What are the new trends in speech signal processing

Speech Signal Processing Prospects

Specialization is very narrow, unless in the Institute, or University for in-depth research, or employment is very difficult.

Now speech coding, speech synthesis, are very mature. Speech recognition, there is still a mess, but the difficulty is too great, as far as the current technology is concerned, there is a big technical bottleneck.

SUU Speech Signal Processing Graduate Employment Prospects

SU’s advantageous majors are mainly literature, management, economics and education majors, speech signal processing is not SUU’s strongest majors, professional strength in the domestic rankings are not very forward, but SUU itself is good, if you choose to employ in the eastern seaboard or in the Jiangsu region, it is still very good, but if it is changed to other regions Employment, compared to the popular majors, the competitiveness will be smaller

What are the three main areas of current research in speech signal processing and what are their respective goals

The three areas of speech signal processing and their respective goals:

1. Speech Synthesis.

Speech synthesis’s is designed to allow computers to produce high-quality, highly natural continuous speech. Computerized speech synthesis systems, also known as text-to-speech (TTS) systems, focus on outputting text as speech. Development process: resonance peak synthesis, LPC synthesis, PSOLA technology.

2. Speech coding.

In the process of transmission of voice signals, the rational use of frequency resources, seems to be very precious, so before transmission, the voice signal is compressed by voice coding.

3. Speech recognition.

Speech recognition involves linguistics, computer science, signal processing, physiology and other related disciplines, is a branch of pattern recognition. Its main purpose is to allow computers to translate speech into executable commands or text through recognition and understanding.

Main research directions: according to the way of speaking, isolated speech recognition system, connective speech recognition system, continuous speech recognition system. According to the speaker, featured person recognition system, non-featured person recognition system. According to vocabulary, small vocabulary speech recognition system, medium vocabulary speech recognition system, large vocabulary speech recognition system, infinite vocabulary recognition system.

How about the outlook and career direction of intelligent information processing at the graduate level

Employment outlook analysis

Communication engineering is mainly for the study of signal generation, transmission, exchange and processing of information, as well as in the computer communication, digital communication, satellite communication, fiber optic communication, cellular communication, personal communication, stratospheric communication, multimedia technology, information superhighway, digital programmed switching, etc. Theoretical and engineering application problems. With the invention of the telegraph by the Americans in the 19th century, modern communication technology has been created. In order to adapt to the growing technological needs, the communications engineering program has become a discipline in American university education, and has developed rapidly with the increasing level of modern technology.

In the new era, a large number of outstanding experts and scholars have emerged. For example, Professor Li Jiandong, is China’s broadband wireless self-organizing networks in the direction of the main academic leader, presided over the development of the world shocked the WAPI wireless network security standards, Tsinghua University, Zhou Binghun academician, the first to carry out the “crystal fiber growth and crystalline fiber optic device research”. Its “narrow linewidth tunable semiconductor lasers and related technologies” through the seven results of the appraisal, linewidth, frequency stability and tuning range of the international advanced level, for the development of coherent optical communication has made an important contribution. In the “fiber optic high temperature sensor”, the fineness of fiber ring cavity and ring laser research reached the international advanced level. In addition, Prof. Lu Da in signal and information processing; Prof. Feng Chongxi in digital communication, voice signal processing and digital duplexing; Prof. Yao Yan in signal detection, estimation and recognition and its application in electronic systems in the field of high-speed real-time information processing and systems; Prof. Cao Zhigang in digital modulation, coding and satellite communications, voice enhancement and digital signal processing technology; Prof. Lin Xinggang in intelligent graphic Information Processing and Recognition, Image Compression and Multimedia Data, Multimedia Communication and its Terminal Technology have made outstanding contributions. These experts and professors have paved the way for China’s modernization of communications to march triumphantly into the 21st century.

Future Prospects

Facing the new century, communication engineering will usher in the development of a broad world. With the increasingly broad application of communications technology, up to space, down to the bottom of the sea, all active in this specialized technical personnel. Now China has joined the WTO, which will inevitably bring more space for the development of China’s information industry. The shortage of excellent talents in communication engineering has become a very unfavorable factor for China to participate in international competition. Therefore, in the next few years, China is bound to pay more attention to the cultivation of talents in this field, pay more attention to the education of communication engineering and improve the level of education.

Employment Direction

In order to help communications engineering college students to understand clearly the direction of the future employment of the profession, China Talent Network editor has collected and organized the following information:

Sales personnel

Mainly refers to the sales of communications products

Career path: sales assistant → sales engineers → sales (marketing) manager

Talent quotations: the demand is large, the requirements of professional background is not particularly deep, suitable for general undergraduates to engage in. The most important thing is that the career development space is big enough, and if you can’t do it, you can also change to other industries to continue to do sales.

