advance communication system electronics

advance communication system

1. INTRODUCTION TO ADVANCE COMMUNICATION Module 1.

2. Everything we do in life revolves around communication. In other words, communication is our way to express ourselves, interact with one another, and make sense of the information that has been passed along. Humans have continually improved communication methods throughout the centuries to make our lives easier and more convenient. As we have become more reliant on technology, online chats and automated phone calls have replaced ancient cave drawings as our primary means of communication. PAST, PRESENT, AND FUTURE

3. Humans created written language as they settled into rural areas. Around 9,000 years ago, societies shifted from hunting-based to agriculture-based non-nomadic lives. Writing became significant as humans recognized the importance of maintaining property records and trades. Initially images were used to represent the objects being discussed in the text. As societies progressed images came to symbolize sounds. Eventually, the visual language gave way to letters in the Western world which were graphic representations of specific sounds By connecting letters, words were formed.

4. Among the earliest forms of communication are prehistoric cave drawings. People who lived in caves were protected from the elements and wild animals by their shelters. People used engravings on the cave walls to record significant events, rituals, and ideas from the past. Until then, language couldn't express these ideas well. Therefore, drawings were used to fill in the gaps

5. Documents have been written by hand for hundreds of years, which is time-consuming. In the past, writing was a skill reserved for the upper class, well-educated, and most of them were priests. Block printing became popular in the early 14th century when it was first introduced. Block printing was a type of printing in which single words or characters were carved into individual wooden blocks. This was a costly and inefficient process. Germany's goldsmith Johannes Gutenberg built a printing machine in 1454 to move printing blocks. Making books accessible and affordable was made possible by Gutenberg's invention.

6. Although the printing press made communication more accessible, the written word could take days or weeks to reach its destination. A faster method of transmitting information was being looked into by scientists. In the late 18th century, French scientists created a light-based communication system. Improved by the invention of a mechanism that converted spoken words into electric signals, American inventor Samuel Morse revolutionized this approach. His telegraph was widely adopted as a fast means of communication.

7. Other advancements in communication technology can be traced back to the telegraph's creation. When Elisha Grey and Alexander Graham Bell utilized the telegraph's principle, they created a telephone device. It converts analog audio into electrical signals used to communicate with other people. The telegraph was overtaken due to this invention, which was more popular than the concept it was built on.

8. There has been a massive technological shift in the field of communication since computers were introduced. To solve complicated mathematical equations, computers were first employed in the early 1980s. Scientists eventually recognized that computers could be used for more than just computation. An earlier version of the internet that allowed scientists to share documents over computers was built in 1989. Then, a short time later, the internet was made available to the whole population. Information flowed more quickly than ever before because of this technological breakthrough. Communication has undergone various developments before its present state that make it convenient and practical. It is our responsibility to use these communication tools properly.

9. DIFFERENT BANDS COMMUNICATION SYSTEM, CONCEPT, ADVANTAGES APPLICATION, AND CHALLENGES. Electromagnetic radiation is one of the forms in which energy travels through space. The electromagnetic energy spreads out in the form of visible light, radio waves,   infrared rays , gamma rays, etc. The electromagnetic spectrum covers all the electromagnetic radiations arranged according to their frequency and wavelength. The frequency and wavelength are inversely proportional to each other. In the electromagnetic spectrum, the higher the frequency, the lower the wavelength.

10. Designating Frequency Bands The Role of IEEE in Frequency Band Designation

11. Frequency Bands and Applications Here is an overview of the applications of frequency bands as per ITU classification. ELF - This frequency band is used for underwater communication, especially for pipeline transportation. SLF - Used for submarine communications and in the electric grid (not as a transmitted wave). ULF - Used for mining communications and military applications.

12. VLF - As this band of frequency exhibits penetration properties through dirt and rock, it is used for geophysics applications, navigation, wireless heart monitoring, etc. LF - In Europe and some parts of Asia, the LF band is used in AM broadcasting. Other LF band applications include RFID, amateur radio, and navigation. MF - This frequency band covers AM broadcasting, coast-to-sea communication, emergency distress signals, etc. HF - This band is also called the short wave band. It is most useful in aviation communication, amateur radio communication, and weather broadcasting applications.

