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Dynamics and level compression - FM vs DAB
I have now put up a page that compares the dynamics and level compression
on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html This is an updated and expanded version of a short item that was published in HFN. The results are broadly similar to the comparisons of FM with DTTV, but I have been able to give more details of the level compression behaviour. I've also covered BBC R1/4 as well as R3. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
Jim Lesurf wrote:
I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html This is an updated and expanded version of a short item that was published in HFN. The results are broadly similar to the comparisons of FM with DTTV, but I have been able to give more details of the level compression behaviour. I've also covered BBC R1/4 as well as R3. Slainte, Jim Maybe there is an answer for the pop stations. I think it is a fair assumption that the little ones now have their favoured (ie radio playlist) tracks on their ipods as soon as they are released. So pop stations don't actually need to broadcast them - just trigger the playing of them from the player, along with suitably inane banalities from a DJ, which could be broadcast. d |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html This is an updated and expanded version of a short item that was published in HFN. The results are broadly similar to the comparisons of FM with DTTV, but I have been able to give more details of the level compression behaviour. I've also covered BBC R1/4 as well as R3. Slainte, Jim And from that I quote;!... "However around the start of the Proms in 2006 i.e. after I’d written the original article the BBC suddenly reduced the bitrate on R3 to 160 Kbps. The result was quite dire, and prompted a great deal of angry complaints. Particularly because for most of the time the BBC were using the ‘stolen’ bitrate to run a rolling trailer for a station that wasn't on-air! One consequence was that the first weeks of Prom broadcasts on DAB that year sounded awful. After initially trying to dismiss the criticisms and pretend that the sound quality hadn't suffered, the BBC finally relented and R3 on DAB reverted to mainly using 192 Kbps". Good old auntie!, shows how deaf the poor old soul is getting and her attitude to sound quality. Perhaps her ear trumpet needs blowing out?. You'd think the old dear could use the greater bandwidth on satellite but she is a stubborn old bitch.. Meanwhile over in Jerryland they use 192 on satellite for mere talk stations preferring 256 or even on Bayern 4 320 K/bits:) Now thats what I call digital quality:)) You ought to treat yourself to a digital satellite system Jim there're sod all money now!. Most all have a SPDIF out for connection to an external DAC.... -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf scribeth thus I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html And from that I quote;!... "However around the start of the Proms in 2006 [snip] I'd recommend people to read the actual article. Not to take just a quote presented out of context. :-) The reasons being the same ones that prompted me to write the article. Namely that: A) Simply considering bitrates and ignoring other factors means you fail to take into account everything that can affect the audible results. B) That when you *do* consider other factors - as the article does, but Tony's quote omits - you might not come to the same conclusion as indicated by the quote presented out of context. C) That your conclusions might change from one radio (or TV) station to another. You ought to treat yourself to a digital satellite system Jim there're sod all money now!. Most all have a SPDIF out for connection to an external DAC.... Perhaps if you consider the entire article you will understand some of the reasons that I have not yet bothered. :-) Slainte, Jim - still thorougly enjoying the proms on DTTV BBC4. :-) -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
"Jim Lesurf" wrote in message
... I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html Interesting. I heard a Prom the other night on DAB, Chicago SO playing Shostakovich 4th symphony. The dynamic range certainly seemed wider than I am used to on R3 FM. Of course FM has to deal with pre-emphasis, so percussion can be quite seriously affected. -- Tony W My e-mail address has no hyphen - but please don't use it, reply to the group. |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Jim Lesurf scribeth thus I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html And from that I quote;!... "However around the start of the Proms in 2006 [snip] I'd recommend people to read the actual article. Not to take just a quote presented out of context. :-) Yes understand that it was all about processing and no real reason from Auntie as usual why its done differently on FM and not DABble and DTV..... The reasons being the same ones that prompted me to write the article. Namely that: A) Simply considering bitrates and ignoring other factors means you fail to take into account everything that can affect the audible results. Indeed.. Tho bitrates are very much a digital broadcast problem as is transcoding etc.. B) That when you *do* consider other factors - as the article does, but Tony's quote omits - you might not come to the same conclusion as indicated by the quote presented out of context. Its made to point out that old auntie BBC hasn't changed her "knows best" ways over the years despite all the bull**** she dispenses.. C) That your conclusions might change from one radio (or TV) station to another. Indeed they might.. You ought to treat yourself to a digital satellite system Jim there're sod all money now!. Most all have a SPDIF out for connection to an external DAC.... Perhaps if you consider the entire article you will understand some of the reasons that I have not yet bothered. :-) Ummm... thats not to receive UK digital radio, but that from France and Germany and other European countries who have higher broadcast standards:).... Slainte, Jim - still thorougly enjoying the proms on DTTV BBC4. :-) Indeed.... and as popular as ever.. The few I've been to this year were packed!... Summer.. what there was of it is --officially-- over once the Proms have finished;).. -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Tony
scribeth thus "Jim Lesurf" wrote in message ... I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html Interesting. I heard a Prom the other night on DAB, Chicago SO playing Shostakovich 4th symphony. The dynamic range certainly seemed wider than I am used to on R3 FM. Of course FM has to deal with pre-emphasis, so percussion can be quite seriously affected. Mind you the Albert hall isn't- -that- quiet for some concerts;!.. The audience population is getting noisier as they age.. -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Tony
wrote: "Jim Lesurf" wrote in message ... I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html Interesting. I heard a Prom the other night on DAB, Chicago SO playing Shostakovich 4th symphony. The dynamic range certainly seemed wider than I am used to on R3 FM. That is my impression, also. I must admit, though, that during the last couple of years I have largely abandoned listening to FM Of course FM has to deal with pre-emphasis, so percussion can be quite seriously affected. I don't know if pre-emphasis plays much part in this, but it is an interesting point. The data does show that any sudden loud peaks have their level swiftly pulled down on FM R3, and that the gain in a following quiet period is slowly ramped up. I can see the point of the compression as it helps pull extended pp periods above the background noise on FM. But I now prefer digital transmissions which don't have the problem. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , John Phillips
