A super heterodyne AM receiver is tuned to a station operating at 1200 KHz .Find local oscillator frequency and image frequency.

A super heterodyne AM receiver is tuned to a station operating at 1200 KHz .Find local oscillator frequency and image frequency.
by

1 Answer

Answer :

A super heterodyne AM receiver is tuned to a station operating at 1200 KHz

Intermediate frequency is 455KHz.

IF frequency=f0-fs

Local oscillator frequency is f0=IF +fs=455K+1200K=1655kHz

The image frequency which gives the same IF is f0+2*IF=2110KHz
by

Related questions

A superheterodyne radio receiver with an IF of 455KHZ is turned to 1000KHZ. Find: (i) Image frequency (ii) Local oscillator frequency

Description : A superheterodyne radio receiver with an IF of 455KHZ is turned to 1000KHZ. Find: (i) Image frequency (ii) Local oscillator frequency

Last Answer : Given Intermediate Frequency fi=455KHz Signal frequency =fs=1000KHz Local oscillator frequency fo=fs+fi  Fo=1000KHz+455KHz  =1455KHz Image frequency is the input frequency which produces the same intermediate frequency fsi=fs+2fi  =1000KHz+2*455KHz  =1910KHz 

An FM receiver whose intermediate frequency is 10.7 MHz, is experiencing image channel interference from a station transmitting on 121.1 MHz. If the local oscillator is tracking above, the receiver is tuned to A. 131.8 MHz B. 110.4 MHz C. 142.5 MHz D. 99.7 MHz

Description : An FM receiver whose intermediate frequency is 10.7 MHz, is experiencing image channel interference from a station transmitting on 121.1 MHz. If the local oscillator is tracking above, the receiver is tuned to A. 131.8 MHz B. 110.4 MHz C. 142.5 MHz D. 99.7 MHz

Last Answer : D. 99.7 MHz

Why should local oscillator frequency be greater than signal frequency in AM receiver? Also explain why IF has constant value?

Description : Why should local oscillator frequency be greater than signal frequency in AM receiver? Also explain why IF has constant value?

Last Answer : Reason for LO frequency to be greater than signal frequency The local oscillator frequency (f0) is made greater than signal frequency (Fs) in radio receiver: Local oscillator frequency range is 995 ... frequency of desired signal because the IF is constant and same for all the incoming RF signal.

Draw the block diagram of FM super heterodyne radio receiver with waveforms.

Description : Draw the block diagram of FM super heterodyne radio receiver with waveforms.

Last Answer : block diagram of FM super heterodyne radio receiver

Describe the functions of mixer and local oscillator in radio receiver

Description : Describe the functions of mixer and local oscillator in radio receiver

Last Answer : Frequency Mixer:- The function of frequency mixer is to heterodyne signal frequency fs and local oscillator frequency fo. At the output, it produces the difference frequency known as ... local oscillator frequency fo is then mixed with incoming frequency to give intermediate frequency. 

Compare TRF and super heterodyne receivers.

Description : Compare TRF and super heterodyne receivers.

Last Answer : Compare TRF and super heterodyne receivers. 

State the super heterodyne principle.

Description : State the super heterodyne principle.

Last Answer : The process of mixing two signals having different frequencies to produce a new frequency i.e., to convert all the incoming frequencies to a lower frequency known as intermediate frequency (IF) . The super heterodyne principle is based on frequency conversion or frequency down conversion.

A superhet receiver has an IF of 455 kHz and is experiencing image-channel interference on a frequency of 1570 kHz. The receiver is tuned to A. 1115 kHz B. 660 kHz C. 2025 kHz D. 910 kHz

Description : A superhet receiver has an IF of 455 kHz and is experiencing image-channel interference on a frequency of 1570 kHz. The receiver is tuned to A. 1115 kHz B. 660 kHz C. 2025 kHz D. 910 kHz

Last Answer : B. 660 kHz

What is the local oscillator frequency range commercial AM broadcast if it is equal to 455 KHz. A. 540 to 1600 KHz B. 0 to 1600 KHz C. 995 to 2055 KHz D. 0 to 455 KHz

Description : What is the local oscillator frequency range commercial AM broadcast if it is equal to 455 KHz. A. 540 to 1600 KHz B. 0 to 1600 KHz C. 995 to 2055 KHz D. 0 to 455 KHz

Last Answer : C. 995 to 2055 KHz

Draw the block diagram of AM. Super heterodyne ratio receiver and state the function of each block

Description : Draw the block diagram of AM. Super heterodyne ratio receiver and state the function of each block

Last Answer : AM super heterodyne receiver works on the principle of super heterodyning. In the super heterodyne receiver, the incoming signal voltage is combined with a Signal generated in the receiver. The ... constant output level at the speaker even though the signal strength at the antenna varies.

