PRC as a amplifier in GPS question.

[Don Pearce]

On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an international
telephone call to a third world country like India. The echo you hear is
usually 100% attributable to poor impedance mismatch at the other end of
the line. And guess what? It's all occurring at audio frequencies (300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places like
India via optical fibre and geo-stationery satellites - not thousands of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it? That
phone doesn't have a hybrid transformer, does it? That transformer doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is there?
That reflected power isn't digitised by the codec is it? That digitised
signal isn't audible at the sending end as an echo is it? And the fact that
these signals might use satellites or optical fibre somehow magically makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

 

[Alan Rutlidge]

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...

On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio
goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an
international
telephone call to a third world country like India. The echo you hear
is
usually 100% attributable to poor impedance mismatch at the other end of
the line. And guess what? It's all occurring at audio frequencies
(300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places
like
India via optical fibre and geo-stationery satellites - not thousands
of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it? That
phone doesn't have a hybrid transformer, does it? That transformer doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is there?
That reflected power isn't digitised by the codec is it? That digitised
signal isn't audible at the sending end as an echo is it? And the fact
that
these signals might use satellites or optical fibre somehow magically
makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

Don,

Fair go mate.(wink) You don't honestly thinks a toaster repairman needs to
know much about impedance mismatch do you?

Oh, and it looks as if I've been elevated from wire tugging status to
Information Technologist virtually overnight. Phil could never get his
lies straight - err no pun intended.. You know, one of these days he's
actually gonna get something right about me. When that happens I'll duck
out and by a lottery ticket.

Cheers,
Alan

 

[Nh]

Phil Allison wrote:

Seriously Phill if you continue with this nonsensical rubbish I am
certain you will be placed under care again I recognize along with any
right thinking person that you are descending into the depths of a
breakdown and may well injure your self
so the question is

Will fucking hurry up and top your self
Listen to those nasty little voices in your head screaming
Die philly die


Then maybe we can get back to discussing group topic.

 

[tb]

Franc Zabkar wrote:

I have a salt water chlorinator, model Q-Diamond 1200, manufactured by
Pool Store International. It has a faulty controller module which I
haven't been able to remove from the front panel. It appears to
consist of two halves, one on each side of the front panel. There are
no screws, just eight dimples in the plastic fascia (4 at the front, 4
at the rear) which suggest some kind of tamper proof snap lock
fasteners may be used. I've decided to drill these out, but before I
do so, does anyone have any experience with these units?

BTW, I've already contacted the manufacturer, but they were of no help
at all.


- Franc Zabkar
You may be able to get the part from www.directpoolsupplies.com.au

 

[Nh]

Phil Allison wrote:

"Nh"


** Who are you ??





......... Phil


Irrelevant toaster boy

all that matter is like any other right thinking person
I await your self inflicted demise with anticipation .

 

[Alan Rutlidge]

"Phil Allison" <philallison@tpg.com.au> wrote in message
news:3nnsguF2dmllU1@individual.net...

"Alan Rutlidge"
Phil Allison

** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Phil Allison the great unqualified is just envious of anyone who has ever
acheived anything in their professional or personal life. Phil isn't even
qualified to fix toasters but of course he'll tell you otherwise.
Phil never graduated from university and has no recognised vocational trade
qualifications either. He self postures here, spending most of his time
desperately attempting to discredit thoise who hold formal and industry
recognised qualifications.

Only the dullest teenagers would fall for such utter shite !!!

So by implications that must also be the case with World recognised learning
institutions such as Alcatel University in Brest, France, which issued my
latest qualification. Which recognised institution issued you last formal
qualification Phil, and in what? Let me guess - bullshitting ????

Oh, and it looks as if I've been elevated from wire tugging status to
Information Technologist virtually overnight.


** A fuckwit, wire tugger is all you are - Arse Bandit.

First it's one thing, then it's the next Phil. Make up you mind. You can't
have it both ways.

Falsely impersonating an IT instructor is what you do.

And you claim to fame? Falsely impersonating a Toaster Repairman?

Chasing under aged boys around Thailand notwithstanding.

Gee Phil, when are you going to stop having these fantasies about other
people doing exactly what you are thinking about all the time. Get yourself
into therapy soon, before you actually do commit an offence.

You know, one of these days he's actually gonna get something right about
me.


** Been doing just that for a very long time.

Yep, in your dreams Phil. You are a know nothing dimwit. I'd be a rich man
if I got a dollar for every bit of bullshit you've published about me.

No surprise that a congenital LAIR & a criminal Arse Bandit would never
agree.

Seeing you are no doubt the former and you are convinced I'm the latter, I
have to agree with that.
(Now go back and read just how much of an ass you've made of yourself Phil.)

.......... Phil

 

[SSJVCmag]

On 9/1/05 12:03 PM, in article
43172666$0$524$5a62ac22@per-qv1-newsreader-01.iinet.net.au, "Alan Rutlidge"
<dont_spam_me_rutlidge@iinet.net.au> wrote:

Phil Allison the great unqualified is just envious
First it's one thing, then it's the next Phil. anding.

Gee Phil, when are you going to stop having these fantasies
Yep, in your dreams Phil. You are a know nothing dimwit.

Alan thanks -So- much for dorkishly splattering your skeet across several
newsgroups uninvited...
Take a copy of our Home Game on your way out!

 

[Alan Rutlidge]

"SSJVCmag" <ten@nozirev.gamnocssj.com> wrote in message
news:BF3CB8AA.10315%ten@nozirev.gamnocssj.com...