wrote: On 2008-09-10, Jim Lesurf wrote: I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html [ 20,000 blank lines snipped! :-) ] The ambience of the RAH when listening to the Proms on R3/FM is probably a "trademark" for BBC R3/FM. It is something I had appreciated and enjoyed over many years, as a measure of the quality and "realism" of the broadcasts. It hadn't really occurred to me until I first listened to R3/DAB that this R3/FM ambience was always much more exaggerated than it was whenever I was in the RAH in person. Comparing FM to DAB made me realize actually that R3/DAB also doesn't get the RAH right either - it actually under-represents the real ambience. Alas, it is many years since I have been able to attend a Prom in person. Distance and decrepitude deter. One reason why the broadcasts and my recordings of them are now important to me! These days I tend to prefer the BBC4 TV Proms to R3. I have gained two impressions wrt ambience. One is that there often seems to be some LF noise, perhaps due to air conditioning or passing traffic. However it may be the audience swaying or breathing! :-) The other is that this varies in being noticable from one Prom to another. Indeed, I get the impression that the entire sound balance changes from one to another. Not sure how much this is the orchestras playing differently, though. For example, the BPO/Rattle Prom of Brahms/Shostakovich seemed to have richer (louder) bass strings than some other proms. For perhaps obvious reasons such ambient noise seems louder when there is something like an extended violin solo. But I am not sure how much this is mic useage, change in overall recording/broadcast gain, or my hearing adapting, or my winding up the volume at home! Nevertheless, the result of my comparison was that I changed my mind about the warm ambience of R3/FM and began to enjoy the restored dynamic range of R3/DAB (and now R3/DTTV and BBC4/DTTV). Even so, I think the human brain's audio appreciation capability is very adaptive if its pre-conceptions will let it just get on and enjoy the music. Yes. If digital broadcasting hadn't appeared I'd probably still be happy enough with FM apart from the background noise level and the way ignition interference can pop up at the most annoying/distracting moments. But these limitations where what drove me to try digital in the first place. One thing I didn't mention on the pages was that I have also been struck my how my older recordings from R3 (back from circa 1980) seem to have a wider dynamic range despite my having to alter the recording gain at times because of the limited SNR of domestic cassette and rtr tape. I presume this ties in with what Trevor Butler reported and that the BBC simply didn't apply automated level compression in past days as they do now. I do sometimes notice level adjustments on the BBC4 prom broadcasts, but they give me the feeling they are being done by a human who is following the score and tweaking with intelligence to make the result. Not done any comparisons as yet, but I have the impression that when they put Proms on BBC1/2 they use more level compression. I do have one or two examples of the same performance on both BBC4 and BBC2 so may use them to check this when the necessary round tuit is in stock. :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
"tony sayer" wrote in message
... Yes understand that it was all about processing and no real reason from Auntie as usual why its done differently on FM and not DABble and DTV..... I don't know what Auntie says, but I would expect the processing to be quite different on DAB and FM as the effects of the overall transmission link are different on the two systems. On DAB, provided that there is enough signal for it to work properly, there is no significant noise associated with the link. For stereo FM it is a very different matter. Also, pre-emphasis. -- Tony W My e-mail address has no hyphen - but please don't use it, reply to the group. |
Dynamics and level compression - FM vs DAB
"Jim Lesurf" wrote in message
... One thing I didn't mention on the pages was that I have also been struck my how my older recordings from R3 (back from circa 1980) seem to have a wider dynamic range despite my having to alter the recording gain at times because of the limited SNR of domestic cassette and rtr tape. I would agree with that. I have noticed that the envelope of recent Prom concert recordings have that flat-topped look which the older ones don't. I've never found the need to adjust the recording level whilst recording from the radio as even R3 never had a wide enough dynamic range to justify that. In any case in the past the background noise of the FM reception was significantly greater than that from the tape. Nowadays I don't have that problem as I get a good view of the local FM/DAB transmitter mast from my living room window. One advantage of FM that wasn't mentioned was the short delay. I can have several radios, all tuned to the same station (usually R4), on at the same time so that I can follow a programme as I move about the house. That doesn't work with DAB or DTV. If I am recording from the radio nowadays I usually use my Sky + and then copy from that via the optical SPDIF link to the computer. David. |
Dynamics and level compression - FM vs DAB
In article ,
David Looser wrote: One advantage of FM that wasn't mentioned was the short delay. I can have several radios, all tuned to the same station (usually R4), on at the same time so that I can follow a programme as I move about the house. That doesn't work with DAB or DTV. What is equally galling is that there is a difference between DAB receivers too - and DTV ones. I dunno if it's intrinsic in the system or just different makers implementation - I've not had the opportunity to try two identical ones. Then, of course, you've got the delay some TV receivers introduce to the sound to bring it into sync with the picture... -- *I'll try being nicer if you'll try being smarter Dave Plowman London SW To e-mail, change noise into sound. |
Dynamics and level compression - FM vs DAB
In article , Dave Plowman (News)
wrote: In article , David Looser wrote: One advantage of FM that wasn't mentioned was the short delay. I can have several radios, all tuned to the same station (usually R4), on at the same time so that I can follow a programme as I move about the house. That doesn't work with DAB or DTV. What is equally galling is that there is a difference between DAB receivers too - and DTV ones. I dunno if it's intrinsic in the system or just different makers implementation - I've not had the opportunity to try two identical ones. Then, of course, you've got the delay some TV receivers introduce to the sound to bring it into sync with the picture... It is difficult to get to the bottom of such matters. I did try for a while asking one well-known 'maker' of DAB tuners what the jargon for one of their prompted 'features' in terms of sound quality actually meant in terms of what was being done to the data. I never got a clear answer, and suspect the actual process was developed by someone else who hadn't told them. Experienced similar responses in some other cases. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , Tony wrote: "Jim Lesurf" wrote in message ... I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html Interesting. I heard a Prom the other night on DAB, Chicago SO playing Shostakovich 4th symphony. The dynamic range certainly seemed wider than I am used to on R3 FM. That is my impression, also. I must admit, though, that during the last couple of years I have largely abandoned listening to FM Of course FM has to deal with pre-emphasis, so percussion can be quite seriously affected. I don't know if pre-emphasis plays much part in this, but it is an interesting point. The data does show that any sudden loud peaks have their level swiftly pulled down on FM R3, and that the gain in a following quiet period is slowly ramped up. I can see the point of the compression as it helps pull extended pp periods above the background noise on FM. But I now prefer digital transmissions which don't have the problem. Doesn't that metallic sheen on digital at those rates annoy you though?.. Course if old Auntie took digital seriously she'd see to it that the bit rates were higher them 192 on satellite at least!.. Perhaps the old moo is being an arse over the rates on DAB can't be seen to be any higher on DSAT and DTV delivered radio.. Whereas the rates on DTV are 256 K/bits.. Odd that Dontcha tink?... Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Tony
