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Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
Training Manual - Communications Technologies.doc
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  • 1. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Introduction to Communication Technology An initiative funded by the Facilitated by
  • 2. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Learning objectives of Communication Technologies At the end of the program participants will be able to Relate to the different communication technologies with regards conservation and development. Acquire knowledge on the fundamental principles of basic radio communications. Apply the relevant communication technologies to their everyday use in the workplace. Be confident and motivated in the use of the communication technologies. Learning Approach Information will be disseminated through instruction, but with a more interactive approach through discussions of personal experiences with information technology. Practical hands on exercises will be used so as to enhance and further appreciate the workings of information technologies. A basic appreciation of the theory of these technologies will be explored. i i A t4cd Training Manual
  • 3. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Table of Contents Introduction to Communication Technology ................................................................... i Learning objectives of Communication Technologies ............................................... ii Session 1: Basic Radio Physics............................................................................................1 1.1 Learning Objective: To get knowledge of the fundamental principles of basic radio communications. ..............................................................................................................1 1.2 Content .......................................................................................................................1 1.2.1 Voice VS Data Communication..........................................................................1 1.3Factors affecting choice of transmission media ..........................................................2 1.4 The Electromagnetic (EM) Spectrum .......................................................................2 1.5 Propagation of Electromagnetic Waves .....................................................................5 1.5.1 Absorption...........................................................................................................6 1.5.2 Reflection ............................................................................................................6 1.5.3 Diffraction ...........................................................................................................6 1.5.4 Interference .........................................................................................................7 1.6 Line-of-Sight Microwave...........................................................................................7 1.7 Applications of Radio technologies ...........................................................................8 1.8 Wireless Fidelity Wi-Fi or 802.11 networking ..........................................................9 1.9Satellite Communication ...........................................................................................10 Session 2: Introduction to Voice and Data Communications ............................................12 2.1 Learning Objective: To understand Data and Voice Communications ...................12 2.2 Voice Transmission .................................................................................................12 2.2.1 Public Switched Telephone Network (PSTN) – “landline” ..............................12 2.3 PSTN Services .........................................................................................................13 2.3.1 Dialup ................................................................................................................13 2.3.2 Faxing ...............................................................................................................13 2.4 Integrated Services Digital Network (ISDN) ...........................................................13 2.5Asynchronous Transfer Mode (ATM) ......................................................................14 2.6X25 packet network ..................................................................................................14 2.7Asymmetric Digital Subscriber Line (ADSL) ..........................................................14 2.8 GSM (Global System for Mobile Communications) ..............................................16 2.8.1 The Mobile Station (MS) ..................................................................................17 2.8.2 The Base Station Subsystem (BSS) ..................................................................17 2.8.3 The Base Transceiver Station (BTS) ................................................................17 2.8.4 The Base Station Controller (BSC)...................................................................18 2.9 Case study ................................................................................................................19 2.10GPRS.......................................................................................................................19 2.11 Data Transmission .................................................................................................20 2.11Features of OSI .......................................................................................................21 2.13 Transmitting data via the Internet ..........................................................................22 2.14.1 Transmission Control Protocol .......................................................................22 2.14.2 Internet Protocol (IP) .....................................................................................23 2.15 Bushmail ................................................................................................................24 Session 3: Tools for Communication .................................................................................25 i i i A t4cd Training Manual
  • 4. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org 3.1 Learning Objective: Summarise the use of the communication tools .....................25 3.2 Content .....................................................................................................................25 3.3 Relevance of Communication Technologies ...........................................................26 Session 4: Practical ............................................................................................................28 4.1 Learning Objective: Attain the skill of using a data and a voice application ..........28 4.2 Practical A ................................................................................................................28 Table of Figures Figure 1: Diffraction over a mountaintop ............................................................................7 Figure 2: A sketch of an LOS microwave radio relay system. ............................................8 Figure 3: Dynamic Pocket Solution. ...................................................................................9 Figure 4: PSTN Network ...................................................................................................12 Figure 5: GSM System Architecture..................................................................................17 Figure 6: GPRS Data Transfer ...........................................................................................20 Figure 7: Bushmail Connection .........................................................................................24 List of Tables Table 1: Uses of Rays ..........................................................................................................3 Table 2: EM Spectrum .........................................................................................................4 Table 3: Features of OSI ....................................................................................................21 Table 4: Use of Communication Tools ..............................................................................25 4 A t4cd Training Manual
  • 5. SAWC Private Bag X3015, Hoedspruit, Northern Province 1380, South Africa, www.wildlifecollege.org.za Session 1: Basic Radio Physics 1.1 Learning Objective: To get knowledge of the fundamental principles of basic radio communications. Framework: Introduce the electromagnetic spectrum Define Wavelength, wave velocity and frequency and wave Discuss the frequency ranges using the electromagnetic spectrum The propagation of electromagnetic waves The effects of absorption, reflection, diffraction and interference on electromagnetic waves Concepts in Radio propagation, Free Space Loss, Fresnel Zones, Line of sight and (Huygens Principle) Radio Waves using WiFi as an example 1.2 Content Communication is a way of conveying information, by means of a written code or verbal means. ‗Technology changes, but communication lasts‘, the availability of communication technologies has made a great impact on human lives, but the challenges of the modern environment (social, political, economic and environmental) all mean, it is increasingly important to take advantage of these tools to share information and collaborate effectively. 1.2.1 Voice VS Data Communication Tele-Communications can therefore be basically grouped into two -voice & data ―Tele‖ means distant, hence telecommunication means communication at a distance. Three basic components that comprise a full communication channel: 1. The Sender – A transmitter encodes the message in a language that can be understood by the receiver. 2. The Receiver –decodes the message. 3. The Medium – Air, copper wires, optical fibre. These carry the message across from the sender to the receiver. In telecommunications a transmission system is a system that transmits a signal from one place to another. The signal can be an electrical, optical or radio signal. As signals are being transmitted there is loss of signal power (attenuation), changes in shape of signal (distortion) and they can pick up undesired signals (noise). In order to receive the same transmitted signals at the receiver end,
  • 6. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org some transmission systems contain repeaters, which amplify a signal prior to re- transmission, or regenerators, which attempt to reconstruct and re-shape the coded message before re-transmission. Repeaters enable the receiver to get the message intact thereby minimising distortion. 1.3 Factors affecting choice of transmission media Information bandwidth – Bandwidth is simply a measure of frequency range. It is easy to see that the bandwidth we define here is closely related to the amount of data you can transmit within it - the more room in frequency space, the more data you can fit in at a given moment. The term bandwidth is often used for something we should rather call a data rate, as in ―my Internet connection has 1 Mbps of bandwidth‖, meaning it can transmit data at 1megabit per second. In communications, fibre optics have an infinite bandwidth, whereas radio systems have very limited information bandwidth. It is for this reason that frequency bands 2GHz and above is used for the PSTN and private network applications. In terms of licensing and sharing, metallic and optic media do not require licensing, whereas radio requires licensing and it is a shared resource. Radio has a high susceptibility to noise and variability in performance. Interference is notable in radio systems than other media. It is also charecterised by delays, which are notable in some radio systems. Satellite systems introduce a 250ms delay in one hop. Radio systems have some draw backs but it has advantages over other types of media Less expensive to implement Less vulnerable to vandalism Not susceptible to accidental cutting of links Often more suited to crossing rough terrains Often more practical to highly urbanised areas Back up to fibre optic cables It is imperative to note that radio communication uses a finite band of the electromagnetic spectrum. 1.4 The Electromagnetic (EM) Spectrum Electromagnetic waves span a wide range of frequencies and similarly a wider range of Wavelengths. This range of frequencies and wavelengths is called the Electromagnetic Spectrum. 2 A t4cd Training Manual
  • 7. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org The EM Spectrum is defined as A full range of frequencies from Radio to Gamma rays. The name given to a bunch of the types of radiation? Radiation is energy that travels and spreads out as it goes. The part of the spectrum most familiar to humans is probably light, the visible portion of the electromagnetic spectrum. Ultraviolet is (on the higher frequencies side of visible light) and Infrared (on the lower frequencies side of visible light) and there are many others. Radio is the term used for the portion of the electromagnetic spectrum in which waves can be generated by applying alternating current to an antenna. This is true for the range from 3 Hz to 300 GHz, but in the more narrow sense of the term, the upper frequency limit would be 1 GHz. When talking about radio, many people think of FM radio, which uses a frequency around 100 MHz. In between radio and infrared we find the region of Microwaves, these have frequencies from about 1 GHz to 300 GHz, and wavelengths from 30 cm to 1 mm. The most popular use of microwaves might be the microwave oven. Most other parts of the electromagnetic spectrum are tightly controlled by licensing legislation, with license values being a huge economic factor. This goes especially for those parts of the spectrum that are suitable for broadcast (TV, radio) as well as voice and data communication. Table 1: Uses of Rays 3 A t4cd Training Manual
  • 8. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org EM Frequency Wavelength Energy Application Gamma Highest Shortest Highest Used by Scientist to discover Rays what matter is made of X- Rays (Nuclear Power) Ultra Violet Used by Doctors to see bones (UV) Emitted by Sun, causes Visible light burning of skin Infrared Seen by the human eye Microwave Used as Heat .In space, maps Radio dust between stars Used to cook popcorn, and also in the study of astronomy Lowest Longest Lowest Aircraft and Shipping Band, AM/FM radios, TV The Electromagnetic Spectrum Table The EM spectrum can be expressed in terms of Energy (photons), wavelength or frequency. Table 2: EM Spectrum 4 A t4cd Training Manual
  • 9. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Source: http://en.wikipedia.org/wiki/Image:Electromagnetic-Spectrum.png Wavelength (λ) is the distance between adjacent peaks in a series of periodic wave. Unit of measurement (meter- m) Frequency (f) is the property of a wave that describes how many wave cycles pass by in a period of a time. Unit of measurement (Hertz – Hz) Wave Speed (c) is the speed of light and is approximately 3X108 m/s Relationship between frequency and wavelength and wave speed Wave speed (c) = Frequency (f) x Wavelength (λ) NB. The longer the wavelength, the further it goes The longer the wavelength, the better it goes through and around things The shorter the wavelength, the more data it can transport 1.5 Propagation of Electromagnetic Waves Electromagnetic Waves as they propagate are subject to 5 A t4cd Training Manual
  • 10. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Absorption Reflection Interference 1.5.1 Absorption Radio waves get dampened or weakened as they pass through any matter whether it is solid, liquid or gas, as energy is transferred to the medium they are travelling through. The absorption of light during wave propagation is often called attenuation which in other words is the degradation of signal power. There is strong Radio wave absorption in conducting materials, metals, and water in all its forms. Intermediate absorption is found in stones, bricks, concrete (depending on the exact parameters of materials). The same goes for wood / trees (depending on the water concentration). With radio implants (tracking devices) it is essential to note that the terrain, vegetation and power lines have an effect on the reception. Implants can either be on the horn or the abdominal cavity of an animal. Abdominal implants (where radio collars are unsuitable) can be attached on the following animals, porcupine, bush pig, warthog and pythons. Horn implants are used on black and white rhino. 1.5.2 Reflection Radio waves are reflected when they come in contact with materials that are suited for radio waves, the main sources of reflection are metal and water surfaces. Reflection rule states that the angle at which a wave hits a surface is the same angle at which it gets deflected. 1.5.3 Diffraction Diffraction is the apparent bending of waves when hitting an object. It is the effect of ―waves going around corners‖. Microwaves, with a wave-length of several centimeters, will show the effects of diffraction when they hit walls, mountain peaks, and other obstacles. It seems as if the obstruction causes the wave to change its direction and go around corners. 6 A t4cd Training Manual
  • 11. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Figure 1: Diffraction over a mountaintop Source: Wireless Book pdf 1.5.4 Interference In wireless technology the term ―interference‖ is generally used to describe, disturbance of radio signals from other Radio Frequency sources e.g. neighbouring radio channels. In communications and especially in telecommunications, interference is anything, which alters, modifies, or disrupts a message as it travels along a channel between a source and a receiver. 1.6 Line-of-Sight Microwave The term line of sight, often abbreviated as LOS, is quite easy to understand when talking about visible light: if we can see a point B from point A where we are, we have line of sight. Simply draw a line from A to B, and if nothing is in the way, we have line of sight. In communications, Line-of-sight (LOS) is a straight line between the transmitting and receiving antennas. It is important to keep the zone around the direct line between signal and receiver as clear as possible Line-of-microwave provides a comparative broadband connectivity of 622Mbps over a single link or a series of links in tandem compared to 100M on copper. On conventional LOS microwave links, the length of a link is a function of antenna height. In this regard, the higher the antenna, the further the reach and therefore the wider the coverage of connectivity. 7 A t4cd Training Manual
  • 12. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Figure 2: A sketch of an LOS microwave radio relay system. Source: Wiley IEEE Press Fundamentals of Telecommunications 2nd Edition Apr 2005 1.7 Applications of Radio technologies Radio tracking is used to study migration patterns of different animal species. A tracking device (collar, back-pack or implant) is attached onto the animal and this sends out radio signals to and from the animal to a transceiver normally at the park management offices. Factors affecting the choice of tracking devices Self powered Low power consumption Long system lifetime. Light to carry Should withstand the different weather conditions, i.e. should be highly reliable. The zone to be covered in terms of coverage area (sufficient sensing coverage) The number of frequency channels available and channel spacing Rangers can obtain the following by studying patterns obtained from the tracking information Migration seasons and patterns. Identify possible reasons for decline in a particular species. Assessment of human-wildlife conflict therefore looks for ways to reduce the human-wildlife conflict. Better planning and park management. Enhancement of conservation education to locals or community. Examples 8 A t4cd Training Manual
  • 13. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Wildtrack program collects and analyses location data, speed, the distance of movement and interaction between animals. Figure 3: Dynamic Pocket Solution. Source: t4cd resource data disk Radio Tracking Equipment developed by Africa Wildlife tracking targets the following species elephants, leopards, cheetahs, buffalos, lions and a lot more. www.awt.co.za 1.8 Wireless Fidelity Wi-Fi or 802.11 networking A wireless network uses radio waves, just like cell phones, televisions and radios do. Wireless networks are easy to set up and inexpensive. They are also unobtrusive (do not attract attention). One wireless router can allow multiple devices to connect to the Internet. 9 A t4cd Training Manual
