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116 Cards in this Set
 Front
 Back
Modulation

put information on high frequency carrier


intelligence single

low frequency information


demodulation

remove in the intelligence from the modulation


transducer

converts energy from one form to another


deciels (db)

calculated values in noise analysis with respect to a standard or specific reference


reference voltage equation

db = 10 log P2/ P1 or 10 log V2^2 / V1^2


voltage gain equation

db = 20 log V2/V1


1 mw equals how many db?

0db


db micoV equation

20 log V2 / 1 microV


electrial noise

undesired voltages or currents or static


external noise

noise in receiver introduced by transmission medium


internal noise

noise caused by the receiver


wave propogation

movement of radio signals through the atmosphere from transmitter to receiver


atmosperic noise

external noise caused by disturbances in Earth atmosphere


Space noise

from outer space


solar noise

cycle, peaks about every 11 years


cosmic noise

from other stars not our sun


thermal, Johnson, or white noise

caused by interaction between the free electrons in vibrating ions in a conductor


power noise equation

Pn = KT deltaF = watts K = 1.38e23, T = resistor temp in kelvin, deltaF = Freq band width of the system


(RMS) noise voltage equation

en = sqr(4K * T * deltaF * R)


how do you convert Celsius to Kelvin?

Add 273


lownoise resistor

resistor with low level of thermal noise


shot noise

noise introduced by carriers in that pn junctions of semiconductors


excess (flicker, pink) noise

at <1kHz, varying in aptitude inversely proportional to frequency


Transittime noise

in semiconductors, when transit time of the carriers crossing a junction is close to the signals., some defuse back to the source or a meter of the semi conductor


signaltonoise ratio equation

signal power / noise power = 10 log Ps / Pn = db (P = V^2/R)


noise figure

how noisy a device is in db's


NF noise figure equation

10 log NR = db


NR noise ratio

input / output (Si/Ni) / (So/No) S = signal, N = noise


octave

upper frequency is double lower frequency


Equivalent bandwidth equation

DeltaFeq = (pi/2)*BW


Friiss's formula purpose

method determined total noise in multistate system (amplifier stages in cascade)


equivalent noise temperature

usually for microwave receivers (>1GHz) especially space systems


equivalent noise temperature equation

Teq = To( NR  1) To = 290 K (kelvin)


SINAD

the effects of noise and distortion on an amplifier or receiver


diode noise generator

use a diode that produces a known noise unto the amplifier under test


DUT device under test

an electronic part or system that you are testing


noise ratio equation

NR = 20 Idc * R I = amps, R = impedance of DUT, T = 290k (room temp)


what is kelvin room temperature

290k


tangential method

method of measuring the amplitude of noise on a signal using an oscilloscope display


information theory

concerned with optimization of transmitted information


channel

a band of frequencies


Hartley's law

greater bandwidth, more information sent information * bandwidth * time of transmission


fourier analysis

method of representing complex repetitive waveforms by sinusoidal (sinewave) components


FFT fast fourier transform

a technique for converting timevarying information to its frequency component


Frequency domain record

data points generated by a time to frequency conversion using the FFT


Aliasing

errors that occur when the input frequency exceeds onehalf the sample rate


practical inductors

(chokes or coils) used at RF (radio frequency) and above


Q quality

ratio of energy stored to, energy loss in a component


leakage

loss of electrical energy between the plates of a capacitor


inductor Q equation

reactance / resistance = w L / R


Capacitor Q equation

susceptance / conductance = w C / G 1000 is a good Q


dissipation D

1/Q (check on this)


resonace

circuit a condition whereby the inductive and capacitive reactance have been balanced (Xl = Xc)


Resonant frequency equation

Fr = 1 /[ 2pi sqr(L*C) ] = Hz


voltage out equation

e out = e in * R2 / (R1 + R2) = volts


total impedance equation

Z total = sqr[ (R1 + R2)^2 + (Xl  Xc)^2] = ohms


XL inductive reactance equation

2pi * F * L F = ohms


XC capacitive reactance equation

1 / (2pi * F * C ) = ohms


Z out equation

sqr[ R2^2 + (Xl  Xc)^2] = ohms


filters bandwidth equation

BW = R / 2pi * L BW(Hz), R = resistance total, L = circuit inductance


filter quality factor equation

Q = Fr / BW


what is a tank circuit?

A parallel LC circuit L = inductor, C = capitor


Poles

Number of RC or LC sections in a filter


constantK filter

filter whose capacitive and inductive reactance are equal to a constant value k


mderived filters

filters that uses a two circuit to provide nearly infinite attenuation at a specific frequency


rolloff

the rate the attenuation in a filter


stray capacitance

undesired capacitance between two points in a circuit or a device


when does an inductor start to look like a complex RLC circuit?

