CN105790780B - Anti- radio reception interference circuit and radio equipment - Google Patents

Abstract

The invention discloses a kind of anti-radio reception interference circuit, including microprocessor, frequency error factor control module and PWM control modules.The invention also discloses a kind of radio equipment, including Switching Power Supply and above-mentioned anti-radio reception interference circuit.The present invention passes through the preset radio reception frequency in microprocessor, mapping relations between the level combinations three of two signal output parts of supply frequency and microprocessor, microprocessor exports level combinations corresponding with current radio reception frequency to frequency error factor control module according to the current radio reception frequency received and the mapping relations, control PWM control modules that the working frequency of Switching Power Supply is switched to supply frequency corresponding with the level combinations of microprocessor output by frequency error factor control module, so that the working frequency of Switching Power Supply is different from current radio reception frequency, the two is not interfere with each other, so as to evade or reduce interference of the Switching Power Supply to radio equipment, improve the antijamming capability of radio equipment.

Description

Anti-radio jamming circuit and radio equipment

technical field

The invention relates to the technical field of anti-jamming of electronic equipment, in particular to a radio interference prevention circuit and radio equipment.

Background technique

In electronic products, the so-called interference means that one system affects another system so that the other system cannot work normally. Generally, interference sources appear as interference at the same frequency, and the path of interference is: interference source → interference path → interfered target. Generally, the impact of interference on the target is reduced from the following three aspects:

(1) Reduce the interference power of the interference source, such as shielding the interference source, and prevent the interference source from radiating interference signals; (2) Turn off the interference path, such as adding magnetic beads or grounding on the transmission path, so that the interference signal is transmitted during transmission Change the path; (3) Protect the target so that it will not be interfered, such as shielding the target to prevent the target from being interfered by external interference signals.

At present, radios are usually powered by a linear power supply to avoid interference. The reason is that if a switching power supply is used for power supply, it will cause serious interference to the radio's medium-wave radio frequency (520KHz-1710KHz). Generally, the operating frequency of switching power supply is tens to hundreds of kilohertz. According to the knowledge of electromagnetic theory, the operating frequency of switching power supply will also emit many harmonics. The odd and even harmonics of different frequencies, such as 3, 5, 7 The octave frequency falls exactly within the radio's medium-wave radio frequency range, and these frequency harmonics will be received directly by the radio antenna. Therefore, when using the AM radio function on radios and high-power audio systems, one of the problems that needs to be solved is how to reduce the interference of the power supply to the radio system.

Traditional AM radios with discrete components have high cost and poor sound quality. Although the digital AM radio system with microprocessor as the core is digitized and combined with switching power supply and Class D power amplifier, the digital AM radio system has the characteristics of good sound quality and convenient channel selection. However, due to The operating frequency harmonics of the switching power supply are very close to the medium wave radio frequency, and the odd harmonics of the switching power supply will seriously interfere with the medium wave radio frequency and seriously affect the radio system, especially the receiving sensitivity of the radio system, thereby improving the digital AM radio system. The anti-interference ability is particularly important.

Contents of the invention

The main purpose of the present invention is to avoid or reduce the interference of the switching power supply to the radio equipment, and improve the anti-interference ability of the radio equipment.

In order to achieve the above object, the present invention provides an anti-radio interference circuit, the anti-radio interference circuit is used to prevent the switching power supply from interfering with radio equipment, and the anti-radio interference circuit includes a microprocessor, a frequency switching control module and a PWM control module ; The two input terminals of the frequency switching control module are respectively connected with the two signal output terminals of the microprocessor, and the two output terminals of the frequency switching control module are all connected to the oscillation frequency setting terminal of the PWM control module connection; wherein, the microprocessor presets the mapping relationship between the radio frequency, the power supply frequency and the level combination of the two signal output ends of the microprocessor, and the microprocessor according to the received current radio frequency and the The above mapping relationship outputs the level combination corresponding to the current radio frequency through the two signal output terminals to the frequency switching control module, and the frequency switching control module controls the frequency switching control module according to the level combination output by the microprocessor. The PWM control module switches the operating frequency of the switching power supply to the power frequency corresponding to the level combination output by the microprocessor, so that the operating frequency of the switching power supply is different from the current radio frequency.

Preferably, the frequency switching control module includes a first switching unit and a second switching unit, the input end of the first switching unit is connected to the first signal output end of the microprocessor, and the first switching unit The output end is connected to the oscillation frequency setting end of the PWM control module; the input end of the second switching unit is connected to the second signal output end of the microprocessor, and the output end of the second switching unit is connected to the The oscillation frequency setting terminal of the PWM control module is connected; the first switching unit is turned on when the first signal output terminal outputs a high-level signal, and is turned off when the first signal output terminal outputs a low-level signal, The second switching unit is turned on when the second signal output terminal outputs a high-level signal, and is turned off when the second signal output terminal outputs a low-level signal, so as to control the PWM control module to switch the switching power supply working frequency.