13. VHF - This band is used for analog television broadcasting, FM radio broadcasting, medical equipment utilizing  magnetic resonance imaging , mobile-land, and marine communication systems. UHF - This frequency band is significant in modern  wireless communication systems  with applications in satellite television, WiFi, GPS, Bluetooth, television broadcasting, mobile communications such as GSM, CDMA, and LTE services. SHF - Modern communications technologies, modern radars, DTH services, 5GHz Wi-Fi channel, radio astronomy, mobile networks, TV broadcasting satellites, microwave devices, broadcasting satellites, and amateur radio are some of the applications of SHF. EHF - EHF is used in radio astronomy, amateur radio, remote sensing at microwave frequency, and high-frequency microwave relays. THF - THF is utilized as an alternative to X-ray and is used in TeraHertz frequency imaging. Other applications include terahertz space-time spectroscopy, solid-state physics, and terahertz computability

14. SINGLE BAND VERSUS MULTIBAND Before we proceed with options for existing receivers, let’s take a brief look at the way GNSS receivers work. The main idea behind the GNSS receiver work is, logically, receiving signals from satellites. Each satellite transmits radio signals in one or more frequency bands. Satellites in different constellations use different frequencies. In the main, all receivers can be divided into two categories: single-band and multi-band. THE core difference is that single-band receivers only work with one frequency, while multi-band receivers fetch several frequency bands.

15. RTK Initialization Time Several factors affect the time required to obtain a fix. This is where the number of tracked frequencies matter. A multi-band receiver is capable of finding a fix solution much more quickly. Since multi-band receivers can work with more than one frequency band, they can use more satellite signals to establish the fix solution. The more signals that are available, the less time is needed to obtain the fix. TTFX for Reach RS2+ is ~5 seconds. Single-band receivers require more time since they can only process one kind of frequency—the L1 frequency. Reach RS+ needs a few minutes to get a fix solution. It doesn’t mean you need to wait for several minutes every time you collect a point. This time is only required at the beginning of the survey or in the case where the fix solution was lost.

16. Single vs Multi: What’s the Difference Getting slightly ahead of ourselves, let us say that in this case, “the more, the better” motto is an uncompromising solution. It means that the multi-band receiver is, in general, easier to use, as it has fewer limitations in its operation. However, your specific project and your budget have the last word—multi-band receivers are more costly than single-band ones. So, the main difference between single-band and multi-band receivers is the number of frequencies they can work with. Other differences technically are the consequences of it.

17. Baseline For different projects, you might need a different distance from the rover to the base. Working near a city, you are more likely to have a base nearby. However, if you mostly work in rural areas, base stations are likely to be further away. Multi-band receivers can work at a longer baseline. Reach RS2+, as a multi-band receiver, can operate with the baseline up to 60 km for RTK, while Reach RS+ single-band receiver’s baseline is limited to 10 km in RTK mode .

18. Sky View Conditions In the case of a blocked sky view, the more signals, the better, meaning the more signals you can catch, the sooner you get the fix solution. Due to their ability to process several frequencies and mitigate the multi-path impact, multi-band receivers can keep the reliable fix solution even in urban areas. Single-band receivers need the open sky to work their best. Otherwise, it might be harder and take longer to establish a fix solution.

19. Accuracy Both single-band and multi-band receivers are capable of cm-level absolute accuracy. The main difference is that more factors can influence the stable fix solution in the single-band receiver. Thus, when using a single-band receiver, you can obtain the same absolute accuracy, but only if you have reasonable working conditions.

20. FCC EMISSION LIMITS FCC proposes to further update and revise its procedures beyond its 2003 proposals.  In the Inquiry the FCC requests comment to determine whether its RF exposure limits and policies need to be reassessed.  Since consideration of the limits themselves is explicitly outside of the scope of ET Docket No. 03-137, the FCC opens a new docket, with the Inquiry to consider these limits in light of more recent developments.  The Inquiry is intended to open discussion on both the currency of our RF exposure limits and possible policy approaches regarding RF exposure.    While the FCC has continuously monitored research and conferred with experts in this field, and is confident in its RF exposure guidelines and the soundness of the basis for its rules, it is a matter of good government to periodically reexamine regulations and their implementation.  

21. PULSE GENERATION, DETECTION, AND MULTIPLE ACCESS TECHNIQUE In the context of communication systems, "pulse generation, detection, and multiple access technique" refers to a method where data is encoded as pulses of signal, detected at the receiver to decode the information, and utilizes a specific "multiple access" strategy to allow multiple users to transmit data simultaneously on the same channel without interference, often achieved by assigning unique pulse patterns or codes to each user. 

22. Pulse Generation MCUs are often required to generate timed output pulses ( signals asserted for a specified period of time ) The application can be strobing a display latch transmitting a code, or metering a reagent in a process control system. However, each application has specific requirements for pulse duration and accuracy. This application note examines methods of generating these pulses in relationship to timing accuracy, coding efficiency, and other controller requirements. The following paragraphs describe the timing of the signals (start time and duration of the pulse). All pulses can be divided into three basic classifications : • Short pulses • Long pulses • Easy pulses

23. PULSE DETECTION Another system problem encountered when applying an MCU to a physical system is the detection and measurement of pulses. These can range from the actuation of a push button to pulse codes detection, detection of the period of rotation of an engine, and accumulation of the ‘on’ time of a process control valve. The periods can range from microseconds to minutes, hours, or more. There are several parameters that characterize a pulse, as Figure 3 illustrates. As far as a digital system is concerned, most of these parameters cannot be measured directly by a digital device such as an MCU.

24. Sometimes a satellite’s service is present at a particular location on the earth station and sometimes it is not present. That means, a satellite may have different service stations of its own located at different places on the earth. They send carrier signal for the satellite . In this situation, we do multiple access to enable satellite to take or give signals from different stations at time without any interference between them. Following are the three types of multiple access techniques. FDMA (Frequency Division Multiple Access) TDMA (Time Division Multiple Access) CDMA (Code Division Multiple Access)

25. FDMA In this type of multiple access, we assign each signal a different type of frequency band (range). So, any two signals should not have same type of frequency range. Hence, there won’t be any interference between them, even if we send those signals in one channel.

26. TDMA As the name suggests, TDMA is a time based access. Here, we give certain time frame to each channel. Within that time frame, the channel can access the entire spectrum bandwidth

27. CDMA In CDMA technique, a unique code has been assigned to each channel to distinguish from each other. A perfect example of this type of multiple access is our cellular system. We can see that no two persons’ mobile number match with each other although they are same X or Y mobile service providing company’s customers using the same bandwidth.

28. CONVENTIONAL VS. MULTI-ACCESS TECHNIQUES Multiple access techniques play a significant role in improving the spectral effectiveness and capacity of a particular communication system. There are various types of multiple access techniques which are used in wireless communication systems for data transmission. Some of these schemes are: frequency division multiple access   (FDMA),    ( TDMA ), (CDMA), ( W-CDMA),    ( SDMA ),  (OFDMA) and other random access techniques. Now a days, NOMA has become a predominant multiple access scheme for wireless communication networks with the aim to ensure the better network connectivity [5]. Also, NOMA has been selected as the best candidate for VLC systems offering higher number of users with high capacity gains. These capacity gains are obtained by permitting multiple users to avail the same frequency bands and time slots simultaneously in code or power domain [6]. In literature, multiple access techniques are broadly categorized as orthogonal multiple access techniques and non-orthogonal multiple access techniques which are briefly described in next subsections.

29. All the multiple access techniques prevailing from first to fourth generation of wireless networks fall into orthogonal category of multiple access techniques in which single user is being served with orthogonal resource block. Collectively, all of these multiple access techniques are referred to as orthogonal multiple access (OMA) techniques

30. INTERFERENCE ISSUE Interference is a problem that occurs when signals are disrupted by other signals or physical obstacles. It can affect media like radio, TV, and the internet, and can cause issues like slower speeds, dropped connections, or data loss. 

31. Thank you!