Cai Bingxin`s homework 2 about radio and sound recording

1. Media of Communication
Radio and Sound Recording
Cai Bingxin
20129869

2. Radio
• Radio is the transmission of signals through free space
by electromagnetic waves with frequencies significantly
below visible light, in the radio frequency range, from
about 3 kHz to 300 GHz. These waves are called radio
waves. Electromagnetic radiation travels by means of
oscillating electromagnetic fields that pass through the air
and the vacuum of space.
• Information, such as sound, is carried by systematically
changing (modulating) some property of the radiated
waves, such as their amplitude, frequency, phase, or
pulse width. When radio waves strike an electrical
conductor, the oscillating fields induce an alternating
current in the conductor. The information in the waves can
be extracted and transformed back into its original form.

3. Radio communication system
• A radio communication system sends signals by radio. Types
of radio communication systems deployed depend
on technology, standards, regulations, radio spectrum
allocation, user requirements, service positioning,
and investment.
• The radio equipment involved in communication
systems includes a transmitter and a receiver, each having
an antenna and appropriate terminal equipment such as
a microphone at the transmitter and a loudspeaker at the
receiver in the case of a voice-communication system.
• The power consumed in a transmitting station varies
depending on the distance of communication and the
transmission conditions. The power received at the receiving
station is usually only a tiny fraction of the transmitter's
output, since communication depends on receiving
the information, not the energy, that was transmitted.

4. EXAMPLE----
• The BBC is a semi-autonomous public service
broadcaster that operates under a Royal Charter and a
Licence and Agreement from the Home
Secretary. Within the United Kingdom its work is funded
principally by an annual television licence fee, which is
charged to all British households, companies and
organisations using any type of equipment to record
and/or receive live television broadcasts; the level of the
fee is set annually by the British Government and
agreed by Parliament.
• Outside the UK, the BBC World Service has provided
services by direct broadcasting and re-transmission
contracts by sound radio since the inauguration of the
BBC Empire Service in December 1932, and more
recently by television and online. Though sharing some
of the facilities of the domestic services, particularly for
news and current affairs output, the World Service has a
separate Managing Director, and its operating costs
have historically been funded mainly by direct grants
from the British government. These grants were
determined independently of the domestic licence fee
and were usually awarded from the budget of the
Foreign and Commonwealth Office.

5. BBC
RADIO
LOGO

6. Sound Recording
• Sound recording and reproduction is an electrical
or mechanical inscription and re-creation
of sound waves, such as spoken voice,
singing, instrumental music, or sound effects.
The two main classes of sound recording
technology are analog recording and digital
recording. Acoustic analog recording is
achieved by a small microphone diaphragm
that can detect changes in atmospheric pressure
(acoustic sound waves) and record them as a
graphic representation of the sound waves on a
medium such as a phonograph (in which a
stylus senses grooves on a record).

7. The age-old recording way

8. The modern recording way

9. EXAMPLE—Black Box
• A flight data recorder (FDR) also called black box is
a placeholder name used casually to refer to a collection of
several different recording devices used in transportation:
the flight recorders (cockpit voice recorder) in aircraft,
the event recorder in railway locomotives, the event data
recorder in automobiles, message case in ships, and other
recording devices in various vehicles.

10. A black box is founded after an crash