Preferably, the first switching unit includes a first power supply terminal, a first photocoupler, a first electronic switch, a first resistor and a second resistor;

The anode of the primary diode of the first photocoupler is connected to the first signal output end of the microprocessor, the cathode of the primary diode of the first photocoupler is grounded, and the secondary of the first photocoupler The collector of the triode is connected to the first power supply terminal, the emitter of the secondary triode of the first photocoupler is connected to the first end of the first electronic switch, and grounded through the first resistor; The second terminal of the first electronic switch is connected to the oscillation frequency setting terminal of the PWM control module via the second resistor, and the third terminal of the first electronic switch is grounded.

Preferably, the first electronic switch is a first NPN triode, the base of the first NPN triode is the first end of the first electronic switch, and the collector of the first NPN triode is the first electronic The second end of the switch, the emitter of the first NPN transistor is the third end of the first electronic switch.

Preferably, the first switching unit further includes a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second capacitor;

One end of the third resistor is connected to the first signal output end of the microprocessor, the other end of the third resistor is grounded through the fourth resistor, and the common connection between the third resistor and the fourth resistor is The end is connected to the anode of the primary diode of the first photocoupler; one end of the first capacitor is connected to the common end of the third resistor and the fourth resistor, and the other end of the first capacitor is grounded;

One end of the fifth resistor is connected to the first power supply end, and the other end of the fifth resistor is connected to the collector of the secondary transistor of the first photocoupler; one end of the second capacitor is connected to the The first end of the first electronic switch is connected, and the other end of the second capacitor is grounded.

Preferably, the second switching unit includes a second power supply terminal, a second photocoupler, a second electronic switch, a sixth resistor, and a seventh resistor;

The anode of the primary diode of the second photocoupler is connected to the second signal output end of the microprocessor, the cathode of the primary diode of the second photocoupler is grounded, and the secondary of the second photocoupler The collector of the triode is connected to the second power supply terminal, the emitter of the secondary triode of the second photocoupler is connected to the first end of the second electronic switch, and grounded through the sixth resistor; The second terminal of the second electronic switch is connected to the oscillation frequency setting terminal of the PWM control module via the seventh resistor, and the third terminal of the second electronic switch is grounded.

Preferably, the second electronic switch is a second NPN transistor, the base of the second NPN transistor is the first end of the second electronic switch, and the collector of the second NPN transistor is the second electronic The second end of the switch, the emitter of the second NPN transistor is the third end of the second electronic switch.

Preferably, the second switching unit further includes an eighth resistor, a ninth resistor, a tenth resistor, a third capacitor and a fourth capacitor;

One end of the eighth resistor is connected to the second signal output end of the microprocessor, the other end of the eighth resistor is grounded through the ninth resistor, and the common connection between the eighth resistor and the ninth resistor is The end is connected to the anode of the primary diode of the second photocoupler; one end of the third capacitor is connected to the common end of the eighth resistor and the ninth resistor, and the other end of the third capacitor is grounded;

One end of the tenth resistor is connected to the second power supply end, and the other end of the tenth resistor is connected to the collector of the secondary transistor of the second photocoupler; one end of the fourth capacitor is connected to the The first end of the second electronic switch is connected, and the other end of the fourth capacitor is grounded.

Preferably, the PWM control module includes a PWM controller, an eleventh resistor, a twelfth resistor and a fifth capacitor;

The oscillation frequency setting pin of the PWM controller is respectively connected to the output end of the first switching unit and the output end of the second switching unit; one end of the eleventh resistor is connected to the oscillation frequency of the PWM controller The setting pin is connected, and is connected to the clock rate modulation pin of the PWM controller via the twelfth resistor, and the other end of the eleventh resistor is grounded; one end of the fifth capacitor is connected to the PWM controller The clock rate modulation pin is connected, and the other end of the fifth capacitor is grounded.

In addition, in order to achieve the above object, the present invention also provides a radio equipment, the radio equipment includes a switching power supply and an anti-radio interference circuit, the anti-radio interference circuit is used to prevent the switching power supply from interfering with the radio equipment, and the anti-radio interference circuit It includes a microprocessor, a frequency switching control module and a PWM control module; the two input terminals of the frequency switching control module are respectively connected to the two signal output terminals of the microprocessor, and the two output terminals of the frequency switching control module Both ends are connected with the oscillation frequency setting end of the PWM control module; wherein, the microprocessor presets the mapping relationship between the radio frequency, the power frequency and the level combination of the two signal output ends of the microprocessor, so The microprocessor outputs a level corresponding to the current radio frequency through two signal output ports according to the received current radio frequency and the mapping relationship to the frequency switching control module, and the frequency switching control module according to the The level combination output by the microprocessor controls the PWM control module to switch the operating frequency of the switching power supply to the power frequency corresponding to the level combination output by the microprocessor, so that the operating frequency of the switching power supply is consistent with the current radio frequency The frequency is different.