For AM, fc =500kHz , fm = 5 kHz Determine: (i) Upper and lower sideband frequencies (ii) Bandwidth

Description : For AM, fc =500kHz , fm = 5 kHz Determine: (i) Upper and lower sideband frequencies (ii) Bandwidth

Last Answer : Given data fc = 500KHz , fm = 5KHz USB =fc+fm USB = 500+5  =505 KHz. LSB =fc – fm LSB = 500 – 5  =495 KHz Bandwidth = 2fm .  = 2* 5 =10 KHz

State the IF frequency and bandwidth of FM receiver.

Description : State the IF frequency and bandwidth of FM receiver.

Last Answer : IF for FM receiver: 10.7 MHz. Bandwidth of FM receiver:88MHz to 108 MHz

In a heterodyne-type frequency meter, what is the difference between the oscillator frequency and the unknown frequency?

Description : In a heterodyne-type frequency meter, what is the difference between the oscillator frequency and the unknown frequency?

Last Answer : Beat frequency.

Define selectivity and sensitivity of AM Receiver.

Description : Define selectivity and sensitivity of AM Receiver. 

Last Answer : Selectivity:-It needs to accept signals of the wanted frequency and reject other unwanted frequencies. Sensitivity:-The sensitivity of a radio receiver is its ability to amplify weak signals. It is ... the receiver input terminals to give a standard output power, measured at the output terminals. 

Explain the following characteristics of AM radio receiver: (i) Sensitivity (ii) Selectivity.

Description : Explain the following characteristics of AM radio receiver: (i) Sensitivity (ii) Selectivity.

Last Answer : Sensitivity:- The ability to amplify the weak signals is called sensitivity. It is the function of overall receiver gain. Sensitivity of radio receiver is decided by the gain of the RF IF ... perfectly the receiver is able to select the desired carrier frequency and reject other frequencies. 

Define: (i) Image frequency and (ii) Double spotting

Description : Define: (i) Image frequency and (ii) Double spotting

Last Answer : i)Image frequency:- Image Frequency is defined as the signal frequency plus twice the intermediate frequency. It is denoted as fsi = fs+2fi Where, fs = Signal Frequency fi =intermediate frequency ... It is due to the poor front end selectivity i.e., inadequate image frequency rejection.

Draw practical set-up and explain the procedure to measure selectivity of radio receiver.

Description : Draw practical set-up and explain the procedure to measure selectivity of radio receiver.

Last Answer : Procedure to measure selectivity of radio receiver: Throughout the measurement the receiver is kept tuned to desired frequency 950 Khz. Now the generator output frequency is deviated below ... the generator output voltage is adjusted to get a standard 50 miliwatt receiver output power.

Explain the working of amplitude limiter in FM receiver with circuit diagram.

Description : Explain the working of amplitude limiter in FM receiver with circuit diagram.

Last Answer : Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy  Circuit Diagram:

State two disadvantages of TRF receiver over superheterodyne receiver.

Description : State two disadvantages of TRF receiver over superheterodyne receiver.

Last Answer : Disadvantages of TRF Receiver: 1. Instability due to oscillatory nature of RF amplifier. 2. Variation in bandwidth over tuning range. 3. Insufficient selectivity at high frequencies 4. Poor adjacent channel rejection capability 

Draw block diagram of FM receiver and explain the use of limiter circuit.

Description : Draw block diagram of FM receiver and explain the use of limiter circuit.

Last Answer : Diagram Explanation Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy.

Describe the block diagram of FM superhetrodyne receiver

Description : Describe the block diagram of FM superhetrodyne receiver

Last Answer : RF amplifier:- There are two important functions of RF amplifier: 1) To increase the strength of weak RF signal. 2) To reject image frequency signal. In FM broadcast the ... FM broadcast, the maximum modulating frequency is 15 kHz. Hence the audio amplifier must have large bandwidth.

Write any two drawbacks of TRF radio receiver.

Description : Write any two drawbacks of TRF radio receiver.

Last Answer : Drawbacks of TRF Receiver: 1. Instability due to oscillatory nature of RF amplifier. 2. Variation in bandwidth over tuning range. 3. Insufficient selectivity at high frequencies 4. Poor adjacent channel rejection capability. 

Draw the TRF receiver block diagram and explain its working.

Description : Draw the TRF receiver block diagram and explain its working. 

Last Answer : Explanation:- 1. TRF receivers are simple and having high sensitivity. The AM transmission takes place in MW band and SW band. MW frequency range is 540KHz to 1640KHz. 2. ... power level to drive the loudspeaker. 7. The loudspeaker converts electrical signal into original sound information.

A tuned circuit has a Q of 100 at its resonant frequency of 500 kHz. Its bandwidth is _____kHz.

