I will try to explain Alaslki phone technology and network communications and access to GSM Aanakal as much as possible, hoping that by some specialists in this field to participate in this subject to be enriched with knowledge accurate and useful ..
Of course, the need for communication does not need or need to explain at all But what is the way to achieve mobile communications and portable? Principled answer is to use a transmitter and receiver technology as it is known in the radio ..
- Wireless Network (Simplex): One frequency for transmission and reception .. And therefore can not be transmitter and receiver together .. Network is a group of persons each of whom holds an organ.And all devices are synthesized on a single frequency transmitter and receiver .. Members have all the working status of hearing .. When one wants to talk by pressing the send key and speaks .. While everyone is listening to what he says .. This network is a simple and effective in many applications such as a convoy of trucks where there is usually the commander gives his orders to stop and hike and so on .. Vestma him everyone and none of the drivers can send a message to the leader and others to teach them, for example, has a problem .. Disadvantages, of course, that there is no secret at all in such a network and it is not possible to talk to several people at once. But though it is still widely used because of its simplicity on the one hand and there are a lot of applications where you want to hear all the appeal and to be always in touch .. Such as the fire brigade and ambulance and the police ..
Network (Duplex): Repeating one used to send and the other for the reception: Here you can send a person receives and that one (like a normal phone) And no need for a key change between the status of send and receive .. And this feature .. But here we can not consist only of this network only two Isttien exchange contact with each other! .. Where Frequency of the transmitter device 1 is the same frequency of the receiver device 2 And frequency of transmission of the device 2 is the same frequency as the reception of the device 1 Show here the problem of using a single antenna transmitter and receiver, it is well known in the science of communications engineering that the antenna transmission or reception must be Mulva in length to a certain amount commensurate with the length of wave action and to obtain the most ability to send and not to be a signal reflected from antenna cause problems at the home of the sender .. The reception circuit is designed Bamadkhmat sensitive to how weak signals can be linked to a transmit antenna gives a signal with the ability of radiation is high?? The answer is through the addition of frequency filters (filters) are placed at the entrance to the reception are reluctant to very high frequency transmitter to easily while allowing the passage of the reception frequency .. This technology is used generally in mobile wireless internal (short-range) and used at home .. Of the main disadvantages of these devices are subject to eavesdropping - unintended - as they interfere with similar devices located at the neighbors in the same area .. And therefore increase the range of these devices increases the likelihood of overlapping with similar devices .. The increase in range and requires high antennas Asttaat send a large (and thus multiple batteries) and of course this is impractical for a mobile device ... is supposed to be personal and small ..
The problem of limited bandwidth display area: It is known that the wireless transmitter restricted set of laws to be followed to ensure the smooth progress of work and the right investment .. Can not be for someone to design a transmission system operates at a frequency of random, because this frequency may be reserved for another application example, television broadcasting occupies an area of particular frequencies, as well as a radio transmitter Almtali amendment and another area for the amendment to send a radio frequency and so on .. For example, this criterion has been ignored it may presumably be senders to a local TV station is working on the area of very high frequency UHF working randomly on the same frequency range causing not capture any of the enclose clearly when viewers .. Thus it is necessary to be agreed and declared the frequency domain the user as will be agreed on the use and coverage area ..
And applies the same standard to wireless communications and telephone Must, in principle, set the frequency range allowed to use it first Secondly, the users are divided to this area so that no one uses the frequency used by the other And here you must calculate the number of different frequencies allowed within a certain area = Number of frequencies (frequency end of the field - the beginning of the frequency domain) / bandwidth And therefore the number of frequencies allowed to use limited and this leads to not being able to service only a limited number of investors, such a system .. That any system in this way is impractical to have each person carries his machine Profile
And here and show primarily a matter of zoning into the cells of a certain size .. And select the frequencies measured in engineering technology leaves no room for overlap or bugs .. Subject of course are going to look together .. This is the front ..
Of course, the need for communication does not need or need to explain at all But what is the way to achieve mobile communications and portable? Principled answer is to use a transmitter and receiver technology as it is known in the radio ..
- Wireless Network (Simplex): One frequency for transmission and reception .. And therefore can not be transmitter and receiver together .. Network is a group of persons each of whom holds an organ.And all devices are synthesized on a single frequency transmitter and receiver .. Members have all the working status of hearing .. When one wants to talk by pressing the send key and speaks .. While everyone is listening to what he says .. This network is a simple and effective in many applications such as a convoy of trucks where there is usually the commander gives his orders to stop and hike and so on .. Vestma him everyone and none of the drivers can send a message to the leader and others to teach them, for example, has a problem .. Disadvantages, of course, that there is no secret at all in such a network and it is not possible to talk to several people at once. But though it is still widely used because of its simplicity on the one hand and there are a lot of applications where you want to hear all the appeal and to be always in touch .. Such as the fire brigade and ambulance and the police ..
Network (Duplex): Repeating one used to send and the other for the reception: Here you can send a person receives and that one (like a normal phone) And no need for a key change between the status of send and receive .. And this feature .. But here we can not consist only of this network only two Isttien exchange contact with each other! .. Where Frequency of the transmitter device 1 is the same frequency of the receiver device 2 And frequency of transmission of the device 2 is the same frequency as the reception of the device 1 Show here the problem of using a single antenna transmitter and receiver, it is well known in the science of communications engineering that the antenna transmission or reception must be Mulva in length to a certain amount commensurate with the length of wave action and to obtain the most ability to send and not to be a signal reflected from antenna cause problems at the home of the sender .. The reception circuit is designed Bamadkhmat sensitive to how weak signals can be linked to a transmit antenna gives a signal with the ability of radiation is high?? The answer is through the addition of frequency filters (filters) are placed at the entrance to the reception are reluctant to very high frequency transmitter to easily while allowing the passage of the reception frequency .. This technology is used generally in mobile wireless internal (short-range) and used at home .. Of the main disadvantages of these devices are subject to eavesdropping - unintended - as they interfere with similar devices located at the neighbors in the same area .. And therefore increase the range of these devices increases the likelihood of overlapping with similar devices .. The increase in range and requires high antennas Asttaat send a large (and thus multiple batteries) and of course this is impractical for a mobile device ... is supposed to be personal and small ..
The problem of limited bandwidth display area: It is known that the wireless transmitter restricted set of laws to be followed to ensure the smooth progress of work and the right investment .. Can not be for someone to design a transmission system operates at a frequency of random, because this frequency may be reserved for another application example, television broadcasting occupies an area of particular frequencies, as well as a radio transmitter Almtali amendment and another area for the amendment to send a radio frequency and so on .. For example, this criterion has been ignored it may presumably be senders to a local TV station is working on the area of very high frequency UHF working randomly on the same frequency range causing not capture any of the enclose clearly when viewers .. Thus it is necessary to be agreed and declared the frequency domain the user as will be agreed on the use and coverage area ..
And applies the same standard to wireless communications and telephone Must, in principle, set the frequency range allowed to use it first Secondly, the users are divided to this area so that no one uses the frequency used by the other And here you must calculate the number of different frequencies allowed within a certain area = Number of frequencies (frequency end of the field - the beginning of the frequency domain) / bandwidth And therefore the number of frequencies allowed to use limited and this leads to not being able to service only a limited number of investors, such a system .. That any system in this way is impractical to have each person carries his machine Profile
And here and show primarily a matter of zoning into the cells of a certain size .. And select the frequencies measured in engineering technology leaves no room for overlap or bugs .. Subject of course are going to look together .. This is the front ..