Anti-radio interference circuit and radio equipment of the present invention, by preset radio frequency, power supply frequency and the mapping relation between the level combination three of two signal output ends of microprocessor in microprocessor, microprocessor according to receiving The current radio frequency and the mapping relationship output and the level corresponding to the current radio frequency are combined to the frequency switching control module, and the PWM control module is controlled by the frequency switching control module to switch the operating frequency of the switching power supply to the level combination output by the microprocessor Corresponding power supply frequency, so that the operating frequency of the switching power supply is different from the current radio frequency, so that the operating frequency of the switching power supply and the current radio frequency do not interfere with each other, so that the interference of the switching power supply to the radio equipment can be avoided or reduced, and the radio equipment can be improved. Anti-interference ability.

Description of drawings

Fig. 1 is the functional block diagram of the preferred embodiment of the radio interference prevention circuit of the present invention;

Fig. 2 is a schematic diagram of the circuit structure of a preferred embodiment of the radio interference prevention circuit of the present invention.

The realization of the purpose, functional characteristics and advantages of the present invention will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The invention provides a radio interference prevention circuit, which is applied to radio equipment, such as consumer electronic products (such as mobile phones), stereos, radios and the like with radio function.

Referring to FIG. 1 , FIG. 1 is a functional block diagram of a preferred embodiment of the radio interference prevention circuit of the present invention.

In a preferred embodiment of the present invention, the radio interference prevention circuit of the present invention is used to prevent the switching power supply from interfering with radio equipment, and the radio interference prevention circuit includes a microprocessor 100, a frequency switching control module 200 and a PWM control module 300; the frequency switching The two input terminals of the control module 200 are respectively connected to the two signal output terminals of the microprocessor 100 , and the two output terminals of the frequency switching control module 200 are both connected to the oscillation frequency setting terminal of the PWM control module 300 .

Wherein, the microprocessor 100 presets the mapping relationship between the radio frequency, the power frequency, and the level combinations of the two signal output ends of the microprocessor 100. In practical applications, when the user uses the radio device to search for a channel, the microprocessor The receiver 100 will receive the radio frequency corresponding to the channel currently searched by the user, that is, the microprocessor 100 receives the current radio frequency. The mapping relationship between the level combination three, the microprocessor 100 according to the received current radio frequency and the above-mentioned mapping relationship, outputs the level combination corresponding to the current radio frequency through the two signal output terminals of the microprocessor 100 to the frequency The switching control module 200, the frequency switching control module 200 controls the PWM control module 300 to switch the operating frequency of the switching power supply to the power frequency corresponding to the level combination output by the microprocessor 100 according to the level combination output by the microprocessor 100, so as to Make the operating frequency of the switching power supply different from the current radio frequency, wherein the combination of levels may be a combination of high and low levels, high and high levels, and low and low levels, which is not limited here.

Since the frequency of medium wave radio in each country is relatively fixed, the whole world is divided into two systems, namely 9KHz per step and 10KHz per step. Therefore, when the radio equipment pre-sets the corresponding sales area in advance, the corresponding frequency interval (9KHz or 10KHz) can be known, and the frequency range of the country where the corresponding medium-wave radio frequency is located, such as in China, the medium-wave radio frequency The range is 531KHz to 1620KHz, and the frequency interval is 9KHz.

After testing, it is found that when the radio frequency is below 999KHz, the switching power supply uses a higher switching frequency (such as 110KHz) to make the receiving sensitivity of the radio equipment higher; when the radio frequency is higher than 1008KHz, the switching power supply uses a lower switching frequency. (such as 80KHz) will make the receiving sensitivity of the radio equipment higher. During the experimental test, the receiving sensitivity data of the radio equipment at all frequency points were obtained by testing the full frequency band 531-1620KHz (9KHz step frequency) and 530-1710KHz (10KHz step frequency), as shown in Table 1 below Take the full frequency band 531-1620KHz (9KHz step frequency) as an illustration. "√" in Table 1 indicates that the receiving sensitivity of the radio equipment is high, and "×" indicates that the receiving sensitivity of the radio equipment is low. For the case of using 10KHz as the step frequency, refer to the table 1. It is similar to using 9KHz as the step frequency, so I won’t repeat it here. Taking 9KHz as the step frequency, there are 122 channels in 531-1620KHz. Through experiments, we can know that the receiving sensitivity corresponding to each channel is different, so the corresponding receiving sensitivity data is different, such as 68dBu, 70dBu, 80dBu, etc. During the test, the different Depending on the operating frequency of the switching power supply, the receiving sensitivity of the radio equipment will also be different.

