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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.
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 ...
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.
In the DSB-SC modulation, unlike in AM, the wave carrier is not transmitted; thus, much of the power is distributed between the side bands, which implies an increase of the cover in DSB-SC, compared to AM, for the same power use. DSB-SC transmission is a special case of double-sideband reduced carrier transmission. It is used for radio data systems
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 ...
Block diagram. The NE612 is an integrated circuit for processing of signals, such as in the transmission of radio signals. It consists of an oscillator and a mixer. [1] It can handle signal frequencies of up to 500 MHz and local oscillator frequencies of up to 200 MHz.
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.
For instance, attenuators used with coaxial lines would be the unbalanced form while attenuators for use with twisted pair are required to be the balanced form. Four fundamental attenuator circuit diagrams are given in the figures on the left. Since an attenuator circuit consists solely of passive resistor elements, it is both linear and ...