On 9/1/05 12:03 PM, in article
43172666$0$524$5a62ac22@per-qv1-newsreader-01.iinet.net.au, "Alan
Rutlidge"
dont_spam_me_rutlidge@iinet.net.au> wrote:

Phil Allison the great unqualified is just envious
First it's one thing, then it's the next Phil. anding.

Gee Phil, when are you going to stop having these fantasies
Yep, in your dreams Phil. You are a know nothing dimwit.

Alan thanks -So- much for dorkishly splattering your skeet across several
newsgroups uninvited...
Take a copy of our Home Game on your way out!

For the record I didn't bring the original thread to this NG - someone else
did.

Phil Allison posted it to three newsgroups. I trimmed one of them off the
reply.
You've never been here before AFAIK (well at least not in a long while), so
to demonstrate how much of a troll you are you thought you'd come over here
and put your 2c worth in.

Oh, and if you must quote, at least do it properly. Also, in case it
happened to slip your attention, most NGs are open public forums (hence the
reason why Phil and you are here).

BTW if skeet shooting is your game, try this -
http://indigo.ie/~gerryq/Skeet/skeet.htm

Cheers,
Alan

 

[Richard Freeman]

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio
goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an
international
telephone call to a third world country like India. The echo you hear
is
usually 100% attributable to poor impedance mismatch at the other end
of
the line. And guess what? It's all occurring at audio frequencies
(300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places
like
India via optical fibre and geo-stationery satellites - not thousands
of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it? That
phone doesn't have a hybrid transformer, does it? That transformer
doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is there?
That reflected power isn't digitised by the codec is it? That digitised
signal isn't audible at the sending end as an echo is it? And the fact
that
these signals might use satellites or optical fibre somehow magically
makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

Don,

Fair go mate.(wink) You don't honestly thinks a toaster repairman needs
to know much about impedance mismatch do you?

Well actually I am afraid that Hybrid leakage is not actually anything to do
with impedance mis-match but rather more to do with Gain of a Transmission
System and the way a Hybrid works - The gain of the System can (obviously)
be affected by Impedance etc however the echo is not the result of reflected
signals due to Impedance mismatch but rather from the fact that a hybrid is
not perfect.
The term signal reflection is often used to refer to hybrid leakage but (and
here is the rub) it is not Impedance reflection.

http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16502325

http://www.iec.org/online/tutorials/echo_cancel/topic02.html

 

[Alan Rutlidge]

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio
goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an
international
telephone call to a third world country like India. The echo you hear
is
usually 100% attributable to poor impedance mismatch at the other end
of
the line. And guess what? It's all occurring at audio frequencies
(300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places
like
India via optical fibre and geo-stationery satellites - not thousands
of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it? That
phone doesn't have a hybrid transformer, does it? That transformer
doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is there?
That reflected power isn't digitised by the codec is it? That digitised
signal isn't audible at the sending end as an echo is it? And the fact
that
these signals might use satellites or optical fibre somehow magically
makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

Don,

Fair go mate.(wink) You don't honestly thinks a toaster repairman needs
to know much about impedance mismatch do you?

Well actually I am afraid that Hybrid leakage is not actually anything to
do with impedance mis-match but rather more to do with Gain of a
Transmission System and the way a Hybrid works - The gain of the System
can (obviously) be affected by Impedance etc however the echo is not the
result of reflected signals due to Impedance mismatch but rather from the
fact that a hybrid is not perfect.
The term signal reflection is often used to refer to hybrid leakage but
(and here is the rub) it is not Impedance reflection.

http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16502325

http://www.iec.org/online/tutorials/echo_cancel/topic02.html

Perhaps the issue of reflected power in an impedance mismatched circuit has
gone a bit too far and turned the corner.

Any energy not absorbed by a termination must go somewhere - agreed?

When the source and load impedances are matched all the power developed by
the source will be transferred to the load without loss. As soon as either
of the impedances vary relative to the other an impedance mismatch occurs.
Under such conditions not all of the power developed by the source will be
transferred to the load. This results in a loss of power which is directly
related to the degree (ratio) of impedance mismatch.

Reflection loss is the logarithmic ratio of the incident power to the load,
that is, the ratio between the power that would be absorbed under correctly
matched conditions, to the power actually absorbed by the load.

Therefore :

Loss due to reflection (dB) = 10 x log(base10) Incident Power / Reflected
Power

or in terms of the impedances -

Loss due to reflection (dB) = 10 x log(base10) (Z1 + Z2) sq / 4Z1 x Z2

As an example, a 1 : 1 ratio results in 0dB loss due to reflection.
A 2 : 1 mismatch results in 0.5dB loss due to reflection.
A 4 : 1 mismatch results in approximately 1.9dB loss due to reflection.
An 8 : 1 mismatch results in approx. 4dB loss due to reflection; and so on.

Impedance mismatch does matter.

Cheers,
Alan

 

[Phil Allison]

"Alan Rutlidge"

"Richard Freeman"

Well actually I am afraid that Hybrid leakage is not actually anything to
do with impedance mis-match but rather more to do with Gain of a
Transmission System and the way a Hybrid works - The gain of the System
can (obviously) be affected by Impedance etc however the echo is not the
result of reflected signals due to Impedance mismatch but rather from the
fact that a hybrid is not perfect.
The term signal reflection is often used to refer to hybrid leakage but
(and here is the rub) it is not Impedance reflection.

http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16502325

http://www.iec.org/online/tutorials/echo_cancel/topic02.html


When the source and load impedances are matched all the power developed by
the source will be transferred to the load without loss.