Analysis of the proposal: including a variety of upstream equipment as well as communication equipment sales. For the sales of upstream equipment, companies in the recruitment of very important professional background, therefore, some of the basic professional courses on communications have to have a more comprehensive understanding. I suggest that those who want to do sales students, in the pre-graduation internships to strive to go to the company’s R & D department – and marketing students in the sales expertise to compete is not wise, we should strengthen the professional background of the core strengths.

In addition, as a matter of course, the communication skills, marketing skills, planning ability to cultivate. There are a lot of students do not care to do things in the university student union, in fact, there can learn other I’m not sure, the development of communication skills and organizational skills is a better way, especially when you do through their own efforts to a certain position. As for reading professional books on sales, I personally think it is not as good as reading professional magazines and newspapers, the former is almost purely theoretical and very hard, while the latter is theory plus practice.

In the school can also begin to prepare is to learn to do marketing plan – the network can be down to some of the best planning and planning projects, compared to slowly learn, this is what you must use in the work, and, some companies in the written test may also be this content. Finally, often do the plan can help you develop a good habit: often organize ideas, things analyzed in an organized manner.

Research and Development

Mainly refers to the communications technology research and development personnel

Career path: R & D → R & D engineers → high-level marketing or management

Talent quotations: a few years ago, the communications industry is in the spring, the field of research and development provides a lot of high-paying jobs, even today, like Huawei, ZTE, UTStarcom and other well-known companies The treatment of R&D positions is still very competitive. But such companies and positions are too few relative to the increasing number of graduates of this specialty every year.

The reason for this, in addition to the stagnation in the size of the communications industry and market development directly brought about by the reduction in demand for talent, there is also the university’s attitude towards the setup of communications majors: “If you have the conditions to be on, you do not have the conditions to be on.” — Many schools actually do not have the strength to open the specialty, the key in the teachers and experimental equipment. But even so, we should likewise not be discouraged, after all, as far as our profession is concerned, undergraduates in terms of professional competence is very difficult to achieve once graduated to meet the employment requirements of enterprises. Therefore, many companies select new employees standard is “solid professional foundation, open-minded, good English, a little creative”.

Analysis of the proposal: “four years of college can get the diploma, degree, English six and computer two certificates can be, the other are by mixing.” Nowadays, the popularity of graduates in such a point of view. I personally believe that this is not the case, at least the study of communications graduates – the vast majority of companies recruiting will conduct a professional exam, with the same test to cope with the school, you can also go to clasp the Buddha’s feet before the exam, but the effect of how good I know: when I graduated from the first time to participate in the recruitment examination, a total of seven questions –Involving analog circuits, digital circuits, mobile communications, high-frequency electronic circuits, C language. The topic is very basic, but involves a wide range of aspects, is not a pre-exam surprise can solve the problem. Even if you get by, because like the calculation questions and so on he may ask you carefully in the next interview to answer the idea (later the supervisor told me that the idea is more important than the answer).

What’s more, they won’t be the same as your teacher, who draws out the key points to you before the exam. As long as you show a hint of professionalism in the paper, your application can be said to be “over”.

About creativity. In fact, the creativity here can be interpreted as novel ideas and design, development consciousness. So, relative to other activities organized in the school, more to participate in activities such as electronic design competitions on our ability is a good exercise, remember, when you put the work or award-winning design on the resume, to carefully prepare the design of the idea, including the design process of the problems arising from the design, as well as the solution and the principle. If the microcontroller and circuit knowledge is good, you can try to do a board to play for yourself, to find a microcontroller development work after graduation to prepare, and then accumulate experience in the work, learning embedded systems knowledge, technical route this way or more appropriate.

Technology to market (management) is the home of many R & D staff. Because with the growth of age, the decline in learning ability, coupled with enterprises in the R & D sector position design bottlenecks, in addition to having a strong technical foundation of the “bottom line”, engineers choose to do a period of time to technical support, customer service and technical department management (technical origin of the management of this advantage is very obvious: in this kind of The technical content of the department is so high, who will serve a even can not read the circuit diagrams of the leadership?)

Operators

Mainly refers to the staff of telecom operators

Career path: staff → supervisor → middle and senior management

Talent market: the service positions in the operator’s low entry threshold, so in some areas of the mobile phone, China Unicom and other companies are close to saturation of talent. Even though several major operators release a relatively large-scale campus recruitment program every year, graduates majoring in communications do not have too obvious an advantage. However, the rise of Internet broadband has brought a lot of job opportunities to the weak job market. All in all, it shouldn’t be too hard for us to find a job after graduation if we’re not too picky. What’s more, if you work for a carrier in sales or something like that, your career path will be a lot more open later on than if you work in technology – you can switch to selling other products or services.

