"Physics Radiation" - There are 10 nuclear power plants in operation in our country now. This definition of radioactivity was given by Marie Curie, a famous physicist. Completed by: Nalivaiko G.G. Illiterate I.A. Small doses of radiation are not dangerous, rather the opposite. Radioactivity helps a person in real life. This source is the energy of atoms.
"Atomic structure of Rutherford's experiment" - The mechanism of dispersion. Facts indicating the complexity of the structure of the atom. Models of the structure of the atom. Rutherford's experience. The structure of the atom. Scientists of antiquity about the structure of matter. All models were speculative and not the result of an experiment. The charge of the nucleus is equal in magnitude to the charge of all electrons, therefore the atom is neutral.
"Thermonuclear reaction" - Especially of great practical importance is the fact that during a thermonuclear reaction, much more energy is released for each nucleon than during a nuclear reaction, for example, when a helium nucleus is synthesized from hydrogen nuclei, an energy equal to 6 MeV is released, and when a uranium nucleus is fission one nucleon accounts for »0.9 MeV. What a huge and "inexhaustible" source of energy a person has!
"Biological effect of radioactive radiation" - A person with the help of the senses is not able to detect any dose of radioactive radiation. Radioactive radiation has a strong biological effect on the tissues of a living organism, consisting in the ionization of atoms and molecules of the medium. Completed: 2009
"Influence of radiation on a person" - - "Vigor hormone". A cell phone affects the entire cardiovascular system as a whole. How to protect yourself from EMF. Ozone layer. How does the state help? Fundamental question: How do radiation and electromagnetic radiation affect human health?
“Model of the atom” - 7., Where? 0 \u003d const, n \u003d 3, 4, 5,… 7.1. Regularities in atomic spectra. 7.3. Bohr's elementary theory. When driving in a circle, there is a centripetal acceleration. The hydrogen atom according to Bohr's theory. Where k \u003d 1, 2, 3, ...; n \u003d k + 1, k + 2,…. In physics, the Rydberg constant is also called another quantity equal to R \u003d R? · S.
There are 11 presentations in total
The purpose of the lesson:development of information and communication competencies of students.
Equipment: screen, projector, magnets, Whatman sheets, green and red highlighters, black markers, cast-iron saucepan.
DURING THE CLASSES
Teacher: The topic of our lesson is close to you, familiar and very relevant. It is encrypted in these pictures.
Appendix 2 ... Slide 1.
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Guessed it: cellular.
Appendix 2 ... Slide 2. (Development stages)
The teacher tells or the student makes a message:
Cellular telephone Is nothing more than radiotelephone... The telephone was invented in 1876, the radio is also a discovery of the century before last. All that remained was to combine these two technologies, and it took almost 100 years. This became possible after the advent of integrated circuits and relatively light batteries. This year the “mobile phone” has a small anniversary - it turned 35 years old.
The first call from a mobile was made in 1973, and it took 10 yearsto bring the invention to the mass consumer.
The first mobile phones were very expensive, while, to put it mildly, did not differ in pocket size. For each such device weighing 1 kg, those who wished were offered to pay neither more nor less 3500 dollars.
However, the communication itself was carried out already according to completely modern principles. –
across base stations, network which looks like a honeycombTherefore, this connection is called cellular.
Teacher: You are probably listening to radio broadcasts. What stations? Can you name? Why do you find 20 radio stations on the air and not 120? What is the reason for this?
The students answer.
Teacher: And there are more than 2 billion mobile subscribers. How is such a connection carried out?
The system uses the principle of dividing some territory into zones, or "cells". Each "cell" is served by a transmitter, the radiation of which is well captured only at a distance of 500 m to 10 kilometers - the radius of the cell. In the neighboring cell, this signal is so weak that it is not picked up by the phone. This allows the same frequency to be reused in another cell without any mutual interference. Thus, working on one dedicated channel, but with a large number of base stations, cellular communication can cover unlimited territories, connecting a large number of subscribers.
Helpful link? Yes!
Please get out your mobile phones.
Are you sure it's safe to keep mobile phones in your pockets?
What kind of device is this - useful or harmful? Let's figure it out!
Slide 4. Cellular communications - for or against?
Teacher: You have information sheets on your desks. Attachment 1
... Everyone works with their own sheet.
Your task - red (color of danger) highlight information about the harmful effects of cellular communications, and in green information about the benefits of cellular communication. You are given to work 3 minutes.
Students work individually.
Teacher: Show the sheets. Something a bit too red in color. There must be weighty arguments to use cellular communication! Is this device useful or harmful?
Students: A useful device, but security measures need to be developed.
Teacher: Let's continue our work. It is necessary to divide into three groups. Each group will carry out their task.
