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The DAB standard was initiated as a European research project in the s. DAB receivers have been available in many countries since the end of the s. DAB is generally more efficient in its use of spectrum than analogue FM radio,  and thus can offer more radio services for the same given bandwidth.
The sound quality can be noticeably inferior if the bit-rate allocated to each audio program is not sufficient.
DAB is more robust with regard to noise and multipath fading for mobile listening,  although DAB reception quality degrades rapidly when the signal strength falls below a critical threshold, whereas FM reception quality degrades slowly with the decreasing signal, providing effective coverage over a larger area.
Norway is the first country to implement a national FM radio analog switchoffin ; however, that only applied to national broadcasters, not local ones. This means that by the end ofacross all EU countries, all radios in new cars must be capable of receiving and reproducing digital terrestrial radio.
DAB was the first standard based on orthogonal frequency division multiplexing OFDM modulation technique, which since then has become one of the most popular transmission schemes for modern wideband digital communication systems. A choice of audio codecmodulation and error-correction coding schemes and first trial broadcasts were made in Public demonstrations were made in in the United Kingdom.
Pilot broadcasts were launched in several countries in Bymillion people worldwide were in the coverage area of DAB broadcasts, although by this time sales of receivers had only taken off in the United Kingdom UK and Denmark.
In there were approximately 1, DAB stations in operation worldwide. In Januaryan updated DAB specification 2. From an OSI model protocol stack viewpoint, the technologies used on DAB inhabit the following layers: the audio codec inhabits the presentation layer.
Below that is the data link layerin charge of statistical time division multiplexing and frame synchronization. Finally, the physical layer contains the error-correction codingOFDM modulationand dealing with the over-the-air transmission and reception of data. Some aspects of these are described below. One of the most important decisions regarding the design of a digital radio broadcasting system is the choice of which audio codec to use because the efficiency of the audio codec determines how many radio stations can be carried on a fixed capacity multiplex at a given level of audio quality.
Error-correction coding ECC is an important technology for a digital communication system because it determines how robust the reception will be for a given signal strength — stronger ECC will provide a more robust reception than a weaker form.
The coding scheme uses unequal error protection UEPwhich means that parts of the audio bit-stream that are more susceptible to errors causing audible disturbances are provided with more protection i. However, the UEP scheme used on DAB results in there being a grey area in between the user experiencing good reception quality and no reception at all, as opposed to the situation with most other wireless digital communication systems that have a sharp digital cliffwhere the signal rapidly becomes unusable if the signal strength drops below a certain threshold.
When DAB listeners receive a signal in this intermediate strength area they experience a "burbling" sound which interrupts the playback of the audio. This combination of Reed-Solomon coding as the inner layer of coding, followed by an outer layer of convolutional coding — so-called "concatenated coding" — became a popular ECC scheme in the s, and NASA adopted it for its deep-space missions.
It also has a far steeper "digital cliff", and listening tests have shown that people prefer this when the signal strength is low compared to the shallower digital cliff on DAB. For details, see the OFDM system comparison table. OFDM allows the use of single-frequency networks SFNwhich means that a network of transmitters can provide coverage to a large area — up to the size of a country — where all transmitters use the same transmission frequency.
Transmitters that are part of an SFN need to be very accurately synchronised with other transmitters in the network, which requires the transmitters to use very accurate clocks. When a receiver receives a signal that has been transmitted from the different transmitters that are part of an SFN, the signals from the different transmitters will typically have different delays, but to OFDM they will appear to simply be different multipaths of the same signal.
Reception difficulties can arise, however, when the relative delay of multipaths exceeds the OFDM guard interval duration, and there are frequent reports of reception difficulties due to this issue when there is a liftsuch as when there's high pressure, due to signals travelling farther than usual, and thus the signals are likely to arrive with a relative delay that is greater than the OFDM guard interval.
Low power gap-filler transmitters can be added to an SFN as and when desired in order to improve reception quality, although the way SFNs have been implemented in the UK up to now they have tended to consist of higher power transmitters being installed at main transmitter sites in order to keep costs down. An ensemble has a maximum bit rate that can be carried, but this depends on which error protection level is used. However, all DAB multiplexes can carry a total of "capacity units".
The number of capacity units, or CU, that a certain bit-rate level requires depends on the amount of error correction added to the transmission, as described above.
