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

Thu Jan 20 00:04:12 UTC 2022

Greetings,

On Wed, 19 Jan 2022, Masataka Ohta wrote:

> Jay Hennigan wrote:
>
>> Radar receivers are typically some form of direct conversion with
>> rather good selectivity, synchronized to the frequency of the
>> transmitted pulse.
>
> No. Direct conversion stage has no inherent frequency
> selectivity and is subject to saturation by noise of
> any frequency unless the noise is removed in advance.
>
> Selectivity can be enjoyed only after successful
> unsaturated conversion, direct or to IF.
>
> But, the solution is to put an LC band pass/stop filter
> between an antenna and a receiver, though I have no
> idea on the difficulty to obtain FAA/FCC approval to
> do so.

    By adding an LC bandpass filter will add to the propogation delay of 
the receiver.  When the round-trip time of the echo at 1000 feet is only 2 
microseconds, that added delay will throw the RA out of calibration. 
Perhaps the calibration circuitry can deal with this added delay.

       --- Jay Nugent  WB8TKL