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What is the need for downconversion of the input frequency into intermediate IF frequency in RF receiver?
Wiki User
∙ 16y ago
Your IF stages, normally three is a filter to give you better selectivity, it filters out all second channels and only let the preferred channel thru to your detector stage, the three stages is always tuned slightly off beat, in SW: 477KHz, 476KHz, 477KHz
Wiki User
∙ 16y ago
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Tell you what an intermediate frequency amplifier do?
The intermediate frequency (IF) amplifier lies between the mixer and the demodulator. The mixer shifts the input radio frequency (RF) signal into the range of the IF amplifier. The IF amplifer is a band pass amplifier, so only RF signals that are the IF frequency distance away from the local oscillator in the mixer can pass through to the demodulator. This process is called the superhetrodyne process.
What is the purpose of a local oscillator in mixer?
A local oscillator is a device that generates a sinusoidal signal with a frequency such that the receiver is able to generate the correct resulting frequency, or intermediate frequency (IF), for further amplification and conversion into audio detection. There is one local oscillator in a single conversion super heterodyne receiver where heterodyning or mixing is used to generate beat frequencies, which may be the sum or the difference of two frequencies. The local oscillator is usually adjustable and in step with the increment or decrement in the receiver frequency. For instance, if the receiver is tuned to 1,455 kilohertz (kHz) as radio frequency input (RF-in), the local oscillator frequency (LOF) may be set to 1,910 kHz for a so-called high side injection. The two signals are fed to an electronic device known as the mixer, which derives LOF - RF-in = IF or 455 kHz, which suggests why amplitude modulation (AM) broadcast receivers have about four stages of low-power amplifiers tuneable to 455 kHz.
What is the purpose of the FM transmitter?
A radio receiver is an electronic device that receives radio wave/signal and convert the information carried by them to a usuable form through speaker. The principal functions of a radio receiver are frequency selection, amplification and detection of signals which are been convert back to its original form through the help of radio speaker.
What was the effect on the input impedance of lowering the operating frequency?
The input impedance should increase slightly for the lower frequency, when using a capacitive circuit.
If the input frequency to a full wave rectifier is 400Hz what is the ripple frequency?
twice the frequency that is rectified.
Why you use 455kHz frequency as an intermediate frequency in communication?
The intermediate frequency in the superheterodyne receiver is chosen as the desired compromise between sensitivity and selectivity. 455kHz is used in AM broadcast applications, while 10.7mHz is used for FM. The IF stage is tuned for a steep skirt passband at that frequency, allowing only the desired heterodyned (shifted) input signal to make it through to the demodulator.
Tell you what an intermediate frequency amplifier do?
The intermediate frequency (IF) amplifier lies between the mixer and the demodulator. The mixer shifts the input radio frequency (RF) signal into the range of the IF amplifier. The IF amplifer is a band pass amplifier, so only RF signals that are the IF frequency distance away from the local oscillator in the mixer can pass through to the demodulator. This process is called the superhetrodyne process.
Why Intermediate frequencies is selected always a difference between two mixing frequencies?
In the frequency domain, if you add two sinusoidal waves to each other, you see four peaks. You have the two input frequencies, you have the sum, and you have the difference. Since the purpose of the Intermediate Frequency in the Superheterodyne design is to move the signal down to a more manageable frequency domain, i.e. one with fewer design challenges, we pick the difference.
What is a lock in range and a capture range?
Lock range is the input frequency range of the PLL over which out frequency changes in step with input frequency, where as capture range is the frequency range over which oput starts to responds to input frequency change.
What is the purpose of a local oscillator in mixer?
A local oscillator is a device that generates a sinusoidal signal with a frequency such that the receiver is able to generate the correct resulting frequency, or intermediate frequency (IF), for further amplification and conversion into audio detection. There is one local oscillator in a single conversion super heterodyne receiver where heterodyning or mixing is used to generate beat frequencies, which may be the sum or the difference of two frequencies. The local oscillator is usually adjustable and in step with the increment or decrement in the receiver frequency. For instance, if the receiver is tuned to 1,455 kilohertz (kHz) as radio frequency input (RF-in), the local oscillator frequency (LOF) may be set to 1,910 kHz for a so-called high side injection. The two signals are fed to an electronic device known as the mixer, which derives LOF - RF-in = IF or 455 kHz, which suggests why amplitude modulation (AM) broadcast receivers have about four stages of low-power amplifiers tuneable to 455 kHz.
What is output frequency of bridge rectifier?
twice the input frequency
What is the purpose of the FM transmitter?
A radio receiver is an electronic device that receives radio wave/signal and convert the information carried by them to a usuable form through speaker. The principal functions of a radio receiver are frequency selection, amplification and detection of signals which are been convert back to its original form through the help of radio speaker.
What is the difference between a Superheterodyne and a Neutrodyne radio receiver?
The superheterodyne converts the desired incoming signal frequency to an (usually lower) intermediate frequency before demodulating it and extracting the audio signal (or video/data, etc).The neutrodyne is a tuned radio frequency design where all amplifying stages operate at the incoming signal frequency. This was the commonest design up to the 1930s. The triode amplifiers used suffered from signal feedback, where a signal from the amplifier's output was coupled back to its input. This could cause the amplifier to act like a transmitter and to oscillate. Neutralization (with capacitors) was invented to prevent this problem and the circuit was named the "neutrodyne".
What effect does an amplifier have on the frequency of the signal?
A; An amplifier will have no effect on the input frequency however its output may not follow the input frequency at the hi end due to the amplifier limitations
What is rf in?
radio frequency input
What is the highest sampling rate if the input frequency is 3 kHz?
According to Niquest Theorem, it has to be more than twice the input frequency.
Why PLL better than VCO?
A PLL is different than a VCO. Each has its own use. Actually a PLL (Phase Locked Loop) contains a VCO (Voltage controlled oscillator). A VCO is an oscillator whose frequency is related to an input voltage. You can use it when you need a varying frequency that is controlled by a varying voltage. But it is not great at outputting a consistant exact voltage because it is very sensitive to its environment (e.g. temperature). A PLL will "lock" its output frequency to some input frequency. So it can oscillate at a frequency that is controlled by an input oscillator. Not too useful if the output frequency is the same as the input. But the output frequency can be divided before it is compared to the input. This allows the output frequency to be higher (some multiple of) the input frequency. Once a PLL is "locked on" to an input frequency it can be very stable.
