How is phase shift used in FM demodulation?
• Very common in TV receivers • It uses a phase shift circuit • It converts the instantaneous frequency deviation in an FM signal to phase shift and then detects the changes of phase – Csresults in -90 deg. Shift – The tuned circuit! additional phase shift proportional to instantaneous frequency deviation from fc Another approach
How is FM demodulation used to detect a signal?
FM demodulation is a key process in the reception of a frequency modulated signal. Once the signal has been received, filtered and amplified, it is necessary to recover the original modulation from the carrier. It is this process that is called demodulation or detection. FM demodulator circuits are found in any receiver
What’s the difference between FM and FM discrimination?
FM demodulation is also called FM detection and sometimes the phrase “FM discrimination” is used, although this term tends to be used with older circuits and technology. FM demodulation is a key process in the reception of a frequency modulated signal.
How to calculate the frequency and bandwidth of tone modulation?
Deviation and Bandwidth • Instantaneous Frequency: f c + k f x(t) • Frequency deviation: Δf=k f x(t) • Maximum frequency deviation, Δf = k f |x(t)| max – For tone modulation: Δf = k f A m • Deviation Ratio, D = Δf/W – For tone modulation: Modulation index, b = Df/f m – b << 1: narrowband
Which is the best type of FM demodulator?
– Phase Shift Discrimination • Noncoherent demodulator • FM!PM!m(t) – Phase-Locked Loop (PLL) Detector • Coherent demodulator • Superior performance; complex and expensive Let’s look at each! Frequency Discrimination • Components – Bandpass Limiter: Consists of Hard Limiter & BP Filter
Is there a slope detector for FM wave output?
Frequency Discrimination FM Wave Output of Tuned Circuit (discriminator) Frequency Discrimination – Slope Detector • In practice the differentiator can be approximated by a slope detectorthat has a linear frequency-to-amplitude transfer characteristic over the bandwidth BW –One drawback is that it is narrow band