A dual-frequency point-type locomotive signal ground equipment detector, characterized in that, include: power supply; The MCU is connected to the power supply. A sine wave generator, connected to an MCU, is used to generate a sine wave signal source; The power amplifier circuit has its input terminal connected to a sine generator, and its output terminal connected to the ground device under test via electromagnetic coupling. A current indicator circuit, connected to the power amplifier circuit, is used to display the coupling status of the ground equipment under test.

2. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 1, characterized in that, The power amplifier circuit includes: An amplifier is connected to a sine generator at its input and to a capacitor C3 and a coil Lj at its output. The coil Lj forms an electromagnetic coupling circuit with the ground sensor coil Ld of the ground device under test.

3. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 2, characterized in that, The amplifier is an LM386 chip, with pin 2 grounded, pin 3 connected to the sine generator, pin 4 grounded, pin 5 connected to capacitor C3, pin 6 connected to the power supply, and pin 7 grounded via capacitor C1.

4. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 3, characterized in that, The power amplifier circuit also includes: capacitor C3 and resistor R1, with capacitor C2 and resistor R1 located between pin 5 and ground.

5. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 3, characterized in that, A potentiometer is installed between the sine generator and pin 3.

6. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 4, characterized in that, The current indicating circuit includes: Coil Lq is connected in series with coil Lj; An ammeter, connected to coil Lq, is used to measure the current in coil Lq.

7. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 6, characterized in that, The current indication circuit also includes a diode D, a current-limiting resistor R2, and a filter capacitor C4. The diode D is connected to the current-limiting resistor R2, and the other end of the current-limiting resistor R2 is grounded after passing through an ammeter. The filter capacitor C4 is connected in series with the current-limiting resistor R2.

8. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 6, characterized in that, Also includes: The power supply, MCU, sine generator, power amplifier circuit and current indicator circuit are all located inside the housing, and the ammeter is located on the housing.

9. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 8, characterized in that, The housing is equipped with a frequency switch, which is connected to the MCU and is used to switch between 1200Hz and 1700Hz sine wave signal sources.

10. The dual-frequency point-type locomotive signal ground equipment detector as described in claim 1, characterized in that, The sine generator includes a phase accumulator, a waveform memory, a digital-to-analog converter, and a low-pass filter connected in sequence.

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