broadband vs baseband

When I read few articles on the internet regarding Baseband vs Broadband , there are one explanation that make me confused .

Baseband is Digital Transmission , but , Broadband is Analog Transmission .
example :

Is this Broadband referred to Internet Access Broadband ( DSL modem broadband ) ??(Question #1)

I thought DSL Broadband is Digital Transmission which is contrast with Dial up ( Analog ) ?? (Question# 2 ).

The LAN data transmission is only using Baseband , any broadband transmission within LAN ??
(Question #3)

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Baseband Such as LAN
Connect Between 1 Computer to 1 Port

Broadband such as DSL
we can use to Connect Internet
and Phone Call in the same time
kcnAuthor Commented:
My question is why Broadband is "analog" , and not digital , I though broadband such as DSL Internet Connection is Digital ??
The page you're looking at is using terminology in a different, technical way. "Broadband" in common parlance is a generic term for all "high bandwidth" (or "broad bandwidth", extending the "width" language, which in this context means speed, not physical size) communications, including DSL, cable, high-speed wireless, and the like. You are correct; DSL is a digital communications method ("Digital Subscriber Line"), as is cable Internet.

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DSL is digital service.  It is provided over an analog signal.  It uses higher frequencies than voice, fax, and traditional dial-up MoDem traffic.  But, you need filters or splitter to isolate the audio frequencies for the DSL signal.

DSL traffic is above 20KHz (shouldn't be heard by humans).  Voice signals should be below 5Khz.

That's one reason why some areas cannot get DSL service, even if they are close to a CO.  I know a location that has limited copper going up a hill to service an area with 10 times as many residences as when the lines were put in in the 1970s.  To extend service, fiber was run.  Voice lines were compressed and consolidated to run up the hill to new customers.  So, many customers cannot run DSL over their copper to the house because the analog signal is being modified (compressed/decompressed) to get it up the hill.

Limited DSL service is subscribed, but it requires that that line is migrated off the fiber and moved to a real copper pair.  There may be none you have to wait until somebody gets service disconnected.  Good news for the incumbent cable company.

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Baseband bandwidth can be measured from zero or near-zero up to the max frequency of the transmission.  Voice is baseband because it is measured from 0Hz to 5KHz (300Hz-3.4KHz in POTS).  Our human hearing is from around 20Hz-20KHz...where 20Hz is close enough (near-zero).

Broadband is non-baseband, because the desired traffic is within a subset of frequencies that does not range down to zero.  In the case of xDSL, it's  It uses DMT, discrete multi-tone modulation  from above 3.4KHz up to 1.1MHz.

LAN connections are often expressed with the label:  10BASE-T,  100BASE-SX, etc.

Modulated signals are not baseband.  Common examples are radio signals using amplitude modulation (AM) and frequency modulation (FM).  Cell phone traffic might use code-division multiple access (CDMA) or time division multiple access (TDMA) used on GSM/EDGE.

Hope that makes sense.
kcnAuthor Commented:
ElronCT , so you confirm BROADBAND is Digital Signal . But a lot of of article when come to compare on baseband & broadband , they will mention broadband is analog signal and baseband is digital signal.

These artcles comparison still make me confused , can you help to comment on those article ...

I cannot understand  your expolanation on " ....using terminology in a different, technical way... "

Aleghart , Thanks for long explanation but I didn't see you explain whethe Broadband is digital or analog signal ???

DSL broadband is an analog signal (tones) on a copper phone line.
kcnAuthor Commented:
No , I disagree DSL Broadband is analog signal .

DSL Broadband is a Digital Signal which is contrast to Dial Up ( Dial up is using analog signal )

Any further comment from other expert  
Again, the term "broadband" has different meanings in different contexts. The page you're referencing is using "broadband" in a technicial sense that is different from the common usage of "broadband" to refer to high speed Internet connections.

See Wikipedia's pages on broadband ( and DSL ( for more explanations.

Looking through the information a bit more, I have to backtrack; DSL is indeed an analog signal, as aleghart states. The term Digital in its name refers to its purpose, not its method of transport. However, that's independent of the use of the "broadband" term in the comparison of "broadband vs. baseband". Using "broadband" in the sense of "high speed communications" is not dependent on whether the signal is provided analog or digitally--fiber optic to the home is considered "broadband" in that sense.
Broadband is used in the context of coexistence of the consumer's internet connection with other traffic/signals on the same medium.

For instance, on a 10BASE-T (baseband) connection in a LAN, there can be no other traffic on the copper wires.