For example, if the radio frequency is 530KHz, when the frequency of the switching power supply is 100KHz, the receiving sensitivity obtained by the test is 68dBu; and when the frequency of the switching power supply is 120KHz, the receiving sensitivity obtained by the test is 75dBu, which means that the operating frequency is 120KHz There is obvious interference to the radio frequency of 530KHz, which reduces the receiving sensitivity by 7dBu. At this time, it can be determined that when the radio frequency is 530KHz, the switching power supply uses a working frequency of 100KHz, which will make the receiving sensitivity of the radio equipment higher.

According to the experimental test data, the mapping relationship between the radio frequency preset in the microprocessor 100, the power frequency and the level combination of the two signal output terminals of the microprocessor 100 in this embodiment is specifically shown in Table 1 below. The logic "1" in the "level combination" column in Table 1 indicates a high level, and the logic "0" indicates a low level, and the unit of the radio frequency and power frequency is KHz.

Table 1 Mapping relation of radio frequency, power frequency and level combination and corresponding receiving sensitivity data

Continued Table 1

Continued Table 1

According to the corresponding relationship of each data in Table 1, the corresponding relationship of each data in the above-mentioned Table 1 is preset in the microprocessor 100, so that when the radio equipment automatically searches or the user receives the search channel, the microprocessor 100 will judge in advance The radio frequency corresponding to a channel, and determine the corresponding relationship of each data according to the data in Table 1, will output different level combinations for different radio frequencies, for example, when searching for 1620KHz, the microprocessor 100 judges the power level that should be output The level combination is "11", that is, the two signal output terminals of the microprocessor 100 both output high levels.

Compared with the prior art, the anti-radio interference circuit of the present invention, through the microprocessor 100 according to the received current radio frequency, and the level combination of the preset radio frequency, power frequency and two signal output ends of the microprocessor 100 The mapping relationship between the three, the output level corresponding to the current radio frequency is combined to the frequency switching control module 200, and the frequency switching control module 200 controls the PWM control module 300 to switch the operating frequency of the switching power supply to the output of the microprocessor 100 The level combination of the corresponding power frequency, so that the operating frequency of the switching power supply is different from the current radio frequency, so that the operating frequency of the switching power supply and the current radio frequency do not interfere with each other, so as to avoid or reduce the interference of the switching power supply to the radio equipment, improve The anti-interference ability of the radio equipment.

The present invention does not need to turn off the switching power supply (that is, the source of interference), nor does it need to shield the switching power supply or the radio system of the radio equipment, but by switching the operating frequency of the switching power supply, the operating frequency of the switching power supply is different from the current radio frequency of the radio equipment , so that the working frequency of the switching power supply and the current radio frequency do not interfere with each other, to avoid or reduce the interference of the switching power supply on the radio equipment, that is, the interference signal radiated by the switching power supply and the current radio frequency of the radio equipment do not appear to interfere, the switching power supply The radiated interference signal does not affect the receiving sensitivity of the radio equipment, thereby improving the anti-interference ability of the radio equipment.

Specifically, as shown in FIG. 1 , the frequency switching control module 200 includes a first switching unit 210 and a second switching unit 220, the input end of the first switching unit 210 is connected to the first signal output end of the microprocessor 100, and the microprocessor The first signal output end of the device 100 can be a general input/input port of the microprocessor 100, the output end of the first switching unit 210 is connected with the oscillation frequency setting end of the PWM control module 300; the input end of the second switching unit 220 Connected with the second signal output end of the microprocessor 100, the second signal output end of the microprocessor 100 can be a general input/input port of the microprocessor 100, the output end of the second switching unit 220 is connected with the PWM control module 300 The oscillation frequency setting terminal is connected; the first switching unit 210 is turned on when the first signal output terminal outputs a high-level signal, and is turned off when the first signal output terminal outputs a low-level signal, and the second switching unit 220 is turned on at the second The signal output end is turned on when a high level signal is output, and is turned off when the second signal output end outputs a low level signal, so as to control the PWM control module 300 to switch the operating frequency of the switching power supply.

When the microprocessor 100 received the current radio frequency, the microprocessor 100 based on the current radio frequency received, and the preset radio frequency, power frequency and the level combination of the two signal output terminals of the microprocessor 100 between the three The mapping relationship of the first signal output terminal and the second signal output terminal of the microprocessor 100 respectively outputs the level corresponding to the current radio frequency and combines them to the first switching unit 210 and the second switching unit in the frequency switching control module 200 220, specifically including outputting a low-level signal to the first switching unit 210 through the first signal output terminal, and outputting a low-level signal at the second signal output terminal. According to Table 1, it can be seen that the level combination at this time is "00"; or through The first signal output terminal outputs a low-level signal to the first switching unit 210, and the second signal output terminal outputs a high-level signal. According to Table 1, it can be seen that the level combination at this time is "01"; or through the first signal output terminal Output a high-level signal to the first switching unit 210, and output a low-level signal at the second signal output terminal. According to Table 1, it can be seen that the level combination at this time is "10"; or output a high-level signal through the first signal output terminal To the first switching unit 210, the second signal output terminal IO2 outputs a high-level signal. According to Table 1, it can be seen that the level combination at this time is "11".

