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Paul Keinanen
Guest
Fri Mar 05, 2010 7:19 am
On Thu, 04 Mar 2010 06:39:17 -0600, Jim Yanik <jyanik_at_abuse.gov>
wrote:
Quote:
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
Guest
Fri Mar 05, 2010 9:38 am
MakeNoAttemptToAdjustYourSet wrote:
Quote:
On Thu, 04 Mar 2010 22:52:44 -0600, "krw_at_att.bizzzzzzzzzzzz"
krw_at_att.bizzzzzzzzzzzz> wrote:
On Thu, 04 Mar 2010 20:39:49 -0800, MakeNoAttemptToAdjustYourSet
DoNotAttemptToAdjustYourSet_at_anytime.org> wrote:
On Thu, 04 Mar 2010 18:05:02 -0600, "krw_at_att.bizzzzzzzzzzzz"
krw_at_att.bizzzzzzzzzzzz> wrote:
Wrong, AlwaysWrong. When v.90 modems first came out I was regularly doing
48-52K on one of my POTS lines (the other was stuck at 28.8 because it went
five miles, all the way back to the CO).
NO, IDIOT. It was "handshaking" at that rate. You NEVER got file
transfers at that rate. Not even today. I WILL BET! FOAD!
Wrong, as always.
Try it with ANY 10MB file, and the numbers and the transfer do not
match. and don't even try to hand me a load of horseshit about packet
headers, you retarded little piece of DUMB motherfucker shit. The Speeds
were NEVER attained, and I was right next door to the goddamned switch
with top gear online, fuckhead!
But clearly without any clue how to make it work correctly.
Quote:
Wrong, as always.
Not to mention that I actually researched it, and I happen to remember
what I learned. You have obviously forgotten. If you ever knew.
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.
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
Robert Baer
Guest
Fri Mar 05, 2010 10:59 am
Jim Yanik wrote:
Quote:
Robert Baer <robertbaer_at_localnet.com> wrote in news:-
aSdnakxDbTj6RLWnZ2dnUVZ_o-dnZ2d_at_posted.localnet:
Paul Ingram wrote:
Does anyone know what are the highest and lowest frequencies that can
be transmitted as CW over a commercial wired telephone network?
Could bypassing the mic and speaker extend this range?
Paul Ingram
I think the bandwidth is supposed to be 3KHz, but do mot know if that
is the 3dB point and do not know the rolloff rate.
However, traditionally (ie up to 5 years ago and maybe later) one
could *reliably* get 48Kbaud data rate with a modem.
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.
Century Link in central Florida is my telco.
Most definitely NOT Qwest, which cares only about money: (1) make a
call, and after about 5 rings you get a recording asking for $1 "for
later delivery"; (2) try *57 on a harassing call 2 or more times ($1
each) then call their so-called caller id bureau(or whatever they call
it) and find that they have NO RECORD of the *57 and refuse to do
anything; (3) their ads included with your bill promise extremely fast
DSL and 985 of "customers" are lucky to get half that rate, other ads
promise a very low rate ($12/mo) and say zilch concerning gotchas,
addons, etc.
This is a SHORT list...
Robert Baer
Guest
Fri Mar 05, 2010 11:05 am
osr_at_uakron.edu wrote:
Quote:
On Mar 4, 3:54 am, Robert Baer <robertb...@localnet.com> wrote:
k...@att.bizzzzzzzzzzzz wrote:
On Thu, 04 Mar 2010 05:02:30 GMT, pauling...@oslotec.com (Paul Ingram) wrote:
Does anyone know what are the highest and lowest frequencies that can
be transmitted as CW over a commercial wired telephone network?
POTS is limited at the upper end by the DACs. They use 8k samples per second,
so that's ideally a 4kHz bandwidth. I'm not sure what the low end limiter is,
but it's supposed the spec is 300Hz.
Could bypassing the mic and speaker extend this range?
No.
Please comment as to WTF telcos did to throttle dial-up from 48Kbaud
to 28.8Kbaud.
Google "concentrator" a widget that pipes more lines down existing
copper pairs..
My beef is that cell uses so much compression, you cant use a modem
with cell.
