Daily broadcast and emergency broadcast switching circuit

Abstract

According to the daily broadcast and emergency broadcast switching circuit provided by the invention, an emergency control signal GPIOCTR from an emergency broadcast system control chip passes through a triode Q1 in a peripheral circuit of an analog switch U1, and then a GPIO signal is input to an IN1 pin of the analog switch U1; if the GPIOCTR is at a high level, the GPIO input to the IN1 pin is at a low level, and an audio signal passes through an NC channel, namely a rheostat RW1, so that adjustable output of volume is realized; if the GPIOCTR is at a low level, the GPIO which passes through the triode Q1 and then is input to the IN1 pin is at a high level, and an audio signal passes through an NO channel, so that a data signal received from the COM1 pin is directly output at the maximum volume; according to the application, the high level and low level switching of the GPIOCTR signal output by the control chip is matched with the analog switch U1, so that the switching of two broadcast modes can be accurately and quickly realized, and the daily broadcast and the emergency broadcast can be accurately processed and played.

Description

Technical Field

[0001] The utility model relates to the technical field of emergency broadcasting, in particular to a daily broadcasting and emergency broadcasting switching circuit. Background Art

[0002] Emergency broadcasting refers to providing a fast and convenient information transmission channel when a major natural disaster, emergency, public health, social security or other public crisis occurs. For example, the patent with publication number CN218473164U discloses an emergency broadcasting system. However, in daily applications, emergency broadcasting is a type of broadcasting that is used less frequently. In order to increase the utilization rate of the broadcasting system hardware, the same set of terminal hardware equipment will be used to support both emergency broadcasting and daily broadcasting. Daily broadcasting is mainly used to play regular programs, such as music, news, entertainment, etc. Its main feature is that it supports volume adjustment, while emergency broadcasting is used to release important information in emergency situations, such as natural disaster warnings, public safety incident notifications, etc. Its main feature is that it is played at maximum volume to ensure that it can serve as a reminder.

[0003] In order to support both daily broadcasting and emergency broadcasting, the circuit that distinguishes between daily broadcasting and emergency broadcasting needs to be able to play daily broadcasting content in a daily broadcasting mode while supporting volume adjustment, and be able to quickly switch to the emergency broadcasting mode in an emergency to play at the maximum volume. Traditional emergency intelligent broadcasting systems, such as the patent with publication number CN104468003B, provide an emergency intelligent broadcasting system, in which daily broadcasting and emergency broadcasting are distinguished by different frequency bands or signal characteristics, and then the playback mode is switched. However, this mode switching method may cause recognition errors due to external interference of the signal, thereby affecting the timeliness and accuracy of emergency broadcasting. Summary of the invention

[0004] In order to solve the problem in the prior art that daily broadcasting and emergency broadcasting are often distinguished by different frequency bands or signal characteristics to achieve mode switching, and there is a certain probability of recognition error, the utility model provides a daily broadcasting and emergency broadcasting switching circuit, which can support fast and accurate switching of broadcast modes, thereby ensuring that both daily broadcasting and emergency broadcasting can be accurately processed and played.

[0005] The structure of the utility model is as follows: a daily broadcast and emergency broadcast switching circuit, characterized in that it includes: a dual-channel operational amplifier module, a multiplexer and a power amplifier module,

[0006] It is characterized in that it also includes: an analog switch;

[0007] The dual-channel operational amplifier module receives the data signals of the daily broadcast signal and the emergency broadcast signal, performs amplitude modulation amplification on the signal, and then inputs the amplitude modulated amplified signal into the multiplexer, and the signal output by the multiplexer is sent to the analog switch;

[0008] The peripheral circuit of the analog switch U1 includes: resistors R1, R2 and R3, transistor Q1 and adjustable resistor RW1;

[0009] One end of the resistor R1 receives the emergency control signal GPIO_CTR of the emergency broadcast system control chip, the other end of the resistor R1 is connected to one end of the resistor R2 and the base of the transistor Q1, the other end of the resistor R2 and the emitter of the transistor are grounded, the collector of the transistor is connected to one end of the resistor R3 and then to the IN1 pin and the IN2 pin of the analog switch U1, and the other end of the resistor R3 is connected to the power supply;

[0010] The NO1 pin of the analog switch U1 is connected to the NO2 pin of U1, and the COM1 pin of the analog switch is connected to the output end of the multiplexer; the NC1 pin of the analog switch U1 is connected to one end of the variable resistor RW1, and the NC2 pin of the analog switch U1 is connected to the other end of the variable resistor RW1; the V+ pin of the analog switch U1 is connected to the power supply; and the COM2 pin of the analog switch U1 is connected to the input end of the power amplifier module.

