Shares information on RF and Microwave, Oscillators, Modulation and Demodulation, Filter applications, Tuned amplifier applications, Phase-locked loops and Synthesizers.
Frequency synthesis is a technique of producing a range of frequencies with crystal-controlled stability. A frequency synthesizer uses phase-locked loop (PLL) to generate output frequencies over a wide range. The typical range is from 1 MHz to 160 MHz.
A phase-locked loop (PLL) is a form of a servo system which consists of a phase detector, low-pass filter and voltage controlled-oscillator (VCO) as illustrated in the block diagram below. The phase detector compares … Read more
A radio frequency (RF) signal generator is used in generating high frequency signals at a specific frequency for testing laboratories. The output frequency may range for example from about 100 kHz to around 40 GHz. A typical RG generator consists … Read more
The operation of a typical AM audio frequency signal is illustrated in the Figure 1.0 where vin is the modulated signal that is shown Figure 1.1.
A typical amplitude modulated signal that is fed … Read more
Developed by the ISO (International Organization for Standards) in 1983, the Open Systems Interconnection (OSI) reference model divides communication functions into seven-layer standard protocol system. The OSI model is a framework for developing a coordinated system of standards. The seven … Read more
In cellular communication systems, there is a two-way wireless transmission between the cellular phone handset and the base station tower. The cell phone converts the audio signals into electrical form using a microphone. This information is imposed on a high … Read more
Light emitting PN junction devices such as LEDs and laser diodes are easily modulated by superimposing signals on to the injected current. This is direct modulation. Laser diodes in high-bit rate and long-span optical communication systems are often used under … Read more
Access control methods are required in a network to ensure that only one user of the network is able to transmit at any one time.
In ring-based local area networks (LANs), two commonly employed techniques are:
Broadband transmission is used for a network in which information is modulated onto a radio frequency carrier which passes through the transmission medium such as a coaxial cable. Broadband transmission allows a number of modulated radio frequency carriers to be … Read more
A tuned amplifier operates over a band of frequencies centered on a resonant frequency. Its two main requirements are to provide high gain and good selectivity.
We have several applications in telecommunications systems where it is necessary to amplify a … Read more
