[ntp:questions] SNTP server + ntpd 4.2.4 client
andy.helten at dot21rts.com
Tue Mar 18 18:57:52 UTC 2008
I use PoE every day -- it powers the outdoor antennae that connects to
my wireless ISP (distance of about 5 miles). I have gotten up to
3000kb/s over this link (which is slightly higher than what I'm paying
for). So, whatever you are debating here, PoE is almost certainly *not*
David Woolley wrote:
> Unruh wrote:
>> Just looked it up. A bit bizarre-- power over the ethernet? The ethernet
>> has no power supply capability. Do you mean that you have to supply the
>> device with 60V running on one of the unused ethernet cable lines? Sounds
>> noisy to me.
> I believe it is a relatively new, but very real, standard. The power is
> transmitted as a phantom between two pairs. In one variation, they are
> the pairs used for normal, 10baseT. I gather one reason is that there
> are exemptions in electrical codes for ELV power feeds as part of
> datacommunication systems, whereas a normal feed would require a
> formally qualified (not just competent) electrician.
> The feed is 48V DC. I'm not 100% sure that counts as ELV, but it is the
> same as most analogue telephone systems.
> The apparent source specification is IEE 802.3-2005, although I haven't
> gone to source.
> As the power is common mode with respect to the signals, the noise
> should not be excessive.
More information about the questions