** You are an absolute fuckwit - Rutmaniac .

As soon as either of the impedances vary relative to the other an
impedance mismatch occurs.

** You are an absolute fuckwit - Rutmaniac .

The max power transfer theorem has nothing to do with the issue.

Under such conditions not all of the power developed by the source will be
transferred to the load. This results in a loss of power which is
directly related to the degree (ratio) of impedance mismatch.

** You are an absolute fuckwit - Rutmaniac .


(snip total irrelevances copied from some beginner's web site)


** You are an absolute fuckwit - Rutmaniac .

Can't even get chasing under aged Thai boys right without losing your shirt.

ROTFL........




........... Phil

 

[Don Pearce]

On Fri, 2 Sep 2005 15:27:47 +0800, Alan Rutlidge wrote:

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio
goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an
international
telephone call to a third world country like India. The echo you hear
is
usually 100% attributable to poor impedance mismatch at the other end
of
the line. And guess what? It's all occurring at audio frequencies
(300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places
like
India via optical fibre and geo-stationery satellites - not thousands
of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it? That
phone doesn't have a hybrid transformer, does it? That transformer
doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is there?
That reflected power isn't digitised by the codec is it? That digitised
signal isn't audible at the sending end as an echo is it? And the fact
that
these signals might use satellites or optical fibre somehow magically
makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

Don,

Fair go mate.(wink) You don't honestly thinks a toaster repairman needs
to know much about impedance mismatch do you?

Well actually I am afraid that Hybrid leakage is not actually anything to
do with impedance mis-match but rather more to do with Gain of a
Transmission System and the way a Hybrid works - The gain of the System
can (obviously) be affected by Impedance etc however the echo is not the
result of reflected signals due to Impedance mismatch but rather from the
fact that a hybrid is not perfect.
The term signal reflection is often used to refer to hybrid leakage but
(and here is the rub) it is not Impedance reflection.

http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16502325

http://www.iec.org/online/tutorials/echo_cancel/topic02.html


Perhaps the issue of reflected power in an impedance mismatched circuit has
gone a bit too far and turned the corner.

Any energy not absorbed by a termination must go somewhere - agreed?

When the source and load impedances are matched all the power developed by
the source will be transferred to the load without loss. As soon as either
of the impedances vary relative to the other an impedance mismatch occurs.
Under such conditions not all of the power developed by the source will be
transferred to the load. This results in a loss of power which is directly
related to the degree (ratio) of impedance mismatch.

Reflection loss is the logarithmic ratio of the incident power to the load,
that is, the ratio between the power that would be absorbed under correctly
matched conditions, to the power actually absorbed by the load.

Therefore :

Loss due to reflection (dB) = 10 x log(base10) Incident Power / Reflected
Power

or in terms of the impedances -

Loss due to reflection (dB) = 10 x log(base10) (Z1 + Z2) sq / 4Z1 x Z2

As an example, a 1 : 1 ratio results in 0dB loss due to reflection.
A 2 : 1 mismatch results in 0.5dB loss due to reflection.
A 4 : 1 mismatch results in approximately 1.9dB loss due to reflection.
An 8 : 1 mismatch results in approx. 4dB loss due to reflection; and so on.

Impedance mismatch does matter.

Cheers,
Alan

We are not actually worried here about the power lost by reflection, but
the fact that it causes an echo - particularly noticeable on an
international line with long delays. In this regard, even quite small
mismatches are important. A mismatch which results in just 0.1dB of signal
loss will cause an echo at -20dB. This will be very audible.

d

 

[Alan Rutlidge]

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:a750c7dhudwb.1h2dtb3ggjv48.dlg@40tude.net...

On Fri, 2 Sep 2005 15:27:47 +0800, Alan Rutlidge wrote:

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

"Alan Rutlidge"
"Arny Krueger"


It takes significant distances for audio electrical signals to
demonstrate things like reflections and standing waves. For most
practical purposes, they never happen because by the time the audio
goes
that far in the modern world, its probably already been digitized.


Digitising an audio signal does not eliminate propagation delay if
the
signal is transmitted over a long distance. To demonstrate this in
combination with the problem of impedance mismatch - make an
international
telephone call to a third world country like India. The echo you
hear
is
usually 100% attributable to poor impedance mismatch at the other
end
of
the line. And guess what? It's all occurring at audio frequencies
(300Hz
to 3400Hz).


** ROTFLMAO !!!!

Does this Rutmaniac, fucking idiot actually teach such monumental
**BULLSHIT** to IT industry trainees ????

Only the dullest teenagers would fall for such utter shite !!!


FYI

Telecommunications data is digital ( not audio) and travels to places
like
India via optical fibre and geo-stationery satellites - not
thousands
of
miles of bloody co-ax !!

What a complete MORON !!!!



.......... Phil

So Phil. It is digital right up to the phone at the far end, is it?
That
phone doesn't have a hybrid transformer, does it? That transformer
doesn't
have a limited sidetone spec, does it? The match of phone to line is
perfect is it? There is no signal reflection from that phone, is
there?
That reflected power isn't digitised by the codec is it? That
digitised
signal isn't audible at the sending end as an echo is it? And the fact
that
these signals might use satellites or optical fibre somehow magically
makes
all these reflected signals disappear, does it?

Only only planet Phil does the world work this way.

d

Don,

Fair go mate.(wink) You don't honestly thinks a toaster repairman
needs
to know much about impedance mismatch do you?