Description : A tuned circuit has a Q of 100 at its resonant frequency of 500 kHz. Its bandwidth is _____kHz. (A) 50000 (B) 0.2 (C) 600 (D) 5

Last Answer : A tuned circuit has a Q of 100 at its resonant frequency of 500 kHz. Its bandwidth is 5 kHz.

ECE Board Exam March 1996 What is the purpose of a beat frequency oscillator (BFO)? A. Aid in the reception of weak voice-modulated signals B. Generates a signal, whose frequency is the same as that of the intermediate frequency C. Generates a 1kHz note for Morse code reception D. Generates an output, whose frequency differs from that of the intermediate frequency by 1 kHz

Description : ECE Board Exam March 1996 What is the purpose of a beat frequency oscillator (BFO)? A. Aid in the reception of weak voice-modulated signals B. Generates a signal, whose frequency is the ... reception D. Generates an output, whose frequency differs from that of the intermediate frequency by 1 kHz

Last Answer : C. Generates a 1kHz note for Morse code reception

What establishes the receiver bandwidth? A. RF amplifier B. Mixer C. Local oscillator D. IF amplifier

Description : What establishes the receiver bandwidth? A. RF amplifier B. Mixer C. Local oscillator D. IF amplifier

Last Answer : D. IF amplifier

What consists the front-end circuit of a VHF TV superheterodyne receiver? A. Mixer, RF amplifier and AFC? B. RF amplifier, Band pass filter and mixer C. Local oscillator, mixer and RF amplifier D. Local oscillator, AGC and antenna

Description : What consists the front-end circuit of a VHF TV superheterodyne receiver? A. Mixer, RF amplifier and AFC? B. RF amplifier, Band pass filter and mixer C. Local oscillator, mixer and RF amplifier D. Local oscillator, AGC and antenna

Last Answer : C. Local oscillator, mixer and RF amplifier

Refers to one of the front end circuit of a VHF TV superheterodyne receiver which is usually a separate circuit coupled to the mixer. A. Antenna feed B. AGC C. RF amplifier D. Local oscillator

Description : Refers to one of the front end circuit of a VHF TV superheterodyne receiver which is usually a separate circuit coupled to the mixer. A. Antenna feed B. AGC C. RF amplifier D. Local oscillator

Last Answer : D. Local oscillator

After the IF stages have been aligned, the next stage to align in FM receiver is. A. local oscillator B. limiter stage C. RF amplifier D. mixer stage

Description : After the IF stages have been aligned, the next stage to align in FM receiver is. A. local oscillator B. limiter stage C. RF amplifier D. mixer stage

Last Answer : A. local oscillator

Define critical frequency w.r. to wave propagation.

Description : Define critical frequency w.r. to wave propagation.

Last Answer : Define critical frequency w.r. to wave propagation.

In a FM system, the maximum deviation is 75KHz. Find bandwidth for modulating frequency i. fm=500Hz ii. fm=5KHz iii. fm=10KHz Draw conclusion for bandwidth of FM from answer.

Description : In a FM system, the maximum deviation is 75KHz. Find bandwidth for modulating frequency i. fm=500Hz ii. fm=5KHz iii. fm=10KHz Draw conclusion for bandwidth of FM from answer.

Last Answer : Given deviation∆=75kHz i) fm=500Hz bandwidth B.W=2(∆+fm)  =2(75k+500)=151kHz  ii). fm=5KHz bandwidth B.W=2(∆+fm)  =2(75k+5k)=160KHz iii) fm=10KHz bandwidth B.W=2(∆+fm)  =2(75k+10k)=170KHz As the modulating frequency increases bandwidth also increases.

A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant

Description : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant

Last Answer : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant

Define: 1)Frequency 2)Bandwidth 3)Wavelength 4)Time period

Description : Define: 1)Frequency 2)Bandwidth 3)Wavelength 4)Time period

Last Answer : Frequency: Frequency is the number of cycles per second. Bandwidth: A range of frequencies within a given band, in particular that used for transmitting a signal. Wavelength: Wavelength can be defined as ... for one complete cycle of vibration to pass a given point.  OR Time period=1/frequency

State the frequency range for audio frequency and voice frequency.

Description : State the frequency range for audio frequency and voice frequency.

Last Answer : The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, The usable voice frequency band ranges from approximately 300 Hz to 3400 Hz.

Explain any four different frequency bands and give their two applications of each.

Description : Explain any four different frequency bands and give their two applications of each.

Last Answer : Explain any four different frequency bands and give their two applications of each.

Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.

Description : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.

Last Answer : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.

