FD-231 high-precision fetus-voice meter AGC conversion circuit

Abstract

The utility model discloses an FD-231 high-precision fetus-voice meter AGC conversion circuit which comprises a front proportional amplifier circuit, an AGC core circuit, a relay proportional amplifier circuit, a shaping circuit, an emitter follower circuit and an active low-pass filter circuit. According to the utility model, the AGC core circuit is adopted to effectively adapt to the change of the size of an input signal. When the fetal heart signal is strong, the intensity of the signal is automatically reduced, so that the condition that the period of the high-frequency signal cannot be distinguished due to the fact that the signal input into the ADC sampling circuit of the single chip microcomputer is too large is avoided. And when the fetal heart signal is weak, the amplitude of the signal is automatically improved, so that the weak signal can be effectively identified, and the calculation precision of the product is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of fetal heart rate monitor equipment, in particular to an FD-231 high-precision fetal heart rate monitor AGC conversion circuit. Background Art

[0002] The normal heart rate of the fetus is between 120 beats / min and 160 beats / min. If the fetal heart rate is 10 beats / min or >160 beats / min for more than 10 minutes, it indicates that the fetal heart rate is abnormal. At present, the use of fetal heart rate monitors has become more popular. During fetal heart rate monitoring, if there is an abnormality in the fetal heart rate graph, it is often used to indicate fetal heart rate abnormality. In most cases, an abnormal fetal heart rate means that the fetus is hypoxic in the uterus. The more severe the abnormal fetal heart rate, the more severe the fetal hypoxia.

[0003] At present, in obstetrics and gynecology, fetal heart rate monitors are needed for fetal heart rate monitoring in the late stage of pregnant women. Fetal heart rate monitors, also known as fetal heart rate monitors, can obtain fetal heart movement information from the abdomen of pregnant women based on the Doppler principle. They are not used for continuous monitoring, but only for obtaining fetal heart movement information to monitor whether the fetal movement is abnormal. According to the fetal heart condition, it is convenient for medical staff to make corresponding treatment according to the fetal heart condition. The detection control circuit of traditional fetal heart rate monitors is easily affected by the change of input signal amplitude, which causes the output signal amplitude to change accordingly. This change in signal amplitude will affect the data of fetal heart rate monitoring by the fetal heart rate monitor, causing errors and easily causing misjudgment.

[0004] Therefore, the prior art has defects and needs to be improved. Utility Model Content

[0005] The utility model aims to overcome the deficiencies of the prior art and provide an FD-231 high-precision fetal heart monitor AGC conversion circuit.

[0006] The technical solution of the utility model is as follows: an FD-231 high-precision fetal heart monitor AGC conversion circuit is provided, comprising: a pre-proportional amplifier circuit, an AGC core circuit, a relay proportional amplifier circuit, a shaping circuit, an emitter follower circuit, and an active low-pass filter circuit. The pre-proportional amplifier circuit and the AGC core circuit are connected in parallel to the relay proportional amplifier circuit, the output end of the relay proportional amplifier circuit is connected to the input end of the shaping circuit, the output end of the shaping circuit is connected to the input end of the emitter follower circuit, and the output end of the emitter follower is connected to the AGC core circuit and the active low-pass filter circuit.

[0007] Furthermore, the pre-proportional amplifier circuit includes: an operational amplifier chip U3A, a resistor R176, a resistor R179, a capacitor C152, and a capacitor C163, one end of the capacitor C152 is connected to the DOP port, the other end of the capacitor C152 is connected to the resistor R179, the other end of the resistor R179 is connected to one end of the resistor R176, one end of the capacitor C163 and the second pin of the operational amplifier chip U3A, the other end of the resistor R176, the other end of the capacitor C163 and the first pin of the operational amplifier chip U3A are connected in parallel and connected in parallel with the AGC core circuit to the relay proportional amplifier circuit.

