CN204349939U - A kind of audio signal edge waveform control circuit - Google Patents

Abstract

An audio signal edge waveform control circuit disclosed by the utility model includes a pulse width modulator unit (001) containing a microcontroller, a low-pass filter unit (002) and a final follower unit (003). The pulse width modulator unit modulates the input signal to generate a modulated wave with a corresponding pulse width, and the modulated wave is filtered by a low-pass filter unit to form an edge control waveform of an audio signal after the high-order harmonics in the modulated wave are filtered out. The edge control waveform of the signal can be formed by the following unit to output the edge control waveform signal of the audio signal. It effectively solves the problem of the gradient of the rising and falling edges of the medical alarm sound. At the same time, the envelope waveform of the output audio signal can be softer and more delicate, which is more in line with the auditory characteristics of human ears. The circuit has the advantages of simple implementation method and low hardware cost.

Description

An audio signal edge waveform control circuit

technical field

The utility model relates to an audio signal edge waveform control technology, in particular to an audio signal edge

Waveform control circuit.

Background technique

An industry standard for medical device alarm systems that describes in detail everything from the medical conditions that trigger the audible alarm to the frequency and waveform of the audible alarm. When an alarm occurs on a medical alarm instrument, medical staff expect to be able to infer the urgency, nature, and even cause of the alarm from the sound alarm, so as to take corresponding measures to deal with emergencies. According to the standards, the audio signal is required to have a gradient form, that is, the sound alarm signal is required to have a rising edge and a falling edge. How to make the rising and falling edges of the alarm tone is a problem to be solved. In the prior art, integrated circuit chips (such as DAC conversion chips, etc.) are used to control the gradient of the rising edge and falling edge of the sound alarm signal. This method has high hardware costs and complicated circuits.

Contents of the invention

The technical problem to be solved by the utility model is to provide an audio signal edge waveform control circuit, which adopts the technical scheme of a pulse width modulator unit containing a microcontroller, a low-pass filter unit and a follower unit, and has

It effectively solves the problem of the rising and falling edge gradient of the medical alarm sound.

In order to achieve the above object, the utility model is achieved through the following technical solutions: an audio signal edge waveform control circuit, including a pulse width modulator unit containing a microcontroller, a low-pass filter unit and a final follower unit, the The pulse width modulator unit containing a microcontroller modulates the input signal to generate a modulated wave with a corresponding pulse width, and the modulated wave is filtered out by a low-pass filter unit to form the edge of the control audio envelope Waveform, the edge waveform of the audio signal is formed after the final follower unit, which can output the edge waveform signal of the control audio envelope.

In the utility model, a pulse width modulator unit containing a micro-controller outputs a pulse sequence showing a gradual linear rise or fall of the duty cycle, and after the high-order harmonics are filtered out by a low-pass filter unit, the resulting rise The edge or falling edge produces a linear change, and then generates the required edge alarm sound output through the final follower unit.

The pulse width modulator unit containing the micro-controller of the utility model outputs the corresponding duty ratio and the duration of the duty ratio to the internal pulse width modulator according to the time sequence, and the pulse width modulator outputs the corresponding pulse Wide modulation waveform; under the action of the input low-pass filter, the modulation waveform filters the high-frequency components of the input modulation waveform through the low-pass part of the low-pass filter unit and integrates the low-frequency components, and passes through the low-pass filter unit Afterwards, the duty cycle that changes sequentially in time is converted into waveform features on the rising or falling edge of the waveform envelope after passing through the low-pass filter unit.

The low-pass filter unit described in the utility model includes one RC low-pass filter circuit or two or more RC low-pass filter circuits.

The final follower unit of the utility model is an integrated circuit or an NPN transistor or an N-channel field effect transistor.

The utility model effectively solves the problem of rising and falling edge gradients of the medical alarm sound by adopting the technical scheme of a pulse width modulator unit containing a microcontroller, a low-pass filter unit and a final follower unit. The set pulse width modulator unit containing a microcontroller modulates the input signal through the pulse width modulator unit containing a microcontroller to generate a modulated wave with a corresponding pulse width, and the modulated wave is filtered by a low-pass filter unit. After the high-order harmonics, a control audio envelope edge waveform is formed, and this control audio envelope edge waveform is then formed by a follower unit to output a control audio envelope edge waveform signal. In summary, as long as the input signal of the pulse width modulator unit containing the microcontroller is properly controlled, the edge waveform of the alarm audio signal that needs to be increased or decreased in time sequence can be realized, which effectively solves the rising and falling edge gradient of the medical alarm sound. The problem. At the same time, the envelope waveform of the output audio signal can be softer and more delicate, which is more in line with the auditory characteristics of human ears. The circuit has the advantages of simple implementation method and low hardware cost.

Description of drawings

Fig. 1 is a structural block diagram of the utility model.

Fig. 2 is a schematic circuit diagram of Embodiment 1 of the utility model.

Fig. 3 is a waveform diagram of the microcontroller input to the pulse width modulator of the present invention.

Fig. 4 is the alarm sound output waveform diagram of the utility model.

Fig. 5 is a schematic circuit diagram of Embodiment 2 of the present utility model.

Fig. 6 is a schematic circuit diagram of Embodiment 3 of the present utility model.

In the figure: 001, pulse width modulator unit, 002, low-pass filter unit, 003, final follower unit.

Detailed ways

In conjunction with the accompanying drawings, the utility model is further described in detail through the embodiments.