Well actually I am afraid that Hybrid leakage is not actually anything
to
do with impedance mis-match but rather more to do with Gain of a
Transmission System and the way a Hybrid works - The gain of the System
can (obviously) be affected by Impedance etc however the echo is not the
result of reflected signals due to Impedance mismatch but rather from
the
fact that a hybrid is not perfect.
The term signal reflection is often used to refer to hybrid leakage but
(and here is the rub) it is not Impedance reflection.

http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16502325

http://www.iec.org/online/tutorials/echo_cancel/topic02.html


Perhaps the issue of reflected power in an impedance mismatched circuit
has
gone a bit too far and turned the corner.

Any energy not absorbed by a termination must go somewhere - agreed?

When the source and load impedances are matched all the power developed
by
the source will be transferred to the load without loss. As soon as
either
of the impedances vary relative to the other an impedance mismatch
occurs.
Under such conditions not all of the power developed by the source will
be
transferred to the load. This results in a loss of power which is
directly
related to the degree (ratio) of impedance mismatch.

Reflection loss is the logarithmic ratio of the incident power to the
load,
that is, the ratio between the power that would be absorbed under
correctly
matched conditions, to the power actually absorbed by the load.

Therefore :

Loss due to reflection (dB) = 10 x log(base10) Incident Power / Reflected
Power

or in terms of the impedances -

Loss due to reflection (dB) = 10 x log(base10) (Z1 + Z2) sq / 4Z1 x Z2

As an example, a 1 : 1 ratio results in 0dB loss due to reflection.
A 2 : 1 mismatch results in 0.5dB loss due to reflection.
A 4 : 1 mismatch results in approximately 1.9dB loss due to reflection.
An 8 : 1 mismatch results in approx. 4dB loss due to reflection; and so
on.

Impedance mismatch does matter.

Cheers,
Alan

We are not actually worried here about the power lost by reflection, but
the fact that it causes an echo - particularly noticeable on an
international line with long delays. In this regard, even quite small
mismatches are important. A mismatch which results in just 0.1dB of signal
loss will cause an echo at -20dB. This will be very audible.

d

Absolutely no disagreement there Don about the fact that impedance mismatch
contributes to echo.

Echo (due to reflection) is a function of the return loss of the circuit.
The formula is -

Return Loss (dB) = 20 x log(base10) (Z1 + Z2) / (Z1 - Z2)

A 2 : 1 mismatch (which results in a power loss of 0.5dB) corresponds to a
return loss of 9.2dB which is pretty poor. A mismatch which results in only
0.1dB loss due to reflection actually achieves a healthy return loss in
excess of 40dB, but as we both know that good figure rapidly deteriorates as
the mismatch ratio increases.

In a transformer hybrid circuit, the return loss between the two paths of
the 4 wire transmission circuits will never go below about 7dB due to
trans-hybrid losses even if the impedance ratio between the load on the 2
wire circuit is infinitely high with respect to that of the network
connected to the balancing network port. In practice, most telecos build
loss into their transmission networks to counteract the effects of
instability due to impedance mismatches. In Australia, the loss from 2 wire
appearance at the MDF of the exchange to the same at the other end is
designed at 6dB for each direction of voice transmission. A nice idea, as
the echo level is reduced by a factor of 2 times the loss of the link in the
network, resulting in a minimum stability margin of at least 12dB even under
the worst possible conditions.

Some other overseas networks aren't anywhere near as good as ours when it
comes to echo performance. In fact a well designed and impedance matched
network requires little or no echo cancellation equipment, resulting in a
clearer network to talk over and minimal VF data transmission / fax
transmission problems.

Cheers,
Alan

 

[Bob Cain]

Alan Rutlidge wrote:

Reflection loss is the logarithmic ratio of the incident power to the load,
that is, the ratio between the power that would be absorbed under correctly
matched conditions, to the power actually absorbed by the load.

Except that considerations of reflections and their effects
on impedence only become relevant when the length of the
connection is some fairly signifigant percentage of the
wavelength of the signal.

In signal transmission, rather than power transmission, it
is the effects of impedence on accurate delivery of the
signal that matters.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

 

[Sir Jean-Paul Turcaud]

Sir,

Your comments are completely to the point, especially that
Quote
- a Tsunami Wave
hitting the East Coast of Australia?
Unquote

All Australians without the exception of 2, are completely impervious nor
aware then of the fatality of such occurrence, and its Geological implacable
logic.
Those 2 are Dr Don Findlay of Perth, WA, and Sir Turcaud of La Rochelle,
France, and the justification of the looming catastrophe is based on the
Earth Expansion Theory.
The Earth Expansion Theory is part of the True Geology teaching whose corner
stone is the UPL, or Universal Pressure Law, which UPL explains the
mechanism of both EE and Orogenesis through Cosmic Encounter, and in clear
as a result the Moon crushing on the Earth 11 700 years ago.

Such understanding is so much above and beyond the grasp of the usual mind
programmed Unversilities Imbeciles of the WAIT, Monash, ANU etc. That it is
not surprising that this most aware gentleman of
in Byron Bay a man, speaking in Public Voice on 22nd February 2005, cogent
and impassioned plea for Byron Shire Council to anticipate a coming
catastrophe was ridiculed indeed.