[0008] Furthermore, the AGC core circuit includes: an operational amplifier chip U3B, a resistor R156, a resistor R159, a resistor R167, a resistor R168, a resistor R170, a resistor R171, a resistor R172, a capacitor C159, a capacitor C162, and a field effect transistor Q13, one end of the resistor R170 is connected to a +5V power input, the other end of the resistor R170 is connected to one end of the resistor R172, one end of the capacitor C162 and the 5th pin of the operational amplifier chip U3B, the other end of the resistor R172 is connected to the other end of the capacitor C162 in parallel with the ground, and one end of the resistor R171 is connected to the emitter and the follower. The follower circuit is connected, the other end of the resistor R171 is connected to one end of the capacitor C159 and the 6th pin of the operational amplifier chip U3B, the 7th pin of the operational amplifier chip U3B is connected to the other end of the capacitor C159 and one end of the resistor R168, the other end of the resistor R168 is connected to one end of the resistor R167 and the gate of the field effect transistor Q13, the other end of the resistor R167 is connected in parallel with the source of the field effect transistor Q13 and one end of the resistor R174 and is connected in parallel with the pre-proportional amplifier circuit to the relay proportional amplifier circuit, and the other end of the resistor R174 is connected in parallel with the drain of the field effect transistor Q13 and grounded.

[0009] Furthermore, the relay proportional amplifier circuit includes: an operational amplifier chip U7D, a resistor R161, a resistor R164, a capacitor C155, a capacitor C156, and a capacitor C157, one end of the capacitor C156 is connected to the pre-proportional amplifier circuit and the AGC core circuit, the other end of the capacitor C156 is connected to one end of the resistor R161, the other end of the resistor R161 is connected to one end of the resistor R164, one end of the capacitor C457 and the 13th pin of the operational amplifier chip U7D, the 14th pin of the operational amplifier chip U7D is connected to the other end of the resistor R164, the other end of the capacitor C157 and one end of the capacitor C155, and the other end of the capacitor C155 is connected to the shaping circuit.

[0010] Furthermore, the shaping circuit includes: an operational amplifier chip U7C, a switching diode Q14, a resistor R154, a resistor R160, and a capacitor C158, one end of the resistor R160 is connected to the relay proportional amplifier circuit, the other end of the resistor R160 is connected to one end of the resistor R154, one end of the capacitor C158, the negative terminal of the switching diode Q14, and the 9th pin of the operational amplifier chip U7C, the 8th pin of the operational amplifier chip U7C is connected to the control electrode of the switching diode Q14, and the positive terminal of the switching diode is connected in parallel with the other end of the resistor R154 and the other end of the capacitor C158 to the emitter follower circuit.

[0011] Furthermore, the emitter follower circuit includes: an operational amplifier chip U7A, the third pin of the operational amplifier chip U7A is connected to the shaping circuit, the fourth pin of the operational amplifier chip U7A is connected to a +5V input power supply, the eleventh pin of the operational amplifier chip U7A is grounded, and the second pin and the first pin of the operational amplifier chip U7A are connected in parallel to the AGC core circuit and the active low-pass filter circuit.

[0012] Further, the active low-pass filter circuit includes: an operational amplifier chip U7B, a switching diode D16, a resistor R161, a resistor R165, a resistor R169, a resistor R173, a resistor R185, a capacitor C160, and a capacitor C161, one end of the resistor R169 is connected to the emitter follower circuit, the other end of the resistor R169 is connected to one end of the capacitor C161 and one end of the resistor R165, the other end of the resistor R165 is connected to the 5th pin of the operational amplifier chip U7B and one end of the capacitor C160, and the capacitor C160 is connected to the 5th pin of the operational amplifier chip U7B. The other end and the 11th pin of the operational amplifier chip U7B are grounded respectively, the 6th pin of the operational amplifier chip U7B is connected to one end of the resistor R173, the 7th pin of the operational amplifier chip U7B is connected to the other end of the capacitor C161, the other end of the resistor R173, and one end of the resistor R185, the other end of the resistor R185 is connected in parallel with the control electrode of the switching diode D16 to the FHR_AD port, the positive terminal of the switching diode D16 is grounded, and the negative terminal of the switching diode D16 and the 4th pin of the operational amplifier chip U7B are connected to the +5V input power supply.

