Amplitude Modulation II

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It consists of Bandpass filters used in amplification and selectivity.

IF Section

Wider bandwidth in the filters in IF Section can cause

undesirable signal to reach in the Audio Section.

_____ occurs during CW Reception if not too narrow a filter bandwidth is used in the IF stage.

Filter Ringing

Which component is not always found in every superheterodyne receiver?

RF Amplifier

Which component in a receiver that improve receiver's noise figure?

RF Amplifier

What is needed done in RF Amplifier to allow weak signals to overcome noise in first mixer?

sufficient gain is needed

When sufficient gain is needed in RF Amplifier to allow weak signals to overcome noise in first mixer to __________.

prevent spurious mixer products

Spurious mixer products are generated when _______

excessive signal energy reaches mixer.

What is needed to prevent spurious oscillation?

Neutralization of RF amplifier

In order to prevent spurious oscillation, the of RF Amplifier ______, rather than neutralizing it.

can be grounded

A transistor in RF amplifier can be tuned for ________

minimum Collector Current in same stage.

It is required in high-performance microwave receivers as the input stage of the RF section to optimize their noise figure.

Low Noise Amplifier

It operate over a relatively narrow, fixed frequency band that aims for selectivity.

First Stage IF Amplifier

If Fet is used as Audio Frequency Amplifier,

it will cause insufficient gain and selectivity.

In most mixers, oscillator frequency is _____ carrier frequency.

higher than

It is the difference between the level of the IF output with an RF input signal to the level of the IF output with an IF input signal.

Conversion Gain

It refers to low frequency oscillations.

Motorboating

Motorboating can be stopped by following except:

By installing capacitor between B + and Lead Ground.

A configuration where the mixer excites itself by feeding energy back to the local oscillator tank circuit to sustain oscillations noise figure.

Self Excited Meter

Linear balance modulator that uses sine wave carrier to produce Double Sideband signals.

Analog Modulator

It is frequency that falls between radio frequency and baseband frequency.

Intermediate Frequency

Intermediate frequency is produced by local oscillator at frequency of:

455 kHz

What must be considered when selecting Intermediate Frequency?

Cross Modulation

Which produce AM at very high frequencies?

PIN Diode

It is the difference in decibels between the minimum input level necessary to discern a signal and the input level that will overdrive the receiver and produce distortion.

Dynamic Range

It refers to input power range over which receiver is useful.

Dynamic Range

Poor Dynamic Range are caused by following except:

Sensitivity

It is the ability of receiver to perform well in the presence of strong signals.

Blocking Dynamic Range

It refers to the output power when the RF amplifier response is 1 dB less than the ideal linear-gain response.

1 dB Compression Point

What is the maximum sideband suppression value using filter system?

50 dB

It occurs when unwanted signal is impressed into desired carrier.

Cross Modulation

It is the ratio of the bandwidth 60dB below maximum signal level and bandwidth 3dB below maximum signal level.

Any of these

Bandwidth Improvement is the noise reduction ratio achieved by:

reducing the Bandwidth.

What distortion is predominantly caused by filtering?

Phase Distortion

The total phase shift encountered by a signal, and can generally be tolerated as long as all frequencies undergo the same amount of phase delay.

Absolute Phase Shift

It occurs when different frequencies undergo different phase shifts and have a detrimental effect on a complex waveform.

Differential Phase Shift

What does non uniform gain in filters and amplifiers causes?

Amplitude Distortion

What happens when frequency present in received signal but not present in original source?

Frequency Distortion

It is special case of intermodulation distortion and predominant cause of frequency distortion.

Second Order Intercept Distortion

The ratio of the power transferred to a load with a filter in the circuit to the power transferred to a load without the filter.

Insertion Loss

It is the parameter associated with the frequencies fall within passband of a filter.

Insertion Loss

It is hypothetical value that cannot be directly measured, and used in low-noise, sophisticated radio receivers rather than noise figure.

Noise Equivalent Temperature

It is frequency synchronized to oscillator frequency.

Synchronous Receiver

No frequencies are generated in the receiver or the frequencies used for demodulation are completely independent from the transmitter’s carrier frequency.

Asynchronous Receiver

Technique where TRF receiver’s instability can be reduced somewhat by tuning each amplifier to a slightly different frequency, slightly above or below the desired center frequency.

Staggered Tuning

It means that the two adjustments are mechanically tied together so that a single adjustment will change the center frequency of the preselector and, at the same time, change the local oscillator frequency.

Gang Tuning

A broad-tuned bandpass filter with an adjustable center frequency that is tuned to desired carrier frequency

Preselector

Preselector provide initial enough bandlimiting to _____

prevent a specific unwanted RF from entering the receiver

It occurs when the local oscillator is tuned above the RF.

High Side Injection

It refers to the side frequencies undergo a sideband reversal during the heterodyning process.

