Telecommunications Use short answers to explain the difference between: Rotary and Dual Tone Multi-frequency (DTMF) Wide Area Telecommunications Service (WATS) and leased lines Private Branch eXchange (PBX) and Centrex The layers of the International Standards Organization-Open Systems Interconnection (ISO-OSI) model 1. Explain the difference between Rotary and Dual Tone Multi-frequency. The major difference between Rotary and Dual Tone Multi-frequency(DTMF) is the method by which they are executed to the phone system. Rotary uses interrupted pulses to communicate the characters or digits on the rotary dial. Rotary systems were different depending on the country in which it was used having certain amounts of pulses to represent certain digits on the rotary dial. For example, in the United States, dialing a number five on a rotary dial set would open and close electrical contacts on the phone five times thus sending five pulses. Dual Tone Multi-frequency(DTMF) also know as touch tone dialing is used by sending a combination of two tones over the phone system. An example of how these two tones are sent can be illustrated by these two tables taken from http://www.answers.com/topic/dual-tone-multi-frequency: DTMF keypad frequencies (with sound clips) 1209 Hz 1336 Hz 1477 Hz 1633 Hz 697 Hz 1 2 3 A 770 Hz 4 5 6 B 852 Hz 7 8 9 C 941 Hz * 0 # D An example of a combination of tones could be illustrated by selecting the number five on the keypad. In this example, when someone would dial the number five, two tones at 770 Hz and 1336 Hz would be sent. DTMF Event Frequencies Event Low frequency High frequency Busy signal 480 Hz 620 Hz Dial tone 350 Hz 440 Hz Ringback tone (US) 440 Hz 480 Hz An example from this table shows that when someone picks up their phone and hears a dial tone, two frequency are actually heard at 350 Hz and 440 Hz. References: http://www.answers.com/topic/rotary-dial http://www.answers.com/topic/dual-tone-multi-frequency 2. Explain the differences between Wide Area Telecommunications Service (WATS) and leased lines. A Wide Area Telecommunications Service or WATS is "a special direct distance dialing (toll) service whereby a subscriber installs a dedicated line arranged for either inward or outward calls (not both) between the customer's premises and a specific geographic area. Monthly charges are based on the size of the area in which the calls are placed, not on the number or length of calls." (http://www.isg-telecom.com/telco_glossary.htm#W) This type of service is typically used for inbound toll-free service such as an 800 number.
FM synthesis can generate both harmonic and in harmonic sounds. For synthesizing harmonic sounds, the modulating signal must have a harmonic relationship to the original carrier signal. IF the amount of frequency modulation increases, the sound grows progressively more complex. Through the use of modulators with frequencies that are non-integer multiples of the carrier signal , atonal and tonal bell-like and percussive sounds can easily be create
Ex 1 [8.3] Will the frequencies all do the same thing, or will something different happen in each one?
Captioned Telephone is a new product of Ultratec, being tested in several states. CapTel is an innovative service in which the operators repeat the words of the hearing party into an automatic speech recognition system for rapid transcription. Voice and data are carried on one line so that the hard of hearing or deaf user can monitor the speech as well as see the transcription. The CapTel phone is set up for “dial through” so that the user does not need to dial the relay service first.
people have phones with multiple lines in order to handle the influx of phone calls. They get
The world’s first mobile phone call was made on April 3, 1973, when Martin Cooper, a senior engineer at Motorola, called a rival telecommunications company and informed them he was speaking via a mobile phone. The phone Cooper used, if you could call it that, weighed a staggering 1.1kg and measured in at 228.6x127x44.4mm. With this prototype device, you got 30 minutes of talk-time and it took around 10 hours to charge.”(knowyourmobile). Back then cell phones weren’t as flashy but everyone was just as excited for them as they are now. “Many of the early cell phones were considered to be “car phones,” as they were too large and cumbersome to carry around in a pocket or purse. However, in 1983, the Motorola DynaTAC 8000x arrived on the market. Though huge by today’s standards, it was considered the first truly mobile phone because it was small enough to carry.”(artinstitutes).
Cell phones use radio frequencies to transmit signals. Radio Frequencies (RF) are a form of electrical waves similar to those used in radios, microwaves, radars or satellite stations. They are emitted from a transmitter, and received using an antenna. This telephony technology is restricted geographically to small zones called “Cells”. Every cell has a base station capable of sending and receiving radio waves. When a call is started a signal leaves the handheld unit headed to the closest base station. This station answers by allocating a specific channel to the unit. When this “channel” is established, modulated radio frequency signals are both received and transmitted. The head of the user is in the near field of use because the distance from the antenna to the head is a few centimeters. (Blettner & Berg 2000) If the antenna is inside the body of the phone, the exposure to Radio Frequencies is greater. The antenna might be requesting a stronger signal to contest with the interference of the battery or the actual shell of the phone’s body.
as Hertz (Hz). The sounds of speech are in the range of 250 Hz to 4000
By using combinations from the above – But this approach has to be made with caution, because confusion can appear in the message.
Cell Phones: A portable phone that uses wireless technology to send and receive phone signals. This technolog...
Despite the short amount of time since the introduction of the smartphone, the rapid development of the software and technology has had a tremendous effect on the everyday life of society today. The concept of communicating through a telephone was developed in the 1870s. Devices to transmit speech electrically were designed by Elisha Gray and Alexander Graham Bell, but Bell's design was patented first. On March 10, 1876, Alexander Graham Bell achieved one of his greatest successes in the making of the telephone. This brought upon a major change in communication and gave leeway to the improvement of the telephone in the days to come (Bellis, 2013b).
Since its inception, the telephone has become one of the most important inventions of all time. Although some were skeptical about its replacement over telegrams, in the end the advent of this fine communication equipment has won the hearts of many. As a matter of fact, the telephone system had come to numerous facelifts that it literally connected the world before the internet was born. Because of its importance, homes and businesses can not live without it. In the U.S. alone, most if not all have a phone in the house.
The waves can be absorbed and reflected by surrounding objects before they reach the nearest cell tower. For example when you put your phone next to your head, during a...
Making a telephone call no longer should conjure up visions of operators connecting cables by hand or even of electrical signals causing relays to click into place and effect connections during dialing. The telephone system now is just a multilevel computer network with software switches in the network nodes to route calls get through much more quickly and reliably than they did in the past. A disadvantage is the potential for dramatic and widespread failures; for as has happened.
People in the present society have turned from the use of the old means of communication to the more advanced and technological ways of communicating. Technology has made it easier for people to communicate in a faster, efficient, and cost saving means through the introduction of the communication channels. The world has turned out to be the centre for technology with different technologies emerging daily as the people continue to develop from time to time to cope with the growing technology. The benefits of adopting the communication technology are explained in this article which shows why people do not function without technology.