Re: What do you think about this airline vs 5G brouhaha?

["Lady Benjamin Cannon of Glencoe, ASCE" <lb () 6by7 net>]

Jay, one thing you’re missing is that a maximum of 2 (and almost always 1) radar altimeter will be in use per airfield, 
as one aircraft will be landing at a time. 

2 at SFO in good weather. (Where it doesn’t matter if they work). 

Apparently some old gear has trouble with even a 500MHz guard band, which I also find astonishingly bad for any time, 
but a lot of aviation tech is truly from another century. 

They also have main lobes approx 80* wide so they still function when the plane is in 40* of bank.

Ms. Lady Benjamin PD Cannon of Glencoe, ASCE
6x7 Networks & 6x7 Telecom, LLC 
CEO 
lb () 6by7 net
"The only fully end-to-end encrypted global telecommunications company in the world.”

FCC License KJ6FJJ

Sent from my iPhone via RFC1149.

> On Jan 18, 2022, at 2:25 PM, Jay Hennigan <jay () west net> wrote:
>
> On 1/18/22 12:29, Michael Thomas wrote:
> > I really don't know anything about it. It seems really late to be having this fight now, right?
>
> From a technical standpoint it seems to me to be a non-issue. There's a 220 MHz guard band. 5G signals top out at 
> 3980 MHz and radar altimeters operate between 4200 and 4400 MHz.
>
> If a signal 220 MHz away is going to interfere, then radar altimeters on other aircraft operating in the same band 
> would clearly be a far greater threat, and those radar altimeter signals will be rather numerous near airports. In 
> other words, if non-correlated signals 220 MHz away are going to interfere, then signals within the same band are 
> going to be a far greater source of interference.
>
> Radar receivers are typically some form of direct conversion with rather good selectivity, synchronized to the 
> frequency of the transmitted pulse. In addition, radar altimeter antennas are pointed at the ground, perpendicular to 
> the horizon. Cell site antennas by design are aimed more or less toward the horizon, not pointed straight up at the 
> sky.
>
> There's also an existing FCC mobile allocation from 4400 to 4500 MHz directly adjacent to the aeronautical radar band 
> on the high side with no guard band, yet no complaints about that.
>
> IMNSHO, the concern that 5G cellular signals will cause airplanes to fall out of the sky has about this >< much more 
> credence than the concern that 5G signals cause coronavirus.
>
> It shouldn't be that hard to instrument an aircraft with test equipment, buzz a few operating cell towers, and come 
> up with hard data.
>
> -- 
> Jay Hennigan - jay () west net
> Network Engineering - CCIE #7880
> 503 897-8550 - WB6RDV