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what bitrate is FM radio broadcast at?

any takers.
cos i have no frigging clue.
im guessing it is roughly 150 kbit but cant be sure.

thanks if anyone knows or has any good ideas.

Reply 1

dh00001

16

160 on bbc dab
i think its station dependant really

Reply 2

AT82

FM is angolue so there is no actual bit rate. As for DAB it is anything from 64 to 192kbps in the UK, most seem to be 128 or 160 though.

Reply 3

space_aura

OP

1

ah ok
but what would be a bit rate equivalent to the normal fm frequency.
can you make an equivalent for it?

Reply 4

dh00001

16

i think it would be 96 kbps

Reply 5

Cromulent

12

FM Radio is the equivalent of about 96kbps if I remember correctly, but as has already been pointed out it is analogue and thus has no actual bit rate.

Edit : Bah beaten to the line.

Reply 6

AT82

FM is a lot higher than 96kbps in terms of quality, in fact a good FM signal does not compare with DAB, FM sounds far superior but you do need a very strong signal to achieve this.

FM is simply analogue so cannot have a comparable bit rate, the only thing that will have a bit rate is possibly the source (e.g CD).

It is also worth remembering that the DAB system is from the early 1990's and is based on an MP2 coding system, this is nothing like as good as MP3. So a 192kbps MP3 file will sound far better than a DAB broadcast at the same bit rate.

There are supposed to introducing a new CODAC for DAB later this year some tuners will able to comptable with a firmware upgrade but many won't :frown:

.

Reply 7

Profesh

20

How can FM possibly sound superior? Perhaps in the sense that an immaculate FM signal would replicate the source at least on a par with 320Kb/s compression, which supersedes the typical DAB bitrate; but otherwise, your assertion strikes me as preposterous.

Reply 8

Profesh

20

AT82

It is also worth remembering that the DAB system is from the early 1990's and is based on an MP2 coding system, this is nothing like as good as MP3. So a 192kbps MP3 file will sound far better than a DAB broadcast at the same bit rate.

That's interesting, actually.

Reply 9

dh00001

16

is there not a way to convert hertz to bytes per second?

Reply 10

AT82

Profesh

How can FM possibly sound superior? Perhaps in the sense that an immaculate FM signal would replicate the source at least on a par with 320Kb/s compression, which supersedes the typical DAB bitrate; but otherwise, your assertion strikes me as preposterous.

I can assure you it does just like vynl sounds far better than CD does to my ears.

DAB can sound better than FM, but as the bit rates are so poor and the coding system is so ancient (from about 1995 I believe) FM currently sounds much better in the UK.

DAB probably sounds better on the cheaper end of the market as you don't get the interferience (unless signal is very poor and you get the block effect).

Reply 11

AT82

dh00001

is there not a way to convert hertz to bytes per second?

I don't think so as it depends on the compression system being used. Hz is a measurement of frequency of an analogue signal where as bitrate is just data, the data has no meaning until it is processed.

Reply 12

Profesh

20

AT82

I can assure you it does just like vynl sounds far better than CD does to my ears.

Ah, well; but of course, audiophilia is a wholly different kettle-of-fish to audio integrity in any strict, objective sense of the term. It's just that, conventionally, one's frame-of-reference as to what 'sounds better' will accord with whatever is (at least, theoretically) the most faithful and accurate reproduction of the original sound; after all, 'sounds better' could well translate as 'sounds louder', but it would be silly to equate that with benchmark superiority.

Reply 13

space_aura

OP

1

^
very tough cookie to crack.but good points raised here.people saying vinyl
sounds better to them is a very vague and hard to prove theorem.
well vinyl apparantly has a warmer feel as it encompasses more frequencies and has a wider "band".
apparantly "dark side of the moon" is a conventional way of testing an audio device's fidelity..you see i don't know if fidelity is the same thing or not??

Reply 14

Tromba

Steven Green, who is a radio specialist has said that FM equates to around 600-800 Kb/sec.

Reply 15

Tromba

Original post by space_aura

ah ok
but what would be a bit rate equivalent to the normal fm frequency.
can you make an equivalent for it?

about 600-800 Kbps

Reply 16

tamefox

From c1972 the BBC used their own PCM system to send Radio 3 in stereo around the country. It used 13-bit 32KHz with no compression or lossy encoding.

iirc they then started using Optimod later to boost the lower volumes for car radios.... ..maybe 1990s..

There is a very detailed article on the web somewhere about all of this.

The only place you could get 'best FM' was near the transmitter in Wrotham (?) (London-ish).

6 major satellite transmitters in the UK then had it piped as PCM to save cost on phone lines.
(Satellite in this context means remote, not things in space).

This eqated to about 850Kbps.

FLAC equates to about 60% file size of pure PCM, and AAC about 15% less iirc. (AAC is lossy though).
So, you would theoretically need to transmit digital radio in AAC format at c400Kbps to match Radio3 13 bit PCM as was (not sure if it still is).
- but as some of the stuff thrown away by lossy encoders is supposed not to matter, then maybe 320Kbps AAC does just about match old, good, Radio3 FM.

Other commercial stations (plus BBC Radio1, 2 etc) are all heavily compressed.
Only Radio 3 FM has a chance of being good quality now - but that depends on what lossy compression and Dynamic Range Compression they are using now.

(edited 8 years ago)

Reply 17

tamefox

Forgot to say, so the new bbc iplayer HLS AAC (labelled as HD) is about as good as you can get - and may be as good as old FM.

So, you're fairly screwed if you want modern non-classical music, but there are some sites out there with higher bit rates.
See:
http://www.radiosurvivor.com/2015/03/04/digital-watch-in-search-of-high-fidelity-internet-radio/

Reply 18

tamefox

oops - forgot about Absolute Radio in the UK....
Supposedly uncompressed FLAC via the www.

Reply 19

tamefox

Also see the BBC site here for more info on their streaming AAC-LC service:
http://iplayerhelp.external.bbc.co.uk/radio/other/radio_hd_sound

I've just started looking at the latest info on these, and it seems that Radio3 FM is still using a similar PCM system as before, but at 14KHZ sampling (not confirmed) - but questionable info I think..

"On its FM frequencies, the station uses less dynamic range compression of the volume of music than rival station Classic FM. On DAB it uses dynamic range control (DRC) which allows compression to be defined by the user.^[49]^[50]^[51]^[52]
The station also uses a BBC-designed pulse code modulation digitisation technique similar to NICAM, which is used for outside broadcasts running through a telephone line. This runs at a sample rate of 14,000 per second per channel.^{[citation needed]} A similar technique was later used for recording at the same rate.

In September 2010, for the final week of the Proms broadcasts, the BBC trialled XHQ (Extra High Quality), a live Internet stream transmitted at a rate of 320kbit/s, instead of Radio 3's usual 192kbit/s, using its AAC-LC 'Coyopa' coding technology.^[53] This technology was later developed further, and Radio 3 became the first BBC Radio station to broadcast permanently in this High Definition Sound (as it has been termed) format."

- https://en.wikipedia.org/wiki/BBC_Radio_3

what bitrate is FM radio broadcast at?

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