In 2000 during the SOG ( Sydney Olympics Game) I rightly anticipated a
Quakes out of the East Coast, and this Quake occurred indeed and was located
a mere 60 miles out at sea. Would it had been as I anticipate it rightly a
9.2 magnitude Quake as the one which later occurred in Banda Ashe, the death
toll for the Eastern Coast of Australia would have amounted to over 2.5
million persons. Such persons would have been rightly evacuated since the
warning of such major quake can be rightly too anticipated by a Very Easy
System to implement .... a system based on the UP understanding. It gives a
48 hours warning allowing all the population of Eastern Coast to be put away
into the safety of the Blue Mountains.

THE MAIN PROBLEM WITH AUSTRALIA are the Dudes in control and wrongly
elected to power. Worthless & non productive Parasites such as Lawyers,
Quacks, Psychochologists and all that type of Unscientific indeed. Never
any Mining Prospector, Geologist, Physicists, Mining Engineer, Farmer,
Fitter, Miner, Surveyor etc reaches the level of Government ... only the
Big Fat Mouth Vermin's do !
As a result poor Australia is led by completely clueless imbeciles who not
only are completely unaware of what is at stakes, but as well completely
unable to take anticipating measures.

Further more such Political Rabble is so much unconcerned about those who
made the Mining History of Australia, like the few Australia Mining Pioneers
still alive, that I doubt personally that this Corrupt Political Rabble does
even know about its own Australia History. As Murphy's said "
§ "A 30 000 $ picture tube will protect a 10c fuse by blowing first"§

Likewise the whole coast of NSW & Queenland will be devastated to protect
the Australian Federal Parliament and the ANU sci000ntic Pride & Blindness

.... and as a conclusion indeed , I would not buy a house on the Gold Coast
which is not at least 100ft above MSL

Yours faithfully

--
Sir Jean-Paul Turcaud
Shadow Ambassador of Australia in France
(Commissioned to prevent French migration to Australia)


Australia Mining Pioneer
Exploration Geologist
Discoverer and Legal Owner of Telfer, Nifty & Kintyre Mines
The Great Sandy Desert of Australia

Founder of the True Geology

* The "Golden Rule" or true story of the Discovery of the Telfer Mine
Author Bob Sheppard President of the APLA (Australian Prospectors' Union)
http://www.tnet.com.au/~warrigal/grule.html ,

* As well as Dr Don Findlay's Geological Site
http://users.indigo.net.au/don/tel/index.html

~~ Ignorance Is The Cosmic Sin, The One Never Forgiven ! ~~




"AussieSeek.com POLITICAL MESSAGEBOARDS" <nswamfm@yahoo.com> a écrit dans le
message de news: 1125796223.254493.200780@z14g2000cwz.googlegroups.com...

Is there a DISASTER CLOCK?
Does anyone know the story of how the Category 5 Levi was sidelined for
a Category 3 Levi because of the difference of $1.5 Billion? It was a
category 5 Hurricane which finally hit.
Are the media in Australia preparing their questions for Philip Ruddock
whose Attorney General's Dept. is responsible for ' Emergency
Management Australia ' whose organisation is run by Director David
Templeman?

Does the media in Australia recognise the Newsworthyness of a series of
stories on Australia's most likely Natural Disaster - a Tsunami Wave
hitting the East Coast of Australia?
Do journalists realise their vast importance, in warning the people of
the East Coast of Australia that a warning system using sirens in all
Coastal Communities, and linked to the EMA Tsunami Warning Centre, is
an absolute requirement for the 500,000 people who face death if a wave
hits?

Does any editor/producer out there realise the giant story they have in
reminding people how the man who warned the Thai Government about an
imminent Tsunami Event was hounded out of his job to ' protect the
Tourist Industry ' AND THEN show how warning sirens for the East Coast
of Australia (which faces live, yes, LIVE, volcanos in N.Z.) are being
denied Coastal Communities and City Populations to protect a
believed(but not real) Real Estate devaluation in the ' Wave Zone '?

In Byron Bay a man, speaking in Public Voice on 22nd February 2005,
made a cogent and impassioned plea for Byron Shire Council to implace
Warning Sirens and establish an Evacuation Plan with the recruitment
and training of 200 Evacuation Volunteers, to save Byron Residents from
the devestating and lethal effects of a Tsunami Wave or Cyclone Event
killing most of the residents, with even a small wave.
Does the Media in NSW realise the importance of Premier Morris Iemma's
statement made to TV that Sirens and Evacuation Volunteers would be
used in the case of a Terrorist Threat in the CBD of Sydney? He may be
new but he's no 'rookie'. Ideas travel fast in this age of info..
Has anyone put it together, that the Aceh Tsunami occurred on 26th
December, and the Newcastle,NSW, Earthquake happened on the 28th
December? On the hottest month of the year, the continent of Australia
expands, putting pressure on the sea floors around it. Although the
Australian continent is stable, the Sea Floors around it aren't.
Australia 65km thick - Pacific Ocean and Tasman Sea 5km thick.
Get it?

 

[Richard Freeman]

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:43180e72$0$518$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:a750c7dhudwb.1h2dtb3ggjv48.dlg@40tude.net...
On Fri, 2 Sep 2005 15:27:47 +0800, Alan Rutlidge wrote:

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

- - - - - - -- - - snipped for brevity - - - - - - - - - - -

As an example, a 1 : 1 ratio results in 0dB loss due to reflection.
A 2 : 1 mismatch results in 0.5dB loss due to reflection.
A 4 : 1 mismatch results in approximately 1.9dB loss due to reflection.
An 8 : 1 mismatch results in approx. 4dB loss due to reflection; and so
on.

Impedance mismatch does matter.

