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116 Cards in this Set

  • Front
  • Back
put information on high frequency carrier
intelligence single
low frequency information
remove in the intelligence from the modulation
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?
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 = 1.38e-23, 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
low-noise 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
Transit-time 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
signal-to-noise 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
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)
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
tangential method
method of measuring the amplitude of noise on a signal using an oscilloscope display
information theory
concerned with optimization of transmitted information
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 time-varying information to its frequency component
Frequency domain record
data points generated by a time to frequency conversion using the FFT
errors that occur when the input frequency exceeds one-half 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
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)
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
Number of RC or LC sections in a filter
constant-K filter
filter whose capacitive and inductive reactance are equal to a constant value k
m-derived filters
filters that uses a two circuit to provide nearly infinite attenuation at a specific frequency
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)
is the nth multiple of the base frequency (it spikes on every odd harmonic)
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
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
impressing a low-frequency intelligence signal onto a higher-frequency 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
side-frequency aptitude equation
Esf = (m * Ec) / 2, Esf = side-frequency 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
high-level modulation
intelligence superimposed on the carrier at the last point before the antenna (for AM), most efficient for high power AM radio
low-level modulation
intelligence superimposed on the care, and THEN amplified before the antenna
neutralizing capacitor
a capacitor that cancels fed-back signals to suppress self-oscillation
parasitic oscillations
higher-frequency self-oscillations 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
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
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
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
how much the receiver can differentiate the desired signals and other signals