Examples of Communication Systems/General Description of ISDN - Revision history

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	All following statements refer to lines with  $0.4$  mm diameter.  For these,  for example,  in  [PW95]<ref name='PW95'>Pollakowski, M.; Wellhausen, H.W.:  Eigenschaften symmetrischer Ortsanschlusskabel im Frequenzbereich bis 30 MHz.  Mitteilung aus dem Forschungs- und Technologiezentrum der Deutschen Telekom AG, Darmstadt, Verlag für Wissenschaft und Leben Georg Heidecker, 1995.</ref>  the following empirically found attenuation and phase curve were given,  where  $l$  denotes the cable length:		All following statements refer to lines with  $0.4$  mm diameter.  For these,  for example,  in  [PW95]<ref name='PW95'>Pollakowski, M.; Wellhausen, H.W.:  Eigenschaften symmetrischer Ortsanschlusskabel im Frequenzbereich bis 30 MHz.  Mitteilung aus dem Forschungs- und Technologiezentrum der Deutschen Telekom AG, Darmstadt, Verlag für Wissenschaft und Leben Georg Heidecker, 1995.</ref>  the following empirically found attenuation and phase curve were given,  where  $l$  denotes the cable length:

	:$${a_{\rm K}(f)}/{ {\rm dB}} = \left [ 5.1 + 14.3 \cdot \left ({f}/{ {\rm MHz}}\right )^{0.59}\right ]\cdot{l}/{ {\rm km}}		:$${a_{\rm K}(f)}/{ {\rm dB}} = \left [ 5.1 + 14.3 \cdot \left ({f}/{ {\rm MHz}}\right )^{0.59}\right ]\cdot{l}/{ {\rm km}}\hspace{0.05cm},$$
	\hspace{0.05cm},$$

	:$${b_{\rm K}(f)}/{ {\rm rad}} = \left [ 32.9 \cdot \frac{f}{ {\rm MHz}} + 2.26 \cdot \left ({f}/{ {\rm MHz}}\right )^{0.5}\right ]\cdot{l}/{ {\rm km}}		:$${b_{\rm K}(f)}/{ {\rm rad}} = \left [ 32.9 \cdot \frac{f}{ {\rm MHz}} + 2.26 \cdot \left ({f}/{ {\rm MHz}}\right )^{0.5}\right ]\cdot{l}/{ {\rm km}}\hspace{0.05cm}.$$
	\hspace{0.05cm}.$$

	With the interactive HTML5/JavaScript applet  [[Applets:Attenuation_of_Copper_Cables\|"Attenuation of copper cables"]]  you can view the attenuation curve of symmetrical lines and coaxial cables with different dimensions and with the  (German language)  SWF applet the  [[Applets:Zeitverhalten_von_Kupferkabeln\|"Time behavior of copper cables"]].		With the interactive HTML5/JavaScript applet  [[Applets:Attenuation_of_Copper_Cables\|"Attenuation of copper cables"]]  you can view the attenuation curve of symmetrical lines and coaxial cables with different dimensions and with the  (German language)  SWF applet the  [[Applets:Zeitverhalten_von_Kupferkabeln\|"Time behavior of copper cables"]].
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	*If the spectrum  $Q(f)$  of the analog source signal  $q(t)$  has components up to the frequency  $f_{\rm NF, \hspace{0.1cm}max}$,  the following must apply for the sampling rate:		*If the spectrum  $Q(f)$  of the analog source signal  $q(t)$  has components up to the frequency  $f_{\rm NF, \hspace{0.1cm}max}$,  the following must apply for the sampling rate:

	:$$f_{\rm A} = \frac{1}{T_{\rm A} } \ge 2 \cdot f_{\rm NF, \hspace{0.05cm}max}		:$$f_{\rm A} = \frac{1}{T_{\rm A} } \ge 2 \cdot f_{\rm NF, \hspace{0.05cm}max}\hspace{0.05cm}.$$
	\hspace{0.05cm}.$$

	*ISDN telephone signals contain spectral components between  $300 \ \rm Hz$  and  $3400 \ \rm Hz$ and the sampling rate is  $f_{\rm A} = 8 \ \rm kHz$   ⇒   $T_{\rm A} = 125 \ \rm µ s$.  Thus,  the sampling theorem is satisfied.		*ISDN telephone signals contain spectral components between  $300 \ \rm Hz$  and  $3400 \ \rm Hz$ and the sampling rate is  $f_{\rm A} = 8 \ \rm kHz$   ⇒   $T_{\rm A} = 125 \ \rm µ s$.  Thus,  the sampling theorem is satisfied.
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	*The ISDN bit rate  $($for each of the two bearer channels$)$  is  $8 · 8000 \ \rm 1/s = 64 \ kbit/s$  according to the above specifications.  The quantization SNR is thus		*The ISDN bit rate  $($for each of the two bearer channels$)$  is  $8 · 8000 \ \rm 1/s = 64 \ kbit/s$  according to the above specifications.  The quantization SNR is thus