scribeth thus "tony sayer" wrote in message ... Yes understand that it was all about processing and no real reason from Auntie as usual why its done differently on FM and not DABble and DTV..... I don't know what Auntie says, but I would expect the processing to be quite different on DAB and FM as the effects of the overall transmission link are different on the two systems. On DAB, provided that there is enough signal for it to work properly, there is no significant noise associated with the link. For stereo FM it is a very different matter. Also, pre-emphasis. I often wonder how many people have a good FM aerial and tuner sometimes;?... FM is capable of giving excellent results.. -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf Doesn't that metallic sheen on digital at those rates annoy you though?.. ....or have you stopped beating your wife? :-) [snip] Odd that Dontcha tink?... Yes. Odd that you seem to be only able to focus on one aspect of a more complex situation... ;- Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Tony scribeth thus [snip] I often wonder how many people have a good FM aerial and tuner sometimes;?... FM is capable of giving excellent results.. Indeed. Alas, it may require rather more that just "a good FM aerial and tuner". As with digital transmissions you seem to overlook other factors which affect the situation when comparing results. :-) The problem is that many systems are 'capable' of giving excellent results, but the list of conditions that have to be met in practice for this to be the case may be longer than you take into account above. For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? I tracked them down and have been reading them as a result of being told about them on the uk.tech.digital-tv group. They make very interesting reading. Remarkable that such results seem to have been largely ignored - maybe for the reasons he suggests in the actual articles... Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
Jim Lesurf wrote:
In article , tony sayer wrote: In article , Tony scribeth thus [snip] I often wonder how many people have a good FM aerial and tuner sometimes;?... FM is capable of giving excellent results.. Indeed. Alas, it may require rather more that just "a good FM aerial and tuner". As with digital transmissions you seem to overlook other factors which affect the situation when comparing results. :-) The problem is that many systems are 'capable' of giving excellent results, but the list of conditions that have to be met in practice for this to be the case may be longer than you take into account above. While we are on the subject, do you happen to know the scheme used for audio on HDTV (via satellite)? When they improved the video resolution I don't suppose they improved the audio too - or is that too much to hope for? Cheers Ian |
Dynamics and level compression - FM vs DAB
In article , Ian Thompson-Bell
wrote: Jim Lesurf wrote: The problem is that many systems are 'capable' of giving excellent results, but the list of conditions that have to be met in practice for this to be the case may be longer than you take into account above. While we are on the subject, do you happen to know the scheme used for audio on HDTV (via satellite)? When they improved the video resolution I don't suppose they improved the audio too - or is that too much to hope for? Afraid I don't know the details of the system they use. I think they may have included the ability to use some form of 'surround sound', but I don't know anything beyond that at present. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Jim Lesurf Doesn't that metallic sheen on digital at those rates annoy you though?.. ...or have you stopped beating your wife? :-) Wouldn't think if it!, shes got some dodgy Russian genes in there somewhere;! Someone cut her up at the traffic lights the other week and then they both arrived in the same car park together standing your ground came to mind;!..!! [snip] Odd that Dontcha tink?... Yes. Odd that you seem to be only able to focus on one aspect of a more complex situation... ;- No not all all 'n all... Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Tony scribeth thus [snip] I often wonder how many people have a good FM aerial and tuner sometimes;?... FM is capable of giving excellent results.. Indeed. Alas, it may require rather more that just "a good FM aerial and tuner". But that does help enormously, as does a good tuner. But just how many of them do you see around?. All they do in this area if fit those poxy halo things;(.. As with digital transmissions you seem to overlook other factors which affect the situation when comparing results. :-) Nothing wrong with digital transmission as such, just the way they go about that and implement it;(.. The problem is that many systems are 'capable' of giving excellent results, but the list of conditions that have to be met in practice for this to be the case may be longer than you take into account above. Don't dispute that.. For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? I tracked them down and have been reading them as a result of being told about them on the uk.tech.digital-tv group. They make very interesting reading. Remarkable that such results seem to have been largely ignored - maybe for the reasons he suggests in the actual articles... Well nothing that a directional aerial won't help much towards for serious listening;).. Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
Alas, it is many years since I have been able to attend a Prom in person.
Distance and decrepitude deter. One reason why the broadcasts and my recordings of them are now important to me! Your excused seeing that the RAH is a very long way away;).. Its bad enough for us here in Cambridge..if you want to do most anything afterwards like dinner or go for a drink you'll miss the last train home and taking the motah;!.. Not too good and idea..as is an overnight stay.. And its never that comfortable an experience either. Was at the St John Passion cramped up in a circle seat all others having been taken..its rather difficult for me with work and other commitments to book in advance and the other seats aren't really that much better for the 18 stone frame;!.. These days I tend to prefer the BBC4 TV Proms to R3. I have gained two impressions wrt ambience. One is that there often seems to be some LF noise, perhaps due to air conditioning or passing traffic. However it may be the audience swaying or breathing! :-) Well the audience can only be -quiet- for short periods do bear in mind that most of the poor old souls are seemingly over 50 odd and creak ands wheeze a bit, there are some young, mainly Asian females;).. Don't recall seeing any differences in the mic arrangements and thats are well darkened so they don't show they seem to be smaller every year.. Or so it appears;).. The other is that this varies in being noticable from one Prom to another. Indeed, I get the impression that the entire sound balance changes from one to another. Not sure how much this is the orchestras playing differently, though. Dunno really .. most all the ones I've attended the mics are still rigged the same 'tho thats no reliable indicator of what your going to hear.. The sound in most of the hall is different to what you will hear at home anyway.. For example, the BPO/Rattle Prom of Brahms/Shostakovich seemed to have richer (louder) bass strings than some other proms. For perhaps obvious reasons such ambient noise seems louder when there is something like an extended violin solo. But I am not sure how much this is mic useage, change in overall recording/broadcast gain, or my hearing adapting, or my winding up the volume at home! I think mics do respond to that better then the 'uman lughole!.. Nevertheless, the result of my comparison was that I changed my mind about the warm ambience of R3/FM and began to enjoy the restored dynamic range of R3/DAB (and now R3/DTTV and BBC4/DTTV). The way the BBC handle processing isn't --that-- logical!.. Even so, I think the human brain's audio appreciation capability is very adaptive if its pre-conceptions will let it just get on and enjoy the music. Indeed.. And very enjoyable most all of it was. Sometimes I just go to see something out of the usual run of the mill and the experience can be very good like the Rameau last year with the Soweto musicians and French dancers:)) However what's very good to know is that most of the time the audiences are at capacity, like the Bach day the other week on a Sunday the 4 PM concert of Simon Preston on Organ was standing room only as was the evening:)).. Yes. If digital broadcasting hadn't appeared I'd probably still be happy enough with FM apart from the background noise level and the way ignition interference can pop up at the most annoying/distracting moments. But these limitations where what drove me to try digital in the first place. I reckon that old local FM TX of yours is an RBR one!.. Anyway if the BBC were serious about digital they could up the bits on Satellite where the is plenty of bandwidth available and leave FM for more localised broadcast and scrap the useless T-DAB system and replace that with something more suited to the 21st century. DAB isn't just about sound quality, there are some serious deficiencies in the system if your a broadcaster too especially a commercial one!.. One thing I didn't mention on the pages was that I have also been struck my how my older recordings from R3 (back from circa 1980) seem to have a wider dynamic range despite my having to alter the recording gain at times because of the limited SNR of domestic cassette and rtr tape. I presume this ties in with what Trevor Butler reported and that the BBC simply didn't apply automated level compression in past days as they do now. Its called "processing";-!.. I do sometimes notice level adjustments on the BBC4 prom broadcasts, but they give me the feeling they are being done by a human who is following the score and tweaking with intelligence to make the result. Not done any comparisons as yet, but I have the impression that when they put Proms on BBC1/2 they use more level compression. I do have one or two examples of the same performance on both BBC4 and BBC2 so may use them to check this when the necessary round tuit is in stock. :-) I thought since you retired you had a lot more;)... Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , Dave Plowman (News) wrote: In article , David Looser wrote: One advantage of FM that wasn't mentioned was the short delay. I can have several radios, all tuned to the same station (usually R4), on at the same time so that I can follow a programme as I move about the house. That doesn't work with DAB or DTV. What is equally galling is that there is a difference between DAB receivers too - and DTV ones. I dunno if it's intrinsic in the system or just different makers implementation - I've not had the opportunity to try two identical ones. Then, of course, you've got the delay some TV receivers introduce to the sound to bring it into sync with the picture... It is difficult to get to the bottom of such matters. I did try for a while asking one well-known 'maker' of DAB tuners what the jargon for one of their prompted 'features' in terms of sound quality actually meant in terms of what was being done to the data. I never got a clear answer, and suspect the actual process was developed by someone else who hadn't told them. Experienced similar responses in some other cases. As far as terrestrial DAB goes its what's done with the bits before it hits the tuner.. Satellite with an External DAC is the way to go for serious listening:)).. -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf scribeth thus For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? Well nothing that a directional aerial won't help much towards for serious listening;).. Your reply indicates you haven't read his articles! I must admit that the more I have looked at this topic, the more curious I have become that it has largely been ignored by broaddcasters, etc, over the years. I now suspect the problems are more common than is generally realised, and that fixing it isn't always a simple matter of having a decent tuner and good antenna (alignment). That may well help, but isn't a panacea. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: Even so, I think the human brain's audio appreciation capability is very adaptive if its pre-conceptions will let it just get on and enjoy the music. Indeed.. And very enjoyable most all of it was. Sometimes I just go to see something out of the usual run of the mill and the experience can be very good like the Rameau last year with the Soweto musicians and French dancers:)) I was really impressed last year by the above - and by the Simon Bolivar YO. Both were delightful unexpected surprises. Special events that made me really wish I'd been in the hall. But also examples of why I still hold the BBC in high regard for organising such events and putting them out on R3 and BBC4. I've also been more and more impressed by the various other 'youth orchestras' like the Mahler and our NYO of BG. They have seemed to me to really put some feeling into the music, as well as bags of skill, in recent years. Excellent that they are proms and appear on TV. Regardless of all else, I'm happy to regard the license fee as a payment to allow me to enjoy the proms each year. Anything else - bonus. :-) I wish they'd put *every* prom onto BBC4, though. Particularly annoying this year that they didn't cover all the Vaughan Williams works despite it being a special year for VW. Instead the focussed on Messiaen, who isn't really my personal favourite. Why on earth weren't items like the VW 7th on BBC4? Why snip out the 'Job' from the VW special concert? I do sometimes notice level adjustments on the BBC4 prom broadcasts, but they give me the feeling they are being done by a human who is following the score and tweaking with intelligence to make the result. Not done any comparisons as yet, but I have the impression that when they put Proms on BBC1/2 they use more level compression. I do have one or two examples of the same performance on both BBC4 and BBC2 so may use them to check this when the necessary round tuit is in stock. :-) I thought since you retired you had a lot more;)... Ah, well, I retired because I was running low of them... :-) These days I work more slowly, or decide to shelve many things. For example I've been putting off sorting out my old Tandberg TP41 portable radio. This is one of the few portables that I've found deliver an excellent sound. But it has taken to eating batteries. (Or rather, flattening the NiCads I've put into it in a few days instead of a charge lasting months!) Something inside needs adjusting or replacing, but as yet I haven't found the problem and fixed it. Been on the list for a tuit for well over a year. Tried a couple of times, but failed. Mind you, the circuit diagram is a shambles and notes in scandihovian don't help me much. ;- I recall some Toshiba data sheets that had "Important Note:" followed by two lines of Japanese. Never did find out if I was doing something wrong! Alas, other things crop up, or I lack time. So work that I would have done quickly a decade ago now seems to take ages to get to. And these days I often struggle to see small details of circuit boards even when using my reading glasses. My brain is probably crumbling, as well... Mind you, having said the above, I do seem to end up spending time doing some things. e.g. the measurements I've been doing on LS cables took ages. Did plan more, but have abandoned that in horror. Maybe next year... ;- Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article ,
Jim Lesurf wrote: I now suspect the problems are more common than is generally realised, and that fixing it isn't always a simple matter of having a decent tuner and good antenna (alignment). That may well help, but isn't a panacea. It's the case in this part of Sauf Lunnon. Despite a large yagi and no nearby tall buildings I can't get a clean R4 FM signal. And here, DAB or Freeview sound rather better than FM on this particular station. Nor can I hear much difference if any between FreeView and DAB on R4. Or R3. -- *Most people have more than the average number of legs* Dave Plowman London SW To e-mail, change noise into sound. |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Jim Lesurf scribeth thus For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? Well nothing that a directional aerial won't help much towards for serious listening;).. Your reply indicates you haven't read his articles! No as it 'appens .. I haven't.. Got an online reference for them?.. I must admit that the more I have looked at this topic, the more curious I have become that it has largely been ignored by broaddcasters, etc, over the years. Well its not really a broadcaster problem Jim after all what can they do about it?.. I now suspect the problems are more common than is generally realised, and that fixing it isn't always a simple matter of having a decent tuner and good antenna (alignment). That may well help, but isn't a panacea. No under serious cases it won't but it does got a long way over and above those simple Halo jobbies;!.. -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf scribeth thus For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? Well nothing that a directional aerial won't help much towards for serious listening;).. Your reply indicates you haven't read his articles! No as it 'appens .. I haven't.. Got an online reference for them?.. No, afraid not. After the references were given in uk.tech.digital-tv I found them in my uni library and took xerox copies. However if you send me your postal address by private email I can perhaps post you a printed copy if you wish. Snag here is copyright as it is a WW article so I assume it would be wrong to simply put a copy online - but maybe someone has done this. If so, I