And I'm stuck in a area with no wimax, so its $$$$ cable or death,
because the previous idiot renter of the apartment signed a paper
allowing removal of the copper pair...
Steve
Check to see if there is wiring from phonejack outlets or places for
them.
Then the problem would be at the entry box where incoming lines
(which i guarantee still physically exist) are nominally connected to
each service line pair.
If you can look there, perhaps you can see the disconnect; put a
short on YOUR pair and use ohmmeter inside to verify; remove short and
call telco for service.
Lettuce (or tomato) know results.
Robert Baer
Guest
Fri Mar 05, 2010 11:10 am
Fred Abse wrote:
Quote:
On Thu, 04 Mar 2010 00:52:56 -0800, Robert Baer wrote:
Paul Ingram wrote:
Does anyone know what are the highest and lowest frequencies that can
be transmitted as CW over a commercial wired telephone network?
Could bypassing the mic and speaker extend this range?
Paul Ingram
I think the bandwidth is supposed to be 3KHz, but do mot know if that
is the 3dB point and do not know the rolloff rate.
However, traditionally (ie up to 5 years ago and maybe later) one
could *reliably* get 48Kbaud data rate with a modem.
Not Kbaud, Kbits/sec. Baud rate is *considerably* lower (1200, or is
it 2400?). Bit rates are obtained by using fancy modulation schemes
yielding many bits per baud. IIRC, usually based on quadrature amplitude
modulation.
Shannon sets the theoretical limit.
But (some??) telcos have deliberately, in some unknown manner,
throttled that so the best one can now do is 28.8Kbaud.
Probably down to SNR (Shannon again).
* Sorry; they tested the line and said noise free, so noise is not the
limiting factor.
Quote:
And the response from then as well as from PUCs is "all we are
required to support is VOICE QUALITY".
All they were ever required to support.
* Not the point; they supported 48+Kbps for ages (20+ YEARS) and all of
a sudden crapped it down to 28.8K ON PURPOSE to get dial-up users to get
pissed off enough to $pend more $$$$$$$$ for their DSL (which BTW is
LESS reliable).
Quote:
Robert Baer
Guest
Fri Mar 05, 2010 11:13 am
Charlie E. wrote:
Quote:
On Thu, 04 Mar 2010 00:54:34 -0800, Robert Baer
robertbaer_at_localnet.com> wrote:
krw_at_att.bizzzzzzzzzzzz wrote:
On Thu, 04 Mar 2010 05:02:30 GMT, paulingram_at_oslotec.com (Paul Ingram) wrote:
Does anyone know what are the highest and lowest frequencies that can
be transmitted as CW over a commercial wired telephone network?
POTS is limited at the upper end by the DACs. They use 8k samples per second,
so that's ideally a 4kHz bandwidth. I'm not sure what the low end limiter is,
but it's supposed the spec is 300Hz.
Could bypassing the mic and speaker extend this range?
No.
Please comment as to WTF telcos did to throttle dial-up from 48Kbaud
to 28.8Kbaud.
Probably not much...
What basically happened, was that more and more, there were 2 or more
subscribers added to a single cable pair, with carrier equipment to
share that pair between them. The carrier equipment didn't have the
bandwidth needed to support the higher modem speeds (that basically,
relied on the fact that the digital CO was digitizing right at the
cable head, so why go back to analog at the ISP...) so people got
frustrated. To the telcos, they were just selling you a voice line,
guaranteed to be usable by a telephone. If you really needed digital
transmission, then you should have to pay for a specially conditioned
line that gave you that much throughput! BTW, the data line usually
cost more than a DSL line does today...
Charlie
Telcos have not been doing party lines since the 50's.
And if i was rich, i would not pay thru the nose for Blue Streak (2
COPPER pairs DIRECT to CO); i would put an antenna on a 100 foot pole
for WiNet.
Robert Baer
Guest
Fri Mar 05, 2010 11:17 am
Joel Koltner wrote:
Quote:
"MakeNoAttemptToAdjustYourSet" <DoNotAttemptToAdjustYourSet_at_anytime.org
wrote in message news:8h21p59cn8jfovss79anlslb0s3kei9qv5_at_4ax.com...
