Elmo Agencies

Delta Modulation and Demodulation Theory:For modulation and demodulation, a modem is the device that is used. In modulation, the information is encoded in a transmitted signal, and in demodulation, the information is decoded in a transmitted signal.

DSB/SSB AM Receiver is a comprehensive learning solution specifically designed to study basic operation as well as to provide conceptual and step by step understanding of a superheterodyne receiver and DSB/SSB Amplitude demodulation system through measurement of voltages and observation of waveforms at various test points. Block wise modular organization of circuit function with supporting technical information makes it easy to understand the process of AM reception and demodulation. The exercises conceived to provide a practical approach to the subjects enable a deep analysis of the subjects and will guide the students to understand each function.

Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency carrier wave. The modulation is accomplished by varying the sine and cosine inputs at a precise time. It is widely used for wireless LANs, RFID and Bluetooth communication.

Any digital modulation scheme uses a finite number of distinct signals to represent digital data. PSK uses a finite number of phases, each assigned a unique pattern of binary digits. Usually, each phase encodes an equal number of bits. Each pattern of bits forms the symbol that is represented by the particular phase. The demodulator, which is designed specifically for the symbol-set used by the modulator, determines the phase of the received signal and maps it back to the symbol it represents, thus recovering the original data. This requires the receiver to be able to compare the phase of the received signal to a reference signal – such a system is termed coherent (and referred to as CPSK).

CPSK requires a complicated demodulator, because it must extract the reference wave from the received signal and keep track of it, to compare each sample to. Alternatively, the phase shift of each symbol sent can be measured with respect to the phase of the previous symbol sent. Because the symbols are encoded in the difference in phase between successive samples, this is called differential phase-shift keying (DPSK). DPSK can be significantly simpler to implement than ordinary PSK, as it is a 'non-coherent' scheme, i.e. there is no need for the demodulator to keep track of a reference wave. A trade-off is that it has more demodulation errors.

The Transistor Amplifier Trainer (MI-A02) has been designed specifically to demonstrate the importance of transistor based amplifiers. This kit is an extremely useful laboratory kit whichprovides facilities for hands on experience to various experiments in the field of analog electronics.

The 7501 DSB/SSB AM transmitter trainer is part of an analogue communication range which provides all the necessary inputs, test points and connections for experimentation. The 7501 trainer teaches students the basics of DSB/SSB Amplitude modulation and transmission systems through measurement of voltages via the on-board test points.

The 7502 DSB/SSB AM Receiver is required to work with this unit.