don't know about it. It seems OK to make one or two copies for research purposes. But not to make it openly available, I fear. Similarly, I'd like to have copies of some of the refs he quotes, but fear these may be difficult to track down. I will be giving it a try, though. FWIW The copyright situation for such things does vex me at times. There is a lot of interesting technical data in old WW, or HFN issues. But their status isn't quite the same as academic journals as it would be easy tread on the toes of those who own copyright. Personally, I'd love it if copyright law allowed all technical journal articles to be freely republished after, say, 10 years. Would make finding reference material much easier and avoid wheel reinventions. Alas, those who have a cash interest and own the copyright for magazine articles can be - quite understandably - against this. I would wish to respect their wishes as I accept the material is theirs to dispose of. I must admit that the more I have looked at this topic, the more curious I have become that it has largely been ignored by broaddcasters, etc, over the years. Well its not really a broadcaster problem Jim after all what can they do about it?.. IIRC one of the comments Hawker makes is along the same lines. The classic, "Well, it was alright when it left us." :-) However it strikes me as somewhat naughty if they are saying this *knowing* that the results may well be much poorer for a large section of the audience for reasons outwith the listener's control. ...unless they move house! The problem here, I suspect (again as IIRC Hawker indicates), is that the broadcasters and set makers were 'promoting' FM for many years and this was uphill work [pun]. This was fair enough as the competition in those days was AM, and so FM was pretty likely to be better. But it may mean they glossed over - and then forgot about - these problems and just how likely they are. Again fair enough if the choice is FM with some multipath versus the interference-ridden AM. Indeed, I assume most RF engineers haven't ever really been aware of this issue in more than general terms, and respond as you have done with the assumption that a good antenna, etc, will be a fix. This is 'conventional wisdom'. I accepted it for many decades and only started to feel it was doubtful when I wanted to write an article about multipath and began to study the topic for myself. This followed my increasing puzzlement that so little previous work seemed findable in the literature. Now, of course, there are many other transmission/distribution systems and the choice isn't as simple as it was a few decades ago. So perhaps time for the skeletons in the FM cupboard to be revealed. :-) I now suspect the problems are more common than is generally realised, and that fixing it isn't always a simple matter of having a decent tuner and good antenna (alignment). That may well help, but isn't a panacea. No under serious cases it won't but it does got a long way over and above those simple Halo jobbies;!.. I agree that in many cases using a good directional antenna - correctly aligned - plus a good tuner will reduce the effects of multipath. But in practice I fear it isn't that simple a lot of the time. Hawker has some comments on this that stuck me as quite perceptive. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: Even so, I think the human brain's audio appreciation capability is very adaptive if its pre-conceptions will let it just get on and enjoy the music. Indeed.. And very enjoyable most all of it was. Sometimes I just go to see something out of the usual run of the mill and the experience can be very good like the Rameau last year with the Soweto musicians and French dancers:)) I was really impressed last year by the above - and by the Simon Bolivar YO. Both were delightful unexpected surprises. Special events that made me really wish I'd been in the hall. But also examples of why I still hold the BBC in high regard for organising such events and putting them out on R3 and BBC4. Indeed.. I've also been more and more impressed by the various other 'youth orchestras' like the Mahler and our NYO of BG. They have seemed to me to really put some feeling into the music, as well as bags of skill, in recent years. Excellent that they are proms and appear on TV. Regardless of all else, I'm happy to regard the license fee as a payment to allow me to enjoy the proms each year. Anything else - bonus. :-) I wish they'd put *every* prom onto BBC4, though. Particularly annoying this year that they didn't cover all the Vaughan Williams works despite it being a special year for VW. Instead the focussed on Messiaen, who isn't really my personal favourite. Well beg to differ on that one but the BBC really ought to televise a lot more cant cost them that much surely?.. Why on earth weren't items like the VW 7th on BBC4? Why snip out the 'Job' from the VW special concert? I do sometimes notice level adjustments on the BBC4 prom broadcasts, but they give me the feeling they are being done by a human who is following the score and tweaking with intelligence to make the result. Not done any comparisons as yet, but I have the impression that when they put Proms on BBC1/2 they use more level compression. I do have one or two examples of the same performance on both BBC4 and BBC2 so may use them to check this when the necessary round tuit is in stock. :-) I thought since you retired you had a lot more;)... Ah, well, I retired because I was running low of them... :-) These days I work more slowly, or decide to shelve many things. For example I've been putting off sorting out my old Tandberg TP41 portable radio. This is one of the few portables that I've found deliver an excellent sound. But it has taken to eating batteries. (Or rather, flattening the NiCads I've put into it in a few days instead of a charge lasting months!) Something inside needs adjusting or replacing, but as yet I haven't found the problem and fixed it. Been on the list for a tuit for well over a year. Tried a couple of times, but failed. Mind you, the circuit diagram is a shambles and notes in scandihovian don't help me much. ;- I recall some Toshiba data sheets that had "Important Note:" followed by two lines of Japanese. Never did find out if I was doing something wrong! Alas, other things crop up, or I lack time. So work that I would have done quickly a decade ago now seems to take ages to get to. And these days I often struggle to see small details of circuit boards even when using my reading glasses. My brain is probably crumbling, as well... Mind you, having said the above, I do seem to end up spending time doing some things. e.g. the measurements I've been doing on LS cables took ages. Did plan more, but have abandoned that in horror. Maybe next year... ;- Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
"Jim Lesurf" wrote in message
... The problem here, I suspect (again as IIRC Hawker indicates), is that the broadcasters and set makers were 'promoting' FM for many years and this was uphill work [pun]. Eh? Sorry I am being thick here! Clue please. This was fair enough as the competition in those days was AM, and so FM was pretty likely to be better. But it may mean they glossed over - and then forgot about - these problems and just how likely they are. Again fair enough if the choice is FM with some multipath versus the interference-ridden AM. I don't remember Pat Hawker's articles, but I have done a bit of work in the past with a multipath 'scope display. I have to say that I am a bit surprised that the problem is as severe as you describe. I nearly always found that multipath could be made acceptable with the right aerial in the right direction. But I wonder if the change to mixed or circular polarisation might have made multipath more difficult to get rid of. As regards the engineering decisions, multipath is not nearly so much of a problem in mono as in stereo, as it is usually worst for high audio frequencies with a large S content. So I think the problem mainly arose with the change to stereo rather than the change from AM to FM. There was pressure on the BBC to do stereo, and I suppose they thought that anyone who was interested enough to get a stereo receiver would also get (or already have) a good outside aerial, which would nearly always be needed anyway for adequate signal to noise ratio. But I'm sure the engineers never forgot multipath, which is one reason why they thought DAB was such a good idea. -- Tony W My e-mail address has no hyphen - but please don't use it, reply to the group. |
Dynamics and level compression - FM vs DAB
In article , Tony
