Re: 60ms cross continent

[Eric Kuhnke <eric.kuhnke () gmail com>]

"no clouds" is overstating the effect somewhat. I've operated a number of
mission critical Ku band based systems that met four nines of overall link
uptime. The operational effect of a cloud that isn't an active downpour of
rain is negligible. Continual overcast of clouds is not much of a problem
at all, it's active rain rate in mm/hour and its statistical likelihood,
climate parameters of the location.

Yes, during rain fade events, current generation VSAT modems will drop all
the way down to BPSK 1/2 code rate to maintain a link, with corresponding
effect on real world throughput in kbps each direction, but entirely
dropping a link is rare.



On Mon, Jul 6, 2020 at 9:40 PM Denys Fedoryshchenko <
nuclearcat () nuclearcat com> wrote:

> On 2020-07-07 06:48, Eric Kuhnke wrote:
> > This is why adaptive coding and modulation systems exist. Also dynamic
> > channel size changes and advanced computationally intensive FECs.
> >
> > You don't think people working on microwave band projects above 10GHz
> > with dollar figures in the hundreds of millions are unaware of basic
> > rain fade and link budget methodology, do you?
> >
> > On Mon, Jul 6, 2020, 8:44 PM Denys Fedoryshchenko
> > <nuclearcat () nuclearcat com> wrote:
> >
> > > On 2020-07-07 05:04, joe mcguckin wrote:
> > > > Theoretically, Starlink should be faster cross country than
> > > terrestrial
> > > > fiber.
> > > >
> > > >
> > > > Joe McGuckin
> > > > ViaNet Communications
> > > >
> > > > joe () via net
> > > > 650-207-0372 cell
> > > > 650-213-1302 office
> > > > 650-969-2124 fax
> > >
> > > When there is no clouds.
>
> In my experience, all that ACM has achieved is that when link becomes
> "slow" and if it rains outside, it means that it will be down completely
> after few seconds.
> Previously with CCM or DVB-S without 2, it simply disappear without
> warning.
> And yes, I have and cheap and expensive Microwaves >10Ghz too.
> ACM/VCM really helps if you want to live on the edge, milking each db,
> (edge of link budget, e.g. small antenna size, interference), and this
> is actually very important to increase profitability, especially in case
> of multipoint VSAT, but it is near useless against rain fade.