NO, IDIOT. It was "handshaking" at that rate. You NEVER got file
transfers at that rate. Not even today. I WILL BET! FOAD!
I used to get ~4.5kB/s downloads with the modem reporting connecting
speeds to 46-52kbps similar to what Keith reported. It wasn't twice the
speed of 28.8kbps modems, but *very* noticeably faster.
Wish Qwest would go back to that...
Robert Baer
Guest
Fri Mar 05, 2010 11:20 am
Paul Keinanen wrote:
Quote:
On Thu, 04 Mar 2010 06:39:17 -0600, Jim Yanik <jyanik_at_abuse.gov
wrote:
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.
Hmm..Not filtering - just added low-level noise that their analog
line tester would report a "good" line?
Martin Brown
Guest
Fri Mar 05, 2010 11:41 am
Robert Baer wrote:
Quote:
Fred Abse wrote:
On Thu, 04 Mar 2010 00:52:56 -0800, Robert Baer wrote:
But (some??) telcos have deliberately, in some unknown manner,
throttled that so the best one can now do is 28.8Kbaud.
Probably down to SNR (Shannon again).
* 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.
Quote:
And the response from then as well as from PUCs is "all we are
required to support is VOICE QUALITY".
All they were ever required to support.
* 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.
Quote:
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
John Walliker
Guest
Fri Mar 05, 2010 12:56 pm
On 4 Mar, 06:05, Jon Kirwan <j...@infinitefactors.org> wrote:
Quote:
Bandwidth is specified as 300Hz - 3000Hz. 2700Hz width. Not
4k. They may provide more, but my more recent tests suggest
they hard limit it pretty close these days. Back when
(1950's), it was much more.
If you can use an ISDN connection at each end the bandwidth is often
dc to just under 4kHz. I have successfully transmitted dc-coupled
audio across Europe and between UK and USA over the public telephone
network using an ISDN-equipped computer at each end of the connection
using the standard A-law/u-law coding at 8 kHz sampling rate.
In case you were wondering why I bothered to do this, it was related
to debugging problems with an IVR system where DC level changes
(caused by silences between prompts being encoded using u-law when the
rest of the system was using A-law) were causing mobile phone network
echo-cancellers to misbehave.
John
Jim Yanik
Guest
Fri Mar 05, 2010 4:53 pm
Robert Baer <robertbaer_at_localnet.com> wrote in
news:MY2dnS5_esNSRA3WnZ2dnUVZ_hCdnZ2d_at_posted.localnet:
Quote:
Joel Koltner wrote:
"MakeNoAttemptToAdjustYourSet"
DoNotAttemptToAdjustYourSet_at_anytime.org> wrote in message
news:8h21p59cn8jfovss79anlslb0s3kei9qv5_at_4ax.com...
NO, IDIOT. It was "handshaking" at that rate. You NEVER got file
transfers at that rate. Not even today. I WILL BET! FOAD!
I used to get ~4.5kB/s downloads with the modem reporting connecting
speeds to 46-52kbps similar to what Keith reported. It wasn't twice
the speed of 28.8kbps modems, but *very* noticeably faster.
Wish Qwest would go back to that...
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.
--
Jim Yanik
jyanik
at
localnet
dot com
Martin Brown
Guest
Fri Mar 05, 2010 5:12 pm
Jim Yanik wrote:
Quote:
Robert Baer <robertbaer_at_localnet.com> wrote in
news:MY2dnS5_esNSRA3WnZ2dnUVZ_hCdnZ2d_at_posted.localnet:
Joel Koltner wrote:
"MakeNoAttemptToAdjustYourSet"
DoNotAttemptToAdjustYourSet_at_anytime.org> wrote in message
news:8h21p59cn8jfovss79anlslb0s3kei9qv5_at_4ax.com...
NO, IDIOT. It was "handshaking" at that rate. You NEVER got file
transfers at that rate. Not even today. I WILL BET! FOAD!
I used to get ~4.5kB/s downloads with the modem reporting connecting
speeds to 46-52kbps similar to what Keith reported. It wasn't twice
the speed of 28.8kbps modems, but *very* noticeably faster.