The task: Group 1 works only on the arguments in favor of cellular communication, group 2 - only on arguments about harmful effects. You need:
1. If possible, combine the information into 2-3 large blocks, categorizing it. Name these categories using no more than 3 words, and portray on diagram with black marker. Picture 1 .
2. For specific examples from the text, use for finer division... You can bring own arguments.
3. Presentation of your work (presentation) can be made by 1-2 people from the group.
For this job – 5 minutes.
Task for group 3: discuss all the pros and cons and make up the rules using a mobile phone... Write them down on a sheet.
This work is given 5 minutes.
Groups post their work.
Presentation.Representatives from the groups are speaking. The rest of the groups can be supplemented.
Teacher: Let's prioritize. Rank the rules according to their importance. Compare with those offered by the experts on the radiometric control committee.
Slide 5. Precautions:
1. Do not use your cell phone unnecessarily
2. Talk continuously for no more than 3 - 4 minutes.
3. Do not allow small children to use the cell phone.
4. When buying, choose a cell phone with a lower radiation power.
5. In the car, use a cell phone in conjunction with a speakerphone system
Teacher: And now let's conduct an experiment: what is the penetrating power of the radiation of mobile phones.
Put the phone in a thick-walled (cast-iron) pan, call - the connection does not occur. Repeat call - connects! The students conclude that when the call is repeated, the signal strength increases.
Add an item to the rules:
6. When calling again, do not keep the device close to your head.
Teacher: What will you choose for yourself the most important and interesting from today's lesson?
Students answer, reflection is carried out.
Trunking Communication within a group, group call to all members of the group Presence of priorities High connection speed Low need for access to the public network Preferential transmission of data Frequent use of half-duplex transmission Protocols: MPT-1327 (analog), TETRA (digital)
Mobile technologies Paging (MHz) Tweaking Cellular telephony Trunking
History of cellular communications The first generation of cellular communications systems 1946 - in St. Louis (USA) - the first radiotelephone communications system in the mid-1940s AT&T Bell Laboratories - the idea of \u200b\u200bdividing the entire service area into cells Late 70s - work on creating unified communication standard (Sweden, Finland, Iceland, Denmark, Norway) - NMT-450 (Nordic Mobile Telephone) 1983 - USA, Chicago - AMPS (Advanced Mobile Phone Service) standard network 1985 - NMT standard - Great Britain - TACS (Total Access Communications System), 1987 - ETACS (Enhanced TACS) 1985 - France - Radiocom-2000
Analog systems An analog method is used to transmit information using conventional frequency or phase modulation, as in conventional radio stations. Disadvantages: there is a possibility of listening to conversations by other subscribers; there are no effective methods to combat signal fading due to the influence of the surrounding landscape and buildings, or due to the movement of subscribers. Solution: widening the frequency range; transition to rational frequency planning.
Global System for Mobile Communications -\u003e 1990 1989 UK - "Personal Communication Networks" PCN (Personal Communication Networks "title \u003d" (! LANG: History of Cellular Communications Second Generation of Cellular Communications 1982) CEPT created Groupe Special Mobile ( GSM) -\u003e Global System for Mobile Communications -\u003e 1990 1989 Great Britain - "Personal Communication Networks" PCN (Personal Communication Networks" class="link_thumb"> 7 !} The history of cellular communications The second generation of cellular communications systems 1982 CEPT created Groupe Special Mobile (GSM) -\u003e Global System for Mobile Communications -\u003e 1990 UK - Personal Communication Networks (PCN) America - Personal Communication Networks communications "PCS (Personal Communication Services 1990 America TIA (Telecommunications Industry Association) - national IS-54 standard (D-AMPS or ADC) The American company Qualcomm began active development of CDMA (Code Division Multiple Access) in Europe - DCS standard -1800 (Digital Cellular System) 1991 in Japan - JDC (Japanese Digital Cellular) 1992 in Germany, the first cellular communication system of the GSM standard entered into commercial operation In 1993, the CDMA standard (IS-95) was adopted in the USA 1993 UK - the first DCS One-to-One network was put into operation Global System for Mobile Communications -\u003e 1990 1989 Great Britain - "Personal Communication Networks" PCN (Personal Communication Networks "\u003e Global System for Mobile Communications -\u003e 1990 1989 Great Britain -" Personal Communication Networks "PCN (Personal Communication Networks) America - "Personal Communication Services" PCS (Personal Communication Services 1990 America TIA (Telecommunications Industry Association) - national IS-54 standard (D-AMPS or ADC) The American company Qualcomm began active development of CDMA (Code Division Multiple Access 1991 in Europe - DCS-1800 standard (Digital Cellular System) 1991 in Japan - JDC (Japanese Digital Cellular) 1992 in Germany, the first cellular communication system of the GSM standard entered into commercial operation In 1993 in the USA the CDMA standard (IS-95) was adopted 1993 Great Britain - the first DCS-1800 One-to-One network was put into operation "\u003e Global System for Mobile Communications -\u003e 1990 1989 Great Britain -" Personal networks Communication Networks ”PCN (Personal Communication Networks" title \u003d "(! LANG: The History of Cellular Communication Second Generation of Cellular Communication Systems 1982) CEPT created Groupe Special Mobile (GSM) -\u003e Global System for Mobile Communications -\u003e 1990 1989 United Kingdom - "Personal Communication Networks" PCN (Personal Communication Networks"> title="History of cellular communications Second generation of cellular communications systems 1982 CEPT created Groupe Special Mobile (GSM) -\u003e Global System for Mobile Communications -\u003e 1990 1989 United Kingdom - Personal Communication Networks (PCN)"> !}
The history of cellular communication Russia In St. Petersburg, in Moscow - systems of the NMT-450i standard - Sotel (1991) 1994 Adoption of the concept of development of land mobile networks Proclamation of the GSM standard as one of the two federal standards (NMT and GSM) Development conditions CDMA networks in Russia are defined by order of the Ministry of Communications of the Russian Federation No. 18 dated February 24, 1996. The first CDMA network began operating in Chelyabinsk, then Moscow, St. Petersburg.
