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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 block diagram representation of a differential encoder. Note that the output is dependent on both the current and previous register state. Another type of differential decoder. A method illustrated above can deal with a data stream inversion (it is called 180° ambiguity).
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.
For example, if 50 MHz is mixed with 94 MHz to produce an output on 144 MHz, the third harmonic of the 50 MHz may appear in the output. This problem is similar to the Image response problem which exists in receivers. One method of reducing the potential for this transmitter defect is the use of balanced and double balanced mixers.
Optical homodyne detection. In electrical engineering, homodyne detection is a method of extracting information encoded as modulation of the phase and/or frequency of an oscillating signal, by comparing that signal with a standard oscillation that would be identical to the signal if it carried null information.
Costas loop working in the locked state. In the classical implementation of a Costas loop, [4] a local voltage-controlled oscillator (VCO) provides quadrature outputs, one to each of two phase detectors, e.g., product detectors.
The expression suggests a quadrature phase detector can be made by summing the outputs of two multipliers. The quadrature signals may be formed with phase shift networks. Two common implementations for multipliers are the double balanced diode mixer, diode ring and the four-quadrant multiplier, Gilbert cell.