What is zero IF architecture?

A: Zero-IF, sometimes called a direct conversion or homodyne architecture, uses a local oscillator which is set equal to the desired carrier frequency being tuned, or very close to it, Figure 1. This reduces the IF frequency to zero or near zero, rather than standard values such as 455 kHz.

What is a homodyne receiver?

Also called a “regenerative receiver,” a radio receiver that detects and demodulates the carrier frequency broadcast by the station without using an intermediate frequency (IF) stage.

What is difference between homodyne and heterodyne?

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 nonzero receiver?

The continuous wave radar with non zero IF provides isolation between transmitter and receiver. Separate antennas are used for transmission and reception to reduce the signal leakage. Local Oscillator provides the carrier signal whose frequency is equal to intermediate frequency.

What is the advantage of Superheterodyning?

The advantages of superheterodyne receiver are many. An obvious advantage is that by reducing to lower frequency, lower frequency components can be used, and in general, cost is proportional to frequency. RF gain at 40 GHz is expensive, IF gain at 1 GHz is cheap as dirt.

What is a disadvantage of a direct conversion receiver?

Disadvantages. Signal leakage paths can occur in the receiver. The high audio frequency gain required can result in difficulty in rejecting mains hum. Local-oscillator energy can leak through the mixer stage to the antenna input and then reflect back into the mixer stage.

What is coherent detection?

Coherent detection allows us to detect arbitrary amplitude and phase information of the received light field by interfering the received signal with a local oscillator.

Why do we convert RF to IF?

So a high frequency signal is converted to a lower IF for more convenient processing. The bandwidth of a filter is proportional to its center frequency. In receivers like the TRF in which the filtering is done at the incoming RF frequency, as the receiver is tuned to higher frequencies, its bandwidth increases.

What are the disadvantages of superheterodyne receiver?

One major disadvantage to the superheterodyne receiver is the problem of image frequency. In heterodyne receivers, an image frequency is an undesired input frequency equal to the station frequency plus (or minus) twice the intermediate frequency.

What are the four conversion strategies?

Conversion Strategies

• Direct changeover.
• Parallel conversion.
• Gradual, or phased, conversion.
• Modular conversion.
• Distributed conversion.

Why do we use coherent detection?

Compared with direct detection, coherent detection offers many advantages: (1) better sensitivity, which can be used to reduce the laser power requirement, to trade for a higher level modulation format to reduce the bandwidth requirement of component, or a high-power margin for a longer link; (2) more tolerance toward …

Why is it called coherent detection?

A “coherent” optical transmission system is characterized by its capability to do “coherent detection,” which means that an optical receiver can track the phase of an optical transmitter (and hence “phase coherence”) so as to extract any phase and frequency information carried by a transmitted signal.