  • 14. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org A computer's wireless adapter translates data into a radio signal and transmits it using an antenna. A wireless router receives the signal and decodes it. It sends the information to the Internet using a physical, wired Ethernet connection. The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter. WiFi radios transmit at frequencies of 2.4 GHz or 5GHz. The higher frequency allows the signal to carry more data. 802.11b transmits in the 2.4 GHz frequency band of the radio spectrum. It can handle up to 11 megabits of data per second. 802.11g also transmits at 2.4 GHz, but it's a lot faster than 802.11b - it can handle up to 54 megabits of data per second. 802.11a transmits at 5GHz and can move up to 54 megabits of data per second. The area covered by one or several access points (AP) is called a hotspot. An AP broadcasts its SSID (Service Set Identifier, "Network name") via packets that are called beacons, which are usually broadcast every 100 ms. If two APs of the same SSID are in range of the client, the client firmware might use signal strength to decide which of the two APs to make a connection to. Wi-Fi cannot do collision detection, and instead uses a packet exchange (RTS/CTS used for Collision Avoidance or CA) to try to avoid collisions. 1.9 Satellite Communication Satellites are highly specialized wireless transmitters and receiver placed in orbit around the earth. They can relay as many signals at the same time, to and from the earth with messages as simple as data messages to as complex as TV signals. Satellite communications are used to: Radio and TV broadcast Internet Services Data and Broadband and multi-media services Fixed position telephony Mobile Communications Satellite phones send radio signals direct to the satellite then down to an earth station from where the call can be connected to the public switched telephone network. They are used where the fixed, or wired lines and or cellular coverage is not available. A satellite phone requires line of sight with the satellite. This means the satellite antennae should be positioned in such a way that it is facing the satellite. Maximum signal strength can be obtained by rotating the antennae lid to a position that receives the signal. Example 1 1 0 A t4cd Training Manual
  • 15. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Satellite Collars (tracking devices attached to an animal) are based on mobile global two way communication using two way data satellite communications. By connecting to Internet, Park Rangers have access to customised maps, historical data and near to real time positions of animals. Satellite tracking uses a platform transmitter terminal (PTT) attached to the animal which sends radio signals to the ARGOS Satellite system. The satellite calculates the animal‘s location and then relays the information to the ground service stations which sends location data to researchers in a remote location. ARGOS satellite system is the most widely used tracking systems. Inmarsat is also used for tracking. Example 2 Broadband Global Area Network: With a BGAN satellite terminal and a telephone handset or headset and a Laptop or PC, a satellite up link is established. BGAN features: An easy to use interface Clear step-by-step instructions on pointing the terminal and setting up a satellite connection Ability to customize the data connection options to match ones application requirements Ability to pre-configure user access settings, enabling one to restrict access to Streaming IP services, for example Convenient online access to account and billing information Personal and corporate versions Access to text messaging and telephony features 1 1 A t4cd Training Manual
  • 16. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Session 2: Introduction to Voice and Data Communications 2.1 Learning Objective: To understand Data and Voice Communications Framework: Basic Voice Transmission, Fixed (PSTN) and Mobile Basic Data Transmission, OSI layer, TCP/IP protocol 2.2 Voice Transmission 2.2.1 Public Switched Telephone Network (PSTN) – “landline” PSTN is a circuit-switched network that is used primarily for voice communications worldwide in much the same way that the Internet is the network of the world‘s public IP-based data (packet-switched) networks. Originally it was a network of fixed-line analogue telephone systems, but it is now almost entirely digital although the signal coming out of the phone where the user is connected is analogue. Verbal communication is usually transmitted over a twisted pair cable as an analogue signal. At the central office this analogue signal is usually digitised, , yielding a 64 kb/s data stream (DS0). This explains why a dial up cannot exceed 56K. Figure 4: PSTN Network Source: http://www.althosbooks.com/intopuswtene.html Features of PSTN The majority of work and expense of the phone system is the wiring outside the central office, or the Outside plant. In the middle 20th century, each subscriber telephone number required an individual pair of wires 1 2 A t4cd Training Manual
  • 17. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org from the switch to the subscriber‘s phone. The outside plant is expensive to maintain and replace To reduce the expense of outside plant, some companies use ―pair gain‖ devices to provide telephone service to subscribers. Pair gain means that from one pair of wires we can have about 8 other devices using that single pair. A large database tracks information about each subscriber pair and the status of each jumper. Each subscriber pair is addressed uniquely by a telephone number defined by ITU-T, E.163/E.164 numbering plan. Dial up speeds can be achieved at 56K for data transmission PSTN is a fixed network and is slowly being the less favored, as other forms of communication such as SMS, email, VOIP are taking a centre stage. There are also private networks run by large companies, which are linked, to the PSTN only through limited gateways, like a large private branch exchange (PBX) system. 2.3 PSTN Services 2.3.1 Dialup Dialup enables web browsing and other features related to the Internet such as chatting, Skype, and email. A modem changes the digital form of data to analogue signals (Modulation) that is compatible on PSTN lines and converts it back to digital at the receiving end (DEModulation). 2.3.2 Faxing Documents can be sent over PSTN by dialling the receiver fax number. 2.4 Integrated Services Digital Network (ISDN) This is a circuit-switched telephone network system, designed to allow digital transmission of voice and data over ordinary telephone copper wires, resulting in better quality and higher speeds than that available with the PSTN system. In ISDN, there are two types of channels, B (for ―Bearer‖) and D (for ―Delta‖). B channels are used for data (which may include voice), and D channels are intended for signalling and control (but can also be used for data). There are three ISDN implementations. 1. Basic Rate Interface (BRI) , also known as Basic Rate Access (BRA) — consists of two B channels, each with bandwidth of 64 kbit/s, and one D channel with a bandwidth of 16 kbit/s. Together these three channels can be designated as 2B+D. 2. Primary Rate Interface (PRI), also known as Primary Rate Access (PRA) 1 3 A t4cd Training Manual