Various different services are embedded into one ensemble which is also typically called a multiplex. These services can include:. DAB is not used in the United States. Traditionally, radio programmes were broadcast on different frequencies via AM and FMand the radio had to be tuned into each frequency as needed.Join our early testers!
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What is DAB radio?
Dry cleaning materials could damage the upholstery and affect the comfort level, and aside from dab bing it with mild soap and water and letting it air dry completely to remove stains, vacuuming is the only recommended form of cleaning.
Mitsubishi Cement Company wants to build a new warehouse and hauling facility along the Tenth Avenue Marine Terminal, which is smack dab in the middle of one of the environmental justice zones established under a state law.
Carol Chapin, vice president of research and development for Simple Green, which makes cleaning solutions, suggested wetting a cotton ball with acetone nail polish remover and dab bing that on the pitch to soften and remove it.
I had nearly a whole bag of cement left over from my dab at orchard renovation, and there were plenty of packing-boxes. I took out the plug and shook out the little dab of quicksilver, and set my teeth in.
On one cheek he had a dab of jelly and his hand and shirt front were covered with broth. Captain Wass showed a resolve to quit pecking at the edges and make a dab at the center of the subject. See Today's Synonym!It is a digital radio service which is broadcast from a UK-wide network of transmitters. Multiplexed radio stations are then broadcast on single frequency networks.
This is an efficient way to provide lots more radio stations using fewer radio frequencies. It rents space on commercial multiplexes to distribute Nations and Local radio stations. Additional radio services.
These include 6 Music and Radio 4 Extra.Its vs It's - English Lessons with inlingua Vancouver
DAB multiplexes. We bundle a number of radio services together, before we broadcast them, into what is known as a multiplex. Your DAB radio can then pull out each individual radio service from the multiplex. We keep an updated list of the BBC radio services and the multiplexes they are carried on.
Single Frequency Network. An SFN is beneficial to listeners if they are able to receive signals from more than one transmitter. The DAB radio will combine all the signals and make the reception more robust. In the DAB multiplexes we also add some additional service data. Please see our help page to see how DAB multiplexes workTherefore, you may not be receiving this service, as there is not a commercial DAB service in your local area. Firstly, poor reception might be down to poor coverage, so it is best to check you are in a DAB coverage area.
Use our transmitter toolwhich will tell you what national and local DAB services are available in your locality.
DAB (dabbed, dabbing)
Secondly, If you are in a good coverage area, and are still receiving poor DAB reception please try our Problem Assistant for further advice. DAB reception is rarely disrupted by high-pressure weather conditions, but under some circumstances, signals from very distant transmitters can cause reception to break up, or be lost for periods of time.
If you suspect this - particularly if you are also getting interference on FM - wait until the weather changes. For more information on finding and storing these services, see our Help guide on DAB secondary services.
This is because the power used is lower, and is forced to work outside of its normal operating parameters, resulting in electrical impulse interference. For more information on interference, please see our RTIS site.
Coverage and location. If you live in a basement flat, or your building is steel-framed or reinforced concrete, coverage may be affected. Most DAB radios can be tuned easily at the touch of a button. Sometimes a full scan is required. Portable radios should be tuned in a location in your home where the best possible signal is received. Most DAB radios come with built in signal strength meters which can be helpful.
From time to time radios should be re-tuned in order to discover new stations.
Telescopic aerials. Telescopic aerials on portable radios should be fully extended to receive a good signal. Tilting and swivelling the aerial will help to get the best signal. Broken aerials may affect reception. An externally mounted aerial can be attached to many types of DAB portable radio and hi-fi systems. An indoor aerial may be good enough, but for the best reception use an outdoor one.
Cables and Connectors. If you have an external aerial, a radio signal will always lose some of its strength as it passes along the cable and through the connectors. It is important to minimise the loss by using good quality cable and connectors. DAB uses different frequencies from FM radio.In slang, dab can be a highly concentrated marijuana extracta type of hip-hop dance, or touching the ground with your foot while you ride a bicycle.
Doing any of these actions is called dabbingand yes, you could feasibly do all three at once—not that we recommend it. Dabin its regular use, is a noun or verb referring to light taps or strokesbut it has taken on a number of slang senses.
