Ratio Detector Circuit: In the Foster-Seeley discriminator, changes in the magnitude of the input signal will give rise to amplitude changes in the resulting output voltage. This makes prior limiting necessary. It is possible to…
Phase Discriminator: This Phase Discriminator is also known as the center-tuned discriminator or the Foster-Seeley discriminator, after its inventors. It is possible to obtain the same S-shaped response curve from a circuit in which the…
Slope Detector FM Demodulation: Consider a frequency-modulated signal fed to a tuned circuit whose resonant frequency is to one side of the center frequency of the FM signal. The output of this tuned circuit will…
Amplitude Limiter in FM Receiver: In order to make full use of the advantages offered by FM, a demodulator must be preceded by an Amplitude Limiter in FM Receiver, as discussed earlier, on the grounds…
FM Receiver Block Diagram: The FM receiver is a superheterodyne receiver, and the FM Receiver Block Diagram of Figure 6-28 shows just how similar it is to an AM receiver. The basic differences are as…
Indirect Synthesizer: Indirect Synthesizer: The required frequency range in most synthesizers nowadays is obtained from a variable voltage-controlled oscillator (VCO), whose output is corrected by comparison with that of a reference source. This inbuilt source…
Direct Synthesizer Block Diagram: A Direct Synthesizer Block Diagram is a piece of apparatus in which multiples and submultiples of a single crystal oscillator frequency are combined by addition and/or subtraction to provide a very…
Automatic Frequency Control Block Diagram: Automatic frequency control: As previously we see, the heart of an AFC circuit is a frequency-sensitive device, such as the phase discriminator, which produces a dc voltage whose amplitude and…
Squelch Circuit: Squelch (muting): When no carrier is present at the input, i.e., in the absence of transmissions on a given channel or between stations, a sensitive receiver will produce a disagreeable amount of loud noise.…
Delayed Automatic Gain Control: Delayed Automatic Gain Control: Simple AGC is clearly an improvement on no AGC at all, in that the gain of the receiver is reduced for strong signals. Unfortunately, as Figures 6-14…
