3 ms·

Interesting, my anecdotal experience is quite different in that I have had trouble getting fixes within both my home and my office with fairly fancy receivers a

by cozzyd 6y ago

Interesting, my anecdotal experience is quite different in that I have had trouble getting fixes within both my home and my office with fairly fancy receivers and antennas with LNAs (u-blox zed-f9p, and m8t). At work, even right by the window is challenging. But these are high-rises in with thick walls in a big city and probably tons of multipath... Did your receiver work at high altitudes? I guess ITAR rules have been relaxed so GNSS receivers are allowed on balloons with no problems nowadays.

myself248 6y ago
Sadly the balloon never flew! Project disbanded for other reasons, after we got half the hardware built. Anyway! One of these days I'm gonna sit down with SatGen and figure out how to make a track that rises to high altitude, then simulate it with gps-sdr-sim and do some ITAR testing. I have a HackRF with a stable enough clock, and I have the shielded test enclosures, I just don't have a good way to generate a track that's not at sea level. As for your results... Those are some pretty fancy receivers, do I know you as a fellow Galmon contributor? There's an F9P on my windowsill as station #41, and I had an M8U on my desk last week. Each has gotten a fix just fine sitting on the desk, by the way. In your office I suspect the glass has a low-E coating which is metallic, and effectively forms a skin over the whole building. