Research: Spent a morning I'll never get back, after wondering why my Sentry can't see a tower near my home drome. . .duh. . .it's because there isn't coverage below 1,500' at my place. How do I know, you ask? I don't KNOW, really, but looking at a Goole Earth file/layers from the FAA, it appears that's the case. FWIW it's worth, and your own entertainment, the file is at: https://www.faa.gov/air_traffic/technology/equipadsb/research/airspace About half-way down the page - you gotta muck with the layers a bit, but there is a "how to" embedded in the file.
I have the locations and MSL altitudes of all the ADS-B sites that I determined from crowd sourcing and FOIA from the FAA. If you can provide your home latitude/longitude to the nearest minute or so, I can give you the location and altitude of the nearest tower. ADS-B is line of sight.
35.57047, 77.04981. FF shows the towers, though I wasn't looking closely at the locations. I don't think I'm seeing non-ADS-B Out aircraft down at pattern altitude there. It's flat lands mostly, but "line of sight" is pretty restricted at 1,000' AGL, and vegetation, contrary to popular opinion, RF transparent! At least not in some parts of the spectrum. Anecdote - I was working on a USAF Reserve aircraft (F105D) back in the day - there were a couple trees between my parking spot and the VORTAC - the OBS moved along with the swaying of the trees in the wind.
Your lack of ADS-B signal on the ground is one reason why I rely on SiriusXM weather rather than FSB.
You are pretty far from any ADS-B towers. The nearest is 53 NM to the west, I would not expect to receive reception probably below 1500 MSL at that location.
That jibes with the FAA coverage map. I'm losing it a bit above 1,500' . . .Guess that explains not seeing some aircraft in the pattern - I assume those are non ADS-B out, so airplane-to-airplane "talk" isn't "on", and no nearby radar to paint them, either, not down low.
