Digital Technologies: Digital Audio Broadcasting (DAB); Digital Radio Mondiale (DRM); the future of FM and DAB; analogue-digital switchover issues; level of digital take-up: digital radio ownership ; Freesat; Wi-Fi
Over the years radio has been broadcast via many different sources. These range from early short wave radio's to the Internet accessible stations of today. Today, DAB (Digital Audio Broadcasting) is being used more commonly and is thus lessening the use of AM and FM radios across the world. In the UK the government wants a switch-over from analogue to digital radio by 2015, having also done this with television over the last few years. Analogue radio consists of AM and FM radios:
AM broadcasting is where the radio implements amplitude modulation. It was first tested in the 1900's and became popular in 1920's with more wider usage of radio. Amplitude modulation increases and decreases the height of the radio waves, along with the strength, as the base signal changes. However, AM is therefore more susceptible to noise as noise affects amplitude, which in turn affects the carrier wave, where the information is stored.
AM radio signals can travel great distances, so a single transmitter can cover large areas. AM radio is broadcast over several frequency bands. The allocations of these bands are governed by various radio regulations as well as the country's telecommunication administration. The three bands that it broadcast over are:
A typical analogue signal(FM and AM):
Long Wave: Long wave is used for radio broadcasting in Europe, Africa and Northern and Central Asia and has generally not been allocated elsewhere. Long waves are the same as a low frequency wave. They are named "long" due to the large spaces in between each wave.
Medium Wave: This wave is generally used in the America's and is the most heavily used band for commercial broadcasting.
Short Wave: The short wave band is used for things such as aircraft, police and military radio.Most radio waves can pass through the earth's atmosphere but short waves are "sky waves", which bounce up and down off of the earth's ionosphere en route to it's destination. Other frequencies can do this, which is caused by charged particles in the iosphere.
Here is a typical radio set, which will pick up radiowaves and convert them into the sound we hear. The radio can be tuned to either FM or any of the AM radio waves (SW,MW,LW)
FM Broadcasting is another form of radio transmission. The FM stands for frequency modulation,as rather than the amplitude being changed, the frequency is changed. FM radio was first developed in the United States in the thirties, by Edwin Armstrong.
FM is less prone to interference than AM and therefore has greater sound quality, due to a higher bandwidth than AM. The BBC first used FM Broadcasting in 1955 and it first took off in the UK during the rise in commercial radio in the 1970's.
A typical digital signal:
DAB digital radio is a new form of radio broadcasting. Beginning in the 1990's digital radio is a series of pulses in two states: on and off. This is in contrast to analogues wave signals. Rather than having to fine tune the radio to get your desired station, DAB radio's have a ready list of radio stations that they pick up automatically, displaying them by name rather than frequency. This allows the user to scroll through and select the station of their choice.
DAB has excellent quality, due to it's signals which pick up virtually no outside interference. On certain digital radios you can also pause and rewind, as well as recording shows.
There are some issues over whether digital radio should replace the old FM and AM radio stations, due to it's costs and only minimal better quality than FM. However, sales of DAB radios have increased significantly in recent years and cars are now commonly being made with digital radios.
Digital Radio Mondiale (DRM) is a part of DAB technologies, designed to fit over the bands currently used by AM radio. DRM has high quality sound, just like DAB. It has been specifically designed as a high quality replacement for analogue radio.
Freesat and Freeview are digital tv services, launched in 2008 and 2002 respectively. They can be accessed through a satellite dish and have national radio stations among their channel lists, which can be recorded or rewinded.
Over the years radio has been broadcast via many different sources. These range from early short wave radio's to the Internet accessible stations of today. Today, DAB (Digital Audio Broadcasting) is being used more commonly and is thus lessening the use of AM and FM radios across the world. In the UK the government wants a switch-over from analogue to digital radio by 2015, having also done this with television over the last few years. Analogue radio consists of AM and FM radios:
AM broadcasting is where the radio implements amplitude modulation. It was first tested in the 1900's and became popular in 1920's with more wider usage of radio. Amplitude modulation increases and decreases the height of the radio waves, along with the strength, as the base signal changes. However, AM is therefore more susceptible to noise as noise affects amplitude, which in turn affects the carrier wave, where the information is stored.
AM radio signals can travel great distances, so a single transmitter can cover large areas. AM radio is broadcast over several frequency bands. The allocations of these bands are governed by various radio regulations as well as the country's telecommunication administration. The three bands that it broadcast over are:
A typical analogue signal(FM and AM):
Medium Wave: This wave is generally used in the America's and is the most heavily used band for commercial broadcasting.
Short Wave: The short wave band is used for things such as aircraft, police and military radio.Most radio waves can pass through the earth's atmosphere but short waves are "sky waves", which bounce up and down off of the earth's ionosphere en route to it's destination. Other frequencies can do this, which is caused by charged particles in the iosphere.
Here is a typical radio set, which will pick up radiowaves and convert them into the sound we hear. The radio can be tuned to either FM or any of the AM radio waves (SW,MW,LW)
FM Broadcasting is another form of radio transmission. The FM stands for frequency modulation,as rather than the amplitude being changed, the frequency is changed. FM radio was first developed in the United States in the thirties, by Edwin Armstrong.
FM is less prone to interference than AM and therefore has greater sound quality, due to a higher bandwidth than AM. The BBC first used FM Broadcasting in 1955 and it first took off in the UK during the rise in commercial radio in the 1970's.
A typical digital signal:
DAB digital radio is a new form of radio broadcasting. Beginning in the 1990's digital radio is a series of pulses in two states: on and off. This is in contrast to analogues wave signals. Rather than having to fine tune the radio to get your desired station, DAB radio's have a ready list of radio stations that they pick up automatically, displaying them by name rather than frequency. This allows the user to scroll through and select the station of their choice.DAB has excellent quality, due to it's signals which pick up virtually no outside interference. On certain digital radios you can also pause and rewind, as well as recording shows.
There are some issues over whether digital radio should replace the old FM and AM radio stations, due to it's costs and only minimal better quality than FM. However, sales of DAB radios have increased significantly in recent years and cars are now commonly being made with digital radios.
Digital Radio Mondiale (DRM) is a part of DAB technologies, designed to fit over the bands currently used by AM radio. DRM has high quality sound, just like DAB. It has been specifically designed as a high quality replacement for analogue radio.
Freesat and Freeview are digital tv services, launched in 2008 and 2002 respectively. They can be accessed through a satellite dish and have national radio stations among their channel lists, which can be recorded or rewinded.
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