analog 3 test 1

modulation

the process of putting information onto a high-frequency carrier for transmission

intelligence signal

low frequency information modulated onto a high frequency carrier in a transmitter

demodulation

process of removing intelligence from the high frequency carrier in a receiver

transducer

a device that converts energy from one to another

dB(decibel)

a unit of measurment used in frequently in electronic communication to describe power gain or loss

electrical noise

any desired voltages or currents that end up appearing in a circuit

man made noise

a noise produced by spark-producing mechanisms such as engine ignition systems and fluerescent lights

static electrical noise

a noise that may occur in the output of a receiver

external noise

noise in a recieved radio signal that has been introduced by the transmutting medium

internal noise

noise in a radio signal that has been introduced by the receivers internal components (resisters, transisters, excess noise

wave propagation

movement of radio signals through the atmosphere from transister to reciever

excess noise

a noise that occurs at extremely low and high frequencies in amplifiers contains resisters also known as transit-time noise

atmospheric noise

external noise caused by naturally occurring disturbances in the earths atmosphere

spare noise

external noise produced outside the earths atmosphere

solar noise

space noise originating from the sun

cosmic noise

spare noise originating from stars other than the sun

equivalant noise temperature

is a convenient means of handling noise calculations involved with microwave recievers

thermal noise

internal noise caused by thermal interactions between free electrons and vibrating ions in a conductor

shot noise

noise introduced by carriers in the Pn junction of semiconductors, directly related to DC currents

white noise

another name for thermal noise because its frequency content is uniform access its spectrum

johnson noise

another name for thermal noise

oscillator

most basic building block in a communication system. it is capable of converting energy from a dc form to ac; in other words, an oscillator generates a waveform

crystal oscillator

provides it highest frequency stability of any oscillator

communication system block

dB References: Dbm

the db using a 1mw reference, is the typical measurment for audio input/output specification. this measurment is also used in low power optical transmitter specification

dB References: Dbm 50

standard defined by 1mw measured with respect to a 50 ohm load. this measurement is commonly used in radio frequency transmission/receiving system

dB References: Dbm 75

the standard defined by 1mw measured with respect to a 75 ohm load

dB References: Dbm dbw

common form per power amplification relative to a law reference(usually 50 ohm). typical applications are found in specification for radio-frequency power amplifier and high power audio amplifier

hartleys law

states that the information that can be transmitted is proportional to the product of the bandwidth utilized times the time of transmission. in other words , the greater the bandwidth, the more information that can be transmitted expressed as an equation

hartleys law example

the human ear is capable of hearing frequencies somewhere between 20hz and 20k hz. therefor, jf a radio station is to broadcast the full range they must have a minimum bandwidth allocates to from from the fcc,of 20khz this is why am stations have been allocated about 30khz and the fm stations about 20khz

fourier analysis

a method of analyzing complex repetitive waveforms. it permits any complex repetitive waveform to be resolved into a series of sine or cos waves. the mathematical tool provided in fourier analysis helps one to understand the meaning of hermonics

the fundamental frequency (sinwt) of a waveform is also referred to as _

the first harmonic w = 2pif. t= time

harmonics

sinusoidal waves whose frequencies are a multiple of the fundamental frequency

tank circuit

after capacitor has been charged to some potential the switch would then be closed, and the resulting waveform would then be created, this is the result of repetitive exchange in energy between the inductor and capacitor