CORRELATION 2 - EST 1-40

• Non-continuous noise of irregular pulses or spikes of duration with high amplitudes is called JITTER
• Shannon-Hartley Theorem sets a limit on the maximum capacity of a channel with a given noise level
• Quantizing noise occurs in PCM
• Noise always affects the signal in a communications system at the CHANNEL
• Noise is the random and unpredictable electric signals from natural causes, both internal and external to the system
• Noise from random acoustic or electric noise that has equal energy per cycle over a specified total frequency band can be:

  • Gaussian Noise
  • White Noise
  • Thermal Noise
• Quantization noise in a PCM system is caused by the approximation of the quantized signal
• A limiter is a particular circuit that rids FM of noise
• The reference noise temperature in degrees Celsius is 17
• Unwanted radio signal on an assigned frequency is referred to as NOISE
• Noise Factor is the reliable measurement for comparing amplifier noise characteristics
• White Noise is measured on a circuit when it is correctly terminated but does not have any traffic
• CCIT G. 151 recommends crosstalk limits
• CCIT REC. G. 172 is utilized in intermodulation noise rates on PCM audio channels
• The reference frequency of CCIT phosphomeric noise measurement is 800 Hz
• Reference temperature used in noise analysis is 290 KELVIN
• Noise produced by lightning discharges in thunderstorms is called ATMOSPHERIC NOISE
• Man-made noise is usually from transmission over power lines and by ground wave
• NIF stands for NOISE IMPROVEMENT FACTOR
• Industrial noise frequency is between 15 to 160 MHz
• External noise fields are measured in terms of peak values
• Form of interference caused by rain or dust storms is precipitation static
• Thermal noise is an electric noise produced by thermal agitation of electrons in conductor and semiconductor
• Crosstalk is the interference coming from other communications channels
• Reference noise level is -90 dBm
• Unit of noise power of psophometer is pWp
• A large emission of hydrogen from the sun that affects communications is a solar flare
• Atmospheric noise is known as static noise
• Standard design reference for environmental noise temperature is 290 Kelvin
• Absolute temperature in Kelvin is ˚C +273
• If bandwidth is doubled, the signal power is not changed
• One or more sources of noise bearing on electronic communications are galaxies and internal combustion engine
• The transmitter technique adopted to reduce the noise effect is preemphasis
• Deemphasis in the receiver in effect attenuates modulating signal components and noise in the high frequency range
• Atmospheric noise or static is not a great problem at frequencies above 30 MHz
• Proper procedure for suppressing electrical noise in a mobile station is to apply shielding and filtering where necessary
• Noise generated that primarily determines the signal-to-noise ratio in a VHF (150 MHz) marine-band receiver is in the receiver front end