TDMA

TDMA:

2TDMA is a digital technique that divides a channel or a band in the time slots . Each time slot is used to send a byte or other portion of the digital signal for each successive serial data format . This technique works well with slow speech data signal , but it is useful for compressed video and other high – speed data.

A good example is the widely used T1 transmission system, which has been used for years in the telecom industry. T1 lines to carry up to 24 individual telephone calls on a single telephone line (fig. 2). Each voice signal usually includes 300 Hz to 3000 Hz , and digitized in an 8 kHz rate, which is just a little more than the minimum Nyquist rate of twice the highest frequency component which is required.

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This digital telephony T1 TDM and TDMA frame describes. Each time slot is assigned to a user. The high data rate enables the user unaware of the lack of simultaneity.

The digitized voice appears as individual serial bytes happened to a 64-kHz rate, and 24 bytes are intertwined, which makes one T1 frame data. list contained in a 1,536 MHz percentage (24 of 64 kHz) to a total of 192 bits. One synchronization bit sequence is added for timing purposes, a total data rate of 1.544 Mbits / s. On the receiving side the individual voice bytes are recovered 64-kHz rate and by a digital-to-analog converter (DAC) which reproduces the digital data.

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The big GSM (Global System for Mobile Communications) cellular telephone system is TDMA basis. It divides the radio spectrum in the 200 kHz band and then uses time division techniques to convert eight phone calls on a channel. Figure 3 shows a TDMA frame of a GSM signal. The eight time slots can be voice or data signal such as a text or email. frame to a 270-kbit / s rate using Gaussian minimum shift keying (GMSK), a form of frequency shift keying (FSK)

This GSM digital cellular scheme shows how to share up to eight users per 200 KHz channel in different time slots within a frame of 1248 bits.

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Posted by on Jul 22 2016. Filed under Latest Updates, TDMA, Mobile Communication, TECHNOLOGY. You can follow any responses to this entry through the RSS 2.0. You can leave a response or trackback to this entry

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