How unbalanced coaxial cables are used for broadcasting TV signals without any problems?(Textbook error?) Nyquist's relation: telegraph speed of transmission
Is there an inconsistency about Natasha Romanoff's middle name in the MCU?
Confirm the ending of a string
Why did it become so much more expensive to start a university?
Are scroll bars dead in 2019?
How are aircraft depainted?
What is a realistic time needed to get a properly trained army?
Can I conceal an antihero's insanity - and should I?
How to say "quirky" in German without sounding derogatory?
When was the earliest opportunity the Voyager crew had to return to the Alpha quadrant?
Can the UK veto its own extension request?
Why is Kirchoff's loop rule true in a DC circuit?
Do all humans have an identical nucleotide sequence for certain proteins, e.g haemoglobin?
A shy person in a queue
What does a Light weapon mean mechanically?
Parallel resistance in electric circuits
The Planck constant for mathematicians
What officially disallows US presidents from driving?
Has SHA256 been broken by Treadwell Stanton DuPont?
How to stabilise the bicycle seatpost and saddle when it is all the way up?
Selecting 2 column in an Inner join
What is this unknown executable on my boot volume? Is it Malicious?
In Germany, how can I maximize the impact of my charitable donations?
Should I leave the first authorship of our paper to the student who did the project whereas I solved it?
Evidence that matrix multiplication cannot be done in O(n^2 poly(log(n))) time
How unbalanced coaxial cables are used for broadcasting TV signals without any problems?
(Textbook error?) Nyquist's relation: telegraph speed of transmission
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
As far as I know, in telephony STP or twisted pair cables are used. This creates balanced line impedances which is useful to mitigate for common mode related interference.
So using balanced cables in telephony and in audio is very crucial to get rid of any EM or RF interference.
On the other hand, in TV broadcasting or many RF systems coaxial cables are used. And most of the coaxial cables I have seen are not balanced. I can see that 50 Ohm concept is good to get rid of reflections in transmission line theory. But how come unbalancedness of coaxial cables have no problem in impedance balancing issues?
telecommunications coaxial stp
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
$endgroup$
add a comment
|
$begingroup$
As far as I know, in telephony STP or twisted pair cables are used. This creates balanced line impedances which is useful to mitigate for common mode related interference.
So using balanced cables in telephony and in audio is very crucial to get rid of any EM or RF interference.
On the other hand, in TV broadcasting or many RF systems coaxial cables are used. And most of the coaxial cables I have seen are not balanced. I can see that 50 Ohm concept is good to get rid of reflections in transmission line theory. But how come unbalancedness of coaxial cables have no problem in impedance balancing issues?
telecommunications coaxial stp
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
$endgroup$
add a comment
|
$begingroup$
As far as I know, in telephony STP or twisted pair cables are used. This creates balanced line impedances which is useful to mitigate for common mode related interference.
So using balanced cables in telephony and in audio is very crucial to get rid of any EM or RF interference.
On the other hand, in TV broadcasting or many RF systems coaxial cables are used. And most of the coaxial cables I have seen are not balanced. I can see that 50 Ohm concept is good to get rid of reflections in transmission line theory. But how come unbalancedness of coaxial cables have no problem in impedance balancing issues?
telecommunications coaxial stp
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
$endgroup$
As far as I know, in telephony STP or twisted pair cables are used. This creates balanced line impedances which is useful to mitigate for common mode related interference.
So using balanced cables in telephony and in audio is very crucial to get rid of any EM or RF interference.
On the other hand, in TV broadcasting or many RF systems coaxial cables are used. And most of the coaxial cables I have seen are not balanced. I can see that 50 Ohm concept is good to get rid of reflections in transmission line theory. But how come unbalancedness of coaxial cables have no problem in impedance balancing issues?
telecommunications coaxial stp
telecommunications coaxial stp
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
asked 8 hours ago
atmntatmnt
1,1962 gold badges8 silver badges35 bronze badges
1,1962 gold badges8 silver badges35 bronze badges
add a comment
|
add a comment
|
2 Answers
2
active
oldest
votes
$begingroup$
But how come unbalancedness of coaxial cables have no problem in
impedance balancing issues?
The beautiful thing about coax is that the shield shunts mostly all electric field interference to ground and the inner wire is largely unaffected. For magnetic field interference a subtle thing happens; the current in the shield due to the presence of an external magnetic field creates a volt drop along the shield and, due to near 1:1 coupling between shield and inner, the same volt drop is present on the inner core. So, providing you use a differential receiver and the sending end has somewhat reasonably the same impedance to ground on shield and inner, the differential receiver can reject the common mode interference.
If you do the math on external fields produced by a regular signal sent down coax, and analysed the external magnetic field from send and return currents individually, you find that at all points outside the shield, the opposing magnetic fields exactly cancel to zero.