Third generation systems In Europe - UMTS (Universal Mobile Telecommunications System) combining the functionality of existing digital communication systems into a single third generation system FPLMTS (Future Public Land Mobile Telecommunications System 2002 - requirements for a single mobile communication system were formulated within the framework of the new IMT program) -2000 (International Mobile Telecommunications).
A method of accessing radio channels Random access (the Aloha method, so named in connection with the first application of the method for communication between a group of Hawaii). Applicable only for light loads. Its development was the MDKN / OK method used in local and corporate networks. (the Aloha method, so named in connection with the first application of the method for communication between a group of Hawaii). Applicable only for light loads. Its development was the MDKN / OK method used in local and corporate networks. By CDMA technology By TDMA technology
CDMA technology Direct Sequence (Pseudo Noise) Spread Spectrum (direct sequence (pseudo-noise) with a wide spectrum) has its own code combination the ability to simultaneously transmit several messages in the allocated frequency band with different symbol codes
NMT-450 Analog communication system Frequency range MHz Direct communication range - several tens of km Disadvantages: Low noise immunity Deficiency of channels Difficulty providing protection from eavesdropping
General characteristics of the GSM standard Use of the mobile spectrum in the MHz range Narrowband time division multiple access (NB TDMA) is used To protect against errors in radio channels when transmitting information messages, block and convolutional coding with interleaving is used Increasing the coding and interleaving efficiency at low movement rates mobile stations are achieved by slow switching of operating frequencies (SFH) during a communication session at a speed of 217 hops per second, equalizers are used to ensure equalization of pulse signals with a standard deviation of the delay time of up to 16 μs. The synchronization system is designed to compensate for the absolute delay time of signals up to 233 μs, which corresponds to maximum communication range or maximum cell radius 35 km Gaussian frequency shift keying with minimum frequency shift (GMSK)
Handset - ME (Mobile Equipment) has IMEI (International Mobile Equipment Identity); SIM (Subscriber Identity Module) smart card contains IMSI (International Mobile Subscriber Identity) )
BSC is a powerful computer that controls the operation of base stations (BTS) and monitors the operability of all units of the base station (BTS), and is also responsible for the handover procedure (transfer of service to a mobile station from one base station to another in a conversation mode). - a powerful computer that controls the operation of base stations (BTS) and monitors the operability of all blocks of the base station (BTS), as well as responsible for the handover procedure (handover of service to a mobile station from one base station to another in a conversation mode).
NSS structure (SSS) MSC (Mobile Switching Center) - switching center; HLR (Home Location Register) - home location register; VLR (Visitor Location Register) - guest location register; AuC (Authentication Center) - Authentication Center.
The main purposes of MSC are signal routing (direction), that is, number analysis for outgoing and incoming calls; establishment, control and disconnection of connections; formation of CDR-files (Call Data Recorder) for submission to the billing system.