wrote: "Jim Lesurf" wrote in message ... The problem here, I suspect (again as IIRC Hawker indicates), is that the broadcasters and set makers were 'promoting' FM for many years and this was uphill work [pun]. Eh? Sorry I am being thick here! Clue please. Pun based on the preference for transmit and receive antennas being high. The problem which I was meaning is that for many years the general public tended to stick with AM and ignored FM. But the BBC - and set makers - were trying to get them to buy FM sets. This was fair enough as the competition in those days was AM, and so FM was pretty likely to be better. But it may mean they glossed over - and then forgot about - these problems and just how likely they are. Again fair enough if the choice is FM with some multipath versus the interference-ridden AM. I don't remember Pat Hawker's articles, but I have done a bit of work in the past with a multipath 'scope display. I have to say that I am a bit surprised that the problem is as severe as you describe. I nearly always found that multipath could be made acceptable with the right aerial in the right direction. But I wonder if the change to mixed or circular polarisation might have made multipath more difficult to get rid of. This is one of the points he deals with. He reports German work that showed that moving away from H polarization to V or non-planar *does* tend to make multipath worse. Quite interesting to read what he says as he makes clear he is aware that because he worked for the IBA he might be felt to engaging in BBC bashing to question their decision to move away from H polarisation for VHF/FM. As regards the engineering decisions, multipath is not nearly so much of a problem in mono as in stereo, as it is usually worst for high audio frequencies with a large S content. Agreed. This also means it is easier for people to overlook if they aren't familiar with what FM can sound like when there is no multipath. This was also something Hawker discussed. So I think the problem mainly arose with the change to stereo rather than the change from AM to FM. The problems probably grew worse when stereo was introduced. There was pressure on the BBC to do stereo, and I suppose they thought that anyone who was interested enough to get a stereo receiver would also get (or already have) a good outside aerial, which would nearly always be needed anyway for adequate signal to noise ratio. But I'm sure the engineers never forgot multipath, which is one reason why they thought DAB was such a good idea. My recollection is that they were aware of fading and flutter problems for FM, but I can't recall those involved saying much about multipath distortion on FM being an audible problem. The multipath resistance of digital transmissions was, I think, mainly to ensure reliable reception cover without fades (or ignition interference). Of course, the goalposts moved here as we have gone from DAB for cars to DAB for general use! TBH I am not sure about the engineers. May depend on the era you have in mind. Only aware that the broadcasters essentially fell silent on the matter. The articles by Hawker are the only ones I have found thus far. I've been reading mags like the audio ones and WW on and off for decades and I can't off-hand recall any other articles that examine multipath in anything more than general terms - and assume it is a minor problem. Interestingly, Hawker does mention some research the BBC engineers did, but this was never officially published! That, I think, also says something about the attitude at the time, but it is hard to know who made the decision to not publish the results as a normal BBC paper. Also my experience is that when I have in the past read about or asked about multipath the 'standard response' has been along the lines of your own initial comments. i.e. That it isn't much of a problem, and can generally be cured by a good RX and carefully aligned antenna. However, I now seriously doubt that is so for many people. Hence my suspicion that the early engineers did know about this, but felt it didn't matter, or wasn't something to bother people about. Then - later on - as stereo and FM grew the mindset may have been established that multipath wasn't a problem. So the then current engineers tended to assume it wasn't a problem as FM had been going for years and no-one had told them it *was* a problem. As with my 'uphill' pun, I think the mindset was to promote FM and then Stereo, not to make a meal of any snags. ( ahem You might like to draw a parallel with DAB here. ;- ) Part of the problem is that a general analysis of this would have been quite difficult before computers were commonly available. Easy now to forget this and that the world before about 1970 was different to today in this respect. General modelling of FM can be quite difficult. Another part is that a statistically useful survey of the problem takes a significant amount of time and effort. So not something engineers would do unless they already thought there was a good reason. Perhaps the history here is a parallel with 'how to cook a crab' stories... :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Jim Lesurf scribeth thus For example, have you ever read Pat Hawker's 1980/81 WW articles on multipath? Well nothing that a directional aerial won't help much towards for serious listening;).. Your reply indicates you haven't read his articles! No as it 'appens .. I haven't.. Got an online reference for them?.. No, afraid not. After the references were given in uk.tech.digital-tv I found them in my uni library and took xerox copies. However if you send me your postal address by private email I can perhaps post you a printed copy if you wish. Snag here is copyright as it is a WW article so I assume it would be wrong to simply put a copy online - but maybe someone has done this. If so, I don't know about it. It seems OK to make one or two copies for research purposes. But not to make it openly available, I fear. Thats very kind of you to offer .. I'll drop U a mail.. Similarly, I'd like to have copies of some of the refs he quotes, but fear these may be difficult to track down. I will be giving it a try, though. FWIW The copyright situation for such things does vex me at times. There is a lot of interesting technical data in old WW, or HFN issues. But their status isn't quite the same as academic journals as it would be easy tread on the toes of those who own copyright. Personally, I'd love it if copyright law allowed all technical journal articles to be freely republished after, say, 10 years. Would make finding reference material much easier and avoid wheel reinventions. Alas, those who have a cash interest and own the copyright for magazine articles can be - quite understandably - against this. I would wish to respect their wishes as I accept the material is theirs to dispose of. I must admit that the more I have looked at this topic, the more curious I have become that it has largely been ignored by broaddcasters, etc, over the years. Well its not really a broadcaster problem Jim after all what can they do about it?.. IIRC one of the comments Hawker makes is along the same lines. The classic, "Well, it was alright when it left us." :-) However it strikes me as somewhat naughty if they are saying this *knowing* that the results may well be much poorer for a large section of the audience for reasons outwith the listener's control. ...unless they move house! Yes but even so what can they do?.. We should be these days moving to digital systems that offer better things than the analogue ones that went before, but the reverse is happening ever since the spectrum was "valued" by Ofcom and the broadcasters discovered bit reduction;!.. The problem here, I suspect (again as IIRC Hawker indicates), is that the broadcasters and set makers were 'promoting' FM for many years and this was uphill work [pun]. This was fair enough as the competition in those days was AM, and so FM was pretty likely to be better. But it may mean they glossed over - and then forgot about - these problems and just how likely they are. Again fair enough if the choice is FM with some multipath versus the interference-ridden AM. Indeed, I assume most RF engineers haven't ever really been aware of this issue in more than general terms, and respond as you have done with the assumption that a good antenna, etc, will be a fix. This is 'conventional wisdom'. I accepted it for many decades and only started to feel it was doubtful when I wanted to write an article about multipath and began to study the topic for myself. This followed my increasing puzzlement that so little previous work seemed findable in the literature. Now, of course, there are many other transmission/distribution systems and the choice isn't as simple as it was a few decades ago. So perhaps time for the skeletons in the FM cupboard to be revealed. :-) Well just what sort of percentage of the population find it a problem in practice?.. I now suspect the problems are more common than is generally realised, and that fixing it isn't always a simple matter of having a decent tuner and good antenna (alignment). That may well help, but isn't a panacea. No under serious cases it won't but it does got a long way over and above those simple Halo jobbies;!.. I agree that in many cases using a good directional antenna - correctly aligned - plus a good tuner will reduce the effects of multipath. But in practice I fear it isn't that simple a lot of the time. Hawker has some comments on this that stuck me as quite perceptive. Well isn't this one of the reasons they devised DAB for;!... Slainte, Jim -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , Tony