[0013] By adopting the above scheme, the utility model adopts the AGC core circuit to effectively adapt to the change of the input signal size. When the fetal heart signal is strong, the signal strength is automatically reduced, so that the signal input to the single-chip ADC sampling circuit will not be unable to distinguish the period of the high-frequency signal due to the signal being too large. When the fetal heart signal is weak, the amplitude of the signal is automatically increased, so that the weak signal can be effectively identified, thereby improving the calculation accuracy of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the circuit module of the pre-proportional amplifier circuit.

[0015] Figure 2 This is a circuit module diagram of the AGC core circuit.

[0016] Figure 3 Schematic diagram of the circuit module of the relay proportional amplifier circuit.

[0017] Figure 4 Schematic diagram of the circuit module of the integer circuit.

[0018] Figure 5 Schematic diagram of the circuit module of the emitter follower circuit.

[0019] Figure 6 Schematic diagram of the circuit module of the active low-pass filter circuit. DETAILED DESCRIPTION

[0020] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0021] The utility model provides an FD-231 high-precision fetal heart monitor AGC conversion circuit, comprising: a pre-proportional amplifier circuit, an AGC core circuit, a relay proportional amplifier circuit, a shaping circuit, an emitter follower circuit, and an active low-pass filter circuit, wherein the pre-proportional amplifier circuit and the AGC core circuit are connected in parallel to the relay proportional amplifier circuit, the output end of the relay proportional amplifier circuit is connected to the input end of the shaping circuit, the output end of the shaping circuit is connected to the input end of the emitter follower circuit, and the output end of the emitter follower is connected to the AGC core circuit and the active low-pass filter circuit. By adopting the AGC core circuit, it is used to effectively adapt to the change in the size of the input signal. When the fetal heart signal is strong, the signal strength is automatically reduced, so that the signal input to the single-chip microcomputer ADC sampling circuit will not be unable to distinguish the period of the high-frequency signal due to the excessive signal. When the fetal heart signal is weak, the amplitude of the signal is automatically increased, so that the weaker signal can be effectively identified, and the calculation accuracy of the product is improved.

[0022] See also Figure 1The preamplifier circuit includes: an op amp chip U3A, a resistor R176, a resistor R179, a capacitor C152, and a capacitor C163. One end of the capacitor C152 is connected to the DOP port, and the other end of the capacitor C152 is connected to the resistor R179. The other end of the resistor R179 is connected to one end of the resistor R176, one end of the capacitor C163, and the second pin of the op amp chip U3A. The other end of the resistor R176, the other end of the capacitor C163, and the first pin of the op amp chip U3A are connected in parallel and connected in parallel with the AGC core circuit to the relay proportional amplifier circuit. The fetal heart audio signal is input from the DOP port direction, and the fetal heart audio signal is amplified by the preamplifier circuit, so that the fetal heart audio signal is amplified to a larger amplitude, which is convenient for providing a suitable signal for the gain control part of the back end.

