Prelim Flashcards by Arct John Zamora

Are time-varying voltages or currents that are continuously

changing such as sine and cosine waves.

analog signals

How well did you know this?

Not at all

Perfectly

Is sometimes referred to as a power loss.

Attenuation

How well did you know this?

Not at all

Perfectly

Is sometimes referred to as a ____________ , If Pout = Pin,

the absolute power gain is 1, and the dB power gain is 0 dB.

Unity Power Gain

How well did you know this?

Not at all

Perfectly

Are voltages or currents that change in discrete steps or

levels.

digital signals

How well did you know this?

Not at all

Perfectly

In 1876, Alexander Graham Bell and Thomas A. Watson were the
first to successfully transfer human conversation over a crude metallic- wire
communications systems using this device.

Telephone

How well did you know this?

Not at all

Perfectly

The first commercial radio broadcasting station in 1920 that

broadcasted amplitude modulated signals in Pittsburgh.

KDKA

How well did you know this?

Not at all

Perfectly

Is a logarithmic unit that can be used to measure ratio.

Decibel ( dB )

How well did you know this?

Not at all

Perfectly

Is a unit of measurement used to indicate the ratio of a power
level with respect to a fixed reference level (1mW).

dBm

How well did you know this?

Not at all

Perfectly

One-tenth of a decibel.

Bel

How well did you know this?

Not at all

Perfectly

A collection of one or more electronic devices or circuits
that converts the original source information to a form more suitable for
transmission over a particular transmission medium.

Transmitter

How well did you know this?

Not at all

Perfectly

Provides a means of transporting signals between a transmitter
and a receiver.

Transmission Medium

How well did you know this?

Not at all

Perfectly

Its fundamental purpose is to transfer information from one

place to another.

Electronic Communication System

How well did you know this?

Not at all

Perfectly

The transmission, reception, and processing of information

between two or more locations using electronic circuits.

Electronic Communication

How well did you know this?

Not at all

Perfectly

A collection of electronic devices and circuits that accepts
the transmitted signals for the transmission medium and then converts those
signals back to their original form.

Receiver

How well did you know this?

Not at all

Perfectly

Is any unwanted electrical signals that interfere with the

information signal.

System Noise

How well did you know this?

Not at all

Perfectly

Because it is often impractical to propagate information
signals over standard transmission media, it is often necessary to modulate
the source information onto a higher-frequency analog signal called a

Carrier

How well did you know this?

Not at all

Perfectly

The process of changing one or more properties of the analog

carrier in proportion with the information signal.

Modulation

How well did you know this?

Not at all

Perfectly

A system in which energy is transmitted and received in analog
form (a continuously varying signals such as a sine wave).

Analog Communication System

How well did you know this?

Not at all

Perfectly

A true digital system where digital pulses (discrete levels
such as +5V and ground) are transferred between two or more points in a
communications system.

Digital Transmission

How well did you know this?

Not at all

Perfectly

The transmittal of digitally modulated analog carriers between
two or more points in a communications system.

digital radio

How well did you know this?

Not at all

Perfectly

A modulation technique where the information signal is analog
and the amplitude (V) of the carrier is varied proportional to the
information signal.

Amplitude Modulation ( AM )

How well did you know this?

Not at all

Perfectly

A modulation technique where the information signal is analog
and the frequency (f) of the carrier is varied proportional to the
information signal.

Frequency Modulation ( FM )

How well did you know this?

Not at all

Perfectly

A modulation technique where the information signal is analog
and the phase (q) of the carrier is varied proportional to the information
signal.

Phase Modulation

How well did you know this?

Not at all

Perfectly

A modulation technique where the information signal is digital
and that amplitude (V) of the carrier is varied proportional to the
information signal.

Amplitude Shift Keying ( ASK )

How well did you know this?

Not at all

Perfectly

A modulation technique where the information signal is digital and the frequency (f) of the carrier is varied proportional to the information signal.

Frequency Shift Keying ( FSK )

A modulation technique where the information signal is digital and the phase (q) of the carrier is varied proportional to the information signal.

Phase Shift Keying | PSK

A modulation technique where both the amplitude and the phase of the carrier are varied proportional to the information signal.

