Rune Allnor wrote:> On 18 Jan, 19:18, Vladimir Vassilevsky <antispam_bo...@hotmail.com> > wrote: > >>I meant moving from one zone of reception to another. With the analog >>radio, you have to switch the channels. With digital, it can be done >>seemlessly. > > > I've used RDS FM radio for more than ten years. Very useful in cars.I am aware of RDS/RBDS and I've been involved with car audio for about the same time. Never seen that RDS thing working or anyone who actually used it. Satellite radio broadcasts like "Sirius" or "XM" are very popular. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
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So whats wrong with OFDM?
Started by ●January 15, 2009
Reply by ●January 18, 20092009-01-18
Reply by ●January 18, 20092009-01-18
On 18 Jan, 21:45, Vladimir Vassilevsky <antispam_bo...@hotmail.com> wrote:> Rune Allnor wrote: > > On 18 Jan, 19:18, Vladimir Vassilevsky <antispam_bo...@hotmail.com> > > wrote: > > >>I meant moving from one zone of reception to another. With the analog > >>radio, you have to switch the channels. With digital, it can be done > >>seemlessly. > > > I've used RDS FM radio for more than ten years. Very useful in cars. > > I am aware of RDS/RBDS and I've been involved with car audio for about > the same time. Never seen that RDS thing working or anyone who actually > used it. Satellite radio broadcasts like "Sirius" or "XM" are very popular.We discussed sattelite radio here a couple of years ago, and as I recall, we found it's a north American thing. Has something to do with cost per audience and covered area to do. In Europe (and maybe elsewhere), where the audience and/or geographical area to be covered is smaller, RDS FM is big. Rune
Reply by ●January 18, 20092009-01-18
On Sun, 18 Jan 2009 12:56:04 -0500, Ben Bradley <ben_nospam_bradley@frontiernet.net> wrote:>On Sun, 18 Jan 2009 09:37:48 -0600, Vladimir Vassilevsky ><antispam_bogus@hotmail.com> wrote: > >> >> >>Eric Jacobsen wrote: >> >>> Personally I think audio broadcast radio should stay analog. You're >>> not going to beat it for simplicity and low power consumption in the >>> receiver, which is something that's desirable for critical >>> infrastructure. > > Modern digital circuitry for decoding the signal takes less power >than an audio amplifier to drive an earbud, so I don't see that part >as a valid argument, unless you're comparing digital to an (AM only) >crystal receiver.You have to have the amp for the earbud or speakers in either case. In the digital case you need a digital demodulator, including a FEC decoder and a decompressor. In the analog case you need a handful of transistors (even for FM). It's very hard to beat a modern analog FM receiver for cost and power consumption when compared to anything digital.> On the other hand, the digital compression (psychoacoustic, just >like mp3) is lossy and has artifacts that are audible and annoying to >a significant number of people. Going digital just trades off some >types of classic analog distortion for Bold, New Distortions No Man >Has Ever Heard Before.Right, so I don't think the audio quality is a huge argument, although I do think it's valid. Even a high SNR FM station doesn't sound that great compared to a good digital stream. So it's a tradeoff, I just don't think the tradeoff is a slam-dunk in favor of digital, or even close. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
Reply by ●January 18, 20092009-01-18
Eric Jacobsen <eric.jacobsen@delete.ieee.org> wrote:>Right, so I don't think the audio quality is a huge argument, although >I do think it's valid. Even a high SNR FM station doesn't sound that >great compared to a good digital stream.I'm wondering how universally true this is. An FM station doesn't sound as good as a high-quality digital stream (CD or SACD quality), but it sounds better than a 128 kbps mp3 stream. (Speaking in rough terms.) They're probably roughly equivalent at intermediate bit rates for AAC or AC3. I am in the broadcast range of some FM stations that also stream live, notably KALX, and the broadcast signal usually sounds somewhat better than even the fastest net-feed. Steve
Reply by ●January 18, 20092009-01-18