Wish Qwest would go back to that...
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
Guest
Fri Mar 05, 2010 9:08 pm
On Thu, 04 Mar 2010 18:06:45 -0600, "krw_at_att.bizzzzzzzzzzzz" <krw_at_att.bizzzzzzzzzzzz> wrote:
Quote:
On Thu, 04 Mar 2010 11:07:46 -0800, Fred Abse <excretatauris_at_invalid.invalid
wrote:
On Thu, 04 Mar 2010 00:52:56 -0800, Robert Baer wrote:
Paul Ingram wrote:
Does anyone know what are the highest and lowest frequencies that can
be transmitted as CW over a commercial wired telephone network?
Could bypassing the mic and speaker extend this range?
Paul Ingram
I think the bandwidth is supposed to be 3KHz, but do mot know if that
is the 3dB point and do not know the rolloff rate.
However, traditionally (ie up to 5 years ago and maybe later) one
could *reliably* get 48Kbaud data rate with a modem.
Not Kbaud, Kbits/sec. Baud rate is *considerably* lower (1200, or is
it 2400?). Bit rates are obtained by using fancy modulation schemes
yielding many bits per baud. IIRC, usually based on quadrature amplitude
modulation.
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.
Quote:
Shannon sets the theoretical limit.
Doesn't he always.
But (some??) telcos have deliberately, in some unknown manner,
throttled that so the best one can now do is 28.8Kbaud.
Don't know if such is done in my area i use DSL. If it is done they manage it
in the digital domain.
Quote:
Probably down to SNR (Shannon again).
And the response from then as well as from PUCs is "all we are
required to support is VOICE QUALITY".
And i remember the "voice quality" wars from one to two decades ago.
Quote:
All they were ever required to support.
...and that snotty attitude has lost Ma' bundles of $$.
Vladimir Vassilevsky
Guest
Fri Mar 05, 2010 9:25 pm
JosephKK wrote:
Quote:
2400 symbols per second and about 12 bits per symbol maximum. Trellis coded
QAM both directions.
I have no idea what are you babbling about, however V.34 provides symbol
rates of up to 3.429k, with 960-point constellation.
Vladimir Vassilevsky
DSP and Mixed Signal Design Consultant
http://www.abvolt.com
krw@att.bizzzzzzzzzzzz
Guest
Sat Mar 06, 2010 1:27 am
On Thu, 04 Mar 2010 20:56:13 -0800, MakeNoAttemptToAdjustYourSet
<DoNotAttemptToAdjustYourSet_at_anytime.org> wrote:
Quote:
On Thu, 04 Mar 2010 22:52:44 -0600, "krw_at_att.bizzzzzzzzzzzz"
krw_at_att.bizzzzzzzzzzzz> wrote:
On Thu, 04 Mar 2010 20:39:49 -0800, MakeNoAttemptToAdjustYourSet
DoNotAttemptToAdjustYourSet_at_anytime.org> wrote:
On Thu, 04 Mar 2010 18:05:02 -0600, "krw_at_att.bizzzzzzzzzzzz"
krw_at_att.bizzzzzzzzzzzz> wrote:
Wrong, AlwaysWrong. When v.90 modems first came out I was regularly doing
48-52K on one of my POTS lines (the other was stuck at 28.8 because it went
five miles, all the way back to the CO).
NO, IDIOT. It was "handshaking" at that rate. You NEVER got file
transfers at that rate. Not even today. I WILL BET! FOAD!
Wrong, as always.
Try it with ANY 10MB file, and the numbers and the transfer do not
match. and don't even try to hand me a load of horseshit about packet
headers, you retarded little piece of DUMB motherfucker shit. The Speeds
were NEVER attained, and I was right next door to the goddamned switch
with top gear online, fuckhead!
Wrong, as always.
Not to mention that I actually researched it, and I happen to remember
what I learned. You have obviously forgotten. If you ever knew.
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.
Yep, and occasionally a little better. *ALWAYS* better than 28.8K, that you
said is impossible.
You're the liar who is AlwaysWrong.
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