Sideband Inversion

It is any frequency other than the selected radio frequency carrier that, if allowed to enter a receiver and mix with the local oscillator, will produce a cross-product frequency that is equal to the intermediate frequency.

Image Frequency

Which circuit does not reject image frequency?

IF Section

The ability of the local oscillator in a receiver to oscillate above or below the selected radio frequency carrier by an amount equal to the IF.

Tracking

The difference between the actual oscillator frequency and the desired frequency.

Tracking Error

The tracking error can be prevented by:

Three Point Tracking

Three point tracking can be achieved using:

Padder Capacitor

It occurs when a receiver picks up the same station at two nearby points on the receiver tuning dial.

Double Splotting

Double Splotting is caused by following factors except:

low gain

What is the most common technique for coupling IF transformers?

Inductive Coupling

Stray coupling can be minimized by:

keeping leads shorter as possible

What occurs when there is loose coupling between the RF stages?

high selectivity

It is point where the reflected resistance is equal to the primary resistance and the Q of the primary tank circuit is halved and the bandwidth doubled.

Critical Coupling

It is caused by the reactive element of the reflected impedance, being significant enough, to change the resonant frequency of the primary tuned circuit.

Double Peaking

It refers to peak output in a double tuned circuit.

Optimum Coupling

It refers to maximum bandwidth in a double tuned circuit.

Over Coupling

Optimum Coupling is the coefficient of coupling approximately ______ the critical value yields a good compromise between flat response and steep skirts.

50% greater than

IF transformer come as specially designed tuned circuits in groundable metal packages.

IF Cans

It refers to circuit wherby primary and secondary sides of transformer are tuned tank circuit.

Double Tuned

What material is contained in the core of IF Transformer?

Powdered Iron

In a receiver, there is crackling sound can be heard even there is no input signal at all. What circuit is used to eliminate this?

Squelch

It remove sporadic, high-amplitude noise transients of short duration, such as impulse noise in the audio section of a receiver. The following circuit has this function except:

Any of these

The clipper or limiter can remove ______

Splatter

PLL receivers need only two external components which are:

Volume Control and Station Tuning Control

The ratio of the demodulated audio output signal level to the RF input signal level.

Net Receiver Gain

The picture portion of a commercial television broadcasting signal.

Vestigial Sideband System

Sideband with no or reduced carrier, improves following except:

Carrier Gain

It refers to the two sidebands and carrier may propagate through the transmission media by different paths and therefore, experience different transmission impairments with double-sideband transmission.

Selective Fading

Which of the following statement is false?

FM and Double Sideband does not suffer from selective fading.

Form of selective fading where there is a reduction of the carrier level of a 100% modulated wave that will make the carrier voltage less than the vector sum of the two sidebands.

Carrier Amplitude Fading

It is condition where the relative positions of the carrier and sideband vectors of the received signal change, causing a decided change in the shape of the envelope, causing a severely distorted demodulated signal.

Carrier Phase Shift

The small carrier component that is always present in the output signal of a balanced modulator.

Carrier Leak

It is reflected energy that cancels and attenuates the incident wave energy.

Destructive Interference

The reflected energy that aids the incident wave energy.

Constructive Interference

It is the difference produced between the transmit and receive local oscillator frequencies in the demodulated information signal.

Frequency Offset Error

It refers to distinction by a normal listeners of 50 hertz or more offset.

Tonal Variation

A narrowband PLL that tracks the pilot carrier in the composite SSBRC receiver signal, and uses the recovered carrier to generate coherent local oscillator frequencies in the synthesizer.

Carrier Recovery Circuit

Systems that provide narrowband voice communications for land-mobile services with nearly the quality achieved with FM systems and do it using less than one-third the bandwidth.

Amplitude Companding Single Sideband

How many voice transmission can be packed into given band for amplitude companded single sideband over conventional FM?

Device mainly used to increase the range of portable and mobile stations.

Repeaters

A small, audible change in a transmitter’s frequency each time it is keyed.

Chirp

The safest way to work on a transmitter or a power supply is ______

turning off the power first

It prevents a portion of signal radiating from its leads.

Neutralization Capacitor

It feed a portion of signal.

Feedthrough Capacitor

The process of cancelling the capacitance of internal device.

Neutralizing

It is caused by strong interference from nearby transmitters.

Receiver Overload

Diagonal Clipping in envelope detection result to ______.

distortion

The 100 MHz carrier signal is modulated by 2.5 MHz audio signal. What will be the sideband frequency?

102.5 MHz

An unmodulated wave has peak to peak voltage of 14 V. When it is modulated, it is increases to peak to peak voltage of 26 V. What is the percent modulation?

85.7%

What is the range of Peak Envelope Power of 90 Watt Transmitter?

22.5 W to 30 W

100

What is the power saving of 25% Modulated Carrier having a supressed carrier?

96.9%

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