  • 18. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org — contains of a greater number of B channels and a D channel with a bandwidth of 64 Kbit/s. The number of B channels for PRI varies according to the nation: in North America and Japan it is 23B+1D, with an aggregate bit rate of 1.544 Mbit/s (T1); in Europe and Australia it is 30B+1D, with an aggregate bit rate of 2.048 Mbit/s (E1). 3. Broadband Integrated Services Digital Network (BISDN) is another ISDN implementation and it is able to manage different types of services at the same time. It is primarily used within network backbones and employs asynchronous transfer mode. 2.5 Asynchronous Transfer Mode (ATM) Another alternative ISDN configuration can be used in which the B channels of an ISDN basic rate interface are bonded to provide a total duplex bandwidth of 128 Kbit/s. This precludes use of the line for voice calls while the internet connection is in use. The D channel can also be used for sending and receiving X.25 data packets, and connection to X.25 packet network. 2.6 X25 packet network X25 is a packet switched data protocol. The packet switching nodes has multiple choices for routing data packets. If a particular route becomes congested or has degraded operation, a packet is sent on another route. Packets are reassembled at the receiving end to give the transmitted data. 2.7 Asymmetric Digital Subscriber Line (ADSL) This is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. ADSL can only be used over short distances, typically less than 5 km. Once the signal reaches the telephone company‘s local office, the ADSL signal is stripped off and immediately routed onto an internet network, while any voice- frequency signal is switched into the phone network. This allows a single telephone connection to be used for both ADSL and voice calls at the same time without any interference. The distinguishing characteristic of ADSL over other forms of DSL is that the volume of data flow is greater in one direction than the other, i.e. it is asymmetric. Higher speed direction for the ―download‖ (8M) from the Internet but a lower speed (1M) in the other direction. With standard ADSL, the band from 25.875 kHz to 138 kHz is used for upstream communication, while 138 kHz – 1104 kHz is used for downstream communication 1 4 A t4cd Training Manual
  • 19. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org 2.8 GSM (Global System for Mobile Communications) The Global System for Mobile Communications (GSM) system is a global digital radio system that uses Time Division Multiple Access (TDMA) technology .We have the GSM900 system where the frequency used is 900 MHz, GSM1800 frequency band used 1800MHz and GSM1900 frequency band used 1900MHz. These three systems differ primarily in the air interface. Besides using different frequency bands, they use a microcellular structure (i.e. a smaller coverage region for each radio cell). This makes it possible to reuse frequencies at closer distances, enabling an increase in subscriber density. The disadvantage is the higher attenuation of the air interface due to the higher frequency. The benefits of GSM include: Support for international roaming Distinction between user and device identification Excellent speech quality Internetworking (e.g. with ISDN, DECT) Extensive security features such as blacklisting all stolen handsets such that they become unusable in the network. GSM stands out from other technologies with its wide range of services: Telephony Asynchronous and synchronous data services (2.4/4.8/9.6 kbit/s) Access to packet data network (X.25) Telematic services (SMS, fax, videotext, etc.) Many value-added features (call forwarding, caller ID, voice mailbox) E-mail and Internet connections Asynchronous data services use the start stop transmission, whereby the beginning of a character and end of a character, is signified by a start and stop bit respectively. Synchronous data service has a reduced overhead, but employs signals that will indicate the start of a data frame and when it will end. Asynchronous and synchronous data transmission does not realise higher transmission speeds because of the control overhead. 1 5 A t4cd Training Manual
  • 20. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Figure 5: GSM System Architecture Source: Pocket Guide for Fundamentals and GSM testing by Marc Kahabka They are characterized as follows: 2.8.1 The Mobile Station (MS) A mobile station may be referred to as a handset, a mobile, a portable terminal or mobile equipment (ME). It also includes a subscriber identity module (SIM) that is normally removable and comes in two sizes. Each SIM card has a unique identification number called IMSI (international mobile subscriber identity). In addition, each MS is assigned a unique hardware identification called IMEI (international mobile equipment identity). In some of the newer applications (data communications in particular), an MS can also be a terminal that acts as a GSM interface, e.g. for a laptop computer. Besides providing a transceiver (TRX) for transmission and reception of voice and data, the mobile also performs a number of very demanding tasks such as authentication, handover, encoding and channel encoding. 2.8.2 The Base Station Subsystem (BSS) The base station subsystem (BSS) is made up of the base station controller (BSC) and the base transceiver station (BTS). 2.8.3 The Base Transceiver Station (BTS) GSM uses a series of radio transmitters called BTSs to connect the mobiles to a cellular network. Their tasks include channel coding/decoding and encryption/decryption. A BTS is comprised of radio transmitters and receivers, antennas, the interface to the PCM facility, etc. The BTS may contain one or 1 6 A t4cd Training Manual
