In the past most of the music was distributed through radios.
The radio broadcasts lives in a close relationship with Mr. Hitler and
Nazis.
After the Mr. Hitler and his European allies, Italians, Hungarians and Finns,
lost the second world war, Germans and other losers were not allowed to make
radio broadcasts and propaganda with long range radio waves. The losers
were allowed to broadcast their propaganda to the locals and own citizens
only.
Due to this demand short ranged FM radios came to the markets. Nowadays almost all
radio broadcasts are done with FM waves. The maximum broadcasting range
of the FM waves is around 50 kilometers.
Both analog and digital radio broadcastings are made with very same FM
waves and broadcasting units. If you are a power keeper, you bought and
built a network for digital broadcasts, with taxpayers money and company.
You wasted taxpayers money for nothing. [ this chapter refers EU and
Europe in the millennium time ]
Anyway. Broadcasting units are much like amplifiers. Instead of speakers, the
broadcasting units sends the signals from storages or recorders to the
big antennas. These antennas radiates the waves around them. You capture
the broadcasts with another antenna which is designed to read and
receive waves from the same range.
FM radios and broadcasters operate with 88 to
110 MHz frequencies. One antenna can and does capture all broadcasts
from the designed frequency range. In this case 88 to 100 MHz.
From the antenna the captured signal is transferred to receiver. And
the receiver unit in the receiver. The receiver unit has two jobs to do.
First it selects the channel-data from the wider broadcast data, it gets
from the antenna. After the selection / filtering is done,
the receiver shifts the broadcast data back to audio data frequencies.
After the shifting the signal is sent to amplifier or audio out pins.
How did it go ?
1. Before the sound is sent to air, the audio data is shifted to the broadcasting frequency.
2. In the receiver unit there is a circuit, which shifts the signals back to the
original storage values. The shifter-selector unit is almost the only unit there
is in the receiver.
RDS
When Radio Station sends RDS data, there are two broadcasting units
in the station. One for the radio broadcasts and one for the RDS. RDS
operates with fixed / predefined frequency. The fixed RDS frequency
varies from country to country.
When your receiver is capable of switching channels according to RDS
data, there are two receiver units in your receiver. Another one reads
signals from RDS frequency and another one from variable broadcasting
frequency.
Add-On units
If the receiver has an automated channel search, the programmed
search has a unit of it's own, but the add-on unit uses the primary
receiver unit for the search.
If your receiver is capable of receiving packed and digital
broadcasts, your receiver has a unit or units for making the required
conversions. Conversions are usually made right before the signal is
sent to the line output pins. These output pins are connected to the
amplifier, external or internal.
If your receiver has digital outputs and your amplifier has digital
inputs, the receiver do not need converters for digital and compressed
audio data. There is a requirement for the connection. The data in technical
specifications for receiver's digital outputs and amplifiers digital
inputs must match to each other. If they don't, you cannot hear a thing
from the connection.
Landline and cellular phones differs from each other in four
things.
1. Landline phones operates with analog audio data. Cellular operates
with digital audio. The old mobile phones which were used in cars,
boats, etc, operates with analog audio data.
2. Power source of the landline phone is in the operators facilities.
Power source for cellular is in phone. Power sources for mobiles are
car/boat/etc batteries.
3. Landline is connected to the distributor / phone operator with
wires. Cellular and
mobile connects to the distributor with electromagnetic radio waves.
4. In quite many countries the second part of the phone number is the
district number. District number has information about the physical
location of the phone. In cellular district numbers are not used. The
number is used to differentiate the operators. In most countries the old
mounted mobile phones had their own nationwide district number.
Mounted mobiles had powerful broadcasting units and long antennas on
the roofs. The mobile was usually selected by the range of the
broadcasting unit. If you lived and operated far from the nearest link,
you had to buy a mobile with powerful broadcaster ... and good
antenna-receiver system, too.
- - - -
Modern cellular phones are like digital broadcasters and receivers.
In general phones and a-likes act like broadcasters and receivers.
When you make a phone call with cellular, your phone acts as
broadcaster. And when you receive the call, your phone acts as
receiver.
Usually your cellular phone number has a unique frequency with what
it operates. The frequency is unique at least within the phone operator's
systems.
When you make a call, your phone contacts the nearest link tower.
From the tower, your call quite often goes to wires. In deserted areas
your call makes few jumps from tower to tower, before it goes to the
wired underground systems.
Eventually your request for the call reaches the distributor units.
The distributor units are in your phone operators facilities.
When you are abroad and you make a
call, your call can end into the facilities of the co-operative phone
operator. An operator, which has made a deal with your phone operator.
About exchanging the numbers.
When the distributor unit gets a request, it checks where the call is
going. First it checks if it is a domestic or foreign call.
If the call is foreign call, the distributor connects to the foreign
country and it's phone operator network system.
Access points to the foreign network
are based on agreements. Depending on country and continent, the
agreements with operators, or with agreements between governments.
Then foreign operator continues to execute the following steps. In
the same way your operator does, when you make a domestic call.
After the country data is extracted from the request, in the next step, the
distributor checks whether the request is made to landline phone or
cellular phone. If the request goes to the landline, the call is
directed to the nationwide landline network. If the call goes to another
cellular operator, the distributor contacts and connects to the distributor units in
there.
When the request is made to some other client of the operator, the
alerting routines are started in the own facilities. When call goes to
some other operator, the local distributor keeps the line on-line until
the call is closed.
Alerting routines
The cellular phones have been optimized so, that your phone informs
the distributor units about it's location, and the nearest tower. Every
time the phone searches new tower for polling, the distributor is
informed about the change. When someone calls you, the distributor unit
actives only one tower. The tower, which is nearest to you.
When your phone is on-line, it polls the given frequency for the
incoming phone calls. The phone alerts, after it detects certain
activities in it's frequency.
If your phone operator has the chosen
a system with a digital polling, your cellular consumes almost as much
energy for polling, than it does during the calls. In digital polling
the phone acts like radio receiver. It takes all calls from the tower to
itself, and the phone checks whether the call was made to this or some
other cellular phone. To the phone operator the digital polling systems
are cheaper to buy and maintain. The operating costs are equal to
frequency based polling.
Web surfing with phone
SMS, latter multimedia messages (MMS ) and almost dead WAP pages operates
with the same principle as cellular calls.
But when you surf in web, and send e-mails with your phone, your
cellular usually switches to the faster and more accurate packet data transfer mode. It is the mode and
style with what the internet and computers operate.
The laws which
protects the privacy of the phone calls prevents the usage of the packet
data system in phone calls. The cellular phone calls are encrypted by
default. In the web, data-packets are not encrypted by default.
Another big thing is, that phone calls need a real time data
transfers. The packet data deliveries are delayed by default.
Interactive dialogue is a bit difficult, when the words are only
partially delivered, or they come to your phone with few minutes delay.
And sometimes they would come in random order.
