today we are going to start our chapter two uh this is uh data communication system and networking this is our lecture one and in this chapter we will uh understand about the data communication system and the devices how it works and how we actually uh use our device and how Network system can uh transferring the data to one device to another device so here at first we have to understand the uh basic uh information of data communication system which is called the data transmission uh element of data transmission system when we are going to transfer a data from one device to another device then we have some uh basic elements other that uh otherwise we can't understand uh we can't deliver our data so that means we need some basic instrument and basic element so uh what is this element so at first we have to understand those uh about those elements so now at first we need a source then we need sender sender or transmitter in this chapter we must call this transmitter instead of cender okay so after that we need a medium medium then need we need a receiver receiver finally we need the destination destination so when we are trying to transfer a data that means at first we need the data and we need a storage which can store our data like uh if you want to send a image to your friend that means we need a mobile phone or a device which device can store your images or store your text so this device called source so like this is it should be our mobile device or desktop or these kinds of electronic device those device can uh store the uh data so this is called Source then we need a sender so what is the sender so if you uh consider that uh when you are going to send image then we need some Network right so this network actually connected to a router in your house or modem okay so this is called the sender which device can send the data our mobile phone can store the data and the router or the modem or the wireless communication system can send the data so that is called the sender or transmitter then we we need a medium so what is the medium medium actually connect the sender station and the receiver station like when you are going to send a data then your router transferring the data to to your router to your friend's router right so that means those devices are connected by a medium it should it can be uh optical fiber or U it should be a wireless medium okay so this is called the medium which medium can connect the sender station and the receiver station so then uh we can call what is the uh receiver so receiver uh same as the sender so it should be router or modem or anything so after that we need another device which device can receive our data okay so that mean this is called the destination so this destination should be the same as source so this is our mobile or desktop okay so that means you can uh say that source and destination is the same kinds of device and sender and uh receiver and also are same and the medium can connect those um sender and receiver station so those five elements are very important to sending a or the or the transferring the data so that's why we call this is the core components of the data communication system and networking okay so if you want to communicate uh or if you want to transfer a data that means you need these five elements or these five components okay so this is the basic of data comination system and networking do you understand yeah okay our second topics is second topics is is bandwidth so what is bandwidth band w dth h bandwidth are you can call as data transmission speed transmission speed or you can call this data transmission rate and also we have another question that is what is BPS so the full form of BPS bit per second this is BPS okay now data transmission speed data transmission rate and the bandwidth are the same things okay so if you are asked for the definition of bandwidth and uh the definition of bandwidth are the same as um data transmission Speed Android so the definition should be uh if you transferring a data to one device to another device if we draw those device sender station and the receiver station okay now if you want to send the div send the data from sender station to the receiver station how much data are transferring from one device to another device per second okay so this data depend on per second that means if you send like uh uh like a example 1 MVPs what is the meaning of one 1 MVPs that means this sender station can transfer 1 MB data each second okay so that is called 1 MVPs per second we have to transfer 1 MB data to Sender station to the receiver station that is called the 1 Mbps if you call uh if you ask for the what is the meaning of 12 kbps that means this device can able to transfer 12 kilobit data per second to one device to the another device okay so this is this is called 12 kbps and also uh you can ask for what is uh the meaning of 10 gbps so GB that means gigabit okay so it means you can send a data 10 GB data to one device to another device each second okay this is called 10 gbps okay now if you ask for like uh the difference between 5 Mbps and 5 Mbps so what is the meaning of this MVPs and this MVPs this smaller B indicates megabit per second and this capital B indicates the meab per second okay so if you ask for this MVPs that means you have to transfer 5 megabyte data per second okay so you have to understand those topics and you have to be conscious about the smaller B and the capital B okay now so the data transmission speed is how much data you can transfer to one device to another device is second is called the data transmission speed or you can call this data transmission rate and also this should be a bandwidth okay if you ask for the BPS that means how much bit you can transfer to another from another one device to another device that is called the BPS okay when you are asked for BPS that means you are uh you have to just uh say about this bit not the entire data if you can uh if you say like uh how much data you can transfer to one device to another device that means you are free from the unit of the data okay so if you lck this unit BPS that means you have to on you have to only call this bit okay if you send how much data instead of how much data you you have to say that how much bit we have we can send one device to another device that is called the BPS or beat per second okay do you understand these topics yes sir okay okay now we have to know about