When the first switching unit 210 receives a high-level signal, the first switching unit 210 is turned on, and when the first switching unit 210 receives a low-level signal, the first switching unit 210 is turned off; when the second switching unit 220 receives The second switch unit 220 is turned on when the signal is high level, and the second switch unit 220 is turned off when the second switch unit 220 receives a low level signal, specifically corresponding to the four level combinations output by the microprocessor 100, the first The first switching unit 210 and the second switching unit 220 have four on-off combination states, that is, when the level combination output by the microprocessor 100 is "00", the first switching unit 210 and the second switching unit 220 are turned off simultaneously, At this time, the PWM control module 300 can be controlled to switch the operating frequency of the switching power supply to the power frequency corresponding to the level combination "00"; when the level combination output by the microprocessor 100 is "01", the first switching unit 210 is turned off , the second switching unit 220 is turned on, and at this time, the PWM control module 300 can be controlled to switch the operating frequency of the switching power supply to the power frequency corresponding to the level combination "01"; the level combination output by the microprocessor 100 is "10" , the first switching unit 210 is turned on, and the second switching unit 220 is turned off. At this time, the PWM control module 300 can be controlled to switch the operating frequency of the switching power supply to the power frequency corresponding to the level combination "10"; when the microprocessor When the level combination of 100 output is "11", the first switching unit 210 and the second switching unit 220 are turned on at the same time, at this time, the PWM control module 300 can be controlled to switch the operating frequency of the switching power supply to the level combination "11" Corresponding power frequency.

As can be seen from the above, corresponding to the four level combinations output by the microprocessor 100, the PWM control module 300 can switch the operating frequency of the switching power supply to four power supply frequencies, and the four power supply frequencies are preset by the microprocessor 100 and the microprocessor The combination of levels output by the processor 100 and the radio frequency form a power frequency in a mapping relationship. The PWM control module 300 switches the operating frequency of the switching power supply so that the operating frequency of the switching power supply is different from the current radio frequency, and the two do not interfere with each other, thereby avoiding the influence of the operating frequency of the switching power supply on the current radio frequency.

Referring to FIG. 2 again, FIG. 2 is a schematic diagram of a circuit structure of a preferred embodiment of the radio interference prevention circuit of the present invention.

Specifically, the first switching unit 210 includes a first power supply terminal VFB, a first photocoupler U1, a first electronic switch Q1, a first resistor R1 and a second resistor R2.

The anode of the primary diode of the first photocoupler U1 is connected to the first signal output terminal IO1 of the microprocessor 100, the cathode of the primary diode of the first photocoupler U1 is grounded, and the set of the secondary triode of the first photocoupler U1 The electrode is connected to the first power supply terminal VFB, the emitter of the secondary triode of the first photocoupler U1 is connected to the first terminal of the first electronic switch Q1, and is grounded through the first resistor R1; the second terminal of the first electronic switch Q1 The terminal is connected to the oscillation frequency setting terminal of the PWM control module 300 via the second resistor R2, and the third terminal of the first electronic switch Q1 is grounded.

Specifically, the first electronic switch Q1 is a first NPN transistor, the base of the first NPN transistor is the first end of the first electronic switch Q1, and the collector of the first NPN transistor is the second end of the first electronic switch Q1. The emitter of an NPN transistor is the third terminal of the first electronic switch Q1.

Specifically, the first switching unit 210 further includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first capacitor C1 and a second capacitor C2.

One end of the third resistor R3 is connected to the first signal output terminal IO1 of the microprocessor 100, the other end of the third resistor R3 is grounded via the fourth resistor R4, and the common end of the third resistor R3 and the fourth resistor R4 is connected to the first optoelectronic The anode of the primary diode of the coupler U1 is connected; one end of the first capacitor C1 is connected to the common end of the third resistor R3 and the fourth resistor R4, and the other end of the first capacitor C1 is grounded.

One end of the fifth resistor R5 is connected to the first power supply terminal VFB, the other end of the fifth resistor R5 is connected to the collector of the secondary transistor of the first photocoupler U1; one end of the second capacitor C2 is connected to the first electronic switch Q1 The first end is connected, and the other end of the second capacitor C2 is grounded.

Specifically, the second switching unit 210 includes a second power supply terminal VFP, a second photocoupler U2, a second electronic switch Q2, a sixth resistor R6 and a seventh resistor R7. The voltages input by the first power supply terminal VFB and the second power supply terminal VFP can be the same or different, as long as the voltage input by the first power supply terminal VFB can drive the first photocoupler U1 to work, the voltage input by the second power supply terminal VFP can drive The second photocoupler U2 only needs to work.