Quadrature Amplitude Modulation | QAM

Modulation is performed in a transmitter by a circuit called

Modulator

The reverse process of modulation and converts the modulated | carrier back to the original information.

Demodulation

Demodulation is performed in a receiver by a circuit called

Demodulator

2 Reasons why modulation is necessary in | electronic communications :

1. It is extremely difficult to radiate low-frequency signals from an antenna in the form of electromagnetic energy. 2. Information signals often occupy the same frequency band and, if signals from two or more sources are transmitted at the same time, they would interfere with each other.

A specific band of frequencies allocated a particular service.

Channel

Process of converting a frequency or band of frequencies to | another location in the total frequency spectrum.

Frequency Translation

The purpose of an electronic communications system is to | communicate information between two or more locations commonly called

Stations

The number of times a periodic motion, such as a sine wave of voltage or current, occurs in a given period of time.

Frequency

Each complete alternation of the waveform.

Cycle

Is an international agency in control of allocating | frequencies and services within the overall frequency spectrum.

International Telecommunications Union ( | ITU)

Are signals in the 0.3THz to 300THz range and are not generally referred to as radio waves. Used in heat seeking guidance systems, electronic photography, and astronomy.

Infrared

Includes electromagnetic frequencies that fall within the | visible range of humans (0.3PHz to 3PHz).

Visible Light

Used for optical fiber systems.

Light-wave Communications

The length that one cycle of an electromagnetic wave occupies in space

Wavelength

Radio transmitter classifications according to bandwidth, | modulation scheme, and type of information.

Emission Classifications

The two most significant limitations on the performance of a | communications system are ________and ________.

Noise and Bandwidth

The difference between the highest and lowest frequencies | contained in the information.

Bandwidth

The bandwidth of a communications channel is the difference between the highest and lowest frequencies that the channel will allow to pass through it.

Passband

A highly theoretical study of the efficient use of bandwidth | to propagate information through electronic communications systems.

Information Theory

The measure of how much information can be propagated through a communications system and is a function of bandwidth and transmission time.

Information Capacity

The most basic digital symbol used to represent information.

Binary Digit / Bit

The number of bits transmitted during one second and is | expressed in bits per second (bps).

Bit Rate

In 1948, mathematician Claude E. Shannon published a paper in the Bell System Technical Journal relating the information capacity of a communications channel to bandwidth and signal-to-noise ratio.

Shannon limit for information capacity

In 1948, mathematician Claude E. Shannon published a paper in the Bell System Technical Journal relating the information capacity of a communications channel to bandwidth and signal-to-noise ratio.

Shannon limit for information capacity

I = Blog2(1+S/N)

Shannon limit for information capacity

Any undesirable electrical energy that falls within the | passband of the signal.

Electrical Noise

Noise present regardless of whether there is a signal present or not.

Uncorrelated Noise

Noise that is generated outside the device or circuit.

External Noise

Noise that is naturally occurring electrical disturbances that originate within Earth’s atmosphere.

Atmospheric Noise

Atmospheric noise is commonly called

Static Electricity

Noise consists of electrical signals that originate from | outside Earth’s atmosphere and is sometimes called deep-space noise.

Extraterrestrial Noise

Extraterrestrial noise is sometimes called

Deep-Space Noise

Noise generated directly from the sun’s heat.

Solar Noise

Noise sources that are continuously distributed throughout the galaxies.

Cosmic Noise

Noise that is produced by mankind.

Man-made Noise

Electrical interference generated within a device or circuit.

Internal Noise

Noise caused by the random arrival of carriers (holes and | electrons) at the output element of an electronic device.

Shot Noise

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

Associated with the rapid and random movement of electrons | within a conductor due to thermal agitation

Thermal Noise

THERMAL AGITATION HAS SEVERAL NAMES, | INCLUDING :

Ø Thermal Noise, because it is temperature dependent; Ø Brownian Noise, after its discoverer; Ø Johnson Noise, after the man who related Brownian particle movement of electron movement; Ø White Noise, because the random movement is at all frequencies;

Johnson proved that ___________ is proportional to the | product of bandwidth and temperature.

