Chapter 5

Question 1

The reverse process of AM modulation.

Answer 1

AM Demodulation

Question 2

The first stage of the receiver of which primary functions are detecting, band limiting, and amplifying the received.

Answer 2

RF Section

Question 3

This section down-converts the received RF frequencies to intermediate frequencies (IFs).

Answer 3

Mixer /

Converter

Question 4

This section primary functions are amplification and selectivity.

Answer 4

IF Section

Question 5

This section demodulates the AM wave and converts it to the original information signal.

Answer 5

AM Detector

Question 6

This section amplifies the recovered information. Comprises several cascaded audio amplifiers and one or more speakers.

Answer 6

Audio Section

Question 7

A receiver parameter that is used to measure the ability of the receiver to accept a given band of frequencies and reject all others.

Answer 7

Selectivity

Question 8

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

Answer 8

Shape Factor

Question 9

The most prevalent form of noise and is directly proportional to bandwidth.

Answer 9

Thermal Noise

Question 10

Noise reduction ratio achieved by reducing the Bandwidth.

Answer 10

Bandwidth Improvement

Question 11

The corresponding reduction in the noise figure due to the reduction in bandwidth expressed mathematically in dB.

Answer 11

Noise Figure Improvement

Question 12

The ________ of a receiver is the minimum RF signal level that can be detected at the input to the receiver and still produce a usable demodulated information signal.
Also known as receiver threshold.

Answer 12

Sensitivity

Question 13

Defined as 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.

Answer 13

Dynamic Range

Question 14

Defined as the output power when the RF amplifier response is 1 dB less than the ideal linear-gain response.

Answer 14

1-dB Compression Point

Question 15

A measure of the ability of a communication system to produce, at the output of the receiver, an exact replica of the original source information.

Answer 15

Fidelity

Question 16

Any frequency, phase, or amplitude variations that are present in the demodulated waveform that were not in the original information signal.

Answer 16

Distortion

Question 17

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.

Answer 17

Absolute Phase Shift

Question 18

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

Answer 18

Differential Phase Shift

Question 19

Defined as 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.

Answer 19

Insertion Loss

IL

Question 20

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

Answer 20

Equivalent Noise Temperature

Question 21

The frequencies generated in the receiver and used for demodulation are synchronized to oscillator frequencies generated in the transmitter.

Answer 21

Coherent /

Synchronous Receiver

Question 22

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

Answer 22

Noncoherent /

Asynchronous Receiver

Question 23

One of the earliest types of AM receivers and are probably the simplest designed radio receivers available today.

Answer 23

Tuned Radio Frequency

Question 24

A phenomenon at radio frequencies where current flow is limited to the outermost area of a conductor.

Answer 24

Skin Effect

Question 25

A 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.

Answer 25

Stagger Tuning

Question 26

Means to mix two frequencies together in a nonlinear device or to translate one frequency to another using nonlinear mixing.

Answer 26

Heterodyne

Question 27

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

Answer 27

Preselector

Question 28

The most common intermediate frequency used in AM broadcast-band receivers is ________.

Answer 28

455 kHz

Question 29

Consists of a series of IF amplifiers and bandpass filters and is often called IF strip.

Answer 29

IF Section

Question 30

Refer to frequencies that are used within a transmitter or receiver that fall somewhere between the radio frequencies and the original source information frequencies.

Answer 30

Intermediate Frequency

Question 31

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.

Answer 31

Gang Tuning

Question 32

When the local oscillator is tuned above | the RF it is?

Answer 32

High-side Injection / | High-beat Injection

Question 33

When the local oscillator is tuned below | the RF it is?

Answer 33

Low-side Injection / | Low-beat Injection

Question 34

The side frequencies undergo a sideband reversal during the heterodyning process called?

Answer 34

Sideband Inversion

Question 35

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 intermediate frequency throughout the entire radio frequency band.

Answer 35

Tracking

Question 36

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

Answer 36

Tracking Error

Question 37

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. Unwanted frequency

Answer 37

Image Frequency

Question 38

A numerical measure of the ability of a preselector to reject the image frequency.

Answer 38

Image-frequency Rejection Ratio

Question 39

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

Answer 39

Double Spotting

Question 40

A high-gain, low-noise, tuned amplifier that, when used, is the first active stage encountered by the received signal.

Answer 40

RF Amplifier

Question 41

High-performance microwave receivers require a ________ as the input stage of the RF section to optimize their noise figure.

Answer 41

Low-noise Amplifier | LNA

Question 42

A FET with a metal-semiconductor junction at the gate of the device, called a Schottky barrier.

Answer 42

MEsa Semiconductor FET Semiconductor FET | MESFET

Question 43

A wideband, unconditionally stable, low-power, dual-gain linear integrated-circuit RF amplifier manufactured by Signetics Corporation.

Answer 43

NE / SA5200

Question 44

This section purpose is to down-convert the incoming radio frequencies to intermediate frequencies proportional to bandwidth.

Answer 44

Mixer / | Converter Stage

Question 45

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.

Answer 45

Conversion Gain

Question 46

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

Answer 46

Self-excited Mixer

Question 47

A low-power VHF monolithic double-balanced mixer with input amplifier, on-board oscillator, and voltage regulator.

Answer 47

NE / SA602A

Question 48

Are relatively high-gain amplifiers that are very similar to RF amplifiers, except that IF amplifiers operate over a relatively narrow, fixed frequency band.

Answer 48

Intermediate Frequency | ( IF ) Amplifier

Question 49

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

Answer 49

Double Peaking

Question 50

The coefficient of coupling approximately 50% greater than the critical value yields a good compromise between flat response and steep skirts.

Answer 50

Optimum Coupling

Question 51

IF transformers come as specially designed tuned circuits in groundable metal packages called _______.

Answer 51

IF Cans

Question 52

The function of this circuit is to demodulate the AM signal and recover or reproduce the original source information.

Answer 52

AM Detector

Question 53

A simple noncoherent AM demodulator using a diode. Also called as diode, shape, or envelope detector.

Answer 53

Peak Detector

Question 54

A distortion in the detection process where the RC time constant is too short, the output waveform resembles a half-wave rectified signal.

Answer 54

Rectifier Distortion

Question 55

A distortion in the detection process where the RC time constant is too long, the slope of the output waveform cannot follow the trailing slope of the envelope.

Answer 55

Diagonal Clipping

Question 56

A circuit that compensates for minor variations in the received RF signal.

Answer 56

Automatic Gain Control | AGC

Question 57

It prevents the AGC feedback voltage from reaching the RF or IF amplifiers until the RF level exceeds a predetermined magnitude.

Answer 57

Delayed AGC

Question 58

Is similar to conventional AGC except that the receive signal is monitored closer to the front end of the receiver and the correction voltage is fed forward to the IF amplifiers.

Answer 58

Forward AGC

Question 59

Are used to remove sporadic, high-amplitude noise transients of short duration, such as impulse noise in the audio section of a receiver.

Answer 59

Limiters / | Clippers

Question 60

This receivers would need only two external components: a volume control and a station tuning control.

Answer 60

PLL Receivers

Question 61

The ratio of the demodulated signal level at the output of the receiver (audio) to the RF signal level at the input to the receiver, or the difference between the audio signal level in dBm and the RF signal level in dBm.

Answer 61

Net Receiver Gain