阅读说明：本技术 一种语音信号单边带调制和解调方法及装置 (Voice signal single-sideband modulation and demodulation method and device ) 是由 郭晓明 田甜 石建飞 张学磊 唐升波 冀石磊 洪小洋 李森 孙连昊 于 2020-04-28 设计创作，主要内容包括：本发明公开了一种语音信号单边带调制方法,将待处理的模拟语音信号转换为数字化语音基带信号；将所述数字化语音基带信号滤除负频率成分,生成第一信号,所述第一信号为复信号,包括实部和虚部；对第一信号的实部和虚部分别进行升采样处理,生成第二信号；对第二信号进行低通滤波处理,生成第三信号；生成正交载波信号,将第三信号与正交载波信号相乘以产生上边带调制信号或下边带调制信号,完成单边带调制过程；本发明还公开了上述语音信号单边带解调方法、调制装置及解调装置。本发明公开的语音信号单边带调制、解调方法容易实现、调试方便、计算量小,可以在低功耗单片机上实现,使得水下通信设备的体积和功耗变小,成本降低。(The invention discloses a voice signal single-side band modulation method, which converts an analog voice signal to be processed into a digital voice baseband signal; filtering negative frequency components of the digitized voice baseband signal to generate a first signal, wherein the first signal is a complex signal and comprises a real part and an imaginary part; respectively performing up-sampling processing on a real part and an imaginary part of the first signal to generate a second signal; carrying out low-pass filtering processing on the second signal to generate a third signal; generating an orthogonal carrier signal, multiplying the third signal by the orthogonal carrier signal to generate an upper sideband modulation signal or a lower sideband modulation signal, and completing a single sideband modulation process; the invention also discloses a single-sideband demodulation method, a modulation device and a demodulation device of the voice signal. The voice signal single-side band modulation and demodulation method disclosed by the invention is easy to realize, convenient to debug and small in calculation amount, and can be realized on a low-power-consumption singlechip, so that the size and the power consumption of underwater communication equipment are reduced, and the cost is reduced.)

1. A method for single sideband modulation of a speech signal, comprising the steps of:

s1: converting an analog voice signal to be processed into a digital voice baseband signal;

s2: filtering negative frequency components of the digitized voice baseband signal to generate a first signal, wherein the first signal is a complex signal and comprises a real part and an imaginary part;

s3: respectively performing up-sampling processing on a real part and an imaginary part of the first signal to generate a second signal;

s4: carrying out low-pass filtering processing on the second signal to generate a third signal;

s5: generating an orthogonal carrier signal, multiplying the third signal with the orthogonal carrier signal to generate an upper sideband modulation signal or a lower sideband modulation signal, and completing a single sideband modulation process.

2. The method of claim 1, wherein the step S5 is to generate the upper sideband modulation signal by using the following formula:

Sm(t)＝m(t)·cos(ωt)+m′(t)·sin(ωt)

wherein m (t), m' (t) are the real and imaginary parts of the third signal, respectively; sin (ω t) and cos (ω t) are the sine and cosine signals, respectively, of the carrier signal.

3. The method of claim 1, wherein the step S5 is to generate the lower sideband modulation signal by using the following formula:

Sm(t)＝m(t)·cos(ωt)-m′(t)·sin(ωt)

wherein m (t), m' (t) are the real and imaginary parts of the third signal, respectively; sin (ω t) and cos (ω t) are the sine and cosine signals, respectively, of the carrier signal.

4. The method according to claim 1, wherein the step S2 is performed by performing positive-frequency band-pass filtering to remove negative frequency components using a complex nonlinear phase-equiphase ripple filter function.

5. The method of claim 1, wherein the quadrature carrier signal frequency is generated using the same sampling rate as in step S3, and four phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees are selected for generating the carrier.

6. The method according to claim 1, wherein the step S3 is performed by up-sampling using a 0-adding method.

7. A method for single sideband demodulation of a speech signal, comprising the steps of:

s1: multiplying the modulated single sideband signal and the demodulation carrier signal to obtain a fourth signal;

s2: filtering the fourth signal through a low-pass filter to obtain a fifth signal;

s3: down-sampling the fifth signal to obtain a digital voice baseband signal;

s4: the digitized voice baseband signal is converted to an analog voice signal.

