Basic Communication II

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When there is decrease in bandwidth, noise current

decreases

When there is increase in bandwidth,

Any of these

______ is caused by the random arrival of carriers at the output element of an electronic device.

Shot Noise

______ refers to any modification to a stream of carriers as they pass from the input to the output of a device produces an irregular, random variations.

Transit Time Noise

_______ is the noise due to single current separating into two or more paths.

Partition Noise

Noise commonly found in transistor.

Shot Noise

_____ is 1/f noise

Flicker Noise

Pink Noise has more energy at lower frequencies less than ______

500 Hz

______ is a f noise and has more energy at higher frequency.

Blue Noise

_______ has less energy at certain band and psychoacoustic equal loudness curve.

Gray Noise

What happens when there is approximation of the signal?

Quantizing Noise

Quantizing Noise occurs in ___?

PCM

_____ occurs when unwanted harmonics of a signal are produced through nonlinear amplification.

Amplitude Distortion

It is the fundamental frequency of harmonics

First Harmonic

______ is the generation of unwanted sum and difference frequencies produced when two or more signals mix in a nonlinear device.

Intermodulation Distortion

It refers to halving or doubling frequency.

Octave

It refers to one tenth or ten times frequency.

Decade

Signal beyond cutoff frequency attenuates at rate of _____ per octave, and ______ per decade.

6 dB, 20 dB

______ is the sum and difference of harmonic frequencies.

Cross Product

The noise temperature is _____

290 K

It is the standard limit for crosstalks.

CCIT G.151

It is standard in intermodulation noise rates on PCM audio channels.

CCIT.172

The reference frequency of CCIT phosphomeric noise measurement.

800 Hz

NIF stands for

Noise Improvement Factor

The reliable measurement for comparing amplifier noise characteristics.

Noise Factor

It indicate how much signal to noise ratio deteriorates as it passes through circuit.

Noise Factor

The receiver characteristics that specifies self generated noise.

Noise Figure

The ideal noise figure.

0 dB

The general way to reduce noise is following except _____

modulating the information signal.

The process of reducing temperature to reduce noise.

Cryogenics

It is small frequencies that separates two neighbouring frequencies to prevent interference.

Guard Band

What is incorporated into receiver to reduce impulse noise?

Noise Blanker

Circuit that boosts high frequency.

Preemphasis

It is used to reduce noise effect in the transmitter.

Preemphasis

It attenuates back the signal to its original form.

Deemphasis

_____ indicates the reduction in the signal-to-noise ratio a signal undergoes as it propagates through a receiver.

Noise Equivalent Temperature

It attenuates the noise of high frequency signals.

Deemphasis

In order to properly suppresses electrical noise in mobile station,

Applying shield and filters

Where does noise generated in VHF Receiver?

Front end

Noise generated at front end receiver primarily determines the ________ in VHF Receiver.

Signal To Noise Ratio

The transmission medium greatly _______ and _________ the transmitted signal.

attenuate and degrades

It is referred as power loss.

Attenuation

Any medium also change signal propagation to a speed _______ the speed of light.

less than

It used to compensate for attenuation.

Amplifier

It is the difference between signal strength and reference level.

Signal Level

It is the common unit of noise measurement in white noise voltage testing.

NPR

It is unit of measurement used to indicate the ratio of a physical quantity with respect to a fixed reference level.

dBa

It is unit of measurement used to indicate the ratio of a power level with respect to a fixed reference level, of 1 milliWatt.

dBm

It is C message weighted, interfering effect of noise.

dBmc

dBrnc is _____

F1A Weighted

A F1A Weighted, 0 deciBel is equal to

-85 dB

It is the power level in which 1 kiloHertz tone causes no interference and is 144 weighted.

-90 dBm

The smallest audible sound.

1 dB

A practical dBrn measurement is always ______

positive

Reference noise level for dBrn is _____

-90 dBm

Reference noise is the noise the creates ____ dBrn in a voice channel.

zero

It refers to 3 deciBel below points

Half Power Points

The following are useful quantity for comparing noise performance except:

Noise Voltage

The lowest noise in receiver.

16 dB

Which solid state device has lowest noise figure in microwave region?

MESFET

What does Noise Weighing Curve shows?

shows interfering effect of other frequencies in a voice channel compared with a reference frequency of one kilohertz.

Noise Density is the total noise power in a ______ bandwidth.

1 kHz

Obviously, _____ SNR is preferred for best performance.

Very high

Which of the following statement is false?

HF amplifier are noiser than HF mixer.

It is highly theoretical study of efficient use of bandwidth to propagate information through electronic communication system.

Information Theory

_______ is measure of how much information can be propagated.

Information Capacity

Information Capacity is measured in _____

bit per second

It relates information capacity to the given bandwidth and transmission time in a noiseless medium.

Hartley's Law

If Bandwidth doubles, the Signal to Noise Ratio ______

decreases by half

It is the process of reducing the information capacity of the system.

Bandlimiting

A typical antenna has gain of _____ deciBel and gain in Nepers of ________.

1, 0.1151

______ are smooth, continuous voltage variations, such as voice or video.

Analog Signals

Which of the following is false?

Analog signals cannot be transmitted digitally.

It contains information.

Any of these

_______ is the direct signal transmission of intelligence signal, without superimposing or impressing it into carrier

Baseband Transmission

______ is a system where digital pulses are transferred between two points in a communication system.

Digital Transmission

_____ is the transmittal of digitally modulated analog carriers between two points in a communication system.

Digital Radio

The following statement is true except:

The baseband signal can be directly transmitted without any attenuation nor absorption and able to preserve itself until reaches receiver.

Which of the following is false except:

Multiplexing is similar process in which a parallel transmission is converted into serial transmission.

The following statement is true except:

In Code Division Multiplexing or CDM, the signals to be transmitted are converted to analog data. The signals modulate a carrier on the same frequency. All use the different communications channel simultaneously.

What is used at the receiver to select the desired signal?

Unique Coding

The most commonly used digital code in communications.

ASCII

_______ convert physical characteristics to electric signals, which modulate a carrier transmitted to a remote location.

Sensor

_______ supplements optical astronomy, by permitting the location, and mapping of stars by the radio waves they emit.

Radio Astronomy

_______ uses the reflection of radio waves from remote objects, for the detection of their presence, direction, and speed.

RADAR

________ is the transmission of computer and other digital data, via the telephone system, microwave links, or satellite.

Digital Transmission

It refers to interconnection of PCs.

LAN

_______ is the range of electromagnetic signals encompassing all frequencies.

Electromagnetic Spectrum

The electromagnetic spectrum is that range of frequencies, from approximately ___ Hertz, to visible light over which electronic communications take place.

30 Hz

It refers to production of radiation by a radio transmitting station.

Emission

_______ is the range of frequencies that contain information.

Bandwidth

It is the range of frequencies required to transmit desired information.

Channel Bandwidth

______ refers to frequency band, in which just sufficient enough to ensure transmission of information, under specified condition and class of emission.

Necessary Bandwidth

What frequency band does the low end of human hearing range is found at?

ELF

What is frequency range of Voice Frequency?

300 Hz to 3000 Hz

What frequency range used in submarine communication?

VLF

Many instruments make sounds in _____

Any of these

What is frequency range of subcarrier?

____ are low frequency signal that carry baseband signal in which in turn modulate the carrier.

Subcarrier

100

At what frequency range is AM used in?

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