the uh classification of this bandwidth or data transmission speed so that means uh if if you have the speed that means the speed can vary okay so there is a three kinds of data transmission speed or bandwidth so one of them is narrow band narrow another one is voice band speed narrow band voice band and finally we have the Broadband we have three kinds of data transmission speed narrow band voice band and the Broadband so uh we have to categorize these kinds of qualification uh based on their speed so narrow band speed means very slow speed here here we have to understand the speed is 45 to 300 BPS okay the invoice band uh contain the speed is uh 9,600 BPS you can also call this 9.6 kbp kbps if you divide this unit divide this data by 1,000 then you'll get uh this 9.6 so 9,600 BPS also uh you can call this 9.6 kbps now the Broadband speed starting from 1 Mbps and this should be 1 gbps okay 1 gbps so this is the mean the range of this data transmission speed so Naran speed is very slower speed we have 45 to 300 BPS only here uh we used this speed when we are using Telegraph or uh when the network actually invented uh the beginning of the civilization where we are just trying to communicate our basic data or very important data like if you uh want to transmit a application to Bangladesh High commission to us High commission then the text uh then the letter only contain the text only so this kinds of uh text is a very uh smaller size of text we have there so that means when we need a need to transmit the basic element or basic uh words so then these kinds of data actually are very smaller size of uh unit okay then we don't need um a very larger speed and the beginning of the internet we have a very uh slower speed okay so that's why uh uh on this time we have very smaller uh smaller data and we have to transferring our data through this narrow band speed so you can uh the example is Telegraph or these kinds of uh transmission system also uh the use case of voice band is our telephone which is Our Land phone actually so land phone can transfer the data in voice band speed the another example of the voice band speed is when we are going to transfer a data to our computer to any kinds of pen drive or any kinds of memory card then this those transmission speed actually contain this voice band speed okay so finally we have the Broadband speed and this speed is very useful in our daily life we're using this Broadband speed in our router or mobile uh mobile phone data transmission system like uh when you're using share it those share it like if you are going to send a image which is 5 Mbps then you are sending this uh image to your friends mobiles so then you need only like 5 Second so that means you have 1 Mbps that means the speed is 1 Mbps so this speed is called the Broadband speed because this Broadband speed starting from this 1 MVPs and it uh it's on like it's 1 gbps so uh it's not necessary to have internet connection to ex uh explain the internet speed or Broadband speed Broadband speed only means the data transmission speed not the internet okay so we have the broadband connection in our house okay this connection can transfer the data higher than 1 MVPs so that's why we are calling that uh the Broadband speed but the Broadband speed can vary okay this uh this is not necessary to explain uh the Broadband uh Broadband only for internet okay it should be anywhere where you have the speed higher than 1 MVPs then this kinds of those kinds of speed should be a Broadband speed okay so we have three kinds of speed narrow band voice band and the broadband and uh if I want to give a example the narrow band is speed such a slower speed that if you want to transfer this 5 MVPs data to your phone to your friend's phone then if if the speed is narrow band then uh it will take five to uh 7 hours okay to send this 5 MPS data so this is a very slower speed this this is called the narrow ban and today we are not using this kinds of speed for transferring higher scale data so that's why we have to use these kinds of broadband connection okay do you get this yes sir okay yes sir now we have to learn about the data transmission method data transmission methods so so the classification of data transmission method is uh there is two kinds of data transmission method one of them is serial method serial and the parallel parallel method so we have two kinds of methods so uh at first uh I'm going to present you about the parallel method so what is the parallel method like consider that this is a sender station and this is a receiver station this is a mobile phone and this is another one also a mobile phone if you send a data this is a this are text Data a then uh computer will not understand this or the mobile phone mobile or any kinds of electronic device is not understand these kinds of data right because this is our language so they must uh transfer uh this language to their language that means to the binary language okay so we are already explained the um the binary of this a can you remember that A to Z okay Z Capital a to capital Z the role number is 65 to 90 this number is in decimal number system and smaller a to smaller Z is 97 to 122 so this is the actually role number or unique code for each character so this upper case or this is a uh this a is a is in uppercase that means this a indicates 65 in decimal number if you convert this 65 to binary number system you will get uh 0 1 0 0 0 0 0 1 so this is 8bit binary so when we are going to send this a so this a should be like this 4 five so this is the 8bit binary so when we want to send this a then they need a different line to transfer each of the bit okay so we have eight different line for this a different bit so after that we are sending this data in this way then our mobile can receive this a okay so that means in a parallel data transmission system you have you need a different line for different bit okay there is a eight different line eight different bit that means we need eight different line if you have 16 bit that means you need 16 different line for transferring those beats so if you have n type um or n amount of uh beit that means you need uh n amount of line okay so this is the uh category how parallel uh method works okay now if I want to explain about uh serial data transmission so we have to device again so now we have only one line to transferring those data so if you want to send this a again so