Cheers,
Alan

We are not actually worried here about the power lost by reflection, but
the fact that it causes an echo - particularly noticeable on an
international line with long delays. In this regard, even quite small
mismatches are important. A mismatch which results in just 0.1dB of
signal
loss will cause an echo at -20dB. This will be very audible.

d

Absolutely no disagreement there Don about the fact that impedance
mismatch contributes to echo.

Echo (due to reflection) is a function of the return loss of the circuit.

The Echo is not due to Line reflections but rather due to Hybrid Transformer
leakage - see Sidetone which is a deliberate result of this leakage being
taken advantage of ....

The formula is -

Return Loss (dB) = 20 x log(base10) (Z1 + Z2) / (Z1 - Z2)

A 2 : 1 mismatch (which results in a power loss of 0.5dB) corresponds to a
return loss of 9.2dB which is pretty poor. A mismatch which results in
only 0.1dB loss due to reflection actually achieves a healthy return loss
in excess of 40dB, but as we both know that good figure rapidly
deteriorates as the mismatch ratio increases.

In a transformer hybrid circuit, the return loss between the two paths of
the 4 wire transmission circuits will never go below about 7dB due to
trans-hybrid losses even if the impedance ratio between the load on the 2
wire circuit is infinitely high with respect to that of the network
connected to the balancing network port. In practice, most telecos build
loss into their transmission networks to counteract the effects of
instability due to impedance mismatches.

you do not have to build loss into Telephone networks - it is there anyway -
it is more a case of keeping your gain down to make sure you do not get
howling due to feedback through the hybrid Transformers at each end -

In Australia, the loss from 2 wire appearance at the MDF of the exchange
to the same at the other end is designed at 6dB for each direction of
voice transmission. A nice idea, as the echo level is reduced by a factor
of 2 times the loss of the link in the network, resulting in a minimum
stability margin of at least 12dB even under the worst possible
conditions.

Some other overseas networks aren't anywhere near as good as ours when it
comes to echo performance. In fact a well designed and impedance matched
network requires little or no echo cancellation equipment, resulting in a
clearer network to talk over and minimal VF data transmission / fax
transmission problems.

Hmmm? what about Side tone ? how do these well designed networks provide
Sidetone ?

 

[Alan Rutlidge]

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:431bf695_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:43180e72$0$518$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:a750c7dhudwb.1h2dtb3ggjv48.dlg@40tude.net...
On Fri, 2 Sep 2005 15:27:47 +0800, Alan Rutlidge wrote:

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

- - - - - - -- - - snipped for brevity - - - - - - - - - - -

As an example, a 1 : 1 ratio results in 0dB loss due to reflection.
A 2 : 1 mismatch results in 0.5dB loss due to reflection.
A 4 : 1 mismatch results in approximately 1.9dB loss due to reflection.
An 8 : 1 mismatch results in approx. 4dB loss due to reflection; and so
on.

Impedance mismatch does matter.

Cheers,
Alan

We are not actually worried here about the power lost by reflection, but
the fact that it causes an echo - particularly noticeable on an
international line with long delays. In this regard, even quite small
mismatches are important. A mismatch which results in just 0.1dB of
signal
loss will cause an echo at -20dB. This will be very audible.

d

Absolutely no disagreement there Don about the fact that impedance
mismatch contributes to echo.

Echo (due to reflection) is a function of the return loss of the circuit.

The Echo is not due to Line reflections but rather due to Hybrid
Transformer leakage - see Sidetone which is a deliberate result of this
leakage being taken advantage of ....

The formula is -

Return Loss (dB) = 20 x log(base10) (Z1 + Z2) / (Z1 - Z2)

A 2 : 1 mismatch (which results in a power loss of 0.5dB) corresponds to
a return loss of 9.2dB which is pretty poor. A mismatch which results in
only 0.1dB loss due to reflection actually achieves a healthy return loss
in excess of 40dB, but as we both know that good figure rapidly
deteriorates as the mismatch ratio increases.

In a transformer hybrid circuit, the return loss between the two paths of
the 4 wire transmission circuits will never go below about 7dB due to
trans-hybrid losses even if the impedance ratio between the load on the 2
wire circuit is infinitely high with respect to that of the network
connected to the balancing network port. In practice, most telecos build
loss into their transmission networks to counteract the effects of
instability due to impedance mismatches.

you do not have to build loss into Telephone networks - it is there
anyway -

Not entirely true. Most of the US Inter Exchange Network (IEN) [digital] is
designed to have a nominal 0dB loss exchange to exchange. The only overall
transmission losses occur on the lines between the exchange and the
customers. Even before the advent of digital transmission and switching
technology, the old Strowger exchange had a fraction of a dB loss through
the exchange on a local call. IEN echo however was not a problem as it was
a two wire circuit through the exchange and the cable network to the
telephone.

it is more a case of keeping your gain down to make sure you do not get
howling due to feedback through the hybrid Transformers at each end -

In a closed 4 wire IEN circuit losses of approximately 7dB occur across the
transformer hybrids at each end of the 4 wire transmission path even under
the worst possible mismatch conditions. This effectively provides a total
of 14dB loss to the singing loop. Therefore, provided the total gains in
the singing loop don't exceed the total losses, the circuit will remain
unconditionally stable. Any difference in favour of the losses over the
gains in the singing loop is known as the Stability Margin.
Example : If the losses total 14dB (trans-hybid losses as the worst
possible condition) and the gain only 1dB in each direction of transmission
to overcome adjacent port losses in the transformer hybrids (total 2dB gain
in the singing loop), therefore:- 14dB (loss) - 2dB (gain) = 12dB stability
margin. In simple terms the closed 4 wire loop can never become unstable.