8. The method of claim 7, wherein the carrier for demodulation in step S1 uses the in-phase component of the modulated carrier, and four phases of 0 degree, 90 degree, 180 degree and 270 degree are selected when the carrier is generated.

9. A single-sideband modulation apparatus for a speech signal, comprising:

the analog-to-digital conversion unit is used for converting an analog voice signal to be processed into a digital voice baseband signal;

the negative frequency filtering unit is used for filtering negative frequency components of the digitized voice baseband signal to generate a first signal;

the up-sampling unit is used for respectively up-sampling the real part and the imaginary part of the first signal to generate a second signal;

the filtering unit is used for carrying out low-pass filtering processing on the second signal to generate a third signal;

a carrier generation unit for generating an orthogonal carrier signal;

and the modulation unit is used for multiplying the third signal by the orthogonal carrier signal to generate an upper sideband modulation signal or a lower sideband modulation signal so as to complete the single sideband modulation process.

10. A single sideband demodulator for a speech signal, comprising:

a demodulation carrier generation unit configured to generate a demodulation carrier signal;

the multiplication unit is used for multiplying the modulated single sideband signal and the demodulation carrier signal to obtain a fourth signal;

the filtering unit is used for filtering the fourth signal through a low-pass filter to obtain a fifth signal;

the down-sampling unit is used for down-sampling the fifth signal to obtain a digital voice baseband signal;

and the digital-to-analog conversion unit is used for converting the digitized voice baseband signal into an analog voice signal.

Technical Field

The invention relates to the technical field of signal processing, in particular to a voice signal single-sideband modulation and demodulation method and device.

Background

With the continuous development of marine resources, the underwater voice communication technology plays an important role in developing marine resources and strengthening national defense construction. Through the underwater acoustic communication technology, the underwater equipment and the base station can be communicated in an underwater environment, the working condition of the underwater equipment is quickly, directly and accurately transmitted to the base station on the shore in real time, and the underwater acoustic communication system plays an important role in guaranteeing the safety of underwater personnel and exploring the underwater environment.

Underwater communication uses medium water as a communication channel, and an underwater acoustic channel is characterized in that available frequency resources are limited and the communication rate is low; the voice signal is a baseband signal and has low-frequency components, a plurality of low-frequency component signals with the same frequency range exist in the underwater acoustic channel, and the voice signal is easily interfered by the noise signals when directly transmitting in water due to the same frequency range, so that the voice communication effect is seriously influenced. At present, the main modes for realizing voice communication comprise OFDM, pinyin coding and single-side band; the OFDM mode has the outstanding advantages that the transmission rate is high, intersymbol interference and channel selective fading can be effectively resisted, but a voice compression module is required to be used as assistance, and the system is relatively complex; the pinyin coding mode has the characteristics that the pinyin coding mode is synthesized at a communication receiving end, the language is clear, and the pinyin coding mode is not easily influenced by environmental noise, but the establishment of a pinyin coding technology corpus is relatively complex; compared with the two modes, the single-sideband mode has the advantages of lower power consumption, simple and convenient realization and better reservation of the tone and the tone of the original voice, and is more suitable for portable underwater communication.

The single side band modulation is to shift the frequency spectrum of the message from the base band to a higher frequency, and the relative relation of the original frequency components in the signal frequency spectrum after the translation is kept unchanged; can be regarded as a special form of AM amplitude modulated signal; the AM amplitude modulated signal consists of a carrier frequency and upper and lower sidebands, the transmitted messages are contained in both sidebands, and each sideband contains the complete message, as the name suggests, a single sideband signal only includes one of the sidebands, i.e., either the upper or lower sideband; the single-sideband modulation occupies less frequency band resources, and the single-sideband communication is very significant for the application of limited underwater available frequency band resources. The traditional single sideband signal is generated by using an analog circuit, and a filtering method, a phase shifting method and a weaver method are generally adopted.

