Thanks for that. Came through on the phone so will check it when I have some time tomorrow...
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- Thread starter DJ...
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Thanks for that. Came through on the phone so will check it when I have some time tomorrow...
Which would mean the dB values for upstream are higher than downstream? Trying to determine your frame of reference here as some people confuse what's better/worse wrt the values.
Mr.Jax
Expert Member
Not sure if this was provided (and it's my understanding, so not necessarily 100%)
ADSL1 has a frequency spectrum of around 1MHz that it can use for upload and download. ADSL2 has 2MHz (double that of ADSL1)
Now, theoretically you can divide this freq spectrum up any way you like, e.g 50/50 for upload and download.
So the question as to why upload is so much less than download? Simply because of the A in ADSL (as others have said), Asymmetric allocation of spectrum between upload and download. Why ? because ADSL is considered more a consumer broadband technology and consumers mostly...well...consume!
The next question as to why SNR and attenuation are better on UPLOAD ? It's because the UPLOAD part of the spectrum is allocated on the LOWER part of the frequency range....(bear with me).
The copper line has all sorts of capacitance and inductance qualities. The inductance results in higher losses, the higher the frequency goes, hence the reason for downstream to have poorer SNR and attenuation values.
ADSL1 frequency plan: http://en.wikipedia.org/wiki/File:ADSL_frequency_plan.svg
ADSL2 frequency plan: http://en.wikipedia.org/wiki/File:ADSL2_frequencies.png
ADSL1 has a frequency spectrum of around 1MHz that it can use for upload and download. ADSL2 has 2MHz (double that of ADSL1)
Now, theoretically you can divide this freq spectrum up any way you like, e.g 50/50 for upload and download.
So the question as to why upload is so much less than download? Simply because of the A in ADSL (as others have said), Asymmetric allocation of spectrum between upload and download. Why ? because ADSL is considered more a consumer broadband technology and consumers mostly...well...consume!
The next question as to why SNR and attenuation are better on UPLOAD ? It's because the UPLOAD part of the spectrum is allocated on the LOWER part of the frequency range....(bear with me).
The copper line has all sorts of capacitance and inductance qualities. The inductance results in higher losses, the higher the frequency goes, hence the reason for downstream to have poorer SNR and attenuation values.
ADSL1 frequency plan: http://en.wikipedia.org/wiki/File:ADSL_frequency_plan.svg
ADSL2 frequency plan: http://en.wikipedia.org/wiki/File:ADSL2_frequencies.png