In Australia, the loss from 2 wire appearance at the MDF of the exchange
to the same at the other end is designed at 6dB for each direction of
voice transmission. A nice idea, as the echo level is reduced by a
factor of 2 times the loss of the link in the network, resulting in a
minimum stability margin of at least 12dB even under the worst possible
conditions.

Some other overseas networks aren't anywhere near as good as ours when it
comes to echo performance. In fact a well designed and impedance matched
network requires little or no echo cancellation equipment, resulting in a
clearer network to talk over and minimal VF data transmission / fax
transmission problems.

Hmmm? what about Side tone ? how do these well designed networks provide
Sidetone ?

The sidetone is developed within the telephone. Older phones (pre the T200
/ T400 series) used what was known as an Anti-SideTone Induction Coil
(ASTIC) which is a purposely leaky hybrid, was designed to feedback a small
amount of the speech energy from the transmitter (microphone) to the
receiver. This sidetone is purposefully locally introduced to make the
caller think the phone was "working okay." The level of sidetone is
critical. Too much and the talker will speak softly (thinking the other
party can hear him /her loud enough). Another problem is background noise
(if loud enough) picked up by the transmitter can tend to drown out incoming
speech and make the speech unintelligible. Conversly, too low a level or
absence of sidetone tends to cause the user to speak too loudly in the false
belief the distant party can't hear them. If they shout loud enough they
could overload the A/D converter in the exchange causing distortion.

BTW. The modern telephone still achieves sidetone, but instead of a bulky
ASTIC, it is achieved with semiconductor technology.

Cheers,
Alan

 

[Bob Quintal]

"Richard Freeman" <bogoff@nospam.spam> wrote in
news:431bf695_1@news.iprimus.com.au:

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in
message
news:43180e72$0$518$5a62ac22@per-qv1-newsreader-
Echo (due to reflection) is a function of the return loss of
the circuit.

The Echo is not due to Line reflections but rather due to
Hybrid Transformer leakage - see Sidetone which is a
deliberate result of this leakage being taken advantage of
....
Hybrid Transformer leakage is caused primarily by impedance

mismatch, measurable as return loss.

--
Bob Quintal

PA is y I've altered my email address.

 

[Richard]

Looks like my ISPs News server is stuffed again .....

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:431c05d4$0$15537$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:431bf695_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:43180e72$0$518$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:a750c7dhudwb.1h2dtb3ggjv48.dlg@40tude.net...
On Fri, 2 Sep 2005 15:27:47 +0800, Alan Rutlidge wrote:

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:4317f1be$1_1@news.iprimus.com.au...

"Alan Rutlidge" <dont_spam_me_rutlidge@iinet.net.au> wrote in message
news:4316b902$0$515$5a62ac22@per-qv1-newsreader-01.iinet.net.au...

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:1jlu9dz4m6nho$.9bip6dnzgr15$.dlg@40tude.net...
On Thu, 1 Sep 2005 17:25:01 +1000, Phil Allison wrote:

- - - - - - -- - - further snipped for brevity - - - - - - - - - - -

loss into their transmission networks to counteract the effects of
instability due to impedance mismatches.

you do not have to build loss into Telephone networks - it is there
anyway -

Not entirely true. Most of the US Inter Exchange Network (IEN) [digital]
is designed to have a nominal 0dB loss exchange to exchange. The only
overall transmission losses occur on the lines between the exchange and
the customers.

True however there is loss (theoretically 6dB - in reality greater than
6dB)
through the Hybrid Transformer - I had meant to flesh this concept out
further yesterday but inadvertantly hit send before I had finished
following
this idea/posting further.

Even before the advent of digital transmission and switching technology,
the old Strowger exchange had a fraction of a dB loss through the exchange
on a local call. IEN echo however was not a problem as it was a two wire
circuit through the exchange and the cable network to the telephone.

so are you starting to suspect that the Hyrbrid has something to do
with the
echo then and not cable reflections ?

it is more a case of keeping your gain down to make sure you do not get
howling due to feedback through the hybrid Transformers at each end -

In a closed 4 wire IEN circuit losses of approximately 7dB occur across
the transformer hybrids at each end of the 4 wire transmission path even
under the worst possible mismatch conditions. This effectively provides a
total of 14dB loss to the singing loop.

Correct - the loop will not be singing if it merely consists of two
sets of
Hybrids - ie no gain in the Transmission system - as per my earlier
comment
that stability is not created by padding a system down (as the basic
system
already contains sufficent loss) but rather about keeping total gain to
a
minimum.

Therefore, provided the total gains in the singing loop don't exceed the
total losses, the circuit will remain unconditionally stable. Any
difference in favour of the losses over the gains in the singing loop is
known as the Stability Margin.
Example : If the losses total 14dB (trans-hybid losses as the worst
possible condition) and the gain only 1dB in each direction of
transmission to overcome adjacent port losses in the transformer hybrids
(total 2dB gain in the singing loop), therefore:- 14dB (loss) - 2dB (gain)
= 12dB stability margin. In simple terms the closed 4 wire loop can never
become unstable.

Exactly the basic system - with no added gain - has a total (using your

figures) of 14dB of loss built in and is by its very nature stable (any

signs of instability in this system would be cause for celebration by
physiscts around the world).