Digital Audio Broadcasting
In the marijuana community, dabbing refers to a more intense form of consuming marijuana. It involves a person smoking hash oil burned with butaneresulting in nearly straight THC —and a very intense high. These cannabis extracts are referred to as dabs. Though the ability to create dabs goes back for decades, dabbing only started catching on in the s, at which point it got the slang name dabbingbased on how one dabs an amount of concentrate to smoke it. There is a serious concern that dabbing is far more dangerous than conventional pot smoking.
Dabbing also became a type of hip-hop dance in the s. It originated in Atlanta, Georgia.
The dance move involves extending one arm up and out while the other arm, parallelcovers at the elbow pit. Dabbing went viral after Carolina Panthers quarterback Cam Newton dabbed in the end zone in This version originates at least by the s but tends to be cycling jargon. People may dab to dance or to celebrate an accomplishment or win. As a result in part, dabbing is often called out as something that is not cool, though it used to be.
Hash dabbingon the other hand, is still highly sought after by its fans, and has become more popular as marijuana has become more legalized. If you hear bicyclists talk about dabbingall they mean is putting their feet on the ground while they ride.
It is based on the idea of dabor to lightly tap. It usually happens when someone is about to fall off their bike as a way of catching themselves. It may incur a penalty in cycling-based competitions.
Florio, Bustle, August This content is not meant to be a formal definition of this term.But, its first usage is recorded around the late nineteenth century — to be precise. It was found in an early American publication which was named Dialect Notes around that time. S Share your thoughts. Add your thoughts Cancel reply. It was fun, I tell you! I accidentally lost my balance while stepping back and my elbow landed smack dab on her ribs.
He was trying to hold me down, that molester. I want to own a farmhouse smack dab in the middle of woods near the city. John accidentally elbowed me smack dab on my nose. The parachute landed smack dab into the middle of the lake. Conversation example: Rina: What happened to you? Why are you on your bed on a Monday morning! So, unlike you! Harold: I fell smack dab on my head this morning! Idiom of the Day being in love being in love Meaning Definition to have strong feelings of love for someone to be infatuated with another adult to be romantically and sexually attracted to someone … Read on.
Latest Idioms crack the whip heads will roll rocket science black mood red-handed. Like Facebook Page. Keep in Touch Subscribe to our new updates in your email. Copy Link.Dictionary entry overview: What does dab mean? Study identifies gene that makes gentle touch feel painful after injury, National Institutes of Health. By and by, when we had dined in a sumptuous manner off boiled dabsmelted butter, and potatoes, with a chop for me, a hairy man with a very good-natured face came home.
One day last spring, in town, I was in company with two men, striking instances of what I am talking of; Lord St Ives, whose father we all know to have been a country curate, without bread to eat; I was to give place to Lord St Ives, and a certain Admiral Baldwin, the most deplorable-looking personage you can imagine; his face the colour of mahogany, rough and rugged to the last degree; all lines and wrinkles, nine grey hairs of a side, and nothing but a dab of powder at top.
Double-click any word on the page to look it up in the dictionary. Study identifies gene that makes gentle touch feel painful after injury, National Institutes of Health "Look here! The Lost World, by Sir Arthur Conan Doyle By and by, when we had dined in a sumptuous manner off boiled dabsmelted butter, and potatoes, with a chop for me, a hairy man with a very good-natured face came home. David Copperfield, by Charles Dickens One day last spring, in town, I was in company with two men, striking instances of what I am talking of; Lord St Ives, whose father we all know to have been a country curate, without bread to eat; I was to give place to Lord St Ives, and a certain Admiral Baldwin, the most deplorable-looking personage you can imagine; his face the colour of mahogany, rough and rugged to the last degree; all lines and wrinkles, nine grey hairs of a side, and nothing but a dab of powder at top.
Persuasion, by Jane Austen. AudioEnglish Definitions Just One Click Away! Click here to add the AudioEnglish. Get unrestricted access to all the English-Learning Units!
Subscribe now. Learn English withAdd smack dab to one of your lists below, or create a new one. A grain of rice and a clove of garlic: making uncountable nouns countable 1. Definitions Clear explanations of natural written and spoken English. Click on the arrows to change the translation direction. Follow us.
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Choose your language. My word lists. Tell us about this example sentence:. The word in the example sentence does not match the entry word. The sentence contains offensive content. Cancel Submit. Your feedback will be reviewed. You called smack dab in the middle of dinner. What is the pronunciation of smack dab? Browse slyest. Test your vocabulary with our fun image quizzes.
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