  • 21. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org more 8 transceivers to provide the required call handling Media Report on Killings of Rare Mountain Gorillas capacity. A cell site may be omni-directional or split into typically three directional cells. Killings of rare mountain gorillas in Virunga National Park, 2.8.4 The Base Station Controller (BSC) Democratic Republic of Congo dated 18 January 2007. Two mountain gorillas were killed in A group of BTSs are connected to a particular BSC which the Democratic Republic of manages the radio resources for them. Today‘s new and Congo (DRC)’s Virunga National intelligent BTSs have taken over many tasks that were previously Park. The gorillas were both handled by the BSCs. The primary function of the BSC is call solitary silverback males, from maintenance. The mobile stations normally send a report of their groups conditioned not to fear humans. Both were killed within received signal strength to the BSC every 480 ms. With this two weeks, and one is believed information the BSC decides to initiate handovers to other cells, to have been eaten. It is feared change the BTS transmitter power, etc. that others may already have Been killed or are in imminent Example 1 danger. Before the attacks, it was thought that just 700 Cellular Collars (tracking devices), Hawk105 was developed by mountain gorillas were left in this Africa Wildlife Tracking. The device is fitted to the animal and region of Africa, approximately determines positions accurately within 10m at specified times half of which were to be found in (scheduled daily or weekly), while the animal is in the field. the Virunga forest block It has not been confirmed who is The gathered position data is logged and sent to the user responsible for the killings of the immediately. The data is downloaded with Hawk105 software gorillas, but it is unlikely to have package. When there is no GSM coverage, a VHF beacon been local people, who do not transmitter is activated automatically providing backup for the eat gorillas and have been logged data up to 240 readings. supportive of conservation work. Hippos and buffalos have also suffered from heavy poaching. The battery life depends on the number of readings taken per Cattle ranching and charcoal day. Typically with D type battery, in a good area, battery life is burning activities are posing two years with 5 readings per day. It has remarkable low power further threats to the park itself. consumption. Its basic requirements are cellular coverage, Thousands of local people have fled their homes and are living in computer and the Internet. poor conditions.” Adapted from flora and fauna Example 2 international webpage Mobile gamming is one application that can educate the community of conservation issues. Masabi developed a secure mobile gamming application that educates on conservation e.g. Silverback. It incorporates platform game play, as well as accurate facts about gorilla habits. One preconception people have about gorillas is that they sit around eating bananas, in the game one gorilla comes up and starts eating a banana, and a pop up bubble comes up to say that they actually don't eat them, they eat mostly leaves instead. Players take on the role of a baby gorilla, which develops over eight levels. The gorilla is separated from its family and has to fend for itself, escape poachers, as 1 7 A t4cd Training Manual
  • 22. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org well as forest fires, and raise a family of its own. This application is both fun and informative. 2.9 Case study Mobile GSM phones have a great impact on human lives. In developing countries like Zimbabwe it is no longer a luxury but a necessity even for the folks and farmers in the rural areas. Small scale entrepreneurs can now contact potential clients, saving on transport costs and loss of perishable goods when a sale does not go through. Farmers use mobile handsets for best prices for their crops Information is disseminated more readily. When an outbreak of foot and mouth occurs in an area, the agricultural extension officer makes a call to the headman of the village informing him of the need to vaccinate all animals. The headman then informs all villagers hence curbing the spread of the disease. Neighbouring villages are informed when army worms threatens their crops, and take precautionary measures. Mobile Communications is much cheaper than the fixed pair gains lines, which was in the reach of a few elite members. With recycled handsets and prepaid mobile lines, communication has been brought closer to home. An improved communication network increases the effectiveness of patrols in protected areas. Voice and SMS raises awareness on conservation issues in the community. 2.10 GPRS General Packet Radio Service (GPRS) provides packed data services to the Global System for Mobile communications (GSM). It provides a basic solution for Internet Protocol (IP) communication between Mobile Stations (MS) and the Internet or corporate Local Area Networks (LAN). GPRS provides the following services: Efficient transport of packets in the cellular network Efficient use of scarce radio resources Flexible service, with prepaid or postpaid charging based on content, volume, or session duration. Fast setup and access time Simultaneous circuit-switched and packet-switched services, which means coexistence without disturbance 1 8 A t4cd Training Manual
  • 23. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Connectivity to other external Packet Data Networks (PDNs), using IP packet data WWW server, that is, a local Web server supplying Web pages Domain Name System (DNS) server providing translation between host names and IP addresses E-mail server, that is, a Post Office Protocol version 3 (POP3) / Simple Mail Transfer Protocol (SMTP) server providing an Internet e-mail address for the end-user Wireless Application Protocol (WAP) server GPRS data transfer is IP based. A message consisting of large quantities of data is divided into several packets. When these packets reach the destination, they are stored in data buffers and reassembled to form the original message. The packet data transmission is thus carried out on an end-to-end basis, including the radio interface. Figure 6: GPRS Data Transfer Source: GPRS Tutorial Pdf Morgan Doyle Limited 2.11 Data Transmission Data networks use the Open System Interconnection (OSI) referencing model to transfer packets between devices. All the processes required for effective communication are divided into logical groupings called layers. 1 9 A t4cd Training Manual
