Hi Joe,
On 20/03/14 01:53, Joe Gwinn wrote:
In article <5328ad2...@rubidium.dyndns.org>, Magnus Danielson
<mag...@rubidium.dyndns.org> wrote:
On 18/03/14 01:24, Joe Gwinn wrote:
I've used IRIG-B004 DCLS before, for cables two meters long within a
cabinet. Worked well. How well do they handle 100 meter cables, in
areas where the concept of "ground" can be elusive?
The rising edge of the 100 Hz is your time reference, the falling edges
is your information. Proper signal conditioning and cabling should not
be a problem given proper drivers and receivers.
IRIG-B004 DCLS also travels nicely over optical connections, and
grounding issues will be less of a problem. Known to work well in power
sub-stations, so there can be off the shelf products if you look for them.
That's a pretty severe environment.
I thought it would get your attention.
I should give more context: On ships at full steam, there can be a
steady seven volts rms or so at power frequency (and harmonics) between
bow and stern, which will cause large currents to flow in the shield.
This is well below the frequency at which inside and outside shield
currents become decoupled due to skin effect, so the full voltage drop
in the shield may be seen on the center conductor.
We use optical links a lot, and triax some.
One can also make RF boxes largely immune with a DC-block capacitor in
series with the center conductor.
Thus, another fairly severe environment.
Maybe, depends on your needs. Consider doing a separate network for PTP.
That approach have been used in systems where you want to make sure it
works.
That fails economically - might as well stick to IRIG.
Indeed. Doing 1 us level might be possible, going lower than that will
cause you more and more grey hairs one way or another.
This is my fear and instinct. But people read the adverts and will
continue to ask. And some customers will demand. So, I'm digging
deeper.
Are there any good places to start?
You asked here, it's not the worst place to start. :)
To be sure.
There is a truism in the standards world, that it take three major
releases (versions) of a standard for it to achieve maturity. PTP is
at version 2, so one more to go.
I'd say it depends on for what application. The trouble is when the
assumed applications increase at a quicker rate than the standard adapts
to handle them.
Cheers,
Magnus
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