CN104811200B - The single channel synchronous acquisition device and method of multiple signals unipolarity quadrature square wave modulation - Google Patents

Abstract

The invention discloses a single-channel synchronous acquisition device and method for multi-channel signal single-polarity orthogonal square wave modulation. The acquisition device collects N-channel signals through an analog-to-digital converter, and specifically includes: the orthogonal square wave controls at least The on-off of the 2-way switch circuit, the measured signal passes through the switch circuit, the orthogonal square wave controls the on-off of at least 2-way switch circuit, the measured signal passes through the switch circuit, the switch circuit is composed of an analog switch and a resistor, and the analog The switch realizes chopping and amplitude modulation; after the amplitude modulated signals of different frequencies are added by the addition operation circuit, the single-channel analog-to-digital converter performs analog-to-digital conversion to obtain a digital signal; the microprocessor processes the digital signal and demodulates it. out each measured signal. The invention realizes synchronous collection of multiple measured signals through a single analog-to-digital converter, and has the characteristics of simple circuit, low cost and accurate measurement.

Description

Single-channel synchronous acquisition device and method for multi-channel signal unipolar quadrature square wave modulation

technical field

The invention relates to the field of signal measurement, in particular to a single-channel synchronous acquisition device and method for multi-channel signal single-polarity orthogonal square wave modulation.

Background technique

The amount of information-carrying changes such as voltage signals is expressed in analog form in its natural state. However, in order to facilitate computer processing, transmission and storage, it is usually converted into a digital signal through an ADC (Analog-to-Digital Converter). Therefore, in signal processing, analog-to-digital conversion is essential.

The inventor found in the process of realizing the present invention that in the existing multi-channel signal acquisition, it is usually necessary to use a multi-chip ADC or a multi-channel analog switch with a single-chip ADC solution. The former has complex circuits, high system power consumption and circuit size. The latter will introduce switching noise due to the switching of the multi-way switch during the acquisition process, and due to the establishment time of the multi-way switch, it will cause mutual interference between adjacent channel signals.

Contents of the invention

The present invention provides a single-channel synchronous acquisition device and method for unipolar orthogonal square wave modulation of multi-channel signals. The present invention realizes the analog-to-digital conversion of multi-channel signals through a single-channel ADC. See the following description for details:

A single-channel synchronous acquisition device for multi-channel signal unipolar quadrature square wave modulation, said single-channel synchronous acquisition device includes: a microprocessor, said microprocessor outputs quadrature square wave,

The single-channel synchronous acquisition device also includes: at least two switch circuits, an addition circuit and a single-channel analog-to-digital converter,

Orthogonal square wave controls the on-off of at least 2 switch circuits, and the measured signal passes through the switch circuit. The switch circuit is composed of an analog switch and a resistor. The analog switch realizes chopping and amplitude modulation; signals of different frequencies after amplitude modulation are passed After the addition operation circuit is added, the single-way analog-to-digital converter performs analog-to-digital conversion to obtain a digital signal;

The microprocessor processes the digital signals and demodulates each measured signal.

Wherein, the microprocessor adopts any one of MCU, ARM, DSP or FPGA.

A collection method for a single-channel synchronous acquisition device for multi-channel signal unipolar quadrature square wave modulation, said method comprising the following steps:

The mixed signal is converted into a digital signal by a single analog-to-digital converter and sent to the microprocessor;

The switching circuit is driven by two kinds of frequency quadrature square waves, and four channels of measured signals are collected for illustration:

The frequency of the quadrature square wave signal output by the microprocessor to control the switch circuit is 2 times f, 2 times f, 1 times f, 1 times f respectively, wherein the phase difference of the square wave with the same frequency is 90 °, and the single-way analog-to-digital conversion The sampling frequency of the device is f _s , and f _s =8f, and it is guaranteed to be sampled between the high and low levels of the highest frequency driving signal;

The sampling frequency f _S is much higher than the change frequency of the measured signal, and the amplitude of each orthogonal square wave signal remains unchanged in a cycle of the lowest driving signal frequency, and the operation is performed on a group of 8 digital signals in order to obtain the measured signal 4 times the signal amplitude of the measured signal.

The beneficial effects of the technical solution provided by the present invention are: the present invention controls the on-off of the switch circuit through an orthogonal square wave, realizes analog-to-digital conversion of multiple signals through a single-channel analog-to-digital converter, and has the advantages of simple circuit, low cost and measurement The advantages of precision and reduced circuit cost meet various needs in practical applications.

Description of drawings

Fig. 1 is the structural representation of the single-channel synchronous acquisition device of a kind of multi-channel signal unipolar quadrature square wave modulation;

Fig. 2 is a schematic diagram of separating different wavelength signals provided by the present invention;

Fig. 3 is a flowchart of a single-channel synchronous acquisition method for multi-channel signal unipolar quadrature square wave modulation.

In the accompanying drawings, the list of parts represented by each label is as follows:

1: switch circuit; 2: addition circuit;

3: Single-channel analog-to-digital converter; 4: Microprocessor.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below.