On Jan 18, 8:04�pm, spop...@speedymail.org (Steve Pope) wrote:> Eric Jacobsen �<eric.jacob...@delete.ieee.org> wrote: > > >Right, so I don't think the audio quality is a huge argument, although > >I do think it's valid. � Even a high SNR FM station doesn't sound that > >great compared to a good digital stream. � > > I'm wondering how universally true this is. �An FM station doesn't > sound as good as a high-quality digital stream (CD or SACD quality), > but it sounds better than a 128 kbps mp3 stream. �(Speaking > in rough terms.) �They're probably roughly equivalent at intermediate > bit rates for AAC or AC3. > > I am in the broadcast range of some FM stations that also stream > live, notably KALX, and the broadcast signal usually sounds > somewhat better than even the fastest net-feed. > > Stevethe reason many FM stations sound bad has nothing to do with limitations of the analog FM system, but rather with often extreame dynamic range compression applied to the audio to make it sound LOUD. There is a belief in the broadcast industry that people will tune into the loudest signal on the dial or that the louder signal can carry further. There was some truth to this in the old days of AM with static but is is no longer true for FM today. But many radio stations still engage in the loudness war. Mark
Reply by ●January 19, 20092009-01-19
On Mon, 19 Jan 2009 01:04:39 +0000 (UTC), spope33@speedymail.org (Steve Pope) wrote:>Eric Jacobsen <eric.jacobsen@delete.ieee.org> wrote: > >>Right, so I don't think the audio quality is a huge argument, although >>I do think it's valid. Even a high SNR FM station doesn't sound that >>great compared to a good digital stream. > >I'm wondering how universally true this is. An FM station doesn't >sound as good as a high-quality digital stream (CD or SACD quality), >but it sounds better than a 128 kbps mp3 stream. (Speaking >in rough terms.) They're probably roughly equivalent at intermediate >bit rates for AAC or AC3. > >I am in the broadcast range of some FM stations that also stream >live, notably KALX, and the broadcast signal usually sounds >somewhat better than even the fastest net-feed. > >SteveYes, I guess the bottom line is that the audio quality doesn't seem to be a clear argument for ditching analog FM and going all-digital. Eric Jacobsen Minister of Algorithms Abineau Communications http://www.ericjacobsen.org Blog: http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
Reply by ●January 19, 20092009-01-19
> > >Rune Allnor wrote: > >> On 18 Jan, 19:18, Vladimir Vassilevsky <antispam_bo...@hotmail.com> >> wrote: >> >>>I meant moving from one zone of reception to another. With the analog >>>radio, you have to switch the channels. With digital, it can be done >>>seemlessly. >> >> >> I've used RDS FM radio for more than ten years. Very useful in cars. > >I am aware of RDS/RBDS and I've been involved with car audio for about >the same time. Never seen that RDS thing working or anyone who actually >used it. Satellite radio broadcasts like "Sirius" or "XM" are verypopular. Sirius and XM are US only things. Outside the US RDS FM radio is extremely popular in cars, and works well. Where have you seen it not work? RDS has even been used to broadcast paging messages to pocket pagers, though the pagers were a bit clumsy compared to a POCSAG or FLEX pager. RDS doesn't provide for the same level of battery savings as a purpose designed paging code. Regards, Steve
Reply by ●January 19, 20092009-01-19
On 18 Jan, 23:44, Eric Jacobsen <eric.jacob...@ieee.org> wrote:> On Sun, 18 Jan 2009 12:56:04 -0500, Ben Bradley> > � On the other hand, the digital compression (psychoacoustic, just > >like mp3) is lossy and has artifacts that are audible and annoying to > >a significant number of people. Going digital just trades off some > >types of classic analog distortion for Bold, New Distortions No Man > >Has Ever Heard Before. > > Right, so I don't think the audio quality is a huge argument, although > I do think it's valid. � Even a high SNR FM station doesn't sound that > great compared to a good digital stream. �So it's a tradeoff, I just > don't think the tradeoff is a slam-dunk in favor of digital, or even > close.The arguments I remember hearing in favour of digital, was based on the (possibly unique) geography and demography of Norway: We are very few people (approacing 5 million), and the average population density is very sparse ( < 1 person ber sq. km). So outside population centra there are just a few radio transitters, which are pushed to the limit to save costs. Add in the mountanous topography, where you get all sorts of shadows or multipaths, and it used to be a mess to obtain good analog radio coverage. The arguments in favour of digital radio was that it could achieve better signal quality with weaker signals and in multipath situations. It used to make a lot of sense, but something has changed over the past couple of decades. It might be that RDS FM has masked the problems of finding good signals while on the road, or the recievers have become better. Whatever the reason, I remember FM radio being far more itchy in the past than it is now. Rune