The filtering method is characterized in that a multiplier is used for carrying out AM modulation on a baseband signal, a band-pass filter is designed, and a filter is used for filtering a single-sideband signal from a modulated signal, so that the principle and the method of the filtering method are simple, but the problems that steep filtering cannot be realized and the demodulation by a common amplitude modulation detector is difficult exist; the phase shift method is realized by imitating the following time domain formula of single sideband signals; sm (t), m (t), cos (ω t) + m '(t), sin (ω t), m' (t) is a 90-degree phase-shifted signal of m (t), orthogonal carrier frequency signals are generated first, then the baseband signals are orthogonally modulated using a multiplier, and the orthogonally modulated signals are added; but the phase shift method has the problem of great difficulty in phase shift of 90 degrees in the full frequency of the original signal; although the weber method combines the advantages of the filtering method and the phase shifting method, only a carrier wave with a single frequency needs to be subjected to phase shifting without a 90-degree phase shift modulation signal, meanwhile, a sideband is filtered, and a filter is easy to meet requirements in a low-frequency range, the weber method still has the problems of large calculation amount, difficulty in realization by a low-power-consumption single chip microcomputer, and difficulty in miniaturization and portability of equipment.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a method for modulating a single-side band of a voice signal, which is easy to implement, convenient to debug, and has a small amount of calculation; meanwhile, the method has small calculated amount, can be realized on a low-power consumption singlechip, has small power consumption in unit time and small integral volume, and can be made into portable equipment for use, thereby being more suitable for underwater communication equipment. .

The second purpose of the invention is to provide a single-side band demodulation method of voice signals, which is easy to implement, convenient to debug, small in calculation amount and capable of being implemented by a single chip microcomputer with low power consumption.

A third object of the present invention is to provide a single-sideband modulation apparatus for voice signals.

It is a fourth object of the present invention to provide a single sideband demodulation apparatus for voice signals.

The first technical scheme adopted by the invention is as follows: a voice signal single sideband modulation method comprises the following steps:

s1: converting an analog voice signal to be processed into a digital voice baseband signal;

s2: filtering negative frequency components of the digitized voice baseband signal to generate a first signal, wherein the first signal is a complex signal and comprises a real part and an imaginary part;

s3: respectively performing up-sampling processing on a real part and an imaginary part of the first signal to generate a second signal;

s4: carrying out low-pass filtering processing on the second signal to generate a third signal;

s5: generating an orthogonal carrier signal, multiplying the third signal with the orthogonal carrier signal to generate an upper sideband modulation signal or a lower sideband modulation signal, and completing a single sideband modulation process.

Preferably, in step S5, the upper sideband modulated signal is generated by a simplification of the following equation:

Sm(t)＝m(t)·cos(ωt)+m′(t)·sin(ωt)

wherein m (t), m' (t) are the real and imaginary parts of the third signal, respectively; sin (ω t) and cos (ω t) are the sine and cosine signals, respectively, of the carrier signal.

Preferably, in step S5, the lower sideband modulated signal is generated by using the following equation:

Sm(t)＝m(t)·cos(ωt)-m′(t)·sin(ωt)

wherein m (t), m' (t) are the real and imaginary parts of the third signal, respectively; sin (ω t) and cos (ω t) are the sine and cosine signals, respectively, of the carrier signal.

Preferably, in step S2, the complex nonlinear phase equiphase ripple filter function is used to perform positive frequency band-pass filtering to filter out negative frequency components.

Preferably, the orthogonal carrier signal frequency is generated using the same sampling rate as in step S3, and four phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees are selected when the carrier is generated.

Preferably, the up-sampling is performed in step S3 by using a 0-adding method.

The second technical scheme adopted by the invention is as follows: a method of single sideband demodulation of a speech signal comprising the steps of:

s1: multiplying the modulated single sideband signal and the demodulation carrier signal to obtain a fourth signal;

s2: filtering the fourth signal through a low-pass filter to obtain a fifth signal;

s3: down-sampling the fifth signal to obtain a digital voice baseband signal;

s4: the digitized voice baseband signal is converted to an analog voice signal.

Preferably, in step S1, the demodulation carrier selects four phases of 0 degrees, 90 degrees, 180 degrees, and 270 degrees when generating the carrier using the in-phase component of the modulated carrier.

The third technical scheme adopted by the invention is as follows: a voice signal single-sideband modulation apparatus, comprising:

the analog-to-digital conversion unit is used for converting an analog voice signal to be processed into a digital voice baseband signal;

the negative frequency filtering unit is used for filtering negative frequency components of the digitized voice baseband signal to generate a first signal;

the up-sampling unit is used for respectively up-sampling the real part and the imaginary part of the first signal to generate a second signal;

the filtering unit is used for carrying out low-pass filtering processing on the second signal to generate a third signal;

a carrier generation unit for generating an orthogonal carrier signal;

and the modulation unit is used for multiplying the third signal by the orthogonal carrier signal to generate an upper sideband modulation signal or a lower sideband modulation signal so as to complete the single sideband modulation process.

