Re: 40 GBit @ 240 GHz across 1 km LoS

[Phil Fagan <philfagan () gmail com>]

Nice...8x300Gbit optical beams; that's awesome.


On Fri, May 17, 2013 at 11:33 AM, Warren Bailey <
wbailey () satelliteintelligencegroup com> wrote:

>  Super high frequency stuff is already in space. Iridium uses ka for
> their space craft to space craft routing network. Not much attenuation in a
> vacuum.. ;)
>
>  Look up vortex beams. These guys should hook up with the vortex guys.
> They were getting like 40bits to hertz using oam.
>
>
>  Sent from my Mobile Device.
>
>
> -------- Original message --------
> From: Phil Fagan <philfagan () gmail com>
> Date: 05/17/2013 10:29 AM (GMT-08:00)
> To: Warren Bailey <wbailey () satelliteintelligencegroup com>
> Cc: Carsten Bormann <cabo () tzi org>,NANOG list <nanog () nanog org>
> Subject: Re: 40 GBit @ 240 GHz across 1 km LoS
>
>
>  Well put; 1kM is a giant leap from .1Km, but its a far cry from rural
> transport.
>
>  I wonder what the fixed mobile/metro use cases might look like;
> Alternate path, aggregate short distance media backhaul...
>
>  I think I like the idea most for non-earth atmosphere use cases, space
> vehicle or exploration vehicle use.
>
>  Can you blast your way through rain, snow, or hell...a sandstorm by
> increasing your power?
>
>
> On Fri, May 17, 2013 at 10:44 AM, Warren Bailey <
> wbailey () satelliteintelligencegroup com> wrote:
>
> > I disagree.
> >
> > It's not the near field stuff that is an issue.. It's the far field stuff
> > further down the road that is going to murder the link.. Look at his Fig 1
> > and Fig 2.
> >
> > Fig 1 is saying that he is getting killed at 50mm/h of rain at 60 gig and
> > at 175 gig. Fig 2 is saying that everything works well until you exceed
> > .1km - where real life kicks back in. His clear sky is normal for anything
> > wireless, but look at what happens at distances exceeding his comfort
> > zone. From .1km to 1km he's taking 30-50dB of loss on his link. I don't
> > know what kind of transmitter he has, but *IF* he were to encounter rain I
> > sure as hell hope he has a form of transmit power control. I also noticed
> > that they're using OOK, which is much better than FSK but runs the risk of
> > being clobbered by a relatively small amount of noise.
> >
> > So yes, this is awesome for running huge data rates across the street.
> > Down the road, you may have a few bad days.
> >
> > On 5/17/13 8:22 AM, "Carsten Bormann" <cabo () tzi org> wrote:
> >
> > > On May 17, 2013, at 16:30, Warren Bailey
> > > <wbailey () satelliteintelligencegroup com> wrote:
> > >
> > > > By not working. At those frequencies you're talking a light moisture
> > > > pocket taking the entire link down.
> > >
> > > Not quite as bad:
> > http://www.uni-stuttgart.de/int/institut/MA_Publikationen/reichart/COMCAS_
> > > 25G_link.pdf
> > >
> > > The ~ 50 mm/h rain they seem to budget for is not yet quite an "end of
> > > the world" torrent, but it's not like you sneeze and the link goes down.
> > > (And if you have more than 50 mm/h sustained, you've got a much, much
> > > bigger problem :-)
> > >
> > > Grüße, Carsten
>
>
>  --
> Phil Fagan
> Denver, CO
> 970-480-7618



-- 
Phil Fagan
Denver, CO
970-480-7618