Wired telephone bandwidth

[MakeNoAttemptToAdjustYourSet]

Wrong, as always.


Wrong, as always.


Obviously wrong, as always.

Give it up, AlwaysWrong. You'll *always* be wrong. It's just you.

Said the utter retard that actually thinks he ever got files over POTS
at 52 kbits per second.

 

[Paul Keinanen]

I'm still on dialup,and I usually log on at 48K,according to the W98SE
taskbar indicator.Sometimes,it logs on at 49K,but it's never stable.
ISTR that the max limit was 52K,but was usually limited by coils in the
lines.

At least in Europe, the "56k" only worked in the downlink direction,
i.e. the ISP had a typically a E1 (2.048 Mbit/s) connection for 30
subscribers and a bit by bit copy at 64 kbit/s 8000 samples/s was
delivered to the DAC in the telephone exchange of the subscriber.

Theoretically, the 8 bits/sample can represent 256 analog values,
since the floating point A-law representations use different step
sizes depending of the "amplitude", the smallest steps are about the
same size as a the LSB of a 12 bit DAC.

The cabling from the local exchange to the subscriber modem will
distort the waveform to the modem and the equalizer in the modem tries
to compensate for the distorted waveform and tries to determine which
actual analog voltage was generated by the DAC. In practice, about
50-100 discrete voltage levels can be reliably detected, thus about
5.5-6.5 bits/sample can be transferred, corresponding to 44-52 kbit/s.

Of course, any noise in the subscriber cable (such as crosstalk from
ADSL connections in other pairs) will degrade the SNR and hence reduce
the throughput.

In the US, the T1 connection and u-law compression may have different
constraints. Are they still using in-band signaling ? This at least
caused a lot of problems in early ISDN and pre-ISDN connections across
the Pond.

If the telco would deliberate want to force the use of 28k even on
downlink, then they either would have to add some LSB noise to the
samples, but only when the sample "amplitude" is low, which would
appear as a slightly added noise in a voice contact. Alternatively,
some analog noise would have to be added after each DAC in each
telephone exchange.

 

[Martin Brown]

But clearly without any clue how to make it work correctly.

Said the utter retard that actually thinks he ever got files over POTS
at 52 kbits per second.

Look in the mirror. KRW is absolutely right about this. The download
speed of the 56k technology is substantially faster than V34+.

I was involved in benchmarking it when the original 56k technology was
under test. There were problems establishing a good connection early on.

But a nominal 48000 56kFlex connection was good for download speeds
5.2kb/s of ZIP file or 9kb/s of news and the rival V90 spec at 48000
gave 5.3kb/s for ZIP and nearly 10kb/s for news on the same hardware.

ISTR the US system robs some of the bandwidth 1/8th? for private
signalling so the numbers in the USA will not be quite so good.

A set of suitable test files for tuning dialup connections is still on
the Demon ftp server if you want to check. Time to download "Fullfile"
will give a very good indication of your raw connection speed. It is
designed to be incompressible even with the best algorithms.

ftp://ftp.demon.co.uk/pub/test/

The highest speed download you can have is the emptyfile which is
extremely compressible and tests the serial interface handshaking.
Certain common misconfigurations show with it. You need an internal
modem or a 230kbaud serial interface to keep up with the datapump.

V34+ could manage 3.7kb/s for ZIP and 7k/s for news on the same line.
And V34+ was always preferable on a shared DACS line where the available
bandwidth was heavily compromised by distortion.

Obviously if you have the option then ADSL or ISDN is better still.

Regards,
Martin Brown

 

[Martin Brown]

* Sorry; they tested the line and said noise free, so noise is not the
limiting factor.

They are doing the US equivalent of DACSing to share your line because
you are an unprofitable cheapskate is standard practice.

* Not the point; they supported 48+Kbps for ages (20+ YEARS) and all of

56kFlex modems were only around since late 90's and only really stable
and interoperable with ISP kit after the V90 standardisation ~1998.

a sudden crapped it down to 28.8K ON PURPOSE to get dial-up users to get
pissed off enough to $pend more $$$$$$$$ for their DSL (which BTW is
LESS reliable).

RTFM and force your modem to do a V34+ 33k6 connection in old world
technology and you should be able to make the best of a bad job. Or
switch to ISDN then they have to give you real copper or better for that.

ADSL is rock solid in most of the civilised world.

Regards,
Martin Brown

 

[Martin Brown]

my downloads thru Opera 9.64 are usually around 5.3 Kbps.
at first read,it goes as high as 12Kbps,but rapidly decays to ~5K.
I figure it's the browser overhead that makes the difference.

Not quite. The initial load is of the main HTML text which is typically
extremely compressible (more so than ordinary text) and so the initial
characters per second peaks at ~12kb/s then the images start to load and
they are almost always uncompressible JPEG or GIFs so the download then
proceeds at the basic rate of the connection for the bulky binaries.