  • 24. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org 2.11 Features of OSI Allows interoperability of network devices from different vendors ie. it provides the basis for connecting open systems for connecting open systems for distributed applications processing. It‘s a seven layered protocol, which eliminates the ―ripple effect‖ when there is a modification in any of the layers. Table 3: Features of OSI Application Provides a user interface between the computer and the user. Runs file, print, message, databases and application services Examples of application services are www, email, financial transactions, internet navigation utilities – Gopher, Google Presentation Presents data to the application layer (translator) Handles processing such as data encryption, compression and data translation and code formatting Ensures that the application layer of another one can read data transferred from the Application layer on one system. Examples of standards – MPEG (Moving Picture Experts Group) for the compression and coding of motion video for CDs. Provides digital storage and bit rates up to 1.5Mbps JPEG (Joint Photographic Experts Group) RTF (Rich Text Format) Session Keeps different applications data separate, i.e. dialogue control between devices Responsible for setting up, managing, and tearing down sessions between presentation layer entities Supports different communication modes – simplex, half duplex and full duplex Examples of protocols Network File System Structured Query Language Transport Provides reliable or unreliable delivery Performs error correction before retransmission Responsible for end to end connection Examples of Protocols –TCP (Transmission Control Protocol) UDP (User Datagram Protocol) 2 0 A t4cd Training Manual
  • 25. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Network Provides logical addressing, hence routing of packets Enables devices that are not physically attached to communicate Examples of protocols IP and IPX, Data Link Combines packets into bytes and bytes into frames( framing) Provides access to media using MAC addresses, ensuring messages are delivered to the proper device Performs error detection not correction Examples of standards Logical Link Control(LLC) 802.2 Media Access Control (MAC) 802.3 Physical Moves bits between devices (physical topology) Mechanical aspects include cabling, connectors necessary to connect equipment to media Electrical specifications such as voltages, impedance, wire speed, pin out of cables and functional requirements for ]activating, maintaining and deactivating a physical link between end systems. Specifies the media, copper wires, optical fibre, radio waves and copper. Standards used , Ethernet, Carrier Sense Multiple Access with Collision Detection (CSMA/CD) WiFi, Orthogonal Frequency-Division Multiplexing (OFDM), Data transmission has evolved from very low speeds such as Telegraphy through to ATM 2.13 Transmitting data via the Internet 2.14.1 Transmission Control Protocol TCP is typically used by applications that require guaranteed delivery. It is a connection –orientated protocol, which is responsible for verifying the correct delivery of data from client to server. Data can be lost in the intermediate network. TCP adds support to detect errors or lost data and to trigger retransmission until the data is correctly and completely received. TCP provides connections that need to be established before sending data. TCP connections have three phases: 1. connection establishment 2. data transfer 3. connection termination 2 1 A t4cd Training Manual
  • 26. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org TCP establishes a full duplex virtual connection between two endpoints. Each endpoint is defined by an IP(internet protocol) address and a TCP port number and is implemented as a finite state machine. The data being sent (the ―byte stream‖) is transferred in segments. The window size determines the amount of data (number of bytes) that can be sent before an acknowledgement from the receiver is necessary. On the contrary User Datagram Protocol UDP can immediately start sending ―packets‖ of data via the internet without guaranteeing the delivery of the packets .It is a connectionless protocol. The two most typical network applications that use TCP are File Transfer Protocol (FTP) and the TELNET. FTP is an application that allows data files to be transferred between devices. Telnet is an application that allows remote access into device. Example FTP is used with Wildtrack, Footprint Identification Technique. A digital camera is used to capture images of footprints, and these are downloaded onto a laptop, and optimised with photo software. With Internet access one transfers the image (using FTP) to a remote database or management system that compares the image with what is in the archives. A confirmation of the species is then generated. This technique is used to monitor and analyse information on endangered species. For efficiency over fast networks with short latency, UDP might be best for example the need for credit card verification processes when paying subscriptions for a service like Bushmail. TCP is best suited where efficiency over long-haul circuits is needed e.g. WAN, the internet cloud. The internet gives voice to people and communities whose natural resources are being threatened. It is a powerful tool that brings together multicultural organisations and communities to share experiences on conservation and development projects regardless of geographical differences. 2.14.2 Internet Protocol (IP) Whilst TCP manages the packets that data is divided up into when it is sent, IP is responsible for forwarding packets of data to the right location and for their delivery. IP forwards each packet based on a four-byte destination address (the IP number). The Internet authorities (AFRINIC, RIPE) assign ranges of numbers to different organizations. The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world. 2 2 A t4cd Training Manual
  • 27. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org 2.15 Bushmail Bushmail is an email facility that uses HF radio powered by a 12 volt battery with an antenna suspended from a tree. Figure 7: Bushmail Connection Source: http://www.bushmail.net Features Allows 100K Excel and Word documents to be sent. Voice communications is supported but it is not secure. Cheap, flat annual rate is charged regardless of usage. Sending of free email SMS messages but no internet browsing. Does not allow spam and through its filters. Slow, email message delivery is slow due to low baud speeds supported of 2000 to 6000. It is robust and runs in remote areas. Has unlimited text email from very remote areas. Used in many reserves including Kruger National Park, some areas in Zimbabwe like Zambezi Valley, Botswana, Zambia, Tanzania, and Mozambique. Coverage is in Africa only. Easy to install, (DIY) 2 3 A t4cd Training Manual
  • 28. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Session 3: Tools for Communication 3.1 Learning Objective: Summarise the use of the communication tools Framework: List the communication tools List their applications How can these tools be used in relevance to the conservation and development? 3.2 Content Table 4: Use of Communication Tools Fixed or Carrier Tool Service/s Uses of the service portable? technology Direct communication, i.e. to GSM network Voice local communities within (voice channel) range, with HQ. data – as above GSM network SMS instant transfer of images Mobile data - portable captured in the field (i.e., to MMS via GSM phone Digital report illegal poaching / network pictures activate response) data – relatively inexpensive field GPRS or 3G (via email based communication for GSM or 3G long-distance / international network) correspondence Voice (Voice) communication in data – extremely remote places or SMS Satellite others not served by GSM or Satellite landline infrastructure portable phones data – (Data) (ditto) Satellite email BGAN unit/ (Data) (ditto) satellite Voice Low-cost voice Air! UHF / VHF communication over distance portable radio Bushmail Entry-level email functionality Air! over distance 2 4 A t4cd Training Manual
