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The FSK (Frequency Shift Keying) modulator circuit works by shifting the carrier, a sine wave of a given frequency, to another frequency back and forth as the input signal changes. On the receiving end, the demodulator works by detecting one or both of the frequencies, often with a band-pass filter, regenerating the input signal. You can also use a signal processor to convert the carrier from time domain to frequency domain with a fourier transform, and then pick off the signal that way.) The FSK method of modulating/demodulation is typically limited to low frequency signal rates, such as 300 bits per second. You can also modulate multiple input signals onto one carrier, but the workable signal rate of each goes down. (In one signalling example, six analog inputs were used to duty cycle modulate six 10 hertz pulse trains, which were then FSK modulated onto one carrier. The receiving end had six band-pass filters, and six converters back to the analog domain.) If you are going to modulate more than one signal, you need to pick the frequencies carefully, so that their harmonic spectra do not intersect, otherwise you could get cross-talk if there is distortion in the carrier.)
What else can I help you with?
In a diode modulator the negative half of the am wave is supplied by the?
tuned circuit
What is reactance modulator?
= A Reactance Modulator =A reactance modulator changes the frequency of the tank circuit of the oscillator by changing its reactance. This is accomplished by a combination of a resistor, a condenser, and a vacuum tube (the modulator) connected across the tank circuit of the oscillator as in Fig. 33 A, and so adjusted as to act as a variable inductance or capacitance. Fig. 33 A. Principle of a reactance modulator The net result is to change the resonant frequency of the LC circuit by amounts proportional to the instantaneous a.f. voltages applied to the grid of the modulator tube, without changing the resistance of the LC circuit or the amplitude of the oscillations. A modulator circuit is shown in Fig. 33 B. Fig 33 B. A reactance modulator The voltages supplied to both the modulator and oscillator must be carefully stabilized to prevent undesired frequency changes. The speech amplifier (Fig. 33 A) does not have to deliver any power and need supply only a small output voltage, say 10 or 15 volts. A pentode and triode, R-C coupled, will be sufficient even with a sensitive microphone and a high-powered oscillator. The frequency change of LC per volt change on the a.f. grid of the modulator tube will be greater when C1,Fig. 33 B, is made smaller. The blocking condenser C2 has a comparatively high value, and hence offers but small reactance to r.f. currents. Fig. 19 H. An RC phase shifter In Fig. 33 B, the radio-frequency voltages which are developed across the tank in the oscillator circuit also appear across the RC1 circuit and across the parallel 6L7 modulator tube. Now look up the phase-shifting circuit of Fig. 19 H. The resistance r has been replaced by the internal resistance of the modulator tube of Fig. 33 B. The voltage drop across C1 is 90° out of phase with the tank voltage. It is applied to the control grid of the 6L7 whose r.f. plate current responds in the same phase. Thus this current is made to lag 90° behind the tank voltage. The r.f. plate current flows through the tank circuit and, combined with the current therein, is equivalent to a new current whose phase differs from the normal value just as though an additional reactance (not resistance) had been connected in with L and C. This, of course, changes the frequency of the LC circuit and hence of the transmitter. When a.f. is fed into the modulator tube, it causes proportionate changes in the r.f. plate current and hence in the equivalent reactance of the LC circuit.
Why is radio frequeny choke used in high level modulating circuit?
Because the output circuits of the modulator would otherwise present an impedance to the RF amplifier in parallel with the transmission line and antenna system, which you don't want. In other words, you want the RF all going up the tower, not down to ground through the modulator.
What are the advantages of FSK?
-> frequency shift keying promotes long distance communication. ->it has high security. ->low noise ->efficiency is high. ->decoding of signal is easy.
How does closed circuit work?
A closed circuit works by having electricity flow in a complete circuit or circle or any closed shape.
What is GFSK technique?
An FSK Modulator is much the same as a GFSK Modulator ,but GFSK uses a Gaussian filter as well. In a GFSK modulator everything is the same as a FSK modulator except that before the baseband pulses (-1, 1) go into the FSK modulator, it is passed through a gaussian filter to make the pulse smoother so to limit its spectral width.
A lattice modulator can be used as the modulator circuit in a SSB transmitter?
No
How do we design binary phase shift keying modulator with detail circuit?
circuit of modulation PSK
In a diode modulator the negative half of the am wave is supplied by the?
tuned circuit
Compear fsk and psk?
fsk and psk
How does a power modulator regulate the flow of electricity in a circuit?
A power modulator regulates the flow of electricity in a circuit by adjusting the voltage or current levels to control the amount of power being delivered to the circuit. This helps to maintain a stable and consistent flow of electricity, preventing damage to the components and ensuring efficient operation of the circuit.
What is a integrated FM modulator?
It's basically a circuit that's integrated into a single package, or is integrated into the complete circuit as an individual unit. There are several parts used in building a discreet modulator circuit and although it's not that complicated, it's by far less expensive for a manufacturer to come up with an IC to do the job as a single unit.
What is fsk in communication?
fsk is nothing but frequency shift keying which is used in low speed modems.....
What is block diagram of frequency shift keying modulation?
Block digram of fsk is the representation of fsk modulation
What is FSK in telecommunication?
FSK stands for Frequency Shift Keying. It allows for voice and data to be digitized and transferred over analog lines. There is a maximum transfer rate of FSK data at 1.6 Mbps.
What is a diode modulator?
A diode modulator is a type of AM modulator constructed using diodes. One type of diode modulator is the ring modulator shown in the image.
What is reactance modulator?
= A Reactance Modulator =A reactance modulator changes the frequency of the tank circuit of the oscillator by changing its reactance. This is accomplished by a combination of a resistor, a condenser, and a vacuum tube (the modulator) connected across the tank circuit of the oscillator as in Fig. 33 A, and so adjusted as to act as a variable inductance or capacitance. Fig. 33 A. Principle of a reactance modulator The net result is to change the resonant frequency of the LC circuit by amounts proportional to the instantaneous a.f. voltages applied to the grid of the modulator tube, without changing the resistance of the LC circuit or the amplitude of the oscillations. A modulator circuit is shown in Fig. 33 B. Fig 33 B. A reactance modulator The voltages supplied to both the modulator and oscillator must be carefully stabilized to prevent undesired frequency changes. The speech amplifier (Fig. 33 A) does not have to deliver any power and need supply only a small output voltage, say 10 or 15 volts. A pentode and triode, R-C coupled, will be sufficient even with a sensitive microphone and a high-powered oscillator. The frequency change of LC per volt change on the a.f. grid of the modulator tube will be greater when C1,Fig. 33 B, is made smaller. The blocking condenser C2 has a comparatively high value, and hence offers but small reactance to r.f. currents. Fig. 19 H. An RC phase shifter In Fig. 33 B, the radio-frequency voltages which are developed across the tank in the oscillator circuit also appear across the RC1 circuit and across the parallel 6L7 modulator tube. Now look up the phase-shifting circuit of Fig. 19 H. The resistance r has been replaced by the internal resistance of the modulator tube of Fig. 33 B. The voltage drop across C1 is 90° out of phase with the tank voltage. It is applied to the control grid of the 6L7 whose r.f. plate current responds in the same phase. Thus this current is made to lag 90° behind the tank voltage. The r.f. plate current flows through the tank circuit and, combined with the current therein, is equivalent to a new current whose phase differs from the normal value just as though an additional reactance (not resistance) had been connected in with L and C. This, of course, changes the frequency of the LC circuit and hence of the transmitter. When a.f. is fed into the modulator tube, it causes proportionate changes in the r.f. plate current and hence in the equivalent reactance of the LC circuit.