Regards,
Martin Brown

 

[JosephKK]

PCM, I think. QAM is used on the, slower, uplink.

2400 symbols per second and about 12 bits per symbol maximum. Trellis coded
QAM both directions. Down channel was typically limited to 50 kbps and up
channel was typically around 10 kbps to reduce up/down interference. Requires
real fancy adaptive equalization.

Doesn't he always.

Don't know if such is done in my area i use DSL. If it is done they manage it
in the digital domain.
And i remember the "voice quality" wars from one to two decades ago.

 

[[email protected]]

Said the utter retard that actually thinks he ever got files over POTS
at 52 kbits per second.

Yep, and occasionally a little better. *ALWAYS* better than 28.8K, that you
said is impossible.

You're the liar who is AlwaysWrong.

 

[[email protected]]

They are doing the US equivalent of DACSing to share your line because
you are an unprofitable cheapskate is standard practice.

You've probably hit the nail squarely here. The various methods are
collectively known as "pair gain", on this side of the pond.

56kFlex modems were only around since late 90's and only really stable
and interoperable with ISP kit after the V90 standardisation ~1998.

X2 and Vflex were usable. I remember choosing ISPs based on which modem banks
they used. I remember when my ISP switched from X2 to Vflex. They denied it
but I gave them the make and series of the old and new modems (I had
development code for my modem that would tell everything about the modem at
the other end). They didn't appreciate being caught in a lie.

RTFM and force your modem to do a V34+ 33k6 connection in old world
technology and you should be able to make the best of a bad job. Or
switch to ISDN then they have to give you real copper or better for that.

ISDN has always been stupidly expensive in the US. DSL is far cheaper.

ADSL is rock solid in most of the civilised world.

If you're close enough to the DACs. The US is a big place and there is a
*lot* outside the range of DSL.

 

[FatBytestard]

my downloads thru Opera 9.64 are usually around 5.3 Kbps.
at first read,it goes as high as 12Kbps,but rapidly decays to ~5K.
I figure it's the browser overhead that makes the difference.

Idiot. Text gets compressed. You lack of knowing even the first thing
about it makes the difference.

 

[FatBytestard]

basic rate of the connection

A number no one here seems to know or understand.

 

[[email protected]]

A number no one here seems to know or understand.

You're clearly clueless, AlwaysWrong.

 

[FatBytestard]

Last I checked, ISDN was VERY EXPENSIVE, if you could even still get
it.
For the price, you would almost certainly go with DSL or cable, maybe
even wireless (if that's an option where the OP is?)

Idiots! I am not talking about ISDN service to the customer. Nobody
bought that shit that had any brains.

I am saying that ALL POTS communications RIGHT NOW are 100% ISDN from
the very first switch on. That is what I said before, and that is what I
meant.

Just because KRWTard makes up horseshit, then claims I said it or
refuted it doesn't mean a damned thing.

So the ONLY factor is the distance from your wall plate to that first
switch.

Get it through your thick skulls.

 

[Paul Keinanen]

AFAIK that is the way it is supposed to work here in the US.

In Europe, the lowest level of digital trunking E1 (2.048 MHz) is
implemented with 32 time slots of which 30 carried the actual audio
signals, one handled the synchronization and one handled the
signaling.

The US T1 1.536 Mbit/s signaling at 24x64 kHz tried to handle both the
signaling (off hook) and voice data in the same stream.

At least this was the reason given to us by some US telcos when trying
to get a 64 kbit/s data stream to our US offices in the 1980's.

 

[Martin Brown]

You've probably hit the nail squarely here. The various methods are
collectively known as "pair gain", on this side of the pond.

Sounds like the same sort of scheme. BT like NASA speaks entirely in
TLAs, ETLAs and SETLAs. DACS stands for Digital Access Carrier System I
think mostly made by Telspec. Is the US pair gain the same technology?

X2 and Vflex were usable. I remember choosing ISPs based on which modem banks
they used. I remember when my ISP switched from X2 to Vflex. They denied it
but I gave them the make and series of the old and new modems (I had
development code for my modem that would tell everything about the modem at
the other end). They didn't appreciate being caught in a lie.

I was an early adopter and involved in the testing of my ISPs server
upgrades. I had automatic logging and statistical analysis of all
connects, EQM and failure codes. Some of it was published in their FAQs
to help others get 56Flex and then later V90 to work reliably.

Certain firmware versions and combinations were very much more reliable
than others. They were interesting times (and like you I had control of
some registers that are no longer user configurable).

ISDN has always been stupidly expensive in the US. DSL is far cheaper.

ADSL is cheaper here too, but if the local copper won't support it then
ISDN still gives you real 64k raw digital without compression and 128kb
with both channels bonded. UK price is about 2.5x that of an ordinary
phone line and it means you have a pair of adjacent phone numbers for
fax/phone. There was a time when ISDN was ludicrously priced to protect
their incredibly lucrative Kilostream fixed line rentals.