scribeth thus "Jim Lesurf" wrote in message ... The problem here, I suspect (again as IIRC Hawker indicates), is that the broadcasters and set makers were 'promoting' FM for many years and this was uphill work [pun]. Eh? Sorry I am being thick here! Clue please. This was fair enough as the competition in those days was AM, and so FM was pretty likely to be better. But it may mean they glossed over - and then forgot about - these problems and just how likely they are. Again fair enough if the choice is FM with some multipath versus the interference-ridden AM. I don't remember Pat Hawker's articles, but I have done a bit of work in the past with a multipath 'scope display. I have to say that I am a bit surprised that the problem is as severe as you describe. I nearly always found that multipath could be made acceptable with the right aerial in the right direction. But I wonder if the change to mixed or circular polarisation might have made multipath more difficult to get rid of. As regards the engineering decisions, multipath is not nearly so much of a problem in mono as in stereo, as it is usually worst for high audio frequencies with a large S content. So I think the problem mainly arose with the change to stereo rather than the change from AM to FM. There was pressure on the BBC to do stereo, and I suppose they thought that anyone who was interested enough to get a stereo receiver would also get (or already have) a good outside aerial, which would nearly always be needed anyway for adequate signal to noise ratio. But I'm sure the engineers never forgot multipath, which is one reason why they thought DAB was such a good idea. I expect that mixed polarisation might just make the problem worse. One of the main reasons for its introduction was for the vertical component to be used by cars the horiz to be used by fixed aerials. But one thing it does do especially in urban areas is that when there is multipath there is sometimes polarisation skew i.e. what was Vertical is now Horiz and vice versa. Course take a Horiz TX and some reflections coming as Vertical will now be discriminated against if you see what I mean.. The good side is that it helps to reduce flutter for mobile systems in that if the vertical component gets skewed then the horiz one will be - bent- to Vertical and thus fill in the -missing- as it were.... You can see this on a spec analyser whilst driving around an area that has mixed and vertical only stations. The mixed is quite stable in level whereas the single Vert is UTP and down like the proverbial... -- Tony Sayer |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf scribeth thus Well its not really a broadcaster problem Jim after all what can they do about it?.. IIRC one of the comments Hawker makes is along the same lines. The classic, "Well, it was alright when it left us." :-) However it strikes me as somewhat naughty if they are saying this *knowing* that the results may well be much poorer for a large section of the audience for reasons outwith the listener's control. ...unless they move house! Yes but even so what can they do?.. Well, what they *could* have done is: 1) Carried out some decent research on the how much this crops up, and how that varies with circumstances. 2) Investigated measures to help reduce problems. 3) Publish the results and ensure people (makers, dealers, and end users) are aware of the outcomes of (1) and (2) However it seems that the BBC did a bit of (1), then didn't publish the results. Instead we have had decades of "It isn't really a problem, and if you get it then buy a better tuner/antenna and waggle the antenna". When the reports I have seen thus far indicate it often simply isn't that easy. Now, of course, there are many other transmission/distribution systems and the choice isn't as simple as it was a few decades ago. So perhaps time for the skeletons in the FM cupboard to be revealed. :-) Well just what sort of percentage of the population find it a problem in practice?.. Hard to tell for various reasons. One is that I can find almost no research that even addresses questions like, "How many people have their FM listening affected by a level of multipath that increases the distortion?" The only report I have seen is via Hawker. This showed it was the *norm* for reception to be degraded by multipath. But this BBC work was apparently never published. Another is that most people aren't aware of the problem. So aren't listening for it. Non audio-enthusiasts will just be using radios, portables, etc, and will simply assume what they hear is what is what they can expect. With no clue or interest in reasons. Audio enthusiasts have been led over the years to expect FM to deliver good results if they have a decent tuner and antenna. So, again, tend to assume that what they hear is OK, and if not, have had no reason to suspect multipath. Nor, indeed, are likely to be able to test for it or measure it. As you will know, most people have no real expectation of 'hifi' or have ever heard what a really good audio system can do when fed excellent source material. How would they realise they had a 'multipath problem' given they are have probably never heard the term? Plus, of course, radio has been largely ignored in audio mags during recent decades... Perhaps because - apart from R3 - the sound on most music stations is awful. So many people may not think they have a problem caused by multipath. But some of them might be surprised if they heard the same broadcasts *without* their local multipath and say, "That sounds quite different to my FM radio!" This is a curious point, given that Vinyl LP also tends to produce higher levels of distortion for high frequency and amplitude combinations, and higher for L-R. People may prefer this as a result of habituation and being led to think it is what the sounds should be like! :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article , tony sayer
I expect that mixed polarisation might just make the problem worse. Yes. Your comments are in line with what Hawker wrote. That mix poln is helpful for mobile reception using V rods, etc. But that it makes multipath more problematic for fixed reception using H plane antennas. The statistical trade off seems to be: less likely to get flutter/fades but with the cost of higher amounts of multipath. Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
Dynamics and level compression - FM vs DAB
In article ,
Jim Lesurf wrote: I expect that mixed polarisation might just make the problem worse. Yes. Your comments are in line with what Hawker wrote. That mix poln is helpful for mobile reception using V rods, etc. But that it makes multipath more problematic for fixed reception using H plane antennas. The statistical trade off seems to be: less likely to get flutter/fades but with the cost of higher amounts of multipath. This was mentioned recently on uk.tech.broadcast as regards using a vertical FM aerial to get a better DAB signal. -- *OK, so what's the speed of dark? * Dave Plowman London SW To e-mail, change noise into sound. |
Dynamics and level compression - FM vs DAB
In article , Jim Lesurf
scribeth thus In article , tony sayer wrote: In article , Jim Lesurf scribeth thus Well its not really a broadcaster problem Jim after all what can they do about it?.. IIRC one of the comments Hawker makes is along the same lines. The classic, "Well, it was alright when it left us." :-) However it strikes me as somewhat naughty if they are saying this *knowing* that the results may well be much poorer for a large section of the audience for reasons outwith the listener's control. ...unless they move house! Yes but even so what can they do?.. Well, what they *could* have done is: 1) Carried out some decent research on the how much this crops up, and how that varies with circumstances. They don't seem to do that or much of it anymore;(.. 2) Investigated measures to help reduce problems. Well -what- in practice can they or anyone reasonably do other then to use the best RX directional aerial they can muster and hope they have someone who can deal with it. Our local rigger has been rigging for years but I rather doubt he'd have anything for assessing it. His answer to an FM aerial requirement is a Horizontal Halo;!.. For really severe cases theres always satellite:)... 3) Publish the results and ensure people (makers, dealers, and end users) are aware of the outcomes of (1) and (2) As number 1 !.. However it seems that the BBC did a bit of (1), then didn't publish the results. Instead we have had decades of "It isn't really a problem, and if you get it then buy a better tuner/antenna and waggle the antenna". When the reports I have seen thus far indicate it often simply isn't that easy. Now, of course, there are many other transmission/distribution systems and the choice isn't as simple as it was a few decades ago. So perhaps time for the skeletons in the FM cupboard to be revealed. :-) Well just what sort of percentage of the population find it a problem in practice?.. Hard to tell for various reasons. Indeed, but you very rarely hear complaints about it perhaps because it isn't as obvious as say ghosting on analogue TV... One is that I can find almost no research that even addresses questions like, "How many people have their FM listening affected by a level of multipath that increases the distortion?" The only report I have seen is via Hawker. This showed it was the *norm* for reception to be degraded by multipath. But this BBC work was apparently never published. Another is that most people aren't aware of the problem. So aren't listening for it. Non audio-enthusiasts will just be using radios, portables, etc, and will simply assume what they hear is what is what they can expect. With no clue or interest in reasons. Audio enthusiasts have been led over the years to expect FM to deliver good results if they have a decent tuner and antenna. So, again, tend to assume that what they hear is OK, and if not, have had no reason to suspect multipath. Nor, indeed, are likely to be able to test for it or measure it. And how many tuners around now have the required outputs on them anyway?.. Although my Audiolab T8000 has the REVOX B261 or Denon's haven't!.. As you will know, most people have no real expectation of 'hifi' or have ever heard what a really good audio system can do when fed excellent source material. How would they realise they had a 'multipath problem' given they are have probably never heard the term? Plus, of course, radio has been largely ignored in audio mags during recent decades... Perhaps because - apart from R3 - the sound on most music stations is awful. Indeed though some of the smaller ones like for instance Radio Jackie on South London go out of their way with regards to audio quality.. And as I've muttered before the BBC services ought to all be available on high bitrate satellite which is an excellent medium for high quality Audio.. You really ought to try Bayern Klassik 4 for what digital radio can do:)) Puts the BBC to shame for detail..can be had from Maplins for around a 100 quid:).. So many people may not think they have a problem caused by multipath. But some of them might be surprised if they heard the same broadcasts *without* their local multipath and say, "That sounds quite different to my FM radio!" This is a curious point, given that Vinyl LP also tends to produce higher levels of distortion for high frequency and amplitude combinations, and higher for L-R. People may prefer this as a result of habituation and being led to think it is what the sounds should be like! :-) Well how many young people are being bought up on a diet of compressed radio and MP3 players have any idea what it should or could be like?.. Slainte, Jim Ah!, Your getting old like a lot of us ... who do know better;-)) -- Tony Sayer |
Dynamics and level compression - FM vs DAB
On 2008-09-12, Jim Lesurf wrote:
In article , John Phillips wrote: On 2008-09-10, Jim Lesurf wrote: I have now put up a page that compares the dynamics and level compression on FM with that on DAB. The page can be found at http://www.audiomisc.co.uk/HFN/DABvs...ewithlike.html [ 20,000 blank lines snipped! :-) ] Err, sorry to everyone about that. I'd like to blame the technology but probably it was more to do with "finger trouble" (but I'd still like to know how I didn't see that many extra blank lines and understand how they got there in the first place.) ... These days I tend to prefer the BBC4 TV Proms to R3. I have gained two impressions wrt ambience. One is that there often seems to be some LF noise, perhaps due to air conditioning or passing traffic. However it may be the audience swaying or breathing! :-) This year I have not really noticed the same degree of difference between BBC4 and R3/DAB that I noticed a few years ago. Possibly I have not been listening to the sound so much and listening to the music instead. Possibly the BBC's audio processing has got to be more consistent? ... For perhaps obvious reasons such ambient noise seems louder when there is something like an extended violin solo. ... At a Prom a few years ago - Mahler 9th Symphony I think - quiet ending on the strings: Someone close to me in the stalls swivelled on their seat and it emitted an unlubricated squeak vastly louder than the orchestra. If that contribution to the ambience had been from me I think I would have died from embarrassment. I don't know how it came over on the broadcast. I do sometimes notice level adjustments on the BBC4 prom broadcasts, but they give me the feeling they are being done by a human who is following the score and tweaking with intelligence to make the result. ... On CD I have a few recordings of live opera from the 1960s where there is some all-too-obvious level adjustment at times. Keeping the peaks below the tape's saturation level, I assume. Probably there's more that goes on which I don't notice because it's done with some musical sensitivity by someone who "knows the score." Actually I can recall at least one other example (a 1970 recording IIRC) that gets very "hot" in places, where they *should* have done this. -- John Phillips |
Dynamics and level compression - FM vs DAB
In article , tony sayer
wrote: In article , Jim Lesurf scribeth thus Well, what they *could* have done is: 1) Carried out some decent research on the how much this crops up, and how that varies with circumstances. They don't seem to do that or much of it anymore;(.. Alas, I agree. Indeed, it now seems close to impossible to even talk to anyone involved with the engineering side of what the BBC transmit! 2) Investigated measures to help reduce problems. Well -what- in practice can they or anyone reasonably do other then to use the best RX directional aerial they can muster and hope they have someone who can deal with it. Our local rigger has been rigging for years but I rather doubt he'd have anything for assessing it. That is one of the problems. Well just what sort of percentage of the population find it a problem in practice?.. Hard to tell for various reasons. Indeed, but you very rarely hear complaints about it perhaps because it isn't as obvious as say ghosting on analogue TV... ....and my experience in the past is that many people seemed either not to notice ghosting, or assumed it was 'normal'. Given that it is much more obvious than the effect on FM sound radio it is hardly surprising that most people have no idea there might be a problem. What is less understandable is that the broadcasts have remained shtum about this, as have the consumer mags. And how many tuners around now have the required outputs on them anyway?.. Although my Audiolab T8000 has the REVOX B261 or Denon's haven't!.. Very few do. My CT7000 does, and even allows you to indicate multipath on its meters, but is unusual in many ways. Ah!, Your getting old like a lot of us ... who do know better;-)) I must confess to getting old. But I am less sure it means I know much more that I did. :-) Slainte, Jim -- Change 'noise' to 'jcgl' if you wish to email me. Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html Audio Misc http://www.audiomisc.co.uk/index.html |
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