With xDSL, several channels are used at varying frequencies to carry different traffic.  You could have 5 channels for upstream, 7 channels for downstream, then another frequency range carrying voice traffic...all over the same copper pair.

FIOS is FTTP in my neighborhood.  It uses BPON, broadband passive optical networking, where there is a shared fiber from the central office to the neighborhood.  Once it reaches the neighborhood (in a giant metal box hanging on a telephone pole) it is split to multiple houses.  Several signals are sent over the fiber: individual voice, individual data, and shared video signals for TV.  I believe they use TDMA, where each home's ONT (terminal) gets a time slice.  I was told by the tech that they limit the split to 32 houses per box, so there is less probability that the shared fiber is oversubscribed at any one point in time.

People who have TiVo DVRs have seen the "broadband" evidence for a while.  In your diagnostics and settings, you can view the tuner settings.  The specific frequency lock for the current channel should be the same frequency for all users on the service.

So, the broadband term, I think, is still technically accurate.
kcnAuthor Commented:
Hi all ,

this is link that discuss DSL as analog signal . .

By way is the data transmitted from CO to DSL Modem is DIGITAL Data , or , ANALOG Data ??

Someone help to confirm above question first before I continue ask some question that might clear my mind .
Digital data.  Analog signal.  I think you're confusing the two.

DSL stands for "digital subscriber line".  It's a confusing marketing term, because you (the subscriber) want internet service for your computer.  The marketing term "digital" helps sell the service.  The carrier is actually analog tone on an analog line, which is a single pair of twisted copper.  But, that doesn't sound attractive when you're trying to convince people to get rid of their "analog" dial-up modems.

xDSL uses a MoDem.  It modulates and demodulates your data into an analog signal, the same way a fax machine takes scan data and transmits it as audio tone.

DSL does this many times faster than a fax or a traditional dial-up modem.  But, it is the same technology.
kcnAuthor Commented:
Hi ,

In fact I am confused on the term "DATA" and "SIGNAL"

If I use OSI Layer to interpret Signal & Data , both of these 2 terms should be identical .

Data at Layer 4 and above ; Signal at Layer 1 ( physical layer in bit ) .

If we say Digital Data but Analog Signal on DSL Modem , then I am confused .

Modem is used to convert Analog to Digital and Digital to Analog .

From  Computer to DSL Modem must be Digital Signal ( digital data ) , after passing through DSL Modem , it become Analog Signal ( Analog data or Digital data ??? ) and this Analog Signal will transmit from DSL Modem to CO through 2 wires UTP cable ???

Yes , I am really confused "DATA" and "SIGNAL"  , please advise , I thought these 2 are identical in term of networking ???
I can give you discrete data from a distance.  Meaning, if I give you one packet of "data", it can't be misread.  If that data is clearly defined, discrete, meaning there is no ambiguity about it...let's call it "digital" as a label.

So...I blast a horn:   ... _ _ _ ...    The signal was analog.  The data upon your reception was discretely decoded as "SOS".

We could go into semaphore and flags too, but you get the idea.  The signal carries the information.

That's why an analog TV broadcast gets fuzzy.  Signal and data are both analog.

"Digital" TV carries digital content.  You either get it, or you don't get it.  So, on a digital TV set you get a picture or you get a blank screen.

That's probably confusing things...sorry.  Don't have a nicer way to explain it.
kcnAuthor Commented:
Sorry , I cannot understand your explanation .

So, are you telling me both DATA and SIGNAL involved on DSL are ANALOG  ??
I've never said DSL data is analog.  I think we must be speaking a different language.

Maybe an electrical engineer could better explain it.  Or someone who has a better grasp of the semantics of the OSI model.
kcnAuthor Commented:
aleghart ,
thanks for your's useful info and alert me the broadband is not digital signal in transmission.

This link will help a lot of people to understand the  digital/analog  Data vs  digital/analog Signal

The key points from above link as below :-
Four possibilities to consider:
• analog data via analog transmission ! “as is” (e.g., radio)
• analog data via digital transmission ! sampling (e.g., voice, audio, video)
• digital data via analog transmission ! broadband & wireless (“high-speed networks”)
• digital data via digital transmission ! baseband (e.g., Ethernet)

So, from Computer  to DSL Modem is : Digital Data via Digital Transmission (Digital signal)
      from DSL Modem to ISP is : Digital Data via Analog Transmission ( Analog signal)

If no other expert object , I will assign points to the experts that help me on this question.

Thanks everybody .
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