Contents
What is heterodyne and homodyne?
The basic difference between Homodyne and Heterodyne Detection is based on the signal carrier and local oscillator frequency. In homodyne detection signal carrier and local oscillator frequency is equal i.e. ωif = 0 and In heterodyne detection signal frequency and carrier frequency are not equal i.e. ωif ≠0.
What is heterodyne technique?
A heterodyne is a signal frequency that is created by combining or mixing two other frequencies using a signal processing technique called heterodyning, which was invented by Canadian inventor-engineer Reginald Fessenden. Heterodyne frequencies are related to the phenomenon of “beats” in acoustics.
What is homodyne receiver?
A direct-conversion receiver (DCR), also known as homodyne, synchrodyne, or zero-IF receiver, is a radio receiver design that demodulates the incoming radio signal using synchronous detection driven by a local oscillator whose frequency is identical to, or very close to the carrier frequency of the intended signal.
What is optical beat?
Optical beat-note frequency stabilization between two lasers using a radio frequency interferometer in the gigahertz frequency band.
What are the disadvantages of TRF receiver?
Disadvantages of TRF receiver Poor selectivity and low sensitivity in proportion to the number of tuned amplifiers used. Selectivity requires narrow bandwidth, and narrow bandwidth at a high radio frequency implies high Q or many filter sections.
How is noise eliminated in homodyne and heterodyne detection?
Both the quantum and the excess noise of the local oscillator can be eliminated by coherent subtraction of the two outputs of a 50–50 beam splitter. This result also demonstrates the fact that the basic quantum noise in homodyning and heterodyning is signal quantum fluctuation, not local-oscillator shot noise.
How is optical homodyne used in coherent detection?
Optical homodyne detection matches the transmitted signal phases to that of the local oscillator phase signal. In the homodyne coherent-detection technique, the LO frequency ω LO is selected to coincide with signal-carrier frequency ω 0 so that ω IF = 0.
How is heterodyne detection used in radiology?
The heterodyne detection used in radio as they boost the angular resolution through inter-ferometry. Optical homodyne detection matches the transmitted signal phases to that of the local oscillator phase signal.
Is there a 3 dB penalty for homodyne detection?
This 3 dB penalty only holds for quantum limit homodyne detection and disappears for classical noise limited signals for which the signal splitting keeps the OSNR nearly unchanged since the signal and the noise are attenuated in the same way.