# Category: Uncategorized

# Category: Uncategorized

#### 8.5-8 We need to design a binary PCM system to transmit an analog TV signa; m(t) of bandwidth 4.5 MHz. The receiver output ratio of signa; to quantization noise ratio is required to be at least 50 db. (a) The TV signal m(t) value is uniformly distributed in the range (-mp, mp). Fimd the minimum number of quantization levels L required. Select the nearest value of L to satisfy. (b) For the value of L in part (a), compute the receiver output SNR assuming the nonthreshold region of operation. (c) For the value of L in part (a), compute the required channel bandwidth for the PCM transmission. (d) If the output SNR is required to be increased by 6 dB (four times), what are the values of L and the percentage increase in transmission bandwidth?

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#### 5.2-2 An television signal (video plus video) has a bandwidth of 4.5 MHz. This signal is sampled quantized, and binary-coded to obtain a PCM signal. (a) Determine the sampling rate if the signal is to be sampled at a rate 2/9 above the Nyquist rate. (b) If the samples are quantized into 1024 levels, determine the number of binary pulses required to encode each sample. (c) Determine the binary pulse rate (bits per second) of the binary-coded signal. (d) Find the minimum bandwidth required to transmit this PC signal.

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#### 4. A television signal (video and audio) has a bandwidth of 4.5MHz. This signal is sampled quantized and binary-coded to obtain a PCM signal. (15 points) (A) Determine the sampling rate if the signal is to be sampled at a rate 20% above the Nyquist rate. (b) If the samples are quantized into 1024 levels, determine the number of binary pulses required to encode each sample. (c) Determine the binary pulse rate (bits per second) of the binary coded signal and the bandwidth required to transmit this signal.

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#### A compact disc (CD) records audio signal digitally by using PCM. Assume that the audio signal bandwidth equals 15KHz. (a) If the Nyquist samples are uniformly into levels and then binary-coded, determine the number of binary digitals required into levels and then binary-coded, determine the number of binary digits required to encode a sample. (b) if the audio signal has a peak voltage of +- IV and an average signal power of 0.1. Find the resulting ratio od signal to quantization noise (SQNR)for the system. (c) Determine the number of binary digits per second (bit/s) required to encode the audio signal. (d) For practical reasons discussed in the text, signals are sampled at a rate well above the Nyquist rate. Practical CDs use 44.100 samples per second. Id L = 65.536, determine the number of bits per second required to encode the signal and the minimum bandwidth required to transmit the encoded signal.

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#### Question 4: (15 points) Consider an audio signal with spectral components in the range from 40 Hz to 5,000 Hz. Assume that a sampling rate of 12kHz will be used to generate a PCM signal. The audio signal has an average power of 0.5W and peak voltage of 4V.C (a) For SNR=25db, what is the number of (uniform) quantization levels needed? How many bits are required to encode the PCM data? (b) What data rate is required? (c) What is the minimum bandwidth required to transmit the encoded signal.

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#### Question 3: (15 points) The American standard code for Information Interchange (ASCII) has 128 character, which are binary coded. If a certain computer generates 100,000 characters per second, determine the following: (a) The number of bits (binary digits) required per character. (b) The number of bits per second required to transmit the computer output, and the minimum bandwidth required to transmit this signal. (c) For single error-detection capability, an additional bit (parity bit) is added to the code of each character. Modify your answers in parts (a) and (b) in view of this information.

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#### 1. Assume we have an analog signal m(t) of bandwidth 4KHz and we sample 20% higher than the Nyquist rate. If we want to convert the analogue signal into four bit PCM, What is the data rate in bits per second (Bps) and the transmission bandwidth? If the signal power is P and the peak amplitude of the quantizer is, what is the SNR?

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#### (5 pts) Pulse Code Modulation A compact disc (CD) records audio signal bandwidth equals 15 kHz. (a) (2 pts) Determine the sampling rate it the signal is to be sampled at a rate 20% above the Nyquist rate. (b) (1 pt) If the samples are uniformly quantized into M=65.536 levels, determine the average signal to noise ratio (SNR). Assume uniform distribution for the audio signal as well. (c) (1 pt) Assuming binary encoding, determine the number of bits per second required to encode the audio signal. (d) (1 pt) Assuming square pulses, determine the first null bandwidth of the PCM signal.

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#### 2) A signal with bandwidth 20KHz is sampled and digitally transmitted. (a) If the maximum acceptable quantization error in sample amplitudes is 0.25% of the peak signal voltage, find the minimum number of bits needed for a uniform quantizer. (b) If the sampling rate must be 20% higher than the minimum rate, find the minimum bit rate of the multiplexed data stream based on the quantizer of part (a). (c) If 5% more bits are added to the multiplexed data for error protection and synchronization, determine the minimum bandwidth needed to transmit the final data stream

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#### 6.2-3 In a satellite radio system, 128 station of stereo quality are to be package in one data stream. For each station, Two (left and right) signals of bandwidth 15,000 Hz are sampled, quantized, and binary-cooled into PCM signals. The transmitter must multiplex the data from the 128 stations into a single stream via time multiplexing. (a) If the maximum acceptable quantization error in sample amplitude is 0.25% of the peak signal voltage, find the minimum number of bits needed for a uniform quantizer. (b) If the sampling rate must be 20% higher than the Nyquist rate, find the minimum bit rate of the multiplexed data stream based on the quantizer of part (a). (c) If 5% more bits are added to the multiplexed data for error protection and synchronization, determine the minimum bandwidth needed to transmit the final data stream to receivers.

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