	:$$\rho_{\rm Q} = 2^{16}\hspace{0.3cm}\Rightarrow \hspace{0.3cm}		:$$\rho_{\rm Q} = 2^{16}\hspace{0.3cm}\Rightarrow \hspace{0.3cm}10 \cdot {\rm lg}\hspace{0.1cm}\rho_{\rm Q}= 10 \cdot {\rm lg}\hspace{0.1cm}2^{16}\approx 48\,{\rm dB}\hspace{0.05cm}.$$
	10 \cdot {\rm lg}\hspace{0.1cm}\rho_{\rm Q}= 10 \cdot {\rm
	lg}\hspace{0.1cm}2^{16}\approx 48\,{\rm dB}
	\hspace{0.05cm}.$$

	*Compact disc  $\rm (CD)$  quality  $(N = 16 \ ⇒ \ M = 65\hspace{0.05cm}536)$  would result in  $10 · \lg ρ_{\rm Q} ≈ 96 \ \rm dB$.  However,  this would require doubling the bit rate to  $128 \ \rm kbit/s$.		*Compact disc  $\rm (CD)$  quality  $(N = 16 \ ⇒ \ M = 65\hspace{0.05cm}536)$  would result in  $10 · \lg ρ_{\rm Q} ≈ 96 \ \rm dB$.  However,  this would require doubling the bit rate to  $128 \ \rm kbit/s$.

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	{{Display}}		{{Display}}
			[[de:Beispiele_von_Nachrichtensystemen/Allgemeine_Beschreibung_von_ISDN]]

Guenter at 17:00, 18 January 2025

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	{{BlaueBox\|TEXT=		{{BlaueBox\|TEXT=
	$\text{ At the time of the English translation of this book  $\rm (2022)$,  it must not be concealed:}$		$\text{ At the time of the English translation of this book  $\rm (2022)$,  the following facts must not be concealed:}$

	ISDN will no longer have a great future in Germany either. In other countries it never had such great importance.		ISDN will no longer have a great future in Germany either. In other countries it never had such great importance.
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	==Goals and features of ISDN ==		==Goals and features of ISDN ==
	<br>		<br>
	The  $\rm ISDN$  ("Integrated Services Digital Network")  standard,  established since the late 1980s,  is a service–integrated digital communications network with the aim,		The  $\rm ISDN$  $($<i>Integrated Services Digital Network </i>$)$  standard,  established since the late 1980s,  is a service–integrated digital communications network with the aim,
	#   to digitize the analog signal transmission over telephone lines that had been common until then,  thereby achieving better voice quality,		#   to digitize the analog signal transmission over telephone lines that had been common until then,  thereby achieving better voice quality,
	#   to continue using the network infrastructure available for analog signal transmission – in particular the copper cables laid at great expense over many years,		#   to continue using the network infrastructure available for analog signal transmission – in particular the copper cables laid at great expense over many years,

Guenter at 18:31, 16 January 2025

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	== # OVERVIEW OF THE FIRST MAIN CHAPTER # ==		== # OVERVIEW OF THE FIRST MAIN CHAPTER # ==
	<br>		<br>
	$\rm I$ntegrated $\rm S$ervices $\rm D$igital $\rm N$etwork   $\rm (ISDN)$  was the first unified digital network for voice,  text,  data,  images,  video and multimedia communications.  It was introduced in the late 1980s ~~and~~ and had about 25 million users in Germany in 2004, for example.		$\rm I$ntegrated $\rm S$ervices $\rm D$igital $\rm N$etwork   $\rm (ISDN)$  was the first unified digital network for voice,  text,  data,  images,  video and multimedia communications.  It was introduced in the late 1980s and had about 25 million users in Germany in 2004, for example.

	Compared with the analog telecommunications methods that were common before,  ISDN has		Compared with the analog telecommunications methods that were common before,  ISDN has offered
	*~~offered~~ many new or enhanced services,		* many new or enhanced services,

	*faster transmission,		*faster transmission,

	*better voice quality~~,  and~~		*better voice quality.

	*an easier use of multiple devices.


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	At the time of the English translation of this book  $\rm (2022)$~~,  however~~,  it must not be concealed:		{{BlaueBox\|TEXT=
	* ISDN will no longer have a great future in Germany either - in other countries it never had such great importance.		$\text{ At the time of the English translation of this book  $\rm (2022)$,  it must not be concealed:}$

	* The German provider   »Deutsche Telekom«  had long announced that it would switch off ISDN in 2018 and replace it with its  "Next Generation Network"  $\rm (NGN)$  with packet-switched network infrastructure.		ISDN will no longer have a great future in Germany either. In other countries it never had such great importance.

			The German provider   »Deutsche Telekom«  had long announced that it would switch off ISDN in 2018 and replace it with its  »Next Generation Network«  $\rm (NGN)$  with packet-switched network infrastructure.   Vodafone will follow this example by 2022 at the latest.

