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A modulator is a device or circuit that performs modulation. A demodulator (sometimes detector ) is a circuit that performs demodulation , the inverse of modulation. A modem (from mod ulator– dem odulator), used in bidirectional communication, can perform both operations.
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.
Unbalanced, symmetrical circuit. Fig. 3. Balanced, asymmetrical circuit. Fig. 4. Balanced, symmetrical circuit. A balanced circuit will normally show a symmetry of its components about a horizontal line midway between the two conductors (example in figure 3). This is different from what is normally meant by a symmetrical circuit, which is a ...
The tank circuit (LC), connected to the collector via a capacitor, contains a pair of varicap diodes. As the voltage applied to the varicaps is changed, the phase shift of the output will change. Phase modulation is mathematically equivalent to direct Frequency modulation with a 6 dB/octave high-pass filter applied to the modulating signal ...
A ring modulator is an electronic device for ring modulation. A ring modulator may be used in music synthesizers and as an effects unit. The name derives from the fact that the analog circuit of diodes originally used to implement this technique takes the shape of a ring: a diode ring. [2]
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.
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.
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.