Digital broadcasting..

[Admiral Huddy]

Ok, I'm going to ask what might seem a daft question, but in the office we are having a debate which can't be settled.

The arguement is

"Is digital broadcasting still sent as an analogue signal, albeit it's sending digital bits rather than an image."

Surely, you can't actually broadcast an elecrical signal that represents digital bits. I was under impression that digital broadcasting requires a higher frequency than that of normal TV and voice. Surely, some kind of D/A or A/D conversion must occur?

What do you think?

[divine]

http://www.explainthatstuff.com/digitalradio.html

Does that help you at all?

[Feek]

Just as people have got used to such niggles, inventors have come up with a new type of radio that promises almost perfect sound. Digital radio, as it's called, sends speech and songs through the air as strings of numbers. No matter what comes between your radio and the transmitter, the signal almost always gets through. That's why digital radio sounds better.

Can't take anything seriously that even remotely suggests that digital radio is superior in sound quality compared to analogue.

[NokkonWud]

I always thought it was. I get better sound from my DAB Radio than my Analogue Radio.

[Del Lardo]

Can't take anything seriously that even remotely suggests that digital radio is superior in sound quality compared to analogue.


Isn't analogue radio something like ~96k due to the compression used?

DAB is 128k so a higher bit rate. Analogue may have the potential to sound better but from my rather basic listening tests DAB has always sounded better.

[divine]

Can't take anything seriously that even remotely suggests that digital radio is superior in sound quality compared to analogue.

If you were broadcasting uncompressed analogue and could ensure absolutely zero interference, yes in theory analogue will always be the closest to perfect reproduction.

However i'm sure you know as well as I that the difference between theory and reality of what arrives at your TV/Radio is vastly different and in such cases digital is virtually always going to be of superior quality in real usage terms.

Digital broadcasts suffer far far far less from interference and even when they do, error correction is much more effective to rectify the problems, whereas analogue, once it has taken on an alteration is ruined really. Your average commercial radio is always going to produce superior results from digital compared to analogue.

[Admiral Huddy]

I always thought it was. I get better sound from my DAB Radio than my Analogue Radio.


I would guess that all depends on how sensitive your hearing is and the sampling rate.

A wave length from a digital broadcast would be manifested. Depending on the sampling during conversion, bits are missing. An analogue signal on the other hand is raw but is subjected to more interference. Would this be correct Feek?

So going back to my OP, the digital signal is still broadcasted over an analogue wave length, but has a higher frequency and bandwidth. i.e. more signal gets through..

[Feek]

A wave length from a digital broadcast would be manifested. Depending on the sampling during conversion, bits are missing. An analogue signal on the other hand is raw but is subjected to more interference. Would this be correct Feek?

Spot on. A good solid strength analogue signal with no interference is always, always, always going to outperform any kind of digital radio service we have in this country and providing you can get that good signal then you'll hear the difference easily. This isn't just a theoretical statement, it's quite easy to get a good strong analogue signal.

I hate all this digital is better than analogue crap. I reach over to the DAB box on my window ledge and tune in Radio 1 - 128kbps. Radio 4, the same. Talk Sport, 64kbps mono. Terrible.

Call me a wireless snob. I probably won't disagree.

[divine]

I've never managed to get anything close to a good analogue signal around here, digital is much better overall for the job at hand, IMO.

[Mark]

I don't think there's any such thing as a true analogue radio station in the UK (with the exception of ghetto set-ups and occasional broadcasts from Radio 3 or Classic FM). Most of the studio kit these days is digital, so even the purest of pure analogue almost certainly isn't.

Fair point about the compression though - it's a shame when broadcasters see fit to overdo the compression in order to cram more stations into a given frequency. Freeview suffers terribly from this - though in most cases people don't watch closely enough to notice. Of the options I've personally tried (which excludes VM), Sky is regrettably often the best option, though even that doesn't escape the bandwidth scrooge (HD channels, for starters). That doesn't justify the £44 I'm about to stop paying for it though.

[Feek]

This (http://www.digitalradiotech.co.uk/digital_radio_samples.htm) is a very interesting read.

[Pumpkinstew]

Surely, you can't actually broadcast an elecrical signal that represents digital bits. I was under impression that digital broadcasting requires a higher frequency than that of normal TV and voice. Surely, some kind of D/A or A/D conversion must occur?

What do you think?

In a word yes. The sound (analogue) is sampled and converted to a digital signal (electrical/optical possibly) for broadcast (via EM or optical) it is then returned to an analogue signal (sound waves) by your radio so that your ears can hear it.

You're right that higher frequencies transmit more information (^bits/second) but this can be alleviated by using codecs to transmit commonly used data in a shortened form. Exactly like converting a 200MB wave file into a compressed 8MB MP3.