you're actually looking at the intersection of three problems: * LTE is very noisy (it has echos in its sidebands for up to 100Mhz) * low-frequency LTE is *lo

you're actually looking at the intersection of three problems: * LTE is very noisy (it has echos in its sidebands for up to 100Mhz) * low-frequency LTE is *loud* -- punch through mountains loud. * These altimiters are doing the RF equivalent of looking for a needle in a haystream While FCC Part15 says "accept any/produce as little as possible", much of this comes down to the physics of RF.