<
User:Itpastorn |
dko
Cable Testing
Overview CCNA 1 - Module 4 (3.1)
- Sine waves and square waves
- Exponents and logarithms
- Decibels on networking media (not audio)
- Terminology related to time, frequency, and noise
- Digital bandwidth and analog bandwidth
- Noise levels
- Attenuation and impedance mismatch
- Define crosstalk, near-end crosstalk, far-end crosstalk, and power sum near-end crosstalk
- Twisted pair wiring and noise
- The ten copper cable tests defined in TIA/EIA-568-B
- Category 5 and Category 6
- Frequency, measured in Hz
- Period, the inverse of frequency
- Wavelength
- Amplitude
Exponents and logarithms
Three important number systems:
- Binary
- Base 2
- Decimal
- Base 10
- Hexadecimal
- Base 16
- Easier to use 109 than 1000000000.
- "Logarithms with 10 as a base are called common logarithms."
dB = 10 log10 (Pfinal / Pref)
dB = 20 log10 (Vfinal / Vref)
"Characters, words, pictures, video, or music can be represented electrically by voltage patterns on wires and in electronic devices..." "these voltage patterns can be converted to light waves or radio waves... and back"
- Oscilloscope - "time-domain analysis"
- Fourier synthesis of a square wave
Noise = undesirable signal
Sources
- Nearby cables
- RFI
- EMI (same article as RFI on Wikipedia)
- Laser noise at the transmitter or receiver
Frequencies affected:
- White noise = all frequencies
- Narrowband interference = small spectrum, but usually stronger
- Digital
broadband = very high speed
- >= 2 Mbps both upstream and downstream, according to Bredbandsutredningen
- Only in marketing: Anything that is not a modem - which is false marketing!
- Analog broadband, opposite of baseband
Copper
- signal ground. Important that devices to be "properly grounded"
- Two basic types of cables (covered in
the last module):
- Shielded: Coaxial, STP, ScTP
- Unshielded: UTP
Fiber
- Less attenuation
- RFI and EMI is no problem
- Grounding seldom a problem
<
User:Itpastorn |
dko
Cable Testing
Overview CCNA 1 - Module 4 (3.1)
- Sine waves and square waves
- Exponents and logarithms
- Decibels on networking media (not audio)
- Terminology related to time, frequency, and noise
- Digital bandwidth and analog bandwidth
- Noise levels
- Attenuation and impedance mismatch
- Define crosstalk, near-end crosstalk, far-end crosstalk, and power sum near-end crosstalk
- Twisted pair wiring and noise
- The ten copper cable tests defined in TIA/EIA-568-B
- Category 5 and Category 6
- Frequency, measured in Hz
- Period, the inverse of frequency
- Wavelength
- Amplitude
Exponents and logarithms
Three important number systems:
- Binary
- Base 2
- Decimal
- Base 10
- Hexadecimal
- Base 16
- Easier to use 109 than 1000000000.
- "Logarithms with 10 as a base are called common logarithms."
dB = 10 log10 (Pfinal / Pref)
dB = 20 log10 (Vfinal / Vref)
"Characters, words, pictures, video, or music can be represented electrically by voltage patterns on wires and in electronic devices..." "these voltage patterns can be converted to light waves or radio waves... and back"
- Oscilloscope - "time-domain analysis"
- Fourier synthesis of a square wave
Noise = undesirable signal
Sources
- Nearby cables
- RFI
- EMI (same article as RFI on Wikipedia)
- Laser noise at the transmitter or receiver
Frequencies affected:
- White noise = all frequencies
- Narrowband interference = small spectrum, but usually stronger
- Digital
broadband = very high speed
- >= 2 Mbps both upstream and downstream, according to Bredbandsutredningen
- Only in marketing: Anything that is not a modem - which is false marketing!
- Analog broadband, opposite of baseband
Copper
- signal ground. Important that devices to be "properly grounded"
- Two basic types of cables (covered in
the last module):
- Shielded: Coaxial, STP, ScTP
- Unshielded: UTP
Fiber
- Less attenuation
- RFI and EMI is no problem
- Grounding seldom a problem