Data transfer medium - Using DTMF tones (View - 3358 times)
November 2, 2016 10:32 am
Dual Tone Multi-Frequency (DTMF) is a method of instructing a telephone switching system to dial telephone numbers, or to issue commands to switching systems or related telephony equipment. It reliably sends the data across long distances. The DTMF system uses eight different frequency signals transmitted in pairs to represent sixteen different numbers, symbols and letters. Frequencies (of the generated tones) used to represent different addresses are shown in Table: 01.
FLOW FHIGH KEY TOW Q4 Q3 Q2 Q1 697 1209 1 H 0 0 0 1 697 1336 2 H 0 0 1 0 697 1477 3 H 0 0 1 1 770 1209 4 H 0 1 0 0 770 1336 5 H 0 1 0 1 770 1477 6 H 0 1 1 0 852 1209 7 H 0 1 1 1 852 1336 8 H 1 0 0 0 852 1477 9 H 1 0 0 1 941 1209 0 H 1 0 1 0 941 1336 . H 1 0 1 1 941 1477 # H 1 1 0 0 697 1633 A H 1 1 0 1 770 1633 B H 1 1 1 0 852 1633 C H 1 1 1 1 941 1633 D H 0 0 0 0 - - ANY L Z Z Z Z L=Logic Low, H=Logic High, Z=High Impedance Major reason to select DTMF tones for the zone selection is that same audio channel is being used for the transmission of the audio data as well as the DTMF tones, since both are associated with audio tones.
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We have selected to develop a low cost public address system suitable for large Institutions, as nowadays it is becoming major requirement for large institutions. In our project we have focused on developing a public''' ....Read More
November 2, 2016 12:13 pm
Dual Tone Multi-Frequency (DTMF) is a method of instructing a telephone switching system to dial telephone numbers, or to issue commands to switching systems or related telephony equipment. It reliably sends the data across long''' ....Read More
November 2, 2016 10:32 am
When user has selected the appropriate zone that he wants to send the message using Graphical User Interface (GUI), main controller will generate Dual Tone Multi Frequency (DTMF) tone containing the zone and the exact''' ....Read More
November 2, 2016 10:30 am
Even though large institutions like schools, hospitals, etc has the same requirement only private institutions can afford this kind of facility due to high cost. Hence we have minimized the total cost, while fulfilling all''' ....Read More
November 2, 2016 10:23 am
A public address (PA) system is an electronic amplification system used as a communication system in public areas. It also refers to an audio transmission system used in institutional and commercial buildings, in which input''' ....Read More
November 2, 2016 10:19 am
Total cost is the summation of cost of main controller, cost of zone controllers and cost of cables, speakers and installation. For a design with16 zones, the cost for the Main and Zone controllers is''' ....Read More
November 1, 2016 10:30 am