	*~~Vodafone will follow~~ this ~~example by 2022 at~~ the ~~latest~~.		*We have nevertheless decided to continue this chapter  $($which was highly topical in the early 2000s$)$  in the  $\rm LNTwww$,  however,  clearly shortened.

			*Although it lacks the topicality of the day,  it is now more of a technical history contribution.}}





	⇒   We have nevertheless decided to continue this chapter  $($which was highly topical in the early 2000s$)$  in the  $\rm LNTwww$.  However,  clearly shortened.   Although it lacks the topicality of the day,  it is now more of a technical history contribution.

Guenter at 16:31, 16 November 2022

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	*the subscribers,  as the network branches out to the maximum in this area.		*the subscribers,  as the network branches out to the maximum in this area.

	[[File:~~EN_LZI_T_4_3_S2~~.png\| right\|frame\|Structure of the local loop area ~~'''KORREKTUR: Fiber'''~~]]		[[File:EN_LZI_T_4_3_S2_neu.png\| right\|frame\|Structure of the local loop area]]
	[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]		[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]

Guenter at 10:19, 10 November 2022

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	$\rm I$ntegrated $\rm S$ervices $\rm D$igital $\rm N$etwork   $\rm (ISDN)$  was the first unified digital network for voice,  text,  data,  images,  video and multimedia communications.  It was introduced in the late 1980s and and had about 25 million users in Germany in 2004, for example.		$\rm I$ntegrated $\rm S$ervices $\rm D$igital $\rm N$etwork   $\rm (ISDN)$  was the first unified digital network for voice,  text,  data,  images,  video and multimedia communications.  It was introduced in the late 1980s and and had about 25 million users in Germany in 2004, for example.

	Compared with the analog telecommunications ~~processes '''KORREKTUR:~~ methods~~?'''~~ that were common before, ISDN has		Compared with the analog telecommunications methods that were common before,  ISDN has
	*offered many new or enhanced services,		*offered many new or enhanced services,

Hwang at 09:30, 2 November 2022

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	*By using large values of  $M$  or  $N$,  one can increase the PCM quality at the expense of the effort,  the transmission rate,  and the high-fruquency bandwidth thus required. For ISDN,  a good compromise  $($for the 1990s$)$  between desirable quality and required bit rate was standardized with  $N = 8$   ⇒   $M = 256$.		*By using large values of  $M$  or  $N$,  one can increase the PCM quality at the expense of the effort,  the transmission rate,  and the high-fruquency bandwidth thus required. For ISDN,  a good compromise  $($for the 1990s$)$  between desirable quality and required bit rate was standardized with  $N = 8$   ⇒   $M = 256$.

	*The ISDN bit rate  $($for each of the two ~~beerer~~ channels$)$  is  $8 · 8000 \ \rm 1/s = 64 \ kbit/s$  according to the above specifications.  The quantization SNR is thus		*The ISDN bit rate  $($for each of the two bearer channels$)$  is  $8 · 8000 \ \rm 1/s = 64 \ kbit/s$  according to the above specifications.  The quantization SNR is thus

	:$$\rho_{\rm Q} = 2^{16}\hspace{0.3cm}\Rightarrow \hspace{0.3cm}		:$$\rho_{\rm Q} = 2^{16}\hspace{0.3cm}\Rightarrow \hspace{0.3cm}

Hwang at 20:00, 1 November 2022

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	==Four-wire and two-wire transmission==		==Four-wire and two-wire transmission==
	<br>		<br>
	A communication link usually operates – as is the case with ISDN – in  '''full duplex mode''',&nbsp i.e. the two communication partners transmit continuously and independently of each other.		A communication link usually operates – as is the case with ISDN – in  '''full duplex mode''',  i.e. the two communication partners transmit continuously and independently of each other.
	[[File:EN_Bei_T_1_1_S4neu.png\|right\|frame\|Four-wire and two-wire transmission]]		[[File:EN_Bei_T_1_1_S4neu.png\|right\|frame\|Four-wire and two-wire transmission]]

Hwang at 19:44, 1 November 2022

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	*the subscribers,  as the network branches out to the maximum in this area.		*the subscribers,  as the network branches out to the maximum in this area.

	[[File:EN_LZI_T_4_3_S2.png\| right\|frame\|Structure of the local loop area '''KORREKTUR: ~~fiber~~''']]		[[File:EN_LZI_T_4_3_S2.png\| right\|frame\|Structure of the local loop area '''KORREKTUR: Fiber''']]
	[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]		[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]

Hwang at 19:44, 1 November 2022

2022-11-01T19:44:09Z

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	*the subscribers,  as the network branches out to the maximum in this area.		*the subscribers,  as the network branches out to the maximum in this area.

	[[File:EN_LZI_T_4_3_S2.png\| right\|frame\|Structure of the local loop area]]		[[File:EN_LZI_T_4_3_S2.png\| right\|frame\|Structure of the local loop area '''KORREKTUR: fiber''']]
	[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]		[[File:EN_LZI_T_4_3_S1b.png\|right\|frame\| Bundling and twisting of copper wires]]