Digital radios

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Richard
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Re: Digital radios

Postby Richard » Wed Jan 09, 2019 3:09 pm

Hi seahermit,

I think the 'tinny' sound is down to the low bitrate, used by some broadcasters, they should use higher but may have financial constraints.
Some use 120 kb/s bit-rate or lower, you really much higher bit-rates.

BBC Radio 3's 24 hour classical music service, is now available as a continuous 320kb AAC high-quality stream. This is as close to the ex-studio feed as you can get.

If you find BBC R3 'tinny' then it must be your speakers... :)

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seahermit
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Re: Digital radios

Postby seahermit » Wed Jan 09, 2019 6:35 pm

I understood some of that! I hadn't thought about the bit-rate (sort of download rate? Is that the right understanding of it?), but it makes sense from the digital point of view.

The problem is largely my cheap radios, for my poor hearing the sound is sharper and clearer but not at all mellow and natural. But I now have various devices to help my lug'oles, so I am getting interested again in good quality analogue radios - you like Roberts radios and those I will be looking at.

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Richard
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Re: Digital radios

Postby Richard » Sat Jan 12, 2019 6:39 pm

Digital signals are transmitted as bits/bytes, whether online to the computer or smartphone, via the internet or through the ether, to digital radio's.
In networking and digital telecommunications, bit rate refers to the per-second measurement of data that passes through a communications network. In this context, bit rate is synonymous with data-transfer rate

Sound quality, at a given bitrate, depends on codec settings and codec quality.
A codec is a compression method and some codecs cut out information and fill it out with extra 'artificial' treble, which sounds awful.

So, you have the minefield of lower bitrate transmissions, which are cheaper to broadcast and the compression codecs which are also a mixed feast.
The original version of DAB used the MP2 audio codec.
The new DAB+ codec 'AAC' (advanced audio coding) is more sophisticated.
AAC is just a different name for MPEG-4 audio.

Listening to the radio over the internet can provide improved sound quality, when compared to DAB. Several stations use the more efficient AAC codec and some of them broadcast at 256 kbps or above, to achieve superior sound quality, when broadcasting online.
BBC radio 3 transmission is usually of much better quality online (computer or smartphone) because 'lossless' compression is used, radio transmissions are compressed using 'Lossy' codecs as bandwidth is restricted, owing to cost factors.

That is my rudimentary understanding, as a bare novice. There are many more layers of complexity which I am not prepared to entertain but anyone with more information is welcome to comment further.
:)

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seahermit
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Re: Digital radios

Postby seahermit » Sat Jan 12, 2019 11:12 pm

Not at all my field, any of this, but interesting and informative. Thanks!

I remain to some extent old-fashioned, in that I never did like the fiddliness of clock radios and I am continuing my search for a straightforward analogue radio with knobs, no DAB and NO push-buttons. Roberts do a "Classic" radio which seems to fit the bill.

I wonder if a few analogue radios of this kind will remain on the market? As far as I can gather, there are numerous parts of the country where DAB radio is still not obtainable.

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Richard
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Re: Digital radios

Postby Richard » Sun Jan 13, 2019 11:27 am

Hi seahermit,

The DAB standard was initiated as a European research project in the 1980s.
In the U.S.A. the only digital radio broadcast technology sanctioned for use, by the FCC, is called HD.
Apparently most radio-users listen in cars, at least that's the most important market in the U.S.A., where drivers can travel long distances everyday and want music to keep them company.
The recent 'push' for HD in cars, is market-led, most Americans don't know what HD means and easily confuse it with HDTV or satellite radio.
Their new cars may have HD pre-installed a 'solution' that nobody really wanted or understood.
However, car manufacturers in the USA are not all committed to HD and may move away from radio into 'connected' cars.
Streaming media into cars' dashboards (Internet Radio) seems to be the way ahead, we can already stream via the smartphone but in a moving car that is not so convenient as 'tuning' the dashboard.

In the U.K. car manufacturers are installing DAB radio as standard and, will no doubt, play catch-up with the U.S.A. and head for 'streaming' into connected cars...

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Richard
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Re: Digital radios

Postby Richard » Sun Jan 13, 2019 7:34 pm

At the end of the day its a commercial world, so there needs to be a balance between cost and quality. 'Velvet ears' like us probably want 256kbps or above, but 'Joe Public' can’t tell the difference, so the compromise is lower than we’d like.

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seahermit
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Re: Digital radios

Postby seahermit » Mon Jan 14, 2019 2:00 am

If DAB radio is so wonderful, why are there numerous parts of the country where it doesn't work well or it can't be obtained at all? And why are analogue radios still on sale?

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Richard
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Re: Digital radios

Postby Richard » Mon Jan 14, 2019 7:34 am

There's been an orchestrated attempt, for several years, to encourage us plebs to purchase digital radio sets but DAB radio sound quality is now considered, by many, to be much worse than analogue transmissions. The reason for this is that, by trying to squeeze more stations into a limited bandwidth, commercial 'digital' stations had to reduce their bit rate and have sometimes changed from stereo to mono transmissions to do this.
Mono doesn't matter for speech transmissions but serious music needs stereo.

There were plans to scrap analogue FM radio by now but these have now been dropped by the BBC as they recognize that choice is important.

If I were to choose DAB it would have to be DAB+
The cheapest 'Roberts' radio to offer this is 'Roberts PLAY M2' Portable Compact Travel Radio with DAB+/DAB/FM. Around £24 on the internet.
The advantage of preset channels, at the touch of a button, would seem to be helpful but I don't mind having to tune in with my old-style analogue radio. Unlike preset digital ones, analogue only 'remember' the last channel I have tuned to but that all seems fair enough.

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seahermit
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Re: Digital radios

Postby seahermit » Mon Jan 14, 2019 2:38 pm

This is clearly an area which you do know well! Very interesting. I noticed this morning that my smaller DAB radio actually quotes the bit-rate - I will check that again later against your figures.

Of the two DAB radios I bought last year, the smaller one has quite a tinny sound, irritating for good music but ok for the news bulletins. The larger one does have quite a decent, almost mellow tone. The preset stations are useful for going quickly to your favourites, but I find it very difficult on DAB to browse the waveband looking for other stations. I greatly prefer an old-fashioned tuning knob - simple and easy.

I will explore the Roberts radios with DAB+. The market will of course keep changing - not always for the better, but it's worth keeping an eye on it.

My small Akai clock-radio is going to a charity shop - the push-button settings are a nightmare!

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Richard
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Re: Digital radios

Postby Richard » Tue Jan 15, 2019 8:22 pm

Hi seahermit,

I am by no means an expert on digital, versus analogue radio signal reception, inside buildings.
From what I can gather, digital radio signal is more likely to be reduced inside buildings with thick walls but I can find no information whatsoever, relating to the penetration of analogue versus digital broadcasts in that regard.
It would be very interesting to learn whether dab is more vulnerable to positioning within a room. From what I can gather, placing a DAB radio near a window is more likely to result in better reception.
Also, electrical appliances within the home may well interfere with dab radio reception.

Nobody really mentioned the problems of DAB reception inside buildings and the possible solution, for an external aerial, like that of a TV, may require one to be fixed high up, on the outside of a building.
Of course this all defeats the purpose of choosing a DAB radio, if you have to use an aerial, when you did not need one to receive the old analogue signal.
A decent signal received on analogue AM/FM/LW is no indicator of DAB reception and a booster would only be of use if there's an aerial socket on the radio.


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