[0011] It is further characterized by:

[0012] The analog switch is implemented based on the SGM3002 chip;

[0013] The dual-channel operational amplifier module is implemented based on the audio driver SGM8903 chip;

[0014] The multiplexer is implemented based on the 74HC4051PW multiplexing chip;

[0015] The multiplexer simultaneously receives a control selection signal from the emergency broadcast system control chip.

[0016] The present application provides a daily broadcast and emergency broadcast switching circuit, in which the emergency control signal GPIO_CTR from the emergency broadcast system control chip is input into the GPIO signal to the IN1 pin of the analog switch U1 after passing through the transistor Q1 in the peripheral circuit of the analog switch U1; if GPIO_CTR is high, the GPIO input to the IN1 pin is low, and the audio signal passes through the NC channel, that is, through the variable resistor RW1, to achieve adjustable volume output; if GPIO_CTR is low, the GPIO input to the IN1 pin after passing through the transistor Q1 is high, and the audio signal passes through the NO channel, so that the data signal received from the COM1 pin is directly output at the maximum volume; the switching circuit of the present application is based on the analog switch U1, and supports accurate and fast switching between the two broadcast modes, ensuring that both daily broadcasts and emergency broadcasts can be accurately processed and played. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the switching circuit between daily broadcast and emergency broadcast;

[0018] Figure 2 Embodiments of switching circuits for daily broadcasting and emergency broadcasting;

[0019] Figure 3 A circuit diagram for analog switches and peripheral circuits;

[0020] Figure 4 Schematic diagram for analog switch PIN configuration;

[0021] Figure 5 is the frequency response curve of the multiplexer 4051;

[0022] Figure 6 This is the frequency response curve of the multi-simulated switch SGM3002;

[0023] Figure 7 This is a schematic diagram of the switching circuit's frequency response effect from 40Hz to 20kHz. DETAILED DESCRIPTION

[0024] like Figure 1 As shown, the utility model includes a daily broadcast and emergency broadcast switching circuit, which includes: a dual-channel operational amplifier module, a multiplexer, an analog switch and a power amplifier module. Among them, the dual-channel operational amplifier is the front-end amplification of the audio signal, the power amplifier is the end amplification of the audio signal, and the back-end is connected to the speaker for direct output. The dual-channel operational amplifier module, the multiplexer and the power amplifier and their supporting circuits are all implemented based on existing technologies. Figure 2 In the illustrated embodiment, the dual-channel operational amplifier module is implemented based on the audio driver SGM8903 chip; the multiplexer is implemented based on the 74HC4051PW (marked as 4051 in the figure) multiplexer chip.

[0025] The daily broadcast data signal FM is sent to the dual-channel operational amplifier module through the FM signal source. The daily broadcast data signal FM is demodulated to become the CODEC_AUD signal. In order to distinguish it from the emergency signal, Figure 1 The signal marked as FM in the figure; the data signal of the emergency broadcast (marked as CODEC_AUD signal in the figure) is sent in through the chip of the emergency broadcast platform control system.

[0026] The daily broadcast and emergency broadcast switching circuit of the present application is part of the emergency broadcast system circuit, which continuously receives the control signal sent by the chip of the emergency broadcast platform control system. The control signal includes: two signals: selection control and emergency control; the GPIO selection control signal is sent to the multiplexer, and the corresponding signal source is switched through high and low level conversion; the GPIO emergency control signal is sent to the analog switch, and the corresponding mode is switched through high and low level conversion.

[0027] The dual-channel operational amplifier module receives data signals of daily broadcast signals and emergency broadcast signals, performs amplitude modulation amplification on the signals, and then inputs the amplitude modulated amplified signals into the multiplexer.

[0028] The emergency broadcast platform selects the signal to be broadcast according to the priority, and transmits the selection control signal to the chip of the emergency broadcast platform control system through the IP stream. The chip of the emergency broadcast platform control system outputs the selection control signal of the multiplexer to select the signal source to be broadcast. The signal output by the multiplexer is sent to the analog switch.