The fourth technical scheme adopted by the invention is as follows: a voice signal single sideband demodulation apparatus comprising:

a demodulation carrier generation unit configured to generate a demodulation carrier signal;

the multiplication unit is used for multiplying the modulated single sideband signal and the demodulation carrier signal to obtain a fourth signal;

the filtering unit is used for filtering the fourth signal through a low-pass filter to obtain a fifth signal;

the down-sampling unit is used for down-sampling the fifth signal to obtain a digital voice baseband signal;

and the digital-to-analog conversion unit is used for converting the digitized voice baseband signal into an analog voice signal.

The beneficial effects of the above technical scheme are that:

(1) compared with the filtering method, the voice signal single-sideband modulation method disclosed by the invention does not need to realize steep filtering, can realize single-sideband modulation only by the steps of analog-to-digital conversion, filtering to form complex signals, filtering processing, orthogonal multiplication simplification and the like, and is easy to realize and convenient to debug.

(2) Compared with the phase shifting method, the voice signal single-sideband modulation method disclosed by the invention has the advantages that the method of converting the digitized voice baseband signal (real signal) into the complex signal in the step S2 is adopted, the problem that the difficulty of phase shifting 90 degrees in the full frequency of the original signal is high in the phase shifting method is solved, and the modulation method disclosed by the invention is easy to realize and convenient to debug.

(3) Compared with the Weber method, the voice signal single-sideband modulation method disclosed by the invention has the advantages that four phases of 0 degree, 90 degrees, 180 degrees and 270 degrees are selected mainly when the carrier signal is generated in the step S5, so that four sampling points of each period are respectively sine signals (0, 1, 0, -1) and cosine signals (1, 0, -1, 0) relative to the carrier signal, sine calculation and cosine calculation in the step are omitted, and the calculation amount is reduced; the method solves the problems that the calculation amount of the Weber method is large and the Weber method is difficult to realize by a single chip microcomputer with low power consumption.

(4) The modulation and demodulation method disclosed by the invention has the advantages of good confidentiality and high real-time property.

(5) The demodulation method disclosed by the invention is easy to realize and small in calculation amount.

(6) The modulation and demodulation method disclosed by the invention can be realized on a low-power-consumption singlechip due to small calculated amount, so that the volume and power consumption of the communication equipment are reduced, the cost is low, and the modulation and demodulation method can be used as portable equipment and is more suitable for underwater communication equipment.

Drawings

FIG. 1 is a schematic diagram illustrating a method for single-sideband modulation of a speech signal according to the present invention.

Fig. 2 is a schematic diagram of a positive frequency bandpass filter.

Fig. 3 is a spectrum of a digitized voice baseband signal.

Fig. 4 is a first signal spectrum.

Fig. 5 is a time-domain real/imaginary signal diagram of the first signal.

Fig. 6 is a partially enlarged view of the time-domain real/imaginary signal of the first signal.

Fig. 7 is a frequency spectrum of the second signal.

Fig. 8 is a frequency spectrum of the third signal.

Fig. 9 is an upper sideband modulated signal spectrum.

FIG. 10 is a schematic diagram illustrating a single sideband demodulation method of a voice signal according to the present invention.

Fig. 11 is a frequency spectrum of the fourth signal.

Fig. 12 is a low pass filter normalized spectrum graph.

Fig. 13 is a frequency spectrum of the fifth signal.

Fig. 14 is a time domain diagram of a digitized audio baseband signal.

Fig. 15 is a single-sideband modulation apparatus for voice signals.

Fig. 16 is a single side band demodulating apparatus for a voice signal.

Detailed Description

The embodiments of the present invention will be described in further detail with reference to the drawings and examples. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the invention and are not intended to limit the scope of the invention, which is defined by the claims, i.e., the invention is not limited to the preferred embodiments described.

In the description of the present invention, it is to be noted that, unless otherwise specified, "a plurality" means two or more; the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the specific meaning of the above terms in the present invention can be understood as appropriate to those of ordinary skill in the art.