Example 1

A single-channel synchronous acquisition device for multi-channel signal unipolar orthogonal square wave modulation, see Figure 1, the single-channel synchronous acquisition device includes: at least two switch circuits 1, an addition circuit 2, and a single-channel analog-to-digital converter 3 and microprocessor 4,

The microprocessor 4 outputs quadrature square waves with different frequencies and a ratio of 2 times. The quadrature square waves control the on-off of at least two switch circuits 1. The measured signal passes through the switch circuit 1. The switch circuit 1 is composed of an analog switch and a resistor. Composed, the switch circuit 1 realizes chopping and amplitude modulation. The amplitude modulated signals of different frequencies are added by the addition operation circuit 2, and the single-channel analog-to-digital converter 3 performs analog-to-digital conversion to obtain a digital signal. The microprocessor 4 processes the digital signals and demodulates each measured signal.

Wherein, the number of switch circuits 1 is greater than or equal to two. During specific implementation, the number and specific implementation forms of the switch circuits 1 are set according to requirements in practical applications, which is not limited in the embodiment of the present invention. The microprocessor 4 can be any one of MCU, ARM, DSP or FPGA.

Example 2

A single-channel synchronous acquisition method of multi-channel signal unipolar quadrature square wave modulation, referring to Fig. 2 and Fig. 3, the method comprises the following steps:

101: the mixed signal is converted into a digital signal by the single-channel analog-to-digital converter 3 and sent to the microprocessor 4;

102: The microprocessor processes the digital signal, and demodulates each measured signal.

For the sake of simplicity, take two frequency quadrature square waves to drive the switch circuit 1 and collect four measured signals as an example. It is assumed that the measured signals V ₁ , V ₂ , V ₃ and V ₄ correspond to the positive drive of the switch circuit 1. The frequencies of the alternating square waves are 2f, 2f, f, f respectively, and V ₁ , V ₂ correspond to the phase difference of the driving square wave of the switching circuit by 90°, and V ₃ , V ₄ correspond to the phase difference of the driving square wave of the switching circuit by 90°.

Assume that the sampling frequency of the single-channel analog-to-digital converter 3 is f _S , and f _S =8f, and it is guaranteed to be sampled between the high and low levels of the V ₁ signal.

digital signal sequence It can be expressed as:

in, and are the amplitudes of the acquisition signals V ₁ , V ₂ , V ₃ and V ₄ respectively, is the magnitude of the DC component.

Assuming that the sampling frequency f _S is much higher than the change frequency of the measured signal, it can be approximately considered that the amplitude of each orthogonal square wave signal remains unchanged in one period of the lowest driving signal frequency. Take the first 8 sampling data as an example:

in, and V ₁ , V ₂ , V ₃ and V ₄ and the magnitude of the DC component, respectively.

In other words, operations are performed in groups of 8 digital signals in sequence:

That is to get 4 times the V ₄ signal amplitude And completely eliminate the DC component Impact.

In the embodiments of the present invention, unless otherwise specified, the models of the devices are not limited, as long as they can complete the above functions.

Those skilled in the art can understand that the accompanying drawing is only a schematic diagram of a preferred embodiment, and the serial numbers of the above-mentioned embodiments of the present invention are for description only, and do not represent the advantages and disadvantages of the embodiments.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (3)

1. a single-channel synchronous acquisition device of multi-channel signal unipolar quadrature square wave modulation, said single-channel synchronous acquisition device comprises: a microprocessor, said microprocessor outputs different frequencies and becomes 2 times ratio relationship quadrature square wave, characterized by, The single-channel synchronous acquisition device also includes: at least two switch circuits, an addition circuit and a single-channel analog-to-digital converter, Orthogonal square wave controls the on-off of at least 2 switch circuits, and the measured signal passes through the switch circuit. The switch circuit is composed of an analog switch and a resistor. The analog switch realizes chopping and amplitude modulation; signals of different frequencies after amplitude modulation are passed After the addition operation circuit is added, the single-way analog-to-digital converter performs analog-to-digital conversion to obtain a digital signal; The microprocessor processes the digital signal and demodulates each measured signal; The device controls the on-off of the switch circuit through an orthogonal square wave, realizes analog-to-digital conversion on multiple signals through a single-channel analog-to-digital converter, and has a simple circuit. 2. the single-channel synchronous acquisition device of a kind of multi-channel signal unipolar quadrature square wave modulation according to claim 1, is characterized in that, described microprocessor adopts any one in MCU, ARM, DSP or FPGA kind. 3. A collection method for a single-channel synchronous acquisition device of a multi-channel signal unipolar quadrature square wave modulation according to any one of claims 1-2, wherein the method comprises The following steps: The mixed signal is converted into a digital signal by a single analog-to-digital converter and sent to the microprocessor; The switching circuit is driven by two kinds of frequency quadrature square waves, and four channels of measured signals are collected for illustration: The frequency of the quadrature square wave signal output by the microprocessor to control the switch circuit is 2 times f, 2 times f, 1 times f, 1 times f respectively, wherein the phase difference of the square wave with the same frequency is 90 °, and the single-way analog-to-digital conversion The sampling frequency of the device is f _s , and f _s =8f, and it is guaranteed to be sampled between the high and low levels of the highest frequency driving signal; The sampling frequency f _S is much higher than the change frequency of the measured signal, and the amplitude of each orthogonal square wave signal remains unchanged in a cycle of the lowest driving signal frequency, and the operation is performed on a group of 8 digital signals in order to obtain the measured signal 4 times the signal amplitude of the measured signal.