At high frequency


Z max equation

Q^2 * R (maximum impedance)


Harmonics

is the nth multiple of the base frequency (it spikes on every odd harmonic)


oscillator

converts energy from DC to AC


flywheel affect

repetitive ex change of energy in a LC circuit from the inductor to the capactor and back


damped

the gradual reduction of a repetitive signal to resistive losses


continuous wave

on dampened sinusoidal waveform produced by an oscillator in a radio transmitter


Barkhausen criteria

two requirements for oscillations: loop gain must be at least unity and looked phase shift must be 0°


What is the advantage of an crystal oscillator?

Have high Q's > 20,000 > a million over a wide temperature range. Grade I keep in frequency +/ .001 % or +/ 10 ppm (parts per million)


Frequency synthesizer

oscillator that generates a wide range of output frequencies use in one reference crystal oscillator


modulation

impressing a lowfrequency intelligence signal onto a higherfrequency carrier signal


nonlinear device

characterized by a nonlinear output versus input signal relationship (hua?)


AM waveform (envelope) equation

e = (Ec + Ei * Sin wi * t) sin wc * T Ec = peak amplitude of carrier signal, Ei = peak amplitude of intelligence signal, Wi T = radio and frequency of intelligence, Wc T = radio and frequency of carrier signal, w = 2pi * F


Upper sideband (USB)

band of frequency produced in a modulator from a creation of sum frequencies between the carrier and the information signals


lower sideband(LSB)

same as USB, just lower end


angular velocity (w)

the rate of phasor rotation


percentage modulation

measure of the extent to which a carrier voltage is varied by the intelligence (for AM systems)


percentage modulation equation

%m = Ei / Ec * 100% (ratio remove 100%)


modulation index

percentage modulation from 0  1 (m = Ei / Ec)


over modulation

excessive intelligence signal overdrive's an AM modulator producing > 100% modulation


sideband splatter

distortion resulting in an over modulated AM transmission creating excess of bandwidth


What is ei?

Intelligence signal


sidefrequency aptitude equation

Esf = (m * Ec) / 2, Esf = sidefrequency aptitude, m = modulation index, Ec = carrier amplitude


transmitted power Total equation

Pt = Pc (1 + M^2 / 2) = Watts, Pt = transmitted power (sideband's and carrier), Pc = carrier power, m = modulation index


transmitted current total equation

It = Ic*sqr( 1 + M^2 / 2), It = total transmitted current, Ic = carrier current, M = modulation index


effective modulation index equation (when modulated by more than one signal)

Meff = sqr( M1^2 + M2^2 + ...)


Base modulation

a modulation system in which the intelligence is injected into the base of a transmitter


highlevel modulation

intelligence superimposed on the carrier at the last point before the antenna (for AM), most efficient for high power AM radio


lowlevel modulation

intelligence superimposed on the care, and THEN amplified before the antenna


neutralizing capacitor

a capacitor that cancels fedback signals to suppress selfoscillation


parasitic oscillations

higherfrequency selfoscillations in RF amplifiers


Modulated amplifier

stage that generates the AM signal


driver amplifier

amplifier stage that amplifies a signal prior to reaching the final amplifier stage in a transmitter


Keying

concerns that oscillator starts by a turning DC on and off


Low excitation

improper bias or locator signal power in an AM modulator


downward modulation

the decrease in DC output current in an AM modulator usually caused by low excitation


spectrum analyzer

instrument used to measure the harmonic content of a signal by displaying a plot of amplitude versus frequency


spurious frequency

extra frequencies components that appear in the spectral display of a single, signifying distortion


Spurs

undesired frequency components of a signal


noise floor

the baseline on a spectrum analyzer display


relative harmonic distortion

expression specifying the fundamental frequency component of a signal with respect to is large is harmonic in db


THD total harmonic distortion

a measure of distortion that takes all significant harmonics into account


THD equation

THD = sqr ( V2^2 + V3^2 + ...) / V1^2)


Dummy antenna

resistive load in place of an antenna for testing so there is no output signal


TRF (tuned radio frequency)

the most elementary receiver design, consisting of RF amplifier stages, a detector and audio amplifier stages


sensitivity

the minimum input RF signal to a receiver required to produce a specified audio signal at output


noise floor

the baseline on a spectrum analyzer display, represent an input noise of the system under test


selectivity

how much the receiver can differentiate the desired signals and other signals
