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When the first mobile phones hit the market, many people were amazed at the advancement of their technology. Indeed, it was just amazing that very little communication equipment could send and transmit messages by voice. This was clearly more beneficial than the two-way radio that was the vogue these days where you could only call base stations and other radios users connected to your channel. Most people who use two-way radios are hobbyists or employees of a company that has a base of contact with field workers to monitor their whereabouts. The advantage of the mobile phone compared to these two-way radios is the longer operating range of the mobile phone, while the two-way radiotelephone has a limited operating range.
However, at this stage, mobile phones, even though they were already using cellular technology by reusing channels, were still considered baby phones as the carrier they are using is analog technology. But first, so that you can better understand how the cell phone works, let me explain the concept of channel reuse. You see, radio signals operate on a certain frequency. These radio signals, to be free from interference, should operate on a different frequency. As with a specific radio frequency at 120 MHz, a different radio frequency should be on a different frequency to avoid signal mixing with a radio signal that is already operating at 120 MHz. However, in the case of mobile phones, many of these units operate on the same frequency, thanks to the principle of channel reuse, so that mobile phones are used by many people. Reusing the channels was made possible by providing limited power to each cell phone unit and providing multiple cell sites or towers. In this way, the mobile phone can only transmit and receive the signal to the nearest cell station or the nearest tower and does not affect another cell station in a different location, allowing other cell phones on the same channel to send and receive signals on other cell sites or towers without interference.
Now that you know how a cell phone works, let’s go back to the first medium used by cell phones, which is an analogue radio frequency transmission system. These types of radio signal carriers are the uplink and downlink radio frequencies that were used in all forms of radio messages before the advent of digital technology. A very good example of these signals can be seen in operating theaters in hospitals, which are usually shown on television and in movies of near-death, showing the up and down movement of moving light on a monitor graph. The moving up and down light is an analog signal frequency representing the sound of the patient’s heartbeat.
As digital signals became available for use in radio communication, it was found that the channel reuse system used in cell phones is more suited to using a digital signal handling system as digital is not susceptible to interference unlike analog. Therefore, telecommunications companies soon began rebuilding their signaling system, adapting it to the digital signal delivery system in mobile phones.
It was at this stage that a communications company in England was able to develop a digital communication system known as Short Messaging Service or SMS for use on cell phones using a digital signal delivery system. Incidentally, SMS could only be possible with a digital operator, but never possible with the old system that was an analog operator. The development of SMS or SMS functions in mobile phones was designed for use by deaf and dumb segments of the community. But now we know what happened to this kind of communication intended for the deaf.
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Source by Sherry Khan