The anode of the primary diode of the second photocoupler U2 is connected to the second signal output terminal IO2 of the microprocessor 100, the cathode of the primary diode of the second photocoupler U2 is grounded, and the set of the secondary triode of the second photocoupler U2 The electrode is connected to the second power supply terminal VFP, the emitter of the secondary triode of the second photocoupler U2 is connected to the first end of the second electronic switch Q2, and is grounded through the sixth resistor R6; the second terminal of the second electronic switch Q2 The terminal is connected to the oscillation frequency setting terminal of the PWM control module 300 via the seventh resistor R7, and the third terminal of the second electronic switch Q2 is grounded.

Specifically, the second electronic switch Q2 is a second NPN transistor, the base of the second NPN transistor is the first end of the second electronic switch Q2, and the collector of the second NPN transistor is the second end of the second electronic switch Q2. The emitters of the two NPN transistors are the third terminals of the second electronic switch Q2.

Specifically, the second switching unit 210 further includes an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a third capacitor C3 and a fourth capacitor C4.

One end of the eighth resistor R8 is connected to the second signal output terminal IO2 of the microprocessor 100, the other end of the eighth resistor R8 is grounded through the ninth resistor R9, and the common end of the eighth resistor R8 and the ninth resistor R9 is connected to the second photoelectric The anode of the primary diode of the coupler U2 is connected; one end of the third capacitor C3 is connected to the common end of the eighth resistor R8 and the ninth resistor R9, and the other end of the third capacitor C3 is grounded.

One end of the tenth resistor R10 is connected to the second power supply terminal VFP, the other end of the tenth resistor R10 is connected to the collector of the secondary transistor of the second photocoupler U2; one end of the fourth capacitor C4 is connected to the second electronic switch Q2 The first end is connected, and the other end of the fourth capacitor C4 is grounded.

Specifically, the PWM control module 300 includes a PWM controller U3, an eleventh resistor R11, a twelfth resistor R12 and a fifth capacitor C5.

The oscillation frequency setting pin OCS of the PWM controller U3 is respectively connected to the output end of the first switching unit 210 and the output end of the second switching unit 220, as shown in FIG. The resistor R2 is connected to the collector of the first electronic switch Q1, and the seventh resistor R7 is connected to the collector of the first electronic switch Q2; one end of the eleventh resistor R11 is connected to the oscillation frequency setting pin OCS of the PWM controller U3, and The twelfth resistor R12 is connected to the clock frequency modulation pin FMOD of the PWM controller U3, the other end of the eleventh resistor R11 is grounded; one end of the fifth capacitor C5 is connected to the clock FMOD frequency modulation pin of the PWM controller U3, and the fifth The other end of the capacitor C5 is grounded.

The operating principle of the radio interference prevention circuit of the present invention is specifically as follows:

According to the preset data shown in Table 1, the microprocessor 100 will output different level combinations through the first signal output terminal IO1 and the second signal output terminal IO2 for different radio frequencies. When the first signal output terminal IO1 of the microprocessor 100 outputs a high-level signal, the primary diode of the first photocoupler U1 emits light, so that the secondary triode of the first photocoupler U1 is turned on, and the first electronic switch The base of Q1 is saturated and turned on due to the obtained voltage. After the first electronic switch Q1 is saturated and turned on, the resistance between the collector and emitter of the first electronic switch Q1 becomes very small, and the second resistance R2 is equivalent to Short circuit is equivalent to the parallel connection of the second resistor R2 and the eleventh resistor R11. Since the total resistance value after the parallel connection of the second resistor R2 and the eleventh resistor R11 becomes smaller, the smaller total resistance value will affect the PWM controller U3 The oscillation frequency of the oscillation circuit formed by the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 will thus change the operating frequency of the switching power supply.

When the first signal output terminal IO1 of the microprocessor 100 outputs a low-level signal, the primary diode of the first photocoupler U1 is turned off, so that the secondary transistor of the first photocoupler U1 is turned off, and at this time the first electronic switch Q1 Because the base is very low level and cut off, after the first electronic switch Q1 is cut off, the resistance between the collector and the emitter of the first electronic switch Q1 becomes very large, and the second resistance R2 is equivalent to an open circuit to the ground, at this time The second resistor R2 does not form a parallel relationship with the eleventh resistor R11, the total resistance value remains unchanged, and the oscillation frequency of the oscillation circuit formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 is also It remains unchanged, that is, the operating frequency of the switching power supply remains unchanged.