Write down different frequencies for following(frequency ranges). (1) Voice frequency (2) High frequency (3) IR frequency (4) Visible frequency(light)

Description : Write down different frequencies for following(frequency ranges). (1) Voice frequency (2) High frequency (3) IR frequency (4) Visible frequency(light)

Last Answer : Sr. No Frequency Range 1 Voice Frequency 300 Hz to 3kHz 2 High Frequency  3 MHz to 30 MHz 3 IR Frequency 30 THz to 430 THz 4 Visible Spectrum (light) 375 THz to 750 THz

Draw amplitude modulated waveform in time domain and frequency domain with proper labeling.

Description : Draw amplitude modulated waveform in time domain and frequency domain with proper labeling.

Last Answer : AM in Time domain  AM in frequency domain

Define the terms: 1) Maximum usable frequency 2) Fading

Description : Define the terms: 1) Maximum usable frequency 2) Fading

Last Answer : 1)Maximum usable frequency:- Maximum usable frequency is defined as the limiting frequency ,when the angle of incidence is other than the normal . OR The highest frequency that can be used for sky ... which left the same source but arrived at the destination by different paths is known as fading.

Which of the following circuit would be preferred for a 455 kHz IF amplifier? A) A resistance loaded B) Double tuned transformer C) Video amplifier D) Class C

Description : Which of the following circuit would be preferred for a 455 kHz IF amplifier? A) A resistance loaded B) Double tuned transformer C) Video amplifier D) Class C

Last Answer : B) Double tuned transformer

Define modulation? State the desirable value of modulation index of AM.

Description : Define modulation? State the desirable value of modulation index of AM.

Last Answer : Modulation: It is the process in which any of these Parameters (Amplitude, Frequency, Phase) of high frequency signal (carrier signal) are varied in accordance with low frequency signal(modulating signal) For an AM, modulation index range is 0 to 1.

Explain effect of 'm' on AM with neat waveforms.

Description : Explain effect of 'm' on AM with neat waveforms.

Last Answer : i)m< 1  If m < 1 or if the percentage of modulation is less than 100% the this type of modulation is known as under modulation The amplitude of modulating signal less than carrier ... greater amplitude part of its information is lost in the process of modulation which is undesirable.

Give the expression for modulation index for AM and FM.

Description : Give the expression for modulation index for AM and FM.

Last Answer : 1.Modulation index for AM ma=Vm / Vc Where Vm is modulating voltage Vc is the carrier voltage 2.Modulation index for FM mf=δ /fm where δ is the deviation fm is the modulating frequency

Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application

Description : Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application

Last Answer : Compare AM and FM on the basis of i)Definition ii)Bandwidth iii) Wave propogation iv)Number of sidebands

Explain the demodulation of AM signal using diode detector.

Description : Explain the demodulation of AM signal using diode detector.

Last Answer : Simple diode detector:- Explanation:- This is essentially just a half wave rectifier which charges a capacitor to a voltage nearly to the peak voltage of the incoming AM waveform s(t). ... detector output is proportional to the signal strength. Stronger Am signal higher is the dc AGC voltage.

Draw the block diagram of AM transmitter, explain its operation.

Description : Draw the block diagram of AM transmitter, explain its operation.

Last Answer : AM transmitter is of two types i)High Level AM Transmitter ii)Low Level AM Transmitter i) RF crystal oscillator: It is a source of carrier signal of desired frequency. The circuit is ... AM signal is then applied to the transmitting antenna which radiates this AM signal into air or space. 

Define modulation index in AM and give its formula.

Description : Define modulation index in AM and give its formula.

Last Answer : In AM wave, the modulation index (m) is defined as the ratio of the amplitude of the modulating signal (Vm ) to the amplitude of carrier signal (Vc). m = Vm / Vc

What is the channel bandwidth of a standard analogue telephone system? A. 300-500 Hz B. 1200 kHz C. 100-300 Hz D. 300-3400 Hz

Description : What is the channel bandwidth of a standard analogue telephone system? A. 300-500 Hz B. 1200 kHz C. 100-300 Hz D. 300-3400 Hz

Last Answer : D. 300-3400 Hz

What is the local oscillator (mixer) frequency of the satellite with an uplink frequency in GHz band? A. 3500 MHz B. 4500 MHz C. 2225 MHz D. 2555 MHz

Description : What is the local oscillator (mixer) frequency of the satellite with an uplink frequency in GHz band? A. 3500 MHz B. 4500 MHz C. 2225 MHz D. 2555 MHz

Last Answer : C. 2225 MHz

A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is hanged between two towers. What is the frequency of its third harmonic? A. 727 kHz B. 6546 kHz C. 436 kHz D. 6.546 kHz

Description : A Hertz antenna is operating on a frequency of 2182 kHz and consists of a horizontal wire that is hanged between two towers. What is the frequency of its third harmonic? A. 727 kHz B. 6546 kHz C. 436 kHz D. 6.546 kHz

Last Answer : B. 6546 kHz