Convert Bits/sec to Hz

I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

"Daku" <dakupoto_at_gmail.com> wrote in message
news:1f08b0d9-9d6a-4cf3-93cc-19803e81b278_at_y32g2000prc.googlegroups.com...
I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Hi,
Tim is quite knowledgeable on these subjects and gave some usefull info but
maybe your question is not quite so deep.
Hertz is used to describe cycles/second (cycles per second). If you allow it
to mean events per second then a bit can be an event.
So 1Gb/sec is 10^9bits / sec or 1 Ghz.
This is for mental clarity and the actual units may vary.

On Thu, 5 Aug 2010 16:19:00 -0400, "Tom Biasi" <tombiasi_at_optonline.net> wrote:


"Daku" <dakupoto_at_gmail.com> wrote in message
news:1f08b0d9-9d6a-4cf3-93cc-19803e81b278_at_y32g2000prc.googlegroups.com...
I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Hi,
Tim is quite knowledgeable on these subjects and gave some usefull info but
maybe your question is not quite so deep.
Hertz is used to describe cycles/second (cycles per second). If you allow it
to mean events per second then a bit can be an event.
So 1Gb/sec is 10^9bits / sec or 1 Ghz.
This is for mental clarity and the actual units may vary.

Yes, Tim touches on the old baud rate (symbol rate) vs frequency that
you're suggesting as the simple answer.

Both are not incorrect (double negative only to show grey area).

For example 100Mbps network link bangs four symbols on each of 1/25MHz
to get the speed, and Gbps copper network links don't run at 1GHz, they
run slower speed, using a couple pairs in each direction.

So, in this case, context matters.

Where I said symbols, Tim said constellation, Tim is more accurate

On Fri, 06 Aug 2010 06:49:33 +1000, Grant <o...@grrr.id.au> wrote:
On Thu, 5 Aug 2010 16:19:00 -0400, "Tom Biasi" <tombi...@optonline.net> wrote:

"Daku" <dakup...@gmail.com> wrote in message
news:1f08b0d9-9d6a-4cf3-93cc-19803e81b278_at_y32g2000prc.googlegroups.com...
I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Hi,
Tim is quite knowledgeable on these subjects and gave some usefull info but
maybe your question is not quite so deep.
Hertz is used to describe cycles/second (cycles per second). If you allow it
to mean events per second then a bit can be an event.
So 1Gb/sec is 10^9bits / sec or 1 Ghz.
This is for mental clarity and the actual units may vary.

Yes, Tim touches on the old baud rate (symbol rate) vs frequency that
you're suggesting as the simple answer.

Both are not incorrect (double negative only to show grey area).

For example 100Mbps network link bangs four symbols on each of 1/25MHz
to get the speed, and Gbps copper network links don't run at 1GHz, they
run slower speed, using a couple pairs in each direction.

So, in this case, context matters.

Where I said symbols, Tim said constellation, Tim is more accurate :)

Not really. Symbols are the stars in a constellation of stars. The symbol is
the basic unit of information transferred. A constellation is a
representation of the possible physical values (voltage, frequency, phase,
whatever).

A little more specifically, a symbol may be a specific value in the
constellation or a transition from the current point to another.

On 08/05/2010 08:04 AM, Daku wrote:
I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Without knowing more, one can't. In general, for a given modulation
scheme, increasing the data rate involves scaling everything down
equally in time, which scales everything up equally in frequency.

But there are so many different ways to encode data onto a signal that
the bandwidth vs. data rate spread is pretty wide. There are practical
systems that have 16-point constellations (four bits/symbol) that can
pack in four bits/Hz; there may be practical (or at least fitfully
practical) systems that can do six bits/Hz. On the other hand, there
are systems that are vastly spectrally inefficient; with those the sky's
the limit as far as wasted bandwidth.

Thanks to all for your feedback. I had thought
about the baud rate idea that Tim elaborated
on, but the context in which I asked this question
was Ethernet bits going from the MAC layer
to the PHY layer at say 1 Gb/s or more (for the
newer standards).

On Fri, 6 Aug 2010 03:42:15 -0700 (PDT), Daku <dakupoto_at_gmail.com> wrote:

Thanks to all for your feedback. I had thought
about the baud rate idea that Tim elaborated
on, but the context in which I asked this question
was Ethernet bits going from the MAC layer
to the PHY layer at say 1 Gb/s or more (for the
newer standards).

Again, you need to know how many bits per symbol are used. IIRC GBE is four
bits (4-pairs in use).

I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Thanks to all for your answers. However, I am a bit confused. In a
very simple situation where e.g., a
clock (1 - 0 - 1 - 0 ....) may I know where the bits/
symbol concept is coming in - I am transferring
some bits. Thanks in advance.

On 05/08/2010 16:04, Daku wrote:

I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

According to the Shannon-Hartley theorem, the highest possible data rate is:

C = B*log2(1 + S/N)

Where C is the channel capacity in bits per second

B is the channel bandwidth in Hz

Log2 is base 2 logarithm

and S/N is the signal to noise power ratio (as a linear ratio not in dB)

In practice you will always get less than this, though some modulation
schemes can get quite close.

--
-----------------------------------------------------------------------
To reply to me directly:

Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris

Bit values may be inferred from the specified voltage levels,
as in stabdard CMOS - analogous to a timing diagram.

On Aug 6, 3:25 am, "k...@att.bizzzzzzzzzzzz"<k...@att.bizzzzzzzzzzzz
wrote:
On Fri, 06 Aug 2010 06:49:33 +1000, Grant<o...@grrr.id.au> wrote:
On Thu, 5 Aug 2010 16:19:00 -0400, "Tom Biasi"<tombi...@optonline.net> wrote:

"Daku"<dakup...@gmail.com> wrote in message
news:1f08b0d9-9d6a-4cf3-93cc-19803e81b278_at_y32g2000prc.googlegroups.com...
I understand that they are different domains (Hz - analog and bits/sec
- digital), how would one
convert e.g., 1Gbit/s to corresponding Hertz
frequency ?

Hi,
Tim is quite knowledgeable on these subjects and gave some usefull info but
maybe your question is not quite so deep.
Hertz is used to describe cycles/second (cycles per second). If you allow it
to mean events per second then a bit can be an event.
So 1Gb/sec is 10^9bits / sec or 1 Ghz.
This is for mental clarity and the actual units may vary.

Yes, Tim touches on the old baud rate (symbol rate) vs frequency that
you're suggesting as the simple answer.

Both are not incorrect (double negative only to show grey area).

For example 100Mbps network link bangs four symbols on each of 1/25MHz
to get the speed, and Gbps copper network links don't run at 1GHz, they
run slower speed, using a couple pairs in each direction.

So, in this case, context matters.

Where I said symbols, Tim said constellation, Tim is more accurate :)

Not really. Symbols are the stars in a constellation of stars. The symbol is
the basic unit of information transferred. A constellation is a
representation of the possible physical values (voltage, frequency, phase,
whatever).

A little more specifically, a symbol may be a specific value in the
constellation or a transition from the current point to another.

Thanks to all for your feedback. I had thought
about the baud rate idea that Tim elaborated
on, but the context in which I asked this question
was Ethernet bits going from the MAC layer
to the PHY layer at say 1 Gb/s or more (for the
newer standards).

Thanks to all for your feedback. I had thought
about the baud rate idea that Tim elaborated
on, but the context in which I asked this question
was Ethernet bits going from the MAC layer
to the PHY layer at say 1 Gb/s or more (for the
newer standards).

OOps -- http://en.wikipedia.org/wiki/Ethernet_over_twisted_pair has a