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# Time Division Multiplexing (TDM) - PowerPoint PPT Presentation

Time Division Multiplexing (TDM). TDM is a technique used for transmitting several message signals over a single communication channel by dividing the time frame into slots, one slot for each message signal. TDM-PAM: Transmitter. TDM-PAM : Receiver. time. 0. Ts. 2Ts. g 1 (t).

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## PowerPoint Slideshow about 'Time Division Multiplexing (TDM)' - ursula-dean

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Presentation Transcript

### Time Division Multiplexing (TDM)

• TDM is a technique used for transmitting several message signals over a single communication channel by dividing the time frame into slots, one slot for each message signal

0

Ts

2Ts

g1(t)

Ts

g2(t)

Ts

2Ts

2

2

1

1

2

3

3

1

3

Time

4

4

1

1

1

2

2

2

3

3

3

Time

g1(t)

g2(t)

g3(t)

g4(t)

g1(t)

g2(t)

2

1

3

4

g3(t)

g4(t)

### TDM-PAM

• Types of TDM:

• Synchronous TDM

• Asynchronous TDM

• Same Sampling rate for all signals.

• Minimum Sampling rate = twice the maximum frequency of all the signals.

• Total number of samples transmitted per second is equal to N times the sampling rate, Fs plus sync pulses.

• Transmission Bandwidth = N. Fs/2

### Problem –1 continued time division multiplexed using PAM. The TDM signal is passed through a Low-pass filter & then transmitted over a channel with a bandwidth of 10KHz.

• What is maximum Sampling rate for each Channel?

• What is the maximum frequency content allowable for each signal?

• Channel Bandwidth = 10 KHz. time division multiplexed using PAM. The TDM signal is passed through a Low-pass filter & then transmitted over a channel with a bandwidth of 10KHz.

• Number of samples that can be transmitted through the channel = 20K

• Maximum Sampling rate for each channel = 10K Samples/sec.

• Maximum Frequency for each Signal = 5KHz

### Problem –2 time division multiplexed using PAM. The TDM signal is passed through a Low-pass filter & then transmitted over a channel with a bandwidth of 10KHz.

• Two signals g1(t) and g2(t) are to transmitted over a common channel by means of TDM. The highest frequency of g1(t) is 1KHz and that of g2(t) is 1.3KHz. What is the permissible sampling rate?

• Ans: 2.6K samples/sec and above.

• { Synchronous TDM}

• 24 voice signals are sampled uniformly and then time division multiplexed . The sampling operation uses the flat-top samples with 1microsec duration. The multiplexing operation includes provision for Synchronization by adding an extra pulse of sufficient amplitude and also 1micro second.

• Contd…

### Problem-3

• Contd.. division multiplexed . The sampling operation uses the flat-top samples with 1microsec duration. The multiplexing operation includes provision for

• Assuming a sampling rate of 8KHz, calculate the spacing between successive pulses of the multiplexed signal.

### Problem-3

• In One frame, Total number of pulses = 25. division multiplexed . The sampling operation uses the flat-top samples with 1microsec duration. The multiplexing operation includes provision for

• Time duration for one time frame = Ts = 125µ seconds.

• Time duration utilized by pulses = 25µ sec

• Time spacing between successive pulses

• = (125- 25)/25 = 4µ sec.

### Problem-4

g and 2KHz respectively are to be transmitted using TDM scheme. Determine 1(t)

g2(t)

2

1

g3(t)

4

3

• Commutator Segment arrangement.

### Problem-4: Solution

3 and 2KHz respectively are to be transmitted using TDM scheme. Determine

3

3

1

1

1

3

3

3

2

2

2

Time