ISDN is good enough to carry almost broadcast quality digital sound.

Even Belgium manages to do ISDN at a sensible price although their ugly
phone connectors look like they are intended to carry 4A mains power!

If you're close enough to the DACs. The US is a big place and there is a
*lot* outside the range of DSL.

I am nominally at the range limit ~12 miles of ADSL in a rural area but
still get almost 4M connection on old wires buried underground. I'd
hazard a guess that it might work at 1M these days out to 20 miles.

They may be better served by mobile phone data services then. That is
becoming affordable here on USB dongles (eg 1 GB @3Mb/s is £10-12 pcm,
although 3Gb @ upto 7Mb/s for £15 is better value).

Regards,
Martin Brown

 

[[email protected]]

Sounds like the same sort of scheme. BT like NASA speaks entirely in
TLAs, ETLAs and SETLAs. DACS stands for Digital Access Carrier System I
think mostly made by Telspec. Is the US pair gain the same technology?

"Pair gain" is used for any technology that "gains" a line by using what's
already there.

I was an early adopter and involved in the testing of my ISPs server
upgrades. I had automatic logging and statistical analysis of all
connects, EQM and failure codes. Some of it was published in their FAQs
to help others get 56Flex and then later V90 to work reliably.

Certain firmware versions and combinations were very much more reliable
than others. They were interesting times (and like you I had control of
some registers that are no longer user configurable).

Yes, that's why the modem developers let us use their instrumented code, so we
could report back on real ISPs and lines.

ADSL is cheaper here too, but if the local copper won't support it then
ISDN still gives you real 64k raw digital without compression and 128kb
with both channels bonded. UK price is about 2.5x that of an ordinary
phone line and it means you have a pair of adjacent phone numbers for
fax/phone. There was a time when ISDN was ludicrously priced to protect
their incredibly lucrative Kilostream fixed line rentals.

ISDN has always been out of the question in the US. The tariff structure has
always been dumb. V.90 put the nail in ISDNs coffin.

ISDN is good enough to carry almost broadcast quality digital sound.

Even Belgium manages to do ISDN at a sensible price although their ugly
phone connectors look like they are intended to carry 4A mains power!

I am nominally at the range limit ~12 miles of ADSL in a rural area but
still get almost 4M connection on old wires buried underground. I'd
hazard a guess that it might work at 1M these days out to 20 miles.

They tell us 17K' (3 miles). I'm right at that limit and recently had to
downgrade to 768K (after 1-1/2 years working at 3Mb).

They may be better served by mobile phone data services then. That is
becoming affordable here on USB dongles (eg 1 GB @3Mb/s is £10-12 pcm,
although 3Gb @ upto 7Mb/s for £15 is better value).

That's way too expensive for anything but mobile use.

 

[FatBytestard]

ISDN has always been out of the question in the US. The tariff structure has
always been dumb. V.90 put the nail in ISDNs coffin.

Yet ALL lines are ISDN from the first digital point onward. Period.

You seem to be 100% retarded as to what ISDN is. It isn't something
some dopey **** like the krw retard calls up some other fucking retard
and gets installed. They FAILED at selling it. That doesn't mean that
it is not still used, idiots.

ALL POTS runs over ISDN schemas from the point which your lines become
digital, which is at the very first switch.

You are glaringly fucking stupid to keep acting as if it doesn't v90
has NOTHING to do with it. Those are at the tail end connection.

 

[FatBytestard]

They tell us 17K' (3 miles). I'm right at that limit and recently had to
downgrade to 768K (after 1-1/2 years working at 3Mb).

Hahhahaah... wuss. I enjoy regular connections at 18Mb/s

 

[[email protected]]

Yet ALL lines are ISDN from the first digital point onward. Period.

Repeating your falsehoods just makes them into lies, AlwaysWrong.

You seem to be 100% retarded as to what ISDN is. It isn't something
some dopey **** like the krw retard calls up some other fucking retard
and gets installed. They FAILED at selling it. That doesn't mean that
it is not still used, idiots.

AlwaysWrong, is wrong. Yawn.

ALL POTS runs over ISDN schemas from the point which your lines become
digital, which is at the very first switch.

Wrong again, AlwaysWrong.

You are glaringly fucking stupid to keep acting as if it doesn't v90
has NOTHING to do with it. Those are at the tail end connection.

Keep it up, ALwaysWrong. Sooner or later you'll pop a cork.

 

[[email protected]]

Hahhahaah... wuss. I enjoy regular connections at 18Mb/s

Over ISDN, too! Everyone with a little dick brags about their size.

 

[FatBytestard]

Over ISDN, too! Everyone with a little dick brags about their size.

Cable, you retarded fucking ditz. If you were any more dirt dumb, I'd
swear that you were related to the Thompson retard.