Long-term data stored in the HLR and VLR International Subscriber Identity Number (IMSI) Subscriber Telephone Number in the Common Sense (MSISDN) Mobile Station Category Subscriber Identity Key (Ki) Supplementary Service Provisions Closed User Group Index Closed User Group Blocking Code Basic Calls, which can be transmitted Calling Party Notification Called Party Number Identification Operation Schedule Called Party Notification Signaling Control for Subscriber Connections Features of a Closed User Group Benefits of a Closed User Group Barred Outgoing Calls in a Closed User Group Maximum Number of Subscribers Passwords Used Priority Access Class
Temporary data stored in the HLR Identity and encryption parameters Identity and encryption parameters Temporary mobile subscriber number (TMSI) Temporary mobile subscriber number (TMSI) Movement register address where the subscriber's Movement register address (VLR) the subscriber is located (VLR) Mobile station movement areas Mobile station movement areas Handover cell number Handover cell number Registration status Registration status No response timer No response timer Composition of currently used password Passwords currently used Communication activity Communication activity
AuC - the authentication center generates parameters for the authentication procedure and determines the encryption keys of subscriber mobile stations. - the authentication center generates parameters for the authentication procedure and determines the encryption keys of the mobile stations of the subscribers. Authentication procedure - the procedure for confirming the subscriber's authenticity (validity, legality, rights to use cellular services) of the GSM network.
Subscriber authentication process SRES \u003d Ki * RAND TMSI (Temporary Mobile Subscriber Identity) When the IMEI is received by the network, it is sent to the EIR, where it is compared with the so-called "lists" of numbers.
Division of the network into LA BTS - base stations (one BTS - one "cell", cell). BTS are united into groups - domains called LA (Location Area). Each LA has its own LAI (Location Area Identity) code.
Handover algorithm Types of channel change within one base station changing the channel of one base station to the channel of another station, but under the patronage of the same BSC. channel switching between base stations controlled by different BSCs, but one MSC channel switching between base stations, for which not only different BSCs, but also MSCs are responsible. Basic diagnostic signals about error Triple beep (duration of each part 330 ms), 1 s pause 950 ± 50 Hz 1400 ± 50 Hz 1800 ± 50 Hz General error 200 ms beep, 200 ms pause 425 ± 15 Hz Mains overload 500 ms beep, 500 ms pause 425 ± 15 Hz Subscriber number busy Signal type Frequency Error type
During the century and a half that have passed since the invention of the telephone, telephone communication has become so firmly established in the everyday life of a modern person that the absence of a telephone in an apartment has practically become an exception. The advantages of wired telephone networks include the reliability of communication and the developed system of subscriber networks, which allows the user to contact a subscriber in almost any country in the world.
However, the "hard binding" of the subscriber to the fixed telephone set, "limited" to the same length of the telephone receiver wire, did not allow the user to be mobile, that is, to move freely in space during conversations or between them.
In the second half of the last century, as technology and technology improved, the idea of \u200b\u200bcreating a worldwide (global) network began to develop. mobile (cellular) telephonyallowing the user to have access to a developed subscriber network using a portable portable (mobile) handset-telephone of a significant (tens of kilometers) range.
The implementation of this idea would allow to bring telephone communication to a new level of popularity and accessibility from the point of view of a user who would have his own individual telephone number and practically unlimited freedom of movement (mobility) during or between calls.
The proposed principle of operation of mobile telephony is quite simple: using a handset (mobile phone), the subscriber communicates with the nearest base station (transmitter) of the network (Fig. 224).
Fig. 224. Cellular base station (transmitter)
This base station, in turn, communicates with the next transmitter of the network, etc. as required by the subscriber (Fig. 225).
Fig. 225. Cellular network of transmitters
The described principle of creating a developed subscriber network is called cellular principle, because according to the same principle, bees build honeycombs inside the hive. Moreover, each created cell serves as the basis for creating the next exactly the same cell, etc.
Due to this circumstance, it is customary to call mobile telephony also cell phone communication. When a subscriber moves (for example, by car) (see Fig. 225), base stations independently monitor him and "transmit" to each other, which happens practically without loss of communication quality, quickly and completely invisible to the user.
The simplest part of the structural diagram of cellular communication - a mobile (portable) telephone, consists of two parts: the actual "handset" or ME (Mobile Equipment) and the subscriber identification module, or smart cards SIM (Subscriber Identity Module), obtained upon concluding a contract with a particular operator.
During production, each cell phone is assigned its own number or an International Mobile Equipment Identity (International Mobile Equipment Identity) to distinguish it from the other exactly the same.
In our country, the standard of second generation networks GSM (Global System for Mobile Communications) is used, which was developed in 1990. This standard uses an operating frequency of ν \u003d 900 MHz, which significantly improves the quality of communication compared to the first generation standards.
The first GSM operator received subscribers in 1991, and by the beginning of 1994 global networks based on this standard had 1.3 million subscribers. By the end of 1995, their number had increased to 10 million!
When a mobile phone with an activated smart card is turned on, it “by itself” finds the nearest base station of the corresponding cellular network, after which the entire package of telephone services of this network becomes available to the subscriber.
Each transmitter provides radio coverage on average at a distance of up to two tens of kilometers from it (Fig. 226). For the rational use of the cellular network of transmitters, optimal schemes of their mutual arrangement on the ground, taking into account its relief, are being developed.