Example 1

As shown in Figure 1: a kind of audio signal edge waveform control circuit described in the present embodiment comprises the pulse width modulator unit 001 that comprises microcontroller, low-pass filtering unit 002 and final stage following unit 003, and described low-pass filtering The unit 002 is respectively connected with the pulse width modulator unit 001 containing a microcontroller and the last-stage follower unit 003 . The described pulse width modulator unit 001 that contained microcontroller was selected to be a known product, including realizing the pulse width modulator function by single-chip microcomputer, microcontroller, DSP chip, FPGA chip, CPLD chip, etc. hardware configuration. This embodiment selects PIC16F690 and all microcontrollers including pulse width modulators, which can realize the modulation range of 0-100% without dead zone; the low-pass filtering unit 002 includes an RC low-pass filter circuit , the low-pass filter circuit can also be two or more, and the selected ones are also known products (among them, R specification: 24kΩ, 0.24W; C specification: 0.01uF, 25V); the final stage follower unit 003 The integrated circuit U1 is also a known product (model: LMV324I).

When used in this embodiment, the step wave signal is controlled through the control input (the timing waveform diagram shown in Figure 3). For example, the control input signal gradually rises or falls linearly; through the pulse width modulator unit 001 containing a microcontroller, the pulse sequence that presents a gradually linear rise or fall of the duty cycle is output, and this duty cycle gradually rises or falls linearly. After the pulse sequence is filtered out by the low-pass filter unit 002, the high-order harmonics in it are filtered out, so that the generated rising or falling edge changes linearly, and then the alarm sound output with the required energy is generated through the final follower unit 003 (Fig. The timing waveform shown in 4), this edge alarm sound output is more in line with the auditory characteristics of the human ear and is softer, more delicate and smoother.

As shown in Figure 2: the pulse width modulator unit 001 containing the microcontroller is averagely divided in time according to the entire time of the rising edge or falling edge to be realized. The divided waveform is shown in Figure 2, and then the corresponding voltage and 100 % of the voltage divided into the corresponding duty cycle D1, D2, D3, ..., the microcontroller will output the corresponding duty cycle and the duration of the duty cycle to its internal pulse width modulator according to the time sequence , the pulse width modulator outputs the modulation waveform of the corresponding pulse width; the modulation waveform is the input signal to the low-pass filter unit, and the high-frequency components in the input modulation waveform are passed through the low-pass filter under the action of the input low-pass filter. The low-pass part of the filter unit filters and integrates the low-frequency components. After passing through the low-pass filter unit, the duty cycle changes sequentially in time. After passing through the low-pass filter unit, it is converted into Waveform characteristics of the falling edge. Because the low-pass filter unit cannot carry a large load, it is used for signal output after the end of the follow-up unit is isolated from the subsequent stage.

Example 2

As shown in Figure 5: the audio signal edge waveform control circuit described in this embodiment is based on the structure of Embodiment 1, and the final stage following unit 003 uses NPN transistor Q1 instead of integrated circuit U1 to reach the final stage follow role. The working principle of this embodiment is the same as that of the embodiment shown in FIG. 1 , which has been explained above and will not be repeated here.

Example 3

As shown in Figure 6: the audio signal edge waveform control circuit described in this embodiment is based on the structure of Embodiment 1, and the final follower unit 003 uses an N-channel field effect transistor Q1 to replace the integrated circuit U1. The final stage follows the action. The working principle of this embodiment is the same as that of the embodiment shown in FIG. 1 , which has been explained above and will not be repeated here.

Claims (5)

1. an audio signal edge waveform control circuit, it is characterized in that: comprise the pulse width modulator unit (001) containing microcontroller, low-pass filter unit (002) and final stage follow unit (003), the described pulse width modulator unit containing microcontroller modulates the modulating wave of the corresponding pulsewidth of rear generation to input signal, namely this modulating wave forms audio signal edge control waveform again after the high order harmonic component in low-pass filter unit filtering modulating wave, what this audio signal edge control waveform was formed after following unit again can output audio signal edge control waveform signal.

2. audio signal edge according to claim 1 waveform control circuit, it is characterized in that: the described pulse width modulator unit (001) containing microcontroller exports and presents the pulse train that duty ratio linearly rises gradually or decline changes, via low-pass filter unit (002) by after the high order harmonic component filtering in interior, make the rising edge of generation or trailing edge produce linear change, then export via the edge alarm sound that final stage is followed needed for unit (003) generation.

3. audio signal edge according to claim 1 waveform control circuit, it is characterized in that: the time that corresponding duty ratio and this duty ratio continue is transferred to the pulse width modulator of its inside by the described pulse width modulator unit (001) containing microcontroller according to time sequencing, namely pulse width modulator exports the modulation waveform of corresponding pulsewidth; The low-passing part of radio-frequency component in the middle of input modulation waveform via low-pass filter unit carries out filtering and low-frequency component is carried out integration by this modulation waveform under the effect of input low pass filter, after low-pass filter unit, namely change duty ratio in time in turn after low-pass filter unit, be converted into the wave character at waveform envelope line rising edge or trailing edge.

4. audio signal edge according to claim 1 waveform control circuit, is characterized in that: described low-pass filter unit (002) comprises a joint RC low-pass filter circuit or two joint or more piece RC low-pass filter circuits.

5. audio signal edge according to claim 1 waveform control circuit, is characterized in that: described final stage follows unit (003) for integrated circuit U1 or NPN transistor Q1 or N channel field-effect pipe Q1.