6. Difference between electronic and electrical.
Ans:
Electronics work on DC and with a
voltage range of -48vDC to +48vDC. If the electronic device is plugged into a
standard wall outlet, there will be a transformer inside which will convert the
AC voltage you are supplying to the required DC voltage needed by the device.
Examples: Computer, radio, T.V, etc... Electric devices use line voltage
(120vAC, 240vAC, etc...). Electric devices can also be designed to operate on
DC sources, but will be at DC voltages above 48v. Examples: are incandescent
lights, heaters, fridge, stove, etc...
7. Explain RF?
Ans:
Radio frequency (RF) is a frequency
or rate of oscillation within the range of about 3 Hz to 300 GHz. This range
corresponds to frequency of alternating current electrical signals used to
produce and detect radio waves. Since most of this range is beyond the
vibration rate that most mechanical systems can respond to, RF usually refers
to oscillations in electrical circuits or electromagnetic radiation.
8. Explain modulation & demodulation? And where it is utilized?
Ans:
Modulation is the process of
varying some characteristic of a periodic wave with an external signals. Radio
communication superimposes this information bearing signal onto a carrier
signal. These high frequency carrier signals can be transmitted over the air
easily and are capable of travelling long distances. The characteristics
(amplitude, frequency, or phase) of the carrier signal are varied in accordance
with the information bearing signal. Modulation is utilized to send an
information bearing signal over long distances.
Demodulation is the act of
removing the modulation from an analog signal to get the original baseband
signal back. Demodulating is necessary because the receiver system receives a
modulated signal with specific characteristics and it needs to turn it to
base-band.
9. Name the modulation techniques.
Ans:
For Analog modulation--AM, SSB,
FM, PM and SM Digital modulation--OOK, FSK, ASK, Psk, QAM, MSK, CPM, PPM, TCM,
OFDM
10. What is multiplexing?
Ans:
Multiplexing (known as muxing) is
a term used to refer to a processwhere multiple analog message signals or
digital data streams are combined into one signal over a shared medium. The aim
is to share an expensive resource. For example, in telecommunications, several
phone calls may be transferred using one wire.
11. What is an Amplifier?
Ans:
An electronic device or
electrical circuit that is used to boost (amplify) the power, voltage or
current of an applied signal.
12. Explain Full duplex and half duplex?
Ans:
Full duplex refers to the
transmission of data in two directions simultaneously. For example, a telephone
is a full-duplex devicebecause both parties can talk at once. In contrast, a
walkie- talkie is ahalf-duplex device because only one party can transmit at a
time. Most modems have a switch that lets you choose between full-duplex and
half-duplex modes. The choice depends on whichcommunications program you are
running. In full-duplex mode, data you transmit does not appear on yourscreen
until it has been received and sent back by the other party. This enables you
to validate that the data has been accurately transmitted. If your display
screen shows two of each character, it probably means that your modem is set to
half-duplex mode when it should be in full-duplex mode.
13. What is Oscillator?
Ans:
An oscillator is a circuit that
creates a waveform output from a direct current input. The two main types of
oscillator are harmonic and relaxation. The harmonic oscillators have smooth
curved waveforms, while relaxation oscillators have waveforms with sharp
changes.
14. What is a transducer and transponder?
Ans:
A transducer is a device, usually
electrical, electronic, electro- mechanical, electromagnetic, photonic, or
photovoltaic that converts one type of energy or physical attribute to another
for various purposes including measurement or information transfer. In
telecommunication, the term transponder (short-forTransmitter-responder and
sometimes abbreviated to XPDR, XPNDR, TPDR or TP) has the following
meanings:
An automatic device that
receives, amplifies, andretransmits a signal on a different frequency (see
alsobroadcast translator).
An automatic device that
transmits a predetermined messagein response to a predefined received signal.
A receiver-transmitter that will
generate a reply signal upon proper electronic interrogation.
A communications satellite’s
channels are called transponders, because each is a separate transceiver or
repeater.
15. What is an Integrated Circuit?
Ans:
An integrated circuit (IC), also called a microchip, is an electronic
circuit etched onto a silicon chip. Their main advantages are low cost, low
power, high performance, and very small size.
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