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In the Armstrong method, the audio signal and the radio frequency carrier signal are applied to the balanced modulator to generate a double sideband suppressed carrier signal. The phase of this output signal is then shifted 90 degrees with respect to the original carrier. The balanced modulator output can either lead or lag the carrier's phase.
Basic self-oscillating circuit. Beam deflection tubes, sometimes known as sheet beam tubes, are vacuum tubes with an electron gun, a beam intensity control grid, a screen grid, sometimes a suppressor grid, and two electrostatic deflection electrodes on opposite sides of the electron beam that can direct the rectangular beam to either of two anodes in the same plane.
A circuit that has the specific purpose of allowing interfacing between balanced and unbalanced circuits is called a balun. A balun could be a transformer with one leg earthed on the unbalanced side as described in the transformer balance section above. Other circuits are possible such as autotransformers or active circuits. [4]
Such circuits are widely used for frequency conversion in radio systems. [1] The advantage of this circuit is the output current is an accurate multiplication of the (differential) base currents of both inputs. As a mixer, its balanced operation cancels out many unwanted mixing products, resulting in a "cleaner" output.
English: The image gives six circuit diagrams (schematics) for balanced line antenna tuners of the tuned-transformer type, discussed in the Wikipedia article "Antenna Tuner" or "ATU". It is an edited version of the original by JNRSTANLEY uploaded 2014-10-15.
A modified constellation diagram of 16-APSK. Typically 16-APSK will have 15 degree phase offset on the outer ring, which is not depicted here. Symbols can be easily distinguished from each other and, moreover, varying of the space between rings is a way to counteract transmission distortions.
A Costas loop is a phase-locked loop (PLL) based circuit which is used for carrier frequency recovery from suppressed-carrier modulation signals (e.g. double-sideband suppressed carrier signals) and phase modulation signals (e.g. BPSK, QPSK). It was invented by John P. Costas at General Electric in the 1950s.
The Foster–Seeley discriminator [1] [2] is a common type of FM detector circuit, invented in 1936 by Dudley E. Foster [3] and Stuart William Seeley. The Foster–Seeley discriminator was envisioned for automatic frequency control of receivers, but also found application in demodulating an FM signal.