AIM
The main aim of this project is to demonstrate the pulse code digitization and companding on a signal and to observe the effects of sampling depths and companding on the signal to noise ratio (SQR).
INTRODUCTION
PCM- In the pulse code modulation (PCM), the signal is a digitally represented analog signal in which the signal magnitude is sampled with uniform intervals. Each sample is quantized to the closest value of the digital signal. In the pulse code modulation, the signal is binary. The two possible states represented in PCM are logic 1(high) and logic 0 (low). The main advantage of PCM signal is that it is derived from analog signal which is multiplexed with data from the computer and carried over a common high-speed channel.
COMPANDING- The combination of compressing and expanding is known as companding. In companding, the data is compressed before it is sent and then expanded at the receiving end using the same non-linear scale. The noise and crosstalk levels at the receiver are reduced due to companding. It is used in wireless microphones for better dynamic range and also in digital and telephony systems for compressing of the input signal and expanding of the output signal.
The below figure 1 shows the demonstration of PCM with and without companding.
Figure1- PCM with and without companding
Procedure to create PCM and companding on excel sheet
The PCM and companding of a signal is done on a spreadsheet using excel. Firstly, a sine wave is created by varying the time with respect to the amplitude. The frequency of the signal is taken as 10 Hz. The quantization process of the signal will be done. A quantized sine wave is then created. Now the number of levels cell (N) should be created. We take the value ...
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...ude=0.1, large N=8.
GRAPH I) Plot of SQR vs Amplitude with Companding (mu=255) and without Companding (mu=0).
GRAPH J) Plot of SQR vs bit depth both with Companding (mu=255) and without Companding (mu=0). Where A=1, and bit depths are 2, 4, 8, 16, 32, 64, 128, 256.
CONCLUSION:
This lab was carried out to compand and quantizes a voice signal. We
In the Using the pulse modulation technique, the analog signal is converted into the digital signal. The process of quantization and companding of a signal is carried on the spreadsheets. To attain a clear signal to quantization noise ratio, the number of samples should be increased. By increasing the sampling depth, the quantization error can be minimized. By companding process, the quantization noise and distortion levels can be minimized. Companding improves response for low amplitude signals.
After compression, the structure data, audio and video must be multiplexed. A number of compressed TV signals are combined by a multiplexer and put unto a shared transition medium. This is done by one of the two possible kinds of multiplexers that result in either a transport or a program stream, which is suited for secure transmission paths since it can contain large amounts of information. In addition multiplexing can be done using various methods. Time division multiplexing allocates a distinct time interval for each channel in a set; with the help of synchronization and a fixed interval order the channels take turns using the common line.
The sender encodes the information and selects the communication channel through which the message is sent, the receiver receives and decodes the message and
program to optimize the analog. As for the last step in determining if an analog is a good
“G.726: 40, 32, 24, 16 kbit/s Adaptive Differential Pulse Code Modulation (ADPCM)”, International Telecommunication Union, 1991.
Contents Page Section 3 ……………… …………………… Introduction 3 ……………… …………………… The Pioneers of the Electronic Age 4 ……………… …………………… The Theory of the Synthesiser 5 ……………… …………………… Other Changes Due to Electronic Technology 6 ………………
Digital is better than analog. Digital is better because analog can be interfered by something. While Digital takes a few seconds to get there and the signal stops. Digital is more accurate because not much people use analog technology because it is somewhat
[8] Q. Chen, Q. Wang and V. K. Bhargava, “Error Performance of Coded SFHiDPSK in Tone Interference and AWGN,” IEEE Confrence Milcom, pp. 63-67, 1992.
Analog communication employs continuous transmission of an electromagnetic wave form that varies in frequency and amplitude.
The need to reallocate the frequency spectrum by the FCC and NTIA is necessary due to the expansion of digital wireless communications. A digital wireless communications circuit requires four times the bandwidth of an analog wireless communications circuit. The shift to digital television, satellite TV, HD TV, and the increase in cell phone usage and cell phones with data plans have been the leading cause for the need to reallocate the frequency spectrum.
One of the latest advancements in wireless data. It is used in GSM (Global System for Mobile Communications) for transferring data in packets.
The current conveyor is a basic building block that can be implemented in analog circuit design. This was introduced by Sedra and Smith in 1968 but its real advantages and innovative impact was not clear at that time. In recent years, current-mode circuits have emerged as an important class of circuits with properties of accuracy, high frequency range and versatility in a wide range of applications. Current conveyor represents the emerging class of high performance analog circuit design based on current mode approach. It has simple architecture, wider bandwidth and capability to operate at low voltage. The c...
throughput by transmitting independent data streams on the different transmit branches simultaneously and at the same carrier frequency.
Use of a channel to transmit the message: the information is then transmitted over a channel that links the sender with the receiver. The message may be oral or writte...
The explosion of the Analog communications industry has led to many developments in design of transrecievers. The Multi standard transceivers used these days for these systems should be able to operate over a wide frequency range with minimal amounts of duplicated hardware. A very critical element of any type of transceiver is the frequency synthesizer (FS). A special frequency synthesizer i.e. multi-standard frequency synthesizer must be able to synthesize different bands of frequencies for the different wireless standards....
This essay will look at the differences of two filters, the infinite impulse response (IIR) and the finite impulse response (FIR). Each filter will be observed and will be discussed how they operate differently to each other. Each filter has its own unique characteristics in the filtration of signal. Each filter has its advantages and disadvantages, each filter operates differently and in turn causes different results when modulating a signal.