Similarly, when the second signal output terminal IO2 pin of the microprocessor 100 outputs a high-level signal, the primary diode of the second photocoupler U2 emits light, so that the secondary triode of the second photocoupler U2 is turned on. The base of the second electronic switch Q2 is saturated and turned on due to the obtained voltage. After the second electronic switch Q2 is saturated and turned on, the resistance between the collector and the emitter of the second electronic switch Q2 becomes very small, and the seventh resistor R7 It is equivalent to a short circuit to the ground, which is equivalent to the parallel connection of the seventh resistor R7 and the eleventh resistor R11, the total resistance value of the seventh resistor R7 and the eleventh resistor R11 will become smaller, and the smaller total resistance value will affect The oscillation frequency of the oscillation loop formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 will thus change the operating frequency of the switching power supply.

When the second signal output terminal IO2 of the microprocessor 100 outputs a low-level signal, the primary diode of the second photocoupler U2 is cut off, so that the secondary triode of the second photocoupler U2 is cut off, and the second electronic switch Q2 Due to the low level of the base and the cut-off of the second electronic switch Q2, the resistance between the collector and the emitter of the second electronic switch Q2 becomes very large, and the seventh resistor R7 is equivalent to an open circuit to the ground. The seventh resistor R7 does not form a parallel relationship with the eleventh resistor R11, the total resistance value remains unchanged, and the oscillation frequency of the oscillation circuit formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 also It remains unchanged, that is, the operating frequency of the switching power supply remains unchanged.

It can be seen from the above that when the first signal output terminal IO1 and the second signal output terminal IO2 both output low-level signals, the oscillation formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 The oscillation frequency of the loop is determined by the resistance value of the eleventh resistor R11. According to Table 1, the PWM controller U3 adjusts the oscillation frequency to 80KHz at this time, that is, the operating frequency of the switching power supply is switched to 80KHz; when the first signal output terminal IO1 outputs low-level signal, when the second signal output terminal IO2 outputs a high-level signal, the oscillation frequency of the oscillation circuit formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 is determined by the seventh resistor The total resistance value after R7 and the eleventh resistor R11 are connected in parallel is determined. According to Table 1, at this time, the PWM controller U3 adjusts the oscillation frequency to 100KHz, that is, the operating frequency of the switching power supply is switched to 100KHz; when the first signal output terminal IO1 outputs High-level signal, when the second signal output terminal IO2 outputs a low-level signal, the oscillation frequency of the oscillation circuit formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 is determined by the second resistor The total resistance value after R2 and the eleventh resistor R11 are connected in parallel is determined. According to Table 1, at this time, the PWM controller U3 adjusts the oscillation frequency to 120KHz, that is, the operating frequency of the switching power supply is switched to 120KHz; when the first signal output terminal IO1 and When the second signal output terminals IO2 both output high-level signals, the oscillation frequency of the oscillation loop formed by the PWM controller U3, the fifth capacitor C5, the eleventh resistor R11, and the twelfth resistor R12 is determined by the second resistor R2, the seventh The total resistance value of the resistor R7 and the eleventh resistor R11 connected in parallel is determined. According to Table 1, the PWM controller U3 adjusts the oscillation frequency to 140KHz at this time, that is, the operating frequency of the switching power supply is switched to 140KHz.

The present invention also provides that the radio equipment includes a switching power supply and an anti-radio interference circuit, the anti-radio interference circuit is used to prevent the switching power supply from interfering with the radio equipment, the circuit structure, working principle and the resulting For the beneficial effects, refer to the above-mentioned embodiments, which will not be repeated here.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related All technical fields are equally included in the scope of patent protection of the present invention.

Claims (10)

