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

Thu Jan 20 06:00:06 UTC 2022

Jay wrote:

>     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. 

Altitude error by the delay is proportional to wavelength of signal
(in this case, 3 inches or so) and shouldn't be so serious.

 > Perhaps the calibration circuitry can deal with this added delay.

According to the following patent filed in 1997:

	https://patents.google.com/patent/US6008754A/en
	Current radio altimeter calibration technology requires
	the radio altimeter to be calibrated by adjusting the
	length of the cable connecting the radio altimeter to
	its antenna during installation.

old altimeters may have some difficulty to fully calibrate the delay.

						Masataka Ohta