[0029] The front-end amplification of the audio signal ensures that the amplitudes of the FM signal and the CODEC_AUD signal are consistent, and the volume difference of the two signals will not be too large during subsequent playback. The multiplexer selects one signal from multiple input signals and forwards it, and outputs different selected signals to the same output line. It can effectively utilize communication resources and improve communication efficiency. In this embodiment, when the GPIO selection control signal is a high level, the multiplexer will forward the data signal of daily broadcasting to the analog switch, and when the GPIO selection control signal is a low level, the multiplexer will forward the data signal of emergency broadcasting to the analog switch.

[0030] like Figure 3As shown, the peripheral circuit of the analog switch U1 includes: resistors R1, R2 and R3, transistor Q1 and adjustable resistor RW1; the analog switch is implemented based on the SGM3002 chip; one end of the resistor R1 receives the emergency control signal GPIO_CTR of the emergency broadcast system control chip, the other end of the resistor R1 is connected to one end of the resistor R2 and the base of the transistor Q1, the other end of the resistor R2 and the emitter of the transistor are grounded, the collector of the transistor is connected to one end of the resistor R3 and then to the IN1 pin and IN2 pin of the analog switch U1, and the other end of the resistor R3 is connected to the power supply; the NO1 pin of the analog switch U1 is connected to the NO2 pin of U1, and the COM1 pin of the analog switch is connected to the output end of the multiplexer; the NC1 pin of the analog switch U1 is connected to one end of the variable resistor RW1, and the NC2 pin of the analog switch U1 is connected to the other end of the variable resistor RW1; the V+ pin of the analog switch U1 is connected to the power supply; the COM2 pin of the analog switch U1 is connected to the input end of the power amplifier module.

[0031] In daily work, the control signal of emergency broadcast is transmitted to the control chip of the emergency broadcast platform control system of the terminal through IP stream. The control chip of the emergency broadcast platform control system receives and processes these control signals, and then forwards them as GPIO_CTR. The switching of daily broadcast and emergency broadcast of the control analog switch is realized. When GPIO_CTR is high, transistor Q1 is turned on, 3.3V is grounded, and GPIO is low. When GPIO_CTR is low, transistor Q1 is not turned on, and GPIO is connected to 3.3v as high level; when 3.3V is grounded, resistor R2 prevents overcurrent.

[0032] Figure 3 The PIN configuration of the analog switch U1, and its corresponding function table is as follows Table 1:

[0033] Table 1: Analog switch function table

[0034]

[0035] From the PIN configuration and function table, we can know that when IN1 and IN2 are low level (LOGIC is 0), the switch switches to the NC channel; when IN1 and IN2 are high level (LOGIC is 1), the switch switches to the NO channel.

[0036] Then: when GPIO_CTR is high, GPIO is low, and the audio signal passes through the NC channel, that is, through the variable resistor RW1. By adjusting the resistance of the variable resistor, the volume of the audio signal can be adjusted, thereby achieving adjustable output of the volume. This is the daily broadcast mode. In this mode, the AUDIO data signal input from the COM1 pin is the AUDIO data signal corresponding to the daily broadcast content output by the multiplexer. The AUDIO data signal is output from the COM2 pin as the AUDIO_OUT signal to the power amplifier module, and supports adjustable volume. Ensure that the functional requirements for adjustable volume in daily broadcasting are met.

[0037] When GPIO_CTR is low, GPIO is high, and the audio signal passes through the NO channel without passing through the variable resistor RW1, that is, it is directly output at the maximum volume. At this time, it is the emergency broadcast mode; in this mode, the AUDIO data signal input from the COM1 pin is the emergency broadcast data signal CODEC_AUD, and the emergency broadcast data signal is output from the COM2 pin as the AUDIO_OUT signal to the power amplifier module at the maximum volume, and output from the terminal speaker. Because emergency broadcasts usually require maximum volume output, in order to cover a wider area in the shortest time, to ensure that the information can be quickly and accurately delivered to the audience.

[0038] In this application, by setting GPIO_CTR to high level and low level, and then using analog switch U1 to switch between daily mode and emergency broadcast mode, the probability of mode switching error is greatly reduced, and the broadcast mode can be switched quickly and accurately.

[0039] In this embodiment, the main audio parameters of the dual-channel operational amplifier SGM8903 are:

[0040] Low Noise and THD

[0041] Typical SNR = 114dB

[0042] Typical V N =5.5Vrms

[0043] Typical THD +N = 0.001% (f = 1kHZ).