  • 29. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org portable Voice communication between Shortwave Voice (within ~ individuals or small teams in Air! radio 5 km) shorter range PSTN (public Voice fixed Voice communication network) Landline Web browsing, sending SMS phone Internet/ fixed via web, email, chat, Skype PSTN email etc. Fax fixed Sending documents PSTN 3.3 Relevance of Communication Technologies The presence of communication technologies has greatly improved information flow especially in areas that are remote and infrastructure for more traditional modes of communication is not in place. The following examples illustrate some of the potential applications of telecommunications for conservation and sustainable development purposes – and the impacts they can generate: To improve access to markets farmers are now using mobile handsets to locate the best prices for their produce, by contacting the buyers before travelling with the orders. This dramatically increases cost-efficiency as deliveries can be made to the most lucrative buyer. Assisting the process of accessing markets can also promote community- based natural resource management (CBNRM) by helping small business enterprises in the marketing and selling of sustainable produced products. To improve sharing of, and access to, information that informs better management of conservation areas and better use of natural resources. Sharing lessons learnt or the latest best practice, or communicating emergency issues that require rapid response. To raise community awareness of local conservation issues, for example, community-based websites can increase knowledge and information on conservation issues (local and national), and help promote protection of the local environment. Mobile news services, broadcast on SMS keeps can keep community stakeholders informed on the latest events, topical competitions & emergency alerts in a very inexpensive way. Supposing there is an outbreak of a disease, fire, poaching or animals straying away, ICTS improve the speed, effectiveness and quality of response to such threats. Opening news lines of communication between protected area authorities and local communities (via SMS, for example) can go a long way towards improving relationships and easing tensions. Targeted use of ICTs could allow for more effective law enforcement by improving in administrative and communications capacity, which in turn help to improve environment and wildlife protective measures. ICTs could enable a proactive, speedier and standardised communications platform for protected area management, resulting in improved environmental planning management and monitoring. 2 5 A t4cd Training Manual
  • 30. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org To enhance data management by providing a new way of recording, sharing, distributing and analysing data (e.g. on elephant populations, wildlife tracking, using Footprint Identification Techniques). Improving external communications by connecting conservation areas to the outside world, e.g. to headquarters of NGOs, and even overseas. It brings together multicultural organisations and communities to share experiences regardless of the geographical differences. To supports eco-tourism, effective communications are essential to access tourism markets and encourage increased visitors to conservation areas To Study of wildlife migration patterns by using GPS Remote Release Collar for Wildlife tracking and tracking. Frequency of wildlife tracking collars range from 215 – 220Mhz To stay in touch with colleagues / local partners when in remote locations lacking extensive communications infrastructure 2 6 A t4cd Training Manual
  • 31. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Session 4: Practical 4.1 Learning Objective: Attain the skill of using a data and a voice application Framework: Demonstrate the use of bulk SMS messaging technology platforms. Web based SMSMalls and stand alone application of FrontlineSMS 4.2 Practical A Aim: Demonstrate the use of FrontlineSMS Demonstrate the following Create and manage all of your SMS-related contact groups Send and receive messages via special on-screen consoles Engage with your contact groups - run surveys, competitions etc. via the Survey Manager Run your own text-based information service via the automated Reply Manager NB* FrontlineSMS messaging solution was developed for the non profit sector Handles flash messages and long messages up to 320 characters in length Provides incoming and outgoing message history for each contact There is no need to be on-line it works on any GSM network via your own PC or laptop Your data is all held locally, and not on a centralised on-line server. When running on a laptop the system continues to work during power outages The system will allow incoming text messages - not all web-based systems are able to do this simply and easily. Two-way communication is a vital function for full field communications or to carry out surveys With this two-way portable communications capability, field-based NGOs can keep in touch with their fieldworkers from anywhere in the field. This provides valuable contact during operations, or for monitoring movements of poachers, wildlife etc. 2 7 A t4cd Training Manual
  • 32. Technologies for Conservation and Development, www.t4cd.org, email:t4cd@resourceafrica.org Bibliography and Websites http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html The Electromagnetic Spectrum http://en.wikipedia.org/wiki/Electromagnetic_spectrum The Electromagnetic Spectrum http://en.wikipedia.org/wiki/Fresnel_zone Fresnel Zone http://www.howstuffworks.com/wireless-network WiFi http://frontlinesms.kiwanja.net FrontlineSMS http://www.kiwanja.net Application of ICTs http://www.bushmail.net Bushmail http://www.awt.co.za Tracking devices http://www.masabi.com/scFFI.html Gaming applications http://www.t4cd.org t4cd website & technology database Rob Flickenger Wireless ebook Propagation of Radio Waves Sebastian Bluettrich Basic Radio physics HANDOUT, wireless.dk T4CD Resource Disk Communication Technologies Wiley GSM Basics, Fundamentals of Telecommunications. 2nd.Edition.Apr.2005 OSI layer Sybex Cisco Certified 640-801 Study Guide 5th Edition 2 8 A t4cd Training Manual

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