[0023] See also Figure 2 The AGC core circuit includes: an operational amplifier chip U3B, a resistor R156, a resistor R159, a resistor R167, a resistor R168, a resistor R170, a resistor R171, a resistor R172, a capacitor C159, a capacitor C162, and a field effect transistor Q13. One end of the resistor R170 is connected to a +5V power input, and the other end of the resistor R170 is connected to one end of the resistor R172, one end of the capacitor C162, and the 5th pin of the operational amplifier chip U3B. The other end of the resistor R172 is connected to the other end of the capacitor C162 in parallel with the ground, and one end of the resistor R171 is connected to the emitter follower The circuit is connected, the other end of the resistor R171 is connected to one end of the capacitor C159 and the 6th pin of the operational amplifier chip U3B, the 7th pin of the operational amplifier chip U3B is connected to the other end of the capacitor C159 and one end of the resistor R168, the other end of the resistor R168 is connected to one end of the resistor R167 and the gate of the field effect tube Q13, the other end of the resistor R167 is connected in parallel with the source of the field effect tube Q13 and one end of the resistor R174 and connected in parallel with the pre-proportional amplifier circuit to the relay proportional amplifier circuit, and the other end of the resistor R174 is connected in parallel with the drain of the field effect tube Q13 to the ground. After the fetal heart audio signal is converted by the emitter follower circuit, a part of it is input to the inverting end of the operational amplifier chip U3B, and the other part is input to the active low-pass filter circuit. A comparison reference voltage is set at the in-phase end of the operational amplifier chip U3B. When the inverting end input signal passes through the integration circuit built by the operational amplifier chip U3B, the capacitor C159 is charged.

[0024] When the charging signal is weak, the output voltage of the operational amplifier chip U3B will drop, thereby controlling the drain current of the field effect transistor Q13 to decrease, reducing the voltage divider ratio of the resistor R166 and the resistor R174, thereby increasing the signal amplitude input to the relay proportional amplifier circuit.

[0025] When the charging signal is strong, the output voltage of the operational amplifier chip U3B will rise, thereby controlling the drain current of the field effect transistor Q13 to increase, increasing the voltage divider ratio of the resistor R166 and the resistor R174, thereby reducing the signal amplitude input to the relay proportional amplifier circuit.

[0026] See also Figure 3 The relay proportional amplifier circuit includes: an operational amplifier chip U7D, a resistor R161, a resistor R164, a capacitor C155, a capacitor C156, and a capacitor C157. One end of the capacitor C156 is connected to the pre-proportional amplifier circuit and the AGC core circuit. The other end of the capacitor C156 is connected to one end of the resistor R161. The other end of the resistor R161 is connected to one end of the resistor R164, one end of the capacitor C457, and the 13th pin of the operational amplifier chip U7D. The 14th pin of the operational amplifier chip U7D is connected to the other end of the resistor R164, the other end of the capacitor C157, and one end of the capacitor C155. The other end of the capacitor C155 is connected to the shaping circuit. The fetal heart audio signal is input from the pre-proportional amplifier circuit or the AGC core circuit, and cooperates with the AGC core circuit to provide a first-level current amplification effect. After the AGC takes effect, it is equivalent to the effect of the resistor voltage divider, so the output current is reduced.

[0027] See also Figure 4 The shaping circuit includes: an operational amplifier chip U7C, a switching diode Q14, a resistor R154, a resistor R160, and a capacitor C158, one end of the resistor R160 is connected to the relay proportional amplifier circuit, the other end of the resistor R160 is connected to one end of the resistor R154, one end of the capacitor C158, the negative end of the switching diode Q14, and the 9th pin of the operational amplifier chip U7C, the 8th pin of the operational amplifier chip U7C is connected to the control electrode of the switching diode Q14, and the positive end of the switching diode is connected in parallel with the other end of the resistor R154 and the other end of the capacitor C158 to the emitter follower circuit. The current is input from the relay proportional amplifier circuit to the shaping circuit, and the waveform with positive and negative symmetry is converted into a negative semi-axis signal only through the shaping circuit to achieve shaping processing of the waveform.

[0028] See also Figure 5, the emitter follower circuit includes: an op amp chip U7A, the 3rd pin of the op amp chip U7A is connected to the shaping circuit, and the 4th pin of the op amp chip U7A is connected to the +5V input power supply. The 11th pin of the op amp chip U7A is grounded, and the 2nd pin and the 1st pin of the op amp chip U7A are connected in parallel to the AGC core circuit and the active low-pass filter circuit. The audio signal is input from the shaping circuit to the emitter follower circuit, and the negative half-axis signal obtained by the shaping circuit is converted into a positive half-axis signal, while the driving ability of the input signal is improved to achieve the effect of current amplification.