Principle of Cell Phone Calling

The reason why a cell phone can make a call is due to the fact that there is a huge system behind it that supports it. In China, analog cell phones belong to the analog network or ETACS system and GSM digital cell phones belong to the GSM digital network or GSM system. Each channel of the analog ETACS system has a different frequency, when the base station sends out a signal to instruct a cell phone to transmit a specified frequency to access the Internet, this user will occupy this channel, and other users will not be able to occupy the same channel; the GSM system adopts the TDMA addressing method, and the channel of the same frequency is divided into eight time slots, which can be occupied by different users at different times, and the signals between users are distributed by the base station. The signals between users are distinguished by certain protocols assigned by the base station. This makes the structure of the GSM cell phone more complex and more resistant to interference.

The voice signal is also known as the voice signal. The frequency of the voice signal is usually between 300 to 3400Hz, to turn it into a pulse signal load on the carrier transmission, the first thing to do is to sample this low-frequency voice signal, quantization. Sampling is a common technique used in analog/digital conversion, as shown in Figure 1. The analog signal is a continuous sine or cosine wave, to use a series of pulse signals to reproduce it basically undistorted, then the sampling frequency should be high enough so that the signal can be restored. According to the law of sampling, the sampling frequency should be greater than or equal to twice the frequency of the sampled signal in order not to be distorted. In the current digital cell phone, the sampling frequency are used 8kHz, this sampling rate is sufficient to ensure the credibility of the signal. The digital pulse signal has only two kinds of 0 and 1. After sampling the pulse wave, the amplitude of its large and small, to accurately describe a pulse wave, we must have a definition of its “height”, which is the process of quantization. Each sampling value is encoded into 8bit code, formed into 8k × 8bit / s = 64kbit / s signal. This is the voice signal into a digital signal of the first step, that is, analog / digital conversion (A/D). But the 64kbit / s signal occupied by the band is too wide, is undoubtedly a waste. Therefore, the signal needs to be compressed, through the voice compression technology we will be 64kbit / s signal into 13kbit / s signal, greatly saving the bandwidth. This series of processes from sampling, quantization to compression is called speech coding.

Figure 1 sampling frequency

After speech coding, we get a set of coherent reflection of the voice information of the 13kbit / s pulse signal, this group of signals will be regrouped, decomposed into the important bit code, the second important bit code and the unimportant bit code, and then they are inserted into the group of codes out of order, which is the inter-division insertion. Why is it necessary to do this? Because wireless signals transmitted over the air encounter a variety of interference, and these interferences are random. If the voice encoder to send the 13kbit / s signal loaded in turn on the carrier to be transmitted without reassembling the inter-division insertion, then in a period of time by the interference will result in a period of time when all the information is lost, due to the lack of information related to this period of time, the recovery of these signals will not be possible. However, with the technique of inter-partition insertion, even if a period of data is destroyed, only a small part of a group of voice clusters is destroyed, and it can be recovered according to the other pulse clusters.

Of course, the recovery of damaged pulses based on correlated pulses is identified by the inclusion of some code elements in the encoding. This coding can be achieved by adding several forms of block convolutional codes, error correcting codes and parity check codes. The process described above is the process of channel coding and interleaving.

A very advanced technology of GSM cell phone compared to ETACS cell phone is the great improvement of its confidentiality, GSM cell phone encryption in many ways, such as in the cell phone power on the registration of the network, to transmit the IMSI number and the MIN number and other unique to each user’s network number, these numbers in the air transmission to go through a ki value of the operation of the SIM card stored on the operation to correspond to the switch, therefore, to be in the air, to be in the air, to be in the air, to be in the air, to be in the air, to be in the air, to be in the air, to be in the air. This operation should correspond to the switch, so it is basically impossible to intercept and break this information in the air. In addition, the GSM system has the function of frequency hopping. As the name suggests, the frequency of the carrier frequency is constantly changing in order to play a role in protecting the information from being stolen. This process we call encryption.

After the above series of processing of the voice signal, the Burst, that is, the frame signal is formed. Through the 0.3 Gaussian minimum shift frequency identification control, that is, 0.3GMSK technology, the binary data will be transformed into a low-frequency modulation signal, so that it loaded on the carrier to the form of electromagnetic waves transmitted out, this is the modulation process.

The above is only a general description of the GSM phone voice coding, which is of practical significance to the maintenance personnel, with a generalized impression of the role of the hardware part of the phone will be clearer on the role of the various integrated blocks, which is conducive to the maintenance of the cause of the failure of the decision. The following is a more intuitive way to summarize the above description, see Figure 2.

Figure 2 Voice Signal Processing Flow