1. an anti-radio interference circuit, for preventing the interference of switching power supply to radio equipment, it is characterized in that, described anti-radio interference circuit comprises microprocessor, frequency switching control module and PWM control module; Described frequency switching control module The two input ends of the microprocessor are respectively connected to the two signal output ends of the microprocessor, and the two output ends of the frequency switching control module are connected to the oscillation frequency setting end of the PWM control module; wherein, the microprocessor The processor presets the mapping relationship between the radio frequency, the power supply frequency and the level combination of the two signal output terminals of the microprocessor, and the microprocessor passes the two signals according to the received current radio frequency and the mapping relationship. The output end outputs a level combination corresponding to the current radio frequency to the frequency switching control module, and the frequency switching control module controls the PWM control module to switch the switching power supply according to the level combination output by the microprocessor. The operating frequency is switched to the power frequency corresponding to the level combination output by the microprocessor, so that the operating frequency of the switching power supply is different from the current radio frequency. 2. The radio interference prevention circuit according to claim 1, wherein the frequency switching control module comprises a first switching unit and a second switching unit, and the input terminal of the first switching unit is connected to the microprocessor The first signal output terminal of the first switching unit is connected, the output terminal of the first switching unit is connected with the oscillation frequency setting terminal of the PWM control module; the input terminal of the second switching unit is connected with the second signal output terminal of the microprocessor The output terminal of the second switching unit is connected to the oscillation frequency setting terminal of the PWM control module; the first switching unit is turned on when the first signal output terminal outputs a high-level signal, and the When the first signal output end outputs a low-level signal, it is turned off, and the second switching unit is turned on when the second signal output end outputs a high-level signal, and when the second signal output end outputs a low-level signal The signal is turned off to control the PWM control module to switch the operating frequency of the switching power supply. 3. The radio interference prevention circuit according to claim 2, wherein the first switching unit comprises a first power supply terminal, a first optocoupler, a first electronic switch, a first resistor and a second resistor; The anode of the primary diode of the first photocoupler is connected to the first signal output end of the microprocessor, the cathode of the primary diode of the first photocoupler is grounded, and the secondary of the first photocoupler The collector of the triode is connected to the first power supply terminal, the emitter of the secondary triode of the first photocoupler is connected to the first end of the first electronic switch, and grounded through the first resistor; The second terminal of the first electronic switch is connected to the oscillation frequency setting terminal of the PWM control module via the second resistor, and the third terminal of the first electronic switch is grounded. 4. The radio interference prevention circuit according to claim 3, wherein the first electronic switch is a first NPN transistor, and the base of the first NPN transistor is the first end of the first electronic switch, The collector of the first NPN transistor is the second terminal of the first electronic switch, and the emitter of the first NPN transistor is the third terminal of the first electronic switch. 5. The radio interference prevention circuit according to claim 3, wherein the first switching unit further comprises a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second capacitor; One end of the third resistor is connected to the first signal output end of the microprocessor, the other end of the third resistor is grounded through the fourth resistor, and the common connection between the third resistor and the fourth resistor is The end is connected to the anode of the primary diode of the first photocoupler; one end of the first capacitor is connected to the common end of the third resistor and the fourth resistor, and the other end of the first capacitor is grounded; One end of the fifth resistor is connected to the first power supply end, and the other end of the fifth resistor is connected to the collector of the secondary transistor of the first photocoupler; one end of the second capacitor is connected to the The first end of the first electronic switch is connected, and the other end of the second capacitor is grounded. 6. The radio interference prevention circuit according to claim 2, wherein the second switching unit comprises a second power supply terminal, a second photocoupler, a second electronic switch, a sixth resistor and a seventh resistor; The anode of the primary diode of the second photocoupler is connected to the second signal output end of the microprocessor, the cathode of the primary diode of the second photocoupler is grounded, and the secondary of the second photocoupler The collector of the triode is connected to the second power supply terminal, the emitter of the secondary triode of the second photocoupler is connected to the first end of the second electronic switch, and grounded through the sixth resistor; The second terminal of the second electronic switch is connected to the oscillation frequency setting terminal of the PWM control module via the seventh resistor, and the third terminal of the second electronic switch is grounded. 7. The radio interference prevention circuit according to claim 6, wherein the second electronic switch is a second NPN transistor, and the base of the second NPN transistor is the first end of the second electronic switch, The collector of the second NPN transistor is the second terminal of the second electronic switch, and the emitter of the second NPN transistor is the third terminal of the second electronic switch. 8. The radio interference prevention circuit according to claim 6, wherein the second switching unit further comprises an eighth resistor, a ninth resistor, a tenth resistor, a third capacitor and a fourth capacitor; One end of the eighth resistor is connected to the second signal output end of the microprocessor, the other end of the eighth resistor is grounded through the ninth resistor, and the common connection between the eighth resistor and the ninth resistor is The end is connected to the anode of the primary diode of the second photocoupler; one end of the third capacitor is connected to the common end of the eighth resistor and the ninth resistor, and the other end of the third capacitor is grounded; One end of the tenth resistor is connected to the second power supply end, and the other end of the tenth resistor is connected to the collector of the secondary transistor of the second photocoupler; one end of the fourth capacitor is connected to the The first end of the second electronic switch is connected, and the other end of the fourth capacitor is grounded. 9. The radio interference prevention circuit according to claim 2, wherein the PWM control module comprises a PWM controller, an eleventh resistor, a twelfth resistor and a fifth capacitor; The oscillation frequency setting pin of the PWM controller is respectively connected to the output end of the first switching unit and the output end of the second switching unit; one end of the eleventh resistor is connected to the oscillation frequency of the PWM controller The setting pin is connected, and is connected to the clock rate modulation pin of the PWM controller via the twelfth resistor, and the other end of the eleventh resistor is grounded; one end of the fifth capacitor is connected to the PWM controller The clock rate modulation pin is connected, and the other end of the fifth capacitor is grounded. 10. A radio equipment, comprising a switching power supply, characterized in that, the radio equipment also includes the radio interference prevention circuit described in any one of claims 1 to 9, the radio interference prevention circuit is used to prevent the switching power supply from Interference with radio equipment.