BozoBin Now Invisible....

sidelight: When I worked as a Broadcast Engineer, I kept trying to use
the POTS for occasional Remote Broadcast purposes.

What Worked:

- On local (not through multiplex systems) exchanges, the actual
bandwidth was about 100 to 5000 Hz. I built couplers on and off the
dialed network that supported that bandwidth and they sounded good.
Built an automatic answerer on a dedicated incoming line and the
prearranged daily "remote studio" calls popped up a light on the
control board, and the DJ could use the regular "remote talkback"
switch to talk to them and confirm. The remote users then heard "Cue
audio" of the station until they heard their cue, the switch went from
CUE to LIVE and they were on the air.

- On long-distance calls, the same system was used but it was obvious
the bandwidth was limited. The most obvious result was loss of lows so
the voices were missing their nice quality. But it was OK for Sports
broadcasts.

Since Back Then:

- Some hardware exists which sends the 50-300 Hertz audio as a
subcarrier in the 2500-3000 Hz range. Some loss of "Highs" in the
audio, but the Lows are restored.

- Some broadcast stations used Modems over the POTS to send processed
audio. Worked pretty well.

- These days, of course, remote broadcasts are routinely sent as VOIP
(but sometimes with specific software with better low end and
automatic gain control etc..)  Anybody currently in Broadcast?? Please
tell us about the current practices...

DSL was seemingly an Impossible Dream "Back Then"...

I worked on ISDN a bit at IBM. It turned out to fit it's internal
acronym: "I Still Don't Need It"...

Regards, Terry King  ..On the Red Sea at KAUST
t...@terryking.us

> BozoBin Now Invisible....

Paul Keinanen wrote:
> On Thu, 04 Mar 2010 06:39:17 -0600, Jim Yanik <j...@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.   
> 
   AFAIK that is the way it is supposed to work here in the US.

On Sat, 06 Mar 2010 01:46:52 -0800, Robert Baer
<r...@localnet.com> wrote:

>Paul Keinanen wrote:
>> On Thu, 04 Mar 2010 06:39:17 -0600, Jim Yanik <j...@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.   
>> 
>   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.
 

k...@att.bizzzzzzzzzzzz wrote:
> On Fri, 05 Mar 2010 10:41:10 +0000, Martin Brown
> <|||newspam|||@nezumi.demon.co.uk> wrote:
> 
>> Robert Baer wrote:
>>> 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.
> 
> 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?
> 
>>>>>    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.
> 
> 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).
> 
>>> 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.
> 
> 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!
> 
>> 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.

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

TerryKing wrote:
> 
> BozoBin Now Invisible....
> 
> sidelight: When I worked as a Broadcast Engineer, I kept trying to use
> the POTS for occasional Remote Broadcast purposes.


   I had to do a live remote on a US Army base with less than an hour's
notice in the early '70s.  I sent our spare audio board to the building
and had the other engineer call me on our quietest phone line, then he
plugged the board into the phone line. I did the same at the studio and
got decent audio for the broadcast.

   Under normal remote use I had to request a copper pair between the
sites at least a month in advance and hope they didn't lose it.

 
> What Worked:
> 
> - On local (not through multiplex systems) exchanges, the actual
> bandwidth was about 100 to 5000 Hz. I built couplers on and off the
> dialed network that supported that bandwidth and they sounded good.
> Built an automatic answerer on a dedicated incoming line and the
> prearranged daily "remote studio" calls popped up a light on the
> control board, and the DJ could use the regular "remote talkback"
> switch to talk to them and confirm. The remote users then heard "Cue
> audio" of the station until they heard their cue, the switch went from
> CUE to LIVE and they were on the air.
> 
> - On long-distance calls, the same system was used but it was obvious
> the bandwidth was limited. The most obvious result was loss of lows so
> the voices were missing their nice quality. But it was OK for Sports
> broadcasts.
> 
> Since Back Then:
> 
> - Some hardware exists which sends the 50-300 Hertz audio as a
> subcarrier in the 2500-3000 Hz range. Some loss of "Highs" in the
> audio, but the Lows are restored.
> 
> - Some broadcast stations used Modems over the POTS to send processed
> audio. Worked pretty well.
> 
> - These days, of course, remote broadcasts are routinely sent as VOIP
> (but sometimes with specific software with better low end and
> automatic gain control etc..)  Anybody currently in Broadcast?? Please
> tell us about the current practices...
> 
> DSL was seemingly an Impossible Dream "Back Then"...
> 
> I worked on ISDN a bit at IBM. It turned out to fit it's internal
> acronym: "I Still Don't Need It"...


   AKA: 'Innovation Subscribers Don't Need'

   Back then, a lot of stations used portable UHF STL equipment for live
remotes. Marti made most of the systems I saw.


-- 
Greed is the root of all eBay.

On Sat, 06 Mar 2010 14:02:02 +0000, Martin Brown
<|||newspam|||@nezumi.demon.co.uk> wrote:

>k...@att.bizzzzzzzzzzzz wrote:
>> On Fri, 05 Mar 2010 10:41:10 +0000, Martin Brown
>> <|||newspam|||@nezumi.demon.co.uk> wrote:
>> 
>>> Robert Baer wrote:
>>>> 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.
>> 
>> 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?

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

>>>>>>    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.
>> 
>> 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).

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

>>>> 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.
>> 
>> 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 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!
>> 
>>> 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.
>
>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.

On Sat, 06 Mar 2010 12:54:15 -0600, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:

>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 fuck 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.

On Sat, 06 Mar 2010 12:54:15 -0600, "k...@att.bizzzzzzzzzzzz"
<k...@att.bizzzzzzzzzzzz> wrote:

>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

On Sat, 06 Mar 2010 11:48:53 -0800, FatBytestard
<F...@somewheronyourharddrive.org> wrote:

>On Sat, 06 Mar 2010 12:54:15 -0600, "k...@att.bizzzzzzzzzzzz"
><k...@att.bizzzzzzzzzzzz> wrote:
>
>>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.

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 fuck 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.