The impact of this is that a proper signal’s magnetic field is only produced in the gap between inner and outer shield. A repercussion of this is that the shield therefore has to have zero inductance. This is because the outer mag field is zero and the signal’s internal magnetic field has zero effect on a tubular conductor (aka shield) hence, the shield behaves like an infinitely thick ground casing surrounding the inner.
The upshot of all my rambling is that it works despite having a significantly unbalanced impedance regime between inner and outer shield. It’s not all that easy to immediately see I grant you so hopefully I’ve done it some justice.
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
$endgroup$
add a comment
|
$begingroup$
Andy talks about how coax works in general, but another point is that video generally doesn't have the same SNR requirements as audio to begin with. Data with 8 to 10 bits per color channel provides very good pictures, and this represents an SNR of only 50 to 60 dB.
On the other hand, to be considered "CD quality", audio must have at least 16 bits of resolution, equivalent to an SNR of almost 100 dB.
Telephony is a special case. While it doesn't require a lot of bandwidth, it does require a dynamic range equivalent to 13-14 bits. (But the coding used reduces the SNR to about 7 bits). UTP (unshielded twisted pair) is used only because it is so cheap to make and so much of it is required.
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
$endgroup$
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
add a comment
|
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("schematics", function ()
StackExchange.schematics.init();
);
, "cicuitlab");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "135"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/4.0/"u003ecc by-sa 4.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f458181%2fhow-unbalanced-coaxial-cables-are-used-for-broadcasting-tv-signals-without-any-p%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
But how come unbalancedness of coaxial cables have no problem in
impedance balancing issues?
The beautiful thing about coax is that the shield shunts mostly all electric field interference to ground and the inner wire is largely unaffected. For magnetic field interference a subtle thing happens; the current in the shield due to the presence of an external magnetic field creates a volt drop along the shield and, due to near 1:1 coupling between shield and inner, the same volt drop is present on the inner core. So, providing you use a differential receiver and the sending end has somewhat reasonably the same impedance to ground on shield and inner, the differential receiver can reject the common mode interference.
If you do the math on external fields produced by a regular signal sent down coax, and analysed the external magnetic field from send and return currents individually, you find that at all points outside the shield, the opposing magnetic fields exactly cancel to zero.
The impact of this is that a proper signal’s magnetic field is only produced in the gap between inner and outer shield. A repercussion of this is that the shield therefore has to have zero inductance. This is because the outer mag field is zero and the signal’s internal magnetic field has zero effect on a tubular conductor (aka shield) hence, the shield behaves like an infinitely thick ground casing surrounding the inner.
The upshot of all my rambling is that it works despite having a significantly unbalanced impedance regime between inner and outer shield. It’s not all that easy to immediately see I grant you so hopefully I’ve done it some justice.
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
$endgroup$
add a comment
|
$begingroup$
But how come unbalancedness of coaxial cables have no problem in
impedance balancing issues?
The beautiful thing about coax is that the shield shunts mostly all electric field interference to ground and the inner wire is largely unaffected. For magnetic field interference a subtle thing happens; the current in the shield due to the presence of an external magnetic field creates a volt drop along the shield and, due to near 1:1 coupling between shield and inner, the same volt drop is present on the inner core. So, providing you use a differential receiver and the sending end has somewhat reasonably the same impedance to ground on shield and inner, the differential receiver can reject the common mode interference.
If you do the math on external fields produced by a regular signal sent down coax, and analysed the external magnetic field from send and return currents individually, you find that at all points outside the shield, the opposing magnetic fields exactly cancel to zero.
The impact of this is that a proper signal’s magnetic field is only produced in the gap between inner and outer shield. A repercussion of this is that the shield therefore has to have zero inductance. This is because the outer mag field is zero and the signal’s internal magnetic field has zero effect on a tubular conductor (aka shield) hence, the shield behaves like an infinitely thick ground casing surrounding the inner.
The upshot of all my rambling is that it works despite having a significantly unbalanced impedance regime between inner and outer shield. It’s not all that easy to immediately see I grant you so hopefully I’ve done it some justice.
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
$endgroup$
add a comment
|
$begingroup$
But how come unbalancedness of coaxial cables have no problem in
impedance balancing issues?
The beautiful thing about coax is that the shield shunts mostly all electric field interference to ground and the inner wire is largely unaffected. For magnetic field interference a subtle thing happens; the current in the shield due to the presence of an external magnetic field creates a volt drop along the shield and, due to near 1:1 coupling between shield and inner, the same volt drop is present on the inner core. So, providing you use a differential receiver and the sending end has somewhat reasonably the same impedance to ground on shield and inner, the differential receiver can reject the common mode interference.
If you do the math on external fields produced by a regular signal sent down coax, and analysed the external magnetic field from send and return currents individually, you find that at all points outside the shield, the opposing magnetic fields exactly cancel to zero.
The impact of this is that a proper signal’s magnetic field is only produced in the gap between inner and outer shield. A repercussion of this is that the shield therefore has to have zero inductance. This is because the outer mag field is zero and the signal’s internal magnetic field has zero effect on a tubular conductor (aka shield) hence, the shield behaves like an infinitely thick ground casing surrounding the inner.
