Broadband vs Baseband

[sivam siva]

Hello

I'm trying to understand the basic please help anyone.

we are using the broadband connection in our home, where Ethernet cable connected from ISP to Modem inside the House,

As studied Ethernet can only support Baseband, then why its called as a broadband connection?

Below is my understanding of Base/broadband:

Baseband: A single signal in a medium. or A single frame introduced in a cable.

Broadband: Multiple signals (with different frequency) in a medium.

Thanks

Siva

[balaji.bandi · Accepted solution]

here is the good document for reference to understand :

https://techdifferences.com/difference-between-baseband-and-broadband-transmission.html

[Giuseppe Larosa]

Hello Sivam,

the two terms have different origins and cannot be compared directly.

With broadband internet access we refer to all the current access technologies like ADSL, VDSL, cable modems, satellite based systems that provide much more bandwidth then the old dialup modems over PSTN ( up to 56 kbps downstream) that are not supported anymore in several countries.

Baseband refers to a signal that uses frequency from 0 Hz to an upper value.

In other terms a Baseband signal does not have a carrier ( a tone at a frequency).

A baseband signal can be used to modulate a carrier and this makes the carrier spectrum to be enlarged.

The simplest modulation tecnique is amplitude modulation (AM) where a carrier signal strenght changes over time using the modulating signal (think of radio AM stations).

For digital signals that need to send sequences of binary digits 01 we can use other forms of modulation based on frequency modulation  (FM) here the modulating signal is used to have an actual frequency of Fcarrier + Modulating_signal.

More complex modulations combining phase and amplitude modulations are possible and are called QAM.

Actually an ADSL or VDSL uses multiple carriers.

This is called Sub Carrier Multiplexing SCM or in ADSL terms DMT = Discrete Multitone modulation.

Classic ADSL uses 256 tones.

The first are unused to provide a protection for PSTN baseband signal.

Then there is range of tones used for upstream (from home to central office)

Then there is a blank range.

The remaining tones are used for downstream sent from CO modem to DTE modem.

Each tone senses the level of noise in its frequency interval and choices a suitable modulation scheme.

So actually an ADSL DMT modem is equivalent to 256 modems at different frequencies (tones).

VDSL uses more tones I think 512 tones the basic idea is the same.

In cable modem some TV carriers can be used for transporting data again two different carriers are needed for the upstream and the downstream direction.

Edit:

actually cable modems are a shared media like it is an ethernet hub so the MAC layer must manage competition for use of resources.

Also all mobile data access networks from GPRS to UMTS to LTE to next generation 5 are shared media: all phones and modems share the resources in the cell provided by a base station.

Hope to help

Giuseppe

[sivam siva]

Hello @balaji.bandi @Giuseppe Larosa 

Thanks for the reply 

I still have confusion,

Baseband I can understand a little bit. I am confusing about Broadband technology.

TV cable carries Multiple frequencies of signals so we call it as broadband.

As I studied from above link broadband is an analog signal (ex: EM waves) so can I assume a connection between my phone and the ISP modem is broadband? and the connection between my phone and the cell tower is broadband?.

I really don't know about DSL ADSL technologies and different kind of signal modulation technologies

Please help me to understand. 

Thanks 

Siva

[Giuseppe Larosa · Accepted solution]

Hello Siva,

from a technical point of view when using multiple carriers like in TV signals it is a form of FDM Frequency Division Multiplexing.

Broadband for me just means "large pipe" and applies to all modern Internet access methods: ADSL, VDSL, cable modem, satellite, mobile any generation.

So yes when you use your smartphone for accessing the internet you are using a form of broadband internet access.

Hope to help

Giuseppe