[0029] See also Figure 6 The active low-pass filter circuit includes: an operational amplifier chip U7B, a switching diode D16, a resistor R161, a resistor R165, a resistor R169, a resistor R173, a resistor R185, a capacitor C160, and a capacitor C161, one end of the resistor R169 is connected to the emitter follower circuit, the other end of the resistor R169 is connected to one end of the capacitor C161 and one end of the resistor R165, the other end of the resistor R165 is connected to the 5th pin of the operational amplifier chip U7B and one end of the capacitor C160, and the other end of the capacitor C160 is connected to the 5th pin of the operational amplifier chip U7B and one end of the capacitor C160. The 6th pin of the operational amplifier chip U7B is connected to one end of the resistor R173, and the 7th pin of the operational amplifier chip U7B is connected to the other end of the capacitor C161, the other end of the resistor R173, and one end of the resistor R185. The other end of the resistor R185 is connected in parallel with the control electrode of the switching diode D16 to the FHR_AD port. The positive end of the switching diode D16 is grounded, and the negative end of the switching diode D16 and the 4th pin of the operational amplifier chip U7B are connected to the +5V input power supply. The fetal heart audio signal is input from the emitter follower circuit to the active low-pass filter circuit, and the positive half-axis signal processed by the emitter follower is input to the active low-pass filter circuit for processing, thereby filtering out the high-frequency noise, and converting the complex audio signal into a simple envelope signal, which is conducive to the recognition of the signal trend by the ADC sampling circuit of the single-chip microcomputer, reducing the difficulty of the single-chip microcomputer in processing the signal, thereby improving the processing efficiency and calculation accuracy of the single-chip microcomputer.

[0030] In summary, the utility model adopts the AGC core circuit to effectively adapt to the change of the input signal size. When the fetal heart signal is strong, the signal strength is automatically reduced, so that the signal input to the single-chip ADC sampling circuit will not be unable to distinguish the period of the high-frequency signal due to the signal being too large. When the fetal heart signal is weak, the signal amplitude is automatically increased, so that the weak signal can be effectively identified, and the calculation accuracy of the product is improved.

[0031] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An FD-231 high-precision fetal heart monitor AGC conversion circuit, characterized in that: include: A pre-proportional amplifier circuit, an AGC core circuit, a relay proportional amplifier circuit, a shaping circuit, an emitter follower circuit, and an active low-pass filter circuit. The pre-proportional amplifier circuit and the AGC core circuit are connected in parallel to the relay proportional amplifier circuit. The output end of the relay proportional amplifier circuit is connected to the input end of the shaping circuit. The output end of the shaping circuit is connected to the input end of the emitter follower circuit. The output end of the emitter follower is connected to the AGC core circuit and the active low-pass filter circuit.

2. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The pre-proportional amplifier circuit includes: an operational amplifier chip U3A, a resistor R176, a resistor R179, a capacitor C152, and a capacitor C163. One end of the capacitor C152 is connected to the DOP port, and the other end of the capacitor C152 is connected to the resistor R179. The other end of the resistor R179 is connected to one end of the resistor R176, one end of the capacitor C163, and the second pin of the operational amplifier chip U3A. The other end of the resistor R176, the other end of the capacitor C163, and the first pin of the operational amplifier chip U3A are connected in parallel and connected in parallel with the AGC core circuit to the relay proportional amplifier circuit.

3. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The AGC core circuit includes: an operational amplifier chip U3B, a resistor R156, a resistor R159, a resistor R167, a resistor R168, a resistor R170, a resistor R171, a resistor R172, a capacitor C159, a capacitor C162, and a field effect transistor Q13, one end of the resistor R170 is connected to a +5V power input, the other end of the resistor R170 is connected to one end of the resistor R172, one end of the capacitor C162 and the 5th pin of the operational amplifier chip U3B, the other end of the resistor R172 and the other end of the capacitor C162 are connected to the ground in parallel, and one end of the resistor R171 is connected to the emitter follower circuit The other end of the resistor R171 is connected to one end of the capacitor C159 and the 6th pin of the operational amplifier chip U3B, the 7th pin of the operational amplifier chip U3B is connected to the other end of the capacitor C159 and one end of the resistor R168, the other end of the resistor R168 is connected to one end of the resistor R167 and the gate of the field effect transistor Q13, the other end of the resistor R167 is connected in parallel with the source of the field effect transistor Q13 and one end of the resistor R174 and is connected in parallel with the pre-proportional amplifier circuit to the relay proportional amplifier circuit, and the other end of the resistor R174 is connected in parallel with the drain of the field effect transistor Q13 and grounded.

4. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The relay proportional amplifier circuit includes: an operational amplifier chip U7D, a resistor R161, a resistor R164, a capacitor C155, a capacitor C156, and a capacitor C157. One end of the capacitor C156 is connected to the pre-proportional amplifier circuit and the AGC core circuit, the other end of the capacitor C156 is connected to one end of the resistor R161, the other end of the resistor R161 is connected to one end of the resistor R164, one end of the capacitor C457, and the 13th pin of the operational amplifier chip U7D, the 14th pin of the operational amplifier chip U7D is connected to the other end of the resistor R164, the other end of the capacitor C157, and one end of the capacitor C155, and the other end of the capacitor C155 is connected to the shaping circuit.

5. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The shaping circuit includes: an operational amplifier chip U7C, a switching diode Q14, a resistor R154, a resistor R160, and a capacitor C158. One end of the resistor R160 is connected to the relay proportional amplifier circuit, and the other end of the resistor R160 is connected to one end of the resistor R154, one end of the capacitor C158, the negative terminal of the switching diode Q14, and the 9th pin of the operational amplifier chip U7C. The 8th pin of the operational amplifier chip U7C is connected to the control electrode of the switching diode Q14, and the positive terminal of the switching diode is connected in parallel with the other end of the resistor R154 and the other end of the capacitor C158 to the emitter follower circuit.

6. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The emitter follower circuit includes: an operational amplifier chip U7A, the third pin of the operational amplifier chip U7A is connected to the shaping circuit, the fourth pin of the operational amplifier chip U7A is connected to a +5V input power supply, the eleventh pin of the operational amplifier chip U7A is grounded, and the second pin and the first pin of the operational amplifier chip U7A are connected in parallel to the AGC core circuit and the active low-pass filter circuit.

7. The FD-231 high-precision fetal heart monitor AGC conversion circuit according to claim 1 is characterized in that: The active low-pass filter circuit includes: an operational amplifier chip U7B, a switching diode D16, a resistor R161, a resistor R165, a resistor R169, a resistor R173, a resistor R185, a capacitor C160, and a capacitor C161, one end of the resistor R169 is connected to the emitter follower circuit, the other end of the resistor R169 is connected to one end of the capacitor C161 and one end of the resistor R165, the other end of the resistor R165 is connected to the 5th pin of the operational amplifier chip U7B and one end of the capacitor C160, and the other end of the capacitor C160 And the 11th pin of the operational amplifier chip U7B are respectively grounded, the 6th pin of the operational amplifier chip U7B is connected to one end of the resistor R173, the 7th pin of the operational amplifier chip U7B is connected to the other end of the capacitor C161, the other end of the resistor R173, and one end of the resistor R185, the other end of the resistor R185 is connected in parallel with the control electrode of the switching diode D16 and the FHR_AD port, the positive terminal of the switching diode D16 is grounded, and the negative terminal of the switching diode D16 and the 4th pin of the operational amplifier chip U7B are connected to the +5V input power supply.

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