chapter 7
voltage
pressure
amperage
amount of water
wattage
power of water by multiplaying the pressure to amount
frequency
how often the signal changing the state or direction
modulation
imposing a signal onto an electrical signal
frequency modulation
sending the signal by shifting the frequency
carrier
the original signal onto which data is added
carrier frequency
when is no data added
polarized
moving into direction
When the electrical signals move in one direction through the wire, what is created?
A magnetic field with the north pole facing in one direction and the south pole facing in the opposite direction.
What happens when the power level crosses the center gray dashed line?"
The magnetic field collapses, resulting in no magnetic field.
When the electrical signal moves in the opposite direction, what occurs to the magnetic field?
It rebuilds, with the north and south poles facing opposite directions.
What effect occurs when placing a wire into a constantly shifting magnetic field?"
Electrical signals are induced in the wire, with the frequency and direction corresponding to the magnetic field's ebb and flow.
What is the term for transferring signals from one wire to another through magnetic fields?
Inductive reactance
What is the primary cause of interference in transmitting wired (and wireless) electrical signals?"
interference
"How do engineers prevent interference between cables caused by magnetic fields?"
shield and twisting
Give an example of how interference can occur between cables."
Running a power cable too close to a data cable can allow the stronger magnetic fields from the power cable to induce signals in the data cable."
What effect can high-power radio transmitters have on nearby cables?"
High-power radio transmitters can induce signals in nearby cables, causing interference.
What happens at Point A when one signal is at its maximum, creating its maximum possible magnetic field polarized in one direction?"
The signal traveling along the second wire creates a magnetic field polarized in the opposite direction, effectively canceling out the magnetic fields around the wires.
What can happen if the wires are untwisted at either end to insert them into a connector?"
It can allow interference, particularly between pairs of wires in the same cable, as it breaks the intended canceling effect of the magnetic fields.
How can interference be avoided when attaching a connector to twisted wires?"
Care should be taken to untwist the amount of wire specified by the connector to avoid disturbing the countermeasure against interference.
What does a shielded cable contain?"
An inner core containing one or more cables 9centre conductor insulator and shield and an outer shield.
What is the purpose of the outer shield in a shielded cable?"
The outer shield absorbs and blocks magnetic and electrical signals from nearby transmitters and cables, preventing external interference from affecting cables in the shield’s center.
What is the return path for power in a coaxial cable?
The return path for power from the receiver to the transmitter is along the shield.
What is a shielded twisted pair?
It's when cables have more than one twisted set of wires in the center of shielding.
What is important to remember when working with shielded cables during installation?
It is important to strip the correct amount of shielding when installing a connector and to connect the shield to a ground.