Noise Power

Noise Power Formula

N = KTB

A form of internal noise that is correlated (mutually related) to the signal and cannot be present in a circuit unless there is a signal. “ no signal, no noise! “

Correlated Noise

Noise that is only present with the signal.

Correlated Noise

Occurs when unwanted harmonics of a signal are produced | through nonlinear amplification (nonlinear mixing).

Harmonic Distortion

The generation of unwanted sum and difference frequencies | produced when two or more signals mix in a nonlinear device.

Inter-modulation Distortion

The original signal is called

Fundamental Frequency

Fundamental Frequency is also called

First Harmonic

A frequency two times the original signal frequency.

Second Harmonic

A frequency three times the original signal frequency.

Third Harmonic

Another name for harmonic distortion.

Amplitude Distortion

Characterized by high-amplitude peaks of short duration in the total noise spectrum.

Impulse Noise

A form of external noise and as the name implies it means to | disturb or detract form.

Interference

Noise produced when information signals from one source produce frequencies that fall outside their allocated bandwidth and interfere with information signals from another source.

Electrical interference

he ratio of the signal power level to the noise power level

Signal-to-Noise Power Ratio ( S/N )

Figures of merit used to indicate how much the signal – to-noise ratio deteriorates as a signal passes through a circuit or series of circuits (unitless)

Noise Factior (F)

Figures of merit used to indicate how much the signal – to-noise ratio deteriorates as a signal passes through a circuit or series of circuits (dB)

Noise Figure (NF)

Formula for Noise Figure (NF)

10logF

A convenient parameter often used rather than noise figure in low noise, sophisticated VHF, UHF, microwave, and satellite radio receivers. It indicates the reduction in the signal-to-noise ratio a signal undergoes as it propagates through a receiver.

Equivalent Noise Temperature ( Te ) Te = T ( F – 1 )

Transfer information from one place to another

Electronic Communications System

Transmission, reception and processing of information between two or more locations using electronic circuits

Electronic Communications System

broadcast first licensed radio transmission

KDKA

Use to measure magnitude of earthquakes, intensity of acoustical signals, power ratios, voltage and current ratios, etc.

DECIBEL (dB)

A transmission-measuring unit used to express relative gains and losses of electronic devices and circuits

DECIBEL (dB)

The measurement unit of choice for virtually all EM frequency bands from ultralow frequencies to light-wave frequencies terminated in a variety of impedances

dBm

A process of changing one or more properties of an analog carrier in proportion with the information signal

Modulation and Demodulation

is an information signal that has been acted on by a carrier

MODULATED WAVE/MODULATED SIGNAL

Why do we need to MODULATE???

It is extremely difficult to radiate low-frequency signals from an antenna in the form of EM energy & Information signals often occupy the same frequency band and if signals from two or more sources are transmitted at the same time, they would interfere with each other

Band Number and Designation of a 30 Hz to 300 Hz frequencies

BN: 2 | Extremely Low Frequencies (ELF)

Band Number and Designation of a 0.3 kHz to 3 kHz frequencies

``` BN: 3 Voice Frequencies (VF) ```

Band Number and Designation of a 3 kHz to 30 kHz frequencies

BN: 4 | Very Low Frequencies (VLF)

Band Number and Designation of a 30 kHz to 300 kHz frequencies

BN: 5 | Low Frequencies

Band Number and Designation of 0.3 MHz to 3 MHz frequencies

BN: 6 | Medium Frequencies

Band Number and Designation of 3MHz to 30 MHz frequencies

BN: 7 | High Freqencies

30 MHz to 300 MHz

8 | Very High Frequencies (VHF)

300 MHz to 3 GHz

9 | Ultra High Frequencies (UHF)

3 GHz to 30 GHz

10 | Super High Frequencies (SHF)

30 GHz to 300 GHz

11 | Extremely High Frequencies (EHF)

Ambient Absolute Temperature (T)

290K

Friiss' Formula

FT(Total Noise Factor) = F1 + (F2-1)/A1 + (F3-1)/A1A2 + ... +(Fn-1)/A1A2...An

Noise Factor Formula

F = (inp SNR/outp SNR

Noise Figure Formula

NF = 10logF