The upshot of all my rambling is that it works despite having a significantly unbalanced impedance regime between inner and outer shield. It’s not all that easy to immediately see I grant you so hopefully I’ve done it some justice.
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
$endgroup$
But how come unbalancedness of coaxial cables have no problem in
impedance balancing issues?
The beautiful thing about coax is that the shield shunts mostly all electric field interference to ground and the inner wire is largely unaffected. For magnetic field interference a subtle thing happens; the current in the shield due to the presence of an external magnetic field creates a volt drop along the shield and, due to near 1:1 coupling between shield and inner, the same volt drop is present on the inner core. So, providing you use a differential receiver and the sending end has somewhat reasonably the same impedance to ground on shield and inner, the differential receiver can reject the common mode interference.
If you do the math on external fields produced by a regular signal sent down coax, and analysed the external magnetic field from send and return currents individually, you find that at all points outside the shield, the opposing magnetic fields exactly cancel to zero.
The impact of this is that a proper signal’s magnetic field is only produced in the gap between inner and outer shield. A repercussion of this is that the shield therefore has to have zero inductance. This is because the outer mag field is zero and the signal’s internal magnetic field has zero effect on a tubular conductor (aka shield) hence, the shield behaves like an infinitely thick ground casing surrounding the inner.
The upshot of all my rambling is that it works despite having a significantly unbalanced impedance regime between inner and outer shield. It’s not all that easy to immediately see I grant you so hopefully I’ve done it some justice.
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
edited 8 hours ago
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
answered 8 hours ago
Andy akaAndy aka
253k11 gold badges194 silver badges450 bronze badges
253k11 gold badges194 silver badges450 bronze badges
add a comment
|
add a comment
|
$begingroup$
Andy talks about how coax works in general, but another point is that video generally doesn't have the same SNR requirements as audio to begin with. Data with 8 to 10 bits per color channel provides very good pictures, and this represents an SNR of only 50 to 60 dB.
On the other hand, to be considered "CD quality", audio must have at least 16 bits of resolution, equivalent to an SNR of almost 100 dB.
Telephony is a special case. While it doesn't require a lot of bandwidth, it does require a dynamic range equivalent to 13-14 bits. (But the coding used reduces the SNR to about 7 bits). UTP (unshielded twisted pair) is used only because it is so cheap to make and so much of it is required.
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
$endgroup$
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
add a comment
|
$begingroup$
Andy talks about how coax works in general, but another point is that video generally doesn't have the same SNR requirements as audio to begin with. Data with 8 to 10 bits per color channel provides very good pictures, and this represents an SNR of only 50 to 60 dB.
On the other hand, to be considered "CD quality", audio must have at least 16 bits of resolution, equivalent to an SNR of almost 100 dB.
Telephony is a special case. While it doesn't require a lot of bandwidth, it does require a dynamic range equivalent to 13-14 bits. (But the coding used reduces the SNR to about 7 bits). UTP (unshielded twisted pair) is used only because it is so cheap to make and so much of it is required.
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
$endgroup$
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
add a comment
|
$begingroup$
Andy talks about how coax works in general, but another point is that video generally doesn't have the same SNR requirements as audio to begin with. Data with 8 to 10 bits per color channel provides very good pictures, and this represents an SNR of only 50 to 60 dB.
On the other hand, to be considered "CD quality", audio must have at least 16 bits of resolution, equivalent to an SNR of almost 100 dB.
Telephony is a special case. While it doesn't require a lot of bandwidth, it does require a dynamic range equivalent to 13-14 bits. (But the coding used reduces the SNR to about 7 bits). UTP (unshielded twisted pair) is used only because it is so cheap to make and so much of it is required.
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
$endgroup$
Andy talks about how coax works in general, but another point is that video generally doesn't have the same SNR requirements as audio to begin with. Data with 8 to 10 bits per color channel provides very good pictures, and this represents an SNR of only 50 to 60 dB.
On the other hand, to be considered "CD quality", audio must have at least 16 bits of resolution, equivalent to an SNR of almost 100 dB.
Telephony is a special case. While it doesn't require a lot of bandwidth, it does require a dynamic range equivalent to 13-14 bits. (But the coding used reduces the SNR to about 7 bits). UTP (unshielded twisted pair) is used only because it is so cheap to make and so much of it is required.
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
answered 7 hours ago
Dave Tweed♦Dave Tweed
135k11 gold badges172 silver badges293 bronze badges
135k11 gold badges172 silver badges293 bronze badges
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
add a comment
|
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
$begingroup$
What I don’t quite get here is that surely TV signals include both audio and video.
$endgroup$
– Todd Wilcox
14 mins ago
add a comment
|
Thanks for contributing an answer to Electrical Engineering Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f458181%2fhow-unbalanced-coaxial-cables-are-used-for-broadcasting-tv-signals-without-any-p%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