now this a becom 0 1 0 0 0 0 0 1 so now they uh they can't transferring their data in different line because they have only one line so but we have all the data so how can we transfer those data that's why we need another device for ascending those data so this device can convert our this bit so this is a converter which can convert our data so this is a parallel method you know that because uh 0 1 0 0 now we have one line so that means this convert convert this parallel method to the serial method so when they convert those bit then this zero starting zero and this one after that they will go this one and also this 0 0 0 0 and finally this one will go there so after that here we we have to receive those data okay so if you have only three bits here like 0 1 0 then this device can display you this a right so you have to receive all the bits for displaying this character so that means here we need also another converter which converter receive the serial beats and converted to the parallel beit so after that they convert this parallel bit then they displaying a okay so this is the actual process to send the data using serial method okay and uh the parallel method use many lines and the CR method only used here one line okay so this is the definition or this is the explanation of Serial method and the parallel method so do you understand those difference yes sir okay now uh you may ask for the difference between serial method and the parallel method so you have to explain those uh difference which uh method should be faster the par exactly so the basic difference should be starting from here like parallel method is faster than the cial method and the cial method is slower than the first parallel method number one so this is very uh important and this is our advantage that parallel method can uh say the data more faster than the Cal that means this is costly okay now um again we have to understand the topics also a memory what does actually memory do memory is a kind of device kind of uh yes kind of device which can store any kinds of data right so when you are going to transferring a data then you need a memory at first or Storage storage so this storage actually necessary for storing the data and after that they send those data like if you uh write here a so that means you have another um bit okay so then you need 16 bits that means 16 different line so your device need to store a b c at first then they are going then they are starting to send their data in a parallel method so they need a storage device but in a Serial method when we write a those converter start to convert those parallel bit and they are sending okay after that they receiving a data when you are typing here B so then this B also starting uh for sending so after sending this a this B is start to send so that means they don't need the storage device okay because they don't store they just send like uh you can uh for an example you can think uh about your keyboard if you write anything in your mobile or computer keyboard those keyboards are transferring your data one by one okay so this is called the uh serial method so here you don't need any kinds of storage device device in serial method but in a parallel method you have to use this storage device because those device can send the data uh in different line okay so this is the basic difference between the serial method and the parallel method so do you have any question okay now uh we need to learn another thing so the serial method can be many types okay so serial method the classification of Serial method can be asynchronous asynchronous then synchronus s y and C synchronus finally the isochronous okay isus so this is the three types of Serial method we have based on the synchronization synchronization so so um a Serial method can make can vary okay so this classification based on the synchronization okay if I tell that Aran is a good girl okay so she can be good girl to her mother but not to her teacher okay because if she can't make the highest result so the teacher must not praise her okay so based on the op of her mother she's a very good girl okay so the classification of the serial method can be changed based on their position so um if you are thinking about the synchronization So based on the synchronization the serial method are three types asynchronous synchronus and isochronous so we must learn this topics in our next class okay so in this class we learned something about data transmission system uh and in networking so here we need five elements or five components sender transmitter medium receiver and the destination H source and uh destination is the same things and sender and receiver are the same thing also just there is a medium which can connect those sender and receiver station okay it should be a cable in your router optical fiber cable or internet cable is the mainly the medium or the connector of those uh device so again uh then we are learned here bandwidth or data transmission speed or data transmission rate which actually U explain the ratio how the data send to one device to the another device so now and this is the classification of the data transmission system there is a three kinds of data transmission system uh sorry the data transmission speed narrow band voice band and the Broadband where narrow band is a very slower process viand is the medium speed and Broadband contain the high speed internet or high speed data transmission connection so finally the method the data transmission method should be uh two types of method here we know we know that serial method and the parallel method serial method can transfer the data in one line one line you can call this bit by bit they can transfer the data bit by bit and the parallel method send all the bit uh in the in there in different line okay so if you have n Type n amount of bit so they needs n amount of line to trans for the data so this is a very important McQ you can ask for your question so if you have n type of or n amount of bit so how many lines you need to transfer for the serial for the parallel method so there the correct answer should be the end n amount of line you need here so now finally the based on the synchronization the serial method can be three types so asynchronous synchronous and is isochronous we have to understand those Topics in details in our next lecture do you have any question from this lecture okay now okay okay till then Allah