In Australia, the loss from 2 wire appearance at the MDF of the exchange
to the same at the other end is designed at 6dB for each direction of
voice transmission. A nice idea, as the echo level is reduced by a
factor of 2 times the loss of the link in the network, resulting in a
minimum stability margin of at least 12dB even under the worst possible
conditions.

Lets see - over 6dB (theoretical) loss each way through the hybrid ....
That sounds about right.

Some other overseas networks aren't anywhere near as good as ours when
it comes to echo performance. In fact a well designed and impedance
matched network requires little or no echo cancellation equipment,
resulting in a clearer network to talk over and minimal VF data
transmission / fax transmission problems.

Hmmm? what about Side tone ? how do these well designed networks provide
Sidetone ?

The sidetone is developed within the telephone. Older phones (pre the
T200 / T400 series) used what was known as an Anti-SideTone Induction Coil
(ASTIC) which is a purposely leaky hybrid, was designed to feedback a
small amount of the speech energy from the transmitter (microphone) to the
receiver. This sidetone is purposefully locally introduced to make the
caller think the phone was "working okay."

The Sidetone was there already as a function of the Hybrid in the
phone, the
ASTIC was wired to cancel the sidetone further than a simple Hybrid did
-
This was only possible as the level (not really the impedance except
where/as
it affected the overall gain) of the signal between the hybrid/Astic
and
the receiver was both known and constant.- In a side note the ASTIC was

actually introduced (around 1939 I believe in Australia) to encourage
people to talk louder into Telephones as it provided less Sidetone than
the normal Hybrid Transformer had previously.
In reality since it is not really impedance mismatches that stop us
supressing Hybrid leakage but rather the fact that we do not know the
overall gain of a System (and hence the exact Signal level we need to
cancel out) - nor does that gain remain constant - largely due
to line length variations etc I would have to argue that in a real
world telephone network no matter how well designed is it not possible
to provide an echo free service without either a VSA (Voice Switched
Amplifier the old method
of echo supression which basically gated the signal in one direction at
a
time) or DSP based echo supression.

The level of sidetone is critical. Too much and the talker will speak
softly (thinking the other party can hear him /her loud enough). Another
problem is background noise (if loud enough) picked up by the transmitter
can tend to drown out incoming speech and make the speech unintelligible.
Conversly, too low a level or absence of sidetone tends to cause the user
to speak too loudly in the false belief the distant party can't hear them.
If they shout loud enough they could overload the A/D converter in the
exchange causing distortion.

ideal Sidetone is considered to be the level we are used to hearing
when we
speak (sorry I don't recall the figure off hand)

BTW. The modern telephone still achieves sidetone, but instead of a bulky
ASTIC, it is achieved with semiconductor technology.

again my apologies I had meant to follow these ideas further before
posting -
However even well designed pure digital Transmission systems require
echo
suppression when the round trip delay exceeds a certain amount of time
(IEC
consider this to be 36mS-
http://www.iec.org/online/tutorials/acrobat/echo_cancel.pdf - which is
actually an excellent tutorial on the whole subject and one that I
recommend
highly ) due to the leakage through the hybrid. If rtd is kept below
36mS
echo does still occur however it is heard by the person speaking as
part of
the sidetone (a variant of this effect called 'double tracking' is an
effect
often used in recordings and live concerts to give vocals more power -
but I
digress .....) over 36mS however this starts being noticed as a
separate
echo and becomes a problem.
I suspect that your 'well designed network' is merely one in which no
call
has an RTD of over 36mS. Unfortunately due to the laws of physics this
precludes networks which have paths of over 5,700 Kms (In Australia we
approach that limit before we even consider processes such as those
within
the codec etc which cause additional delay). Of course when/if you add
a
Satellite to the equation you also add 50,000 Kms of path or 166mS and
a
very noticeable echo - I believe (but not working there am unable to
confirm) that India makes (or maybe made) extensive use of satellite
technology as a (relatively) cheap way of providing telecommunications.

- Alternatively ISDN type connections do not naturally have Sidetone or

suffer from echo when both ends terminate on ISDN (try any call through
a
tester such as an IBT 1A) - however this is due to the fact that there
is in
fact no hybrid in such a system - anywhere! TX and RX are maintained as

completely isolated paths through the entire network. Sidetone for ISDN

phones is added deliberately by the handset manufacturer.

Bottom line is (and getting back to the point of the thread - at least
the
point where I joined) echo is not caused by cable reflections but
rather by
Hybrid leakage - which is often incorrectly called a 'reflection - yes
cable
reflections do occur and this is put to good use by the pulse echo
tester -
however they do not occur at levels sufficient to cause noticeable
problems
at VF (Voice Frequency).

regards
Richard Freeman

 

[pedro]

Matt2 - Amstereo wrote:

I think I'll stick with the 100 + foxtail digital channels over the
10 grainy analogue channels on galaxy. And I reckon if you actually
thought before you posted, you'd do the same thing too or is your
spelling a reflection of your intelligence?

ur a dickhead - all galaxy satelite channels were digital. fox by sat
is still the same now technology wise as galaxy was back in its day.
and it was more like 30 channels....
there is technically no difference between regular austar by sat and
'austar digital' Same shit different badge the only thing that
changed was the encryption which makes no diff to the actual pic/audio
quality.

The Galaxy cable service was grainy analogue as he said. BTW I still
have a Galaxy cable box. Is it useful for anything? I think it still
gets the shopping channel.

--
rgds,

Pete
-----
http://pedro.spyw.com
The time here is- http://tinyurl.com/6sfgd
'What do you do when you see an endangered animal eating an endangered plant?'