[0044] It can be seen that the signal-to-noise ratio is 114dB and the typical distortion is 0.001%.

[0045] The experiment was conducted under the following test environment:

[0046] Vcc=4.5V; GND=0V; V EE =-4.5V; R L =50Ω, R source= 1kΩ; where R L and R source is the external resistor, RL is the load resistor, and Rsource is the resistance at the signal source.

[0047] Get as Figure 5 The frequency response curve of the multiplexer 4051 shown in the figure has the horizontal axis f(kHz) being the frequency unit (kHz) and the vertical axis being the frequency response in (dB). For the frequency response of 20Hz~20KHz heard by the human ear, it is almost 0, which does not have much influence on the audio.

[0048] Figure 6 This is the frequency response curve of the analog switch SGM3002. The horizontal axis frequency (MHz) is the frequency, unit (MHz), and the vertical axis is the frequency response, unit (dB); the frequency response of 20Hz~20KHz heard by the human ear is almost 0.

[0049] The SGM3001orSGM3002 in the figure indicates that the frequency response curves of SGM3001 and SGM3002 are consistent with the trend of this figure. + =+5v, T A =+25℃, V+ refers to the operating voltage of SGM3002 which is 5V, and TA refers to the typical operating temperature.

[0050] Figure 7 This is a schematic diagram of the switching circuit's frequency response effect on 40Hz~20kHz. The horizontal axis frequency(Hz) is the frequency unit (Hz), and the vertical axis is the frequency response, in units (dB). Figure 7 It can be seen that the frequency response of the switching circuit to the audio signal of 40Hz~20kHz is -0.65~0.038dB, which is within ±1dB. Therefore, the audio signal within this range will not sound much different to the human ear.

[0051] After using the technical solution of the utility model, through this design, the emergency broadcasting platform can quickly and accurately switch the broadcasting mode according to the actual situation, ensuring that both daily broadcasting and emergency broadcasting can be properly processed and played. This technology has high practicality and reliability in practical applications, and is of great significance for improving the efficiency and response speed of the broadcasting system.

Claims

1. A daily broadcast and emergency broadcast switching circuit, characterized in that: It includes: Dual op amp modules, multiplexers and power amplifier modules, It is characterized in that it also includes: an analog switch; The dual-channel operational amplifier module receives the data signals of the daily broadcast signal and the emergency broadcast signal, performs amplitude modulation amplification on the signal, and then inputs the amplitude modulated amplified signal into the multiplexer, and the signal output by the multiplexer is sent to the analog switch; The peripheral circuit of the analog switch U1 includes: resistors R1, R2 and R3, transistor Q1 and variable resistor RW1; One end of the resistor R1 receives the emergency control signal GPIO_CTR of the emergency broadcast system control chip, the other end of the resistor R1 is connected to one end of the resistor R2 and the base of the transistor Q1, the other end of the resistor R2 and the emitter of the transistor are grounded, the collector of the transistor is connected to one end of the resistor R3 and then to the IN1 pin and the IN2 pin of the analog switch U1, and the other end of the resistor R3 is connected to the power supply; The NO1 pin of the analog switch U1 is connected to the NO2 pin of U1, and the COM1 pin of the analog switch is connected to the output end of the multiplexer; the NC1 pin of the analog switch U1 is connected to one end of the variable resistor RW1, and the NC2 pin of the analog switch U1 is connected to the other end of the variable resistor RW1; the V+ pin of the analog switch U1 is connected to the power supply; and the COM2 pin of the analog switch U1 is connected to the input end of the power amplifier module.

2. According to claim 1, a daily broadcast and emergency broadcast switching circuit is characterized in that: The analog switch is implemented based on the SGM3002 chip.

3. According to claim 1, a daily broadcast and emergency broadcast switching circuit is characterized in that: The dual-channel operational amplifier module is implemented based on the audio driver SGM8903 chip.

4. According to claim 1, a daily broadcast and emergency broadcast switching circuit is characterized in that: The multiplexer is implemented based on the 74HC4051PW multiplexing chip.

5. According to claim 1, a daily broadcast and emergency broadcast switching circuit is characterized in that: The multiplexer simultaneously receives a control selection signal from the emergency broadcast system control chip.

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