POTS line quality help
in [Design]
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From: Joel Koltner on 24 Apr 2010 22:14 <miso(a)sushi.com> wrote in message news:bc14ad42-bf0a-47b0-abe0-f73205a82b41(a)n20g2000prh.googlegroups.com... On Apr 24, 12:06 pm, Robert Baer <robertb...(a)localnet.com> wrote: >I was at Excess Solutions (Milpitas CA) today and they have two >Rockwell 56k modems on the shelf for some crazy price like $15 each. >In Silicon Valley, they are worthless. Purportedly 1200bps and 2400bps modems are still worth something because they're still so commonly used by ATM machines, credit card machines, etc. -- since there's only some hundredsof bytes to be exchanged, the total call time is shorter than with a 56kbps model since there's no fancy training sequence/synchronization/etc. I guess that will likely go away within the next decade or so as well, as direct Internet access become nearly ubiquitous even in the boonies. > But if you had to use dial up > in the boonies, I'd be using Rockwell gear. They always made the best > modems. [I worked for the competition, so trust me on this one. We > never could meet their specs.] The fallback modes on Rockwell gear > were great. You paid for such performance dearly. I remember the old 9600bps Telebit models (OMG THAT WAS FAST), and then the Netblazer which had a *built-in router!* as well... all for something in the low 4-digit price range. Now a DSL modem with built-in router and wireless and NAS-like features via USB is under $200... Amazing that the entire history of Telebit spanned no more than a decade, really. ---Joel
From: J B on 25 Apr 2010 00:28 You may be thinking of 3002 leased line conditioning C2 For further info you can find a table describing it at: http://www.sageinst.com/downloads/925an/vfmeas.pdf It has been a long time since I have had to think of those conditioned lines for modems. bye, Jim Robert Baer wrote: > > Once upon a time, a long time ago, there was only analog modems and > nice paper manuals came with them. > Some of those manuals, in the back discussed that for best use, one > should order a specific quality of phone line and disclosed the BELLCO > designation to use when ordering the line. > As i remember it, that designation was something simple like (making > this up) Z9. > I think that the TekCom modem manual at that time was one that gave > that info. > Question: What is that designation? > Thanks.
From: Martin Brown on 25 Apr 2010 04:40 Robert Baer wrote: > JosephKK wrote: >> On Tue, 20 Apr 2010 16:29:17 -0700, Robert Baer <robertbaer(a)localnet.com> >> wrote: >> >>> Once upon a time, a long time ago, there was only analog modems and >>> nice paper manuals came with them. >>> Some of those manuals, in the back discussed that for best use, one >>> should order a specific quality of phone line and disclosed the >>> BELLCO designation to use when ordering the line. >>> As i remember it, that designation was something simple like >>> (making this up) Z9. >>> I think that the TekCom modem manual at that time was one that gave >>> that info. >>> Question: What is that designation? >>> Thanks. >> >> The last i heard you wanted a 3002 line. Should be able to provide 56k >> on typical current modems. > THANK YOU!!!!! They won't give you one. Real copper circuits are now reserved for their profitable ADSL customers. Ordinary voice is bandwidth limited to get two (or more) customer voice channels down one physical circuit. Most of the worlds telecoms companies are doing exactly the same trick. > I will see if that works here with Qwest in as much as they are rather > customer hostile; they only want money and care less about anything else. > You make a call and find the line busy; an *automated* voice prompts > "for _only_ eightyfive cents we will try your call for later delivery" > (price something like that) Never Mind that it _costs_ them NOTHING to > do this; it is a way of extracting money from captive customers. > I could cite a fair number of other examples like the phone line > problem i have. > Up to about 6 months ago (roughly) i could reliably connect at 45K to > 48+Kbaud and then all of a sudden i got 28.8Kbaud and now am at 26.4K > and who knows how more it will sink? > The have been actively pushing DSL like crazy (3-5 inserts in monthly > bills, newspaper ads, etc) and PURPOSELY choking modem bandwidth to > "force" a change in $pending (= = ca$h to them). > Too bad the internet does not connect by way of semaphore flags... If you have been DACSd (or whatever acronym the US gives it) then you need to find a US based service provider that will do a frequency response line test and feed you back the results. If you are DACS then forcing a non-56k connection will almost certainly get you a better connection. DACS and the other ways of multiplexing voice onto copper violates the foundations of the way 56k works. Namely that there is nothing altering the signal between the exchange and you so that accurate ADC conversion yields meaningful values. You might find a prehistoric early 56k UK FAQ helpful in trying to configure your modem to work retro style. http://www.pierrot.demon.co.uk/faq/dtm.faq (it is out of date and UK based but still has good hints) Regards, Martin Brown
From: denali on 25 Apr 2010 18:24 To the best of my knowledge, USWEST/QWEST did not offer a guaranteed dialup data rate. The rate you got depended on the facility type serving your premises; it might be non-loaded cable (up to about 9kft as I recall), or loaded cable (for a length of cable having a 1 kHz loss not exceeding 8 dB, or a pair gain multiplexer channel. Also, if you believe the circuit is noisy or the transmission amplitude is week, they should measure those characteristics, but if they find no trouble they may charge you for their efforts. If you can't exceed 26.4 at all, I suspect line "trouble." Beyond that, there is a possibility they moved you to a multiplexer that uses only 32kbit/s coding instead of the normal 64 kbit/s coding. Since you are having a service problem they should tell you what the facility is. If it IS 32 kbit/s coded channel (ADPCM) tell them to put you on a non-ADPCM channel. The Public Utility Commission can be your friend. I may be able to help if needed. Sorry for being a top poster. No comments please. On Apr 24, 12:06 pm, Robert Baer <robertb...(a)localnet.com> wrote: > JosephKK wrote: > > On Tue, 20 Apr 2010 16:29:17 -0700, Robert Baer <robertb...(a)localnet.com> > > wrote: > > >> Once upon a time, a long time ago, there was only analog modems and > >> nice paper manuals came with them. > >> Some of those manuals, in the back discussed that for best use, one > >> should order a specific quality of phone line and disclosed the BELLCO > >> designation to use when ordering the line. > >> As i remember it, that designation was something simple like (making > >> this up) Z9. > >> I think that the TekCom modem manual at that time was one that gave > >> that info. > >> Question: What is that designation? > >> Thanks. > > > The last i heard you wanted a 3002 line. Should be able to provide 56k > > on typical current modems. > > THANK YOU!!!!! > I will see if that works here with Qwest in as much as they are > rather customer hostile; they only want money and care less about > anything else. > You make a call and find the line busy; an *automated* voice prompts > "for _only_ eightyfive cents we will try your call for later delivery" > (price something like that) Never Mind that it _costs_ them NOTHING to > do this; it is a way of extracting money from captive customers. > I could cite a fair number of other examples like the phone line > problem i have. > Up to about 6 months ago (roughly) i could reliably connect at 45K to > 48+Kbaud and then all of a sudden i got 28.8Kbaud and now am at 26.4K > and who knows how more it will sink? > The have been actively pushing DSL like crazy (3-5 inserts in monthly > bills, newspaper ads, etc) and PURPOSELY choking modem bandwidth to > "force" a change in $pending (= = ca$h to them). > Too bad the internet does not connect by way of semaphore flags...
From: Robert Baer on 26 Apr 2010 03:10
miso(a)sushi.com wrote: > On Apr 24, 12:06 pm, Robert Baer <robertb...(a)localnet.com> wrote: >> JosephKK wrote: >>> On Tue, 20 Apr 2010 16:29:17 -0700, Robert Baer <robertb...(a)localnet.com> >>> wrote: >>>> Once upon a time, a long time ago, there was only analog modems and >>>> nice paper manuals came with them. >>>> Some of those manuals, in the back discussed that for best use, one >>>> should order a specific quality of phone line and disclosed the BELLCO >>>> designation to use when ordering the line. >>>> As i remember it, that designation was something simple like (making >>>> this up) Z9. >>>> I think that the TekCom modem manual at that time was one that gave >>>> that info. >>>> Question: What is that designation? >>>> Thanks. >>> The last i heard you wanted a 3002 line. Should be able to provide 56k >>> on typical current modems. >> THANK YOU!!!!! >> I will see if that works here with Qwest in as much as they are >> rather customer hostile; they only want money and care less about >> anything else. >> You make a call and find the line busy; an *automated* voice prompts >> "for _only_ eightyfive cents we will try your call for later delivery" >> (price something like that) Never Mind that it _costs_ them NOTHING to >> do this; it is a way of extracting money from captive customers. >> I could cite a fair number of other examples like the phone line >> problem i have. >> Up to about 6 months ago (roughly) i could reliably connect at 45K to >> 48+Kbaud and then all of a sudden i got 28.8Kbaud and now am at 26.4K >> and who knows how more it will sink? >> The have been actively pushing DSL like crazy (3-5 inserts in monthly >> bills, newspaper ads, etc) and PURPOSELY choking modem bandwidth to >> "force" a change in $pending (= = ca$h to them). >> Too bad the internet does not connect by way of semaphore flags... > > I'm baffled why anyone would use dial up. Somewhere in my paper > documents I should have tossed (and might already have), I have the > frequency responses from the old AEA phone line simulator. I had a > tech run the spectrum analyzer on every line prior to designing a > proprietary filter for (gasp) 2400bps. I don't recall the designators, > but it should be documented in some dusty corner of an old Bell > manual. > > The problem you have with a 56k modem is the fallback modes are > intentionally crappy. What you would do in a modem design is throw the > kitchen sink at doing the best possible performance on the top speed > of the modem, and then do a minimal job on the fallback modes because > they were just to have a check off on the datasheet. > > I was at Excess Solutions (Milpitas CA) today and they have two > Rockwell 56k modems on the shelf for some crazy price like $15 each. > In Silicon Valley, they are worthless. But if you had to use dial up > in the boonies, I'd be using Rockwell gear. They always made the best > modems. [I worked for the competition, so trust me on this one. We > never could meet their specs.] The fallback modes on Rockwell gear > were great. You paid for such performance dearly. > > I remember when we bought the AEA phone line simulator. It was about > $20k in the early 80s. In the 90's, I saw it at RA Surplus for $200. > I have US Robotics modem and it seems to have the Rockwell chip; does that sound correct? |