[time-nuts] Fw: Optical transfer of time and frequency

[Javier Serrano]

On Sun, May 1, 2016 at 9:50 AM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> If I recall correctly, there where some White Rabbit stuff available from
> vendors, was it only Ethernet switches or also cards?

Yes, the switch is available from two vendors that I know of. They are
referenced at [1]. For nodes, we have a page describing what hardware
support is needed [2]. Then there are various boards available
commercially which implement that hardware support, like [3].

For the particular case of WR-enabled TDCs, one could use the SPEC
PCIe carrier [3] with a TDC FMC [4] or a simple DIO FMC [5],
delegating then the TDC function to the FPGA on the carrier, using an
HDL core like [6]. Or roll your own, of course.

Has anybody experienced with free-space optical gigabit Ethernet
links? I am curious about whether the transceivers have a fixed
latency or at least a latency one can easily quantify online. This is
the trickiest part for adding WR support on top of a given physical
layer.

Cheers,

Javier

[1] http://www.ohwr.org/projects/white-rabbit/wiki/Switch#Commercial-producers
[2] http://www.ohwr.org/projects/white-rabbit/wiki/WRReferenceDesign
[3] http://www.ohwr.org/projects/spec/wiki
[4] http://www.ohwr.org/projects/fmc-tdc/wiki
[5] http://www.ohwr.org/projects/fmc-dio-5chttla/wiki
[6] http://www.ohwr.org/projects/tdc-core/wiki