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The mixer circuit in a superhetrodyne receiver, used for both AM and FM receivers, is a local oscillator that is tuned to 455 KHz away from the desired signal (AM), or 10.7 MHz away from the signal (FM), followed by a broad band summing amplifier or, more typically, just a pair of diodes, resulting in shifting the RF signal into the IF range. By Fourier analysis, when you add two signals, you get four results, each signal, their sum, and their difference. The IF strip following the mixer, a steep skirt bandpass filter, is tuned to the difference, providing the selectivity necessary for good reception.
The preceding RF stage is a semi broad band, partially tuned, bandpass tank/amplifier circuit that simply enhances the input signal, providing sensitivity instead of selectivity.
What else can I help you with?
What is effect on amplitude shift keying modulation and demodulation due to use of transistor SL100?
The SL100 is a PNP medium power transistor, suitable for use up to ~100MHz. This can be used in the power amplifier stage, with the output connected to a tuning network/transformer + antenna for AM modulation. It's purpose, if used in this application, is to supply current (usually a voltage amplifier circuit will precede this one) to drive the antenna.
What is pulse position modulation and demodulation?
It is used for the radio control of model aircraft,boats, cars.
Why frequency modulation is superior to amplitude modulation?
FM provides noise immunity, whereas AM is easily affected by noise. With FM, the amplitude of the sound is converted into a shift in frequency. So the volume is limited by the bandwidth, but the frequency of the sound can vary as much as it likes, giving a higher fidelity sound. Spikes induced on the signal usually affect the amplitude of the signal. The amplitude of an FM signal is not used in the demodulation process and is therefore immune to spikes in the signal. AM was first used in radio because it is very easy to achieve using basic components. A single rectifier only, is needed to recover the audio. FM is quite a complicated process and could only be achieved once electronics had progressed.
What is asynchronous and self synchronous demodulation?
Synchronous demodulation is done using the same modulating signals such as cos(2000t) that was used in the transmitter. It still has to use Band-Pass (if multiple signals are present) and Low-Pass filter
What is a powered audio mixer used for?
A powered audio mixer is used for combining, mixing, routing and changing the level, timbre or dynamics of audio signals. They can mix analog or digital signals depending on the mixer.
What is attueneter?
attenuator is a circuit which is used to reduce the amplitude of the signal.
What is the difference between coherent demodulation and non coherent demodulation?
In case of coherent demodulation carrier used for demodulation purpose is in phase and frequency synchronism with carrier used for modulation purpose. For non-coherent demodulation it is not in synchronism.
What is effect on amplitude shift keying modulation and demodulation due to use of transistor SL100?
The SL100 is a PNP medium power transistor, suitable for use up to ~100MHz. This can be used in the power amplifier stage, with the output connected to a tuning network/transformer + antenna for AM modulation. It's purpose, if used in this application, is to supply current (usually a voltage amplifier circuit will precede this one) to drive the antenna.
What is amplifier and oscillator?
amplifier is electronic circuit which is used to increase the amplitude of the input signal without affecting its frequency and phase.
What can be used as a substitute for a paddle attachment for a mixer?
A whisk attachment can be used as a substitute for a paddle attachment in a mixer.
Advantages and disadvantage of self bias circuit?
the advantage of self bias circuit will be stable for greater range of amplitude signal than the fixed biased amplifier circuit the disadvantage is it only partially effective and therefore is only used where moderate changes in ambient temperature are expected
PLL is used for demodulation of?
Carrier signals that carry information by the process of frequency- or phase-modulation.
What is pulse position modulation and demodulation?
It is used for the radio control of model aircraft,boats, cars.
Why amplitude division multiplexing is not used?
what is function of amplitude division multiplexing
Why we use resistance?
the resitance would be used to reduce a voltage amplitude to a level suitable to be used in an application, to limit the amount of current flowing within the circuit , or in some cases the resistor could be used as a heating - effect.
Why frequency modulation is superior to amplitude modulation?
FM provides noise immunity, whereas AM is easily affected by noise. With FM, the amplitude of the sound is converted into a shift in frequency. So the volume is limited by the bandwidth, but the frequency of the sound can vary as much as it likes, giving a higher fidelity sound. Spikes induced on the signal usually affect the amplitude of the signal. The amplitude of an FM signal is not used in the demodulation process and is therefore immune to spikes in the signal. AM was first used in radio because it is very easy to achieve using basic components. A single rectifier only, is needed to recover the audio. FM is quite a complicated process and could only be achieved once electronics had progressed.
What is asynchronous and self synchronous demodulation?
Synchronous demodulation is done using the same modulating signals such as cos(2000t) that was used in the transmitter. It still has to use Band-Pass (if multiple signals are present) and Low-Pass filter
