Prev: Energizer USB Duo battery charger hides a Trojan
Next: How to run FreeRtos on MSP430
From: Vladimir Vassilevsky on 11 Mar 2010 15:10


RalfM wrote:

> Hi, here's some beginners questions:
>
> digital data transfer on a wired copper medium is done usually by setting
> a DC voltage (for example 5V) for a defined duration to indicate
> a binary 1 value, and say 0V to indicate binary 0.
> I think the duration of such a signal is called "bit period".
>
> Here are some questions & thoughts:
> What are the chips doing this switching for transmitting are called?
> (modulator? DAC?)
> How is it done one the receiving side? (via an ADC ?)
> How many such binary signals can a say 2 GHz CPU generate in real-world
> per second?

Are you Radium the Troll ?

VLV

From: Tim Wescott on 11 Mar 2010 15:32
Vladimir Vassilevsky wrote:
>
>
> RalfM wrote:
>
>> Hi, here's some beginners questions:
>>
>> digital data transfer on a wired copper medium is done usually by setting
>> a DC voltage (for example 5V) for a defined duration to indicate
>> a binary 1 value, and say 0V to indicate binary 0.
>> I think the duration of such a signal is called "bit period".
>>
>> Here are some questions & thoughts:
>> What are the chips doing this switching for transmitting are called?
>> (modulator? DAC?)
>> How is it done one the receiving side? (via an ADC ?)
>> How many such binary signals can a say 2 GHz CPU generate in
>> real-world per second?
>
> Are you Radium the Troll ?
>
> VLV
>
Perhaps his brother?

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
From: RalfM on 11 Mar 2010 15:35
Grant Edwards wrote:
> On 2010-03-11, RalfM<rm(a)invalid.invalid> wrote:
>> Tim Wescott wrote:
>>> RalfM wrote:
>>>
>>>> but instead of transmitting just 1 bit per cycle use instead say 8
>>>> bits per cycle,
>>>> ie. 8 DC voltage levels much like done with a DAC and ADC.
>>>
>>> That's been fiddled with. About the only place that it's really popular
>>> is over really long stretches of wire. If the wire run is short (e.g.
>>> USB, IEEE-1394, LVDS), or if it can be well controlled (e.g. lower speed
>>> Ethernet) then the signaling is usually binary with some sort of BEC, or
>>> FEC combined with BEC.
>>
>> Hmm. I don't understand why restrict yourself to use only binary
>> signalling
>
> Because it's cheap, reliable, and works well.
>
>> when it can be done byte-wise (or even more) in the same
>> time.
>
> _You_ claim it can be done. Everybody else seems to have failed and
> chosen methods like phase/amplitude modulation and various other
> schemes.
>
>> This could dramatically increase the speed, regardless of the
>> distance.
>
> Again, you seem to be making a claim that contradicts what everybody
> who has worked in the data communication industry has experienced.

It is IMO so simple and easy. Let's say we use a 5.12V DC source,
then we divide this by 256 and get 20 mV DC range for each of the 256 codes
in a byte. Now tell me where is the problem to transmit the output of
such a DAC over a twisted pair wire and use the reverse process on the
other side by using an ADC?

For full-duplex one of course would need 2 pairs of twisted wires.
It all depends on the speed of the DAC and the ADC, and they are
IMO sufficiently fast. For example 1 Gbps means 125 MB/s. Then a byte could
be sent in 8 ns. Ie. the DAC and ADC would need to have a sampling rate
of 125 MSps, and I think this is easily possible with todays chips.

My preliminary calcs indicate that one even could get 1000 GBps and more
with this method, ie. at least 10 times more than the draft 100 GBps Ethnernet.
From: RalfM on 11 Mar 2010 15:41
Grant Edwards wrote:
>
> Nobody with more than five firing neurons would think they could send
> 4 billion different DC levels down a cable and correctly discriminate
> them at the far end.

And, what about just 256 levels? Would that be impossible too?

From: RalfM on 11 Mar 2010 15:47
Grant Edwards wrote:
> On 2010-03-11, RalfM<rm(a)invalid.invalid> wrote:
>
>> It is IMO so simple and easy.
>
> Congratulations for hooking as many people as you did.
>
> This has been a very nicely done troll, but you tipped your hat when
> you started making claims like it would be simple to use 2**32
> distinct signalling levels.

1.2 nV range per code. Is this impossible with todays technology?
But 32 bit was just an example. Let's stay at 8 bit.
First  |  Prev  |  Next  |  Last
Pages: 1 2 3 4
Prev: Energizer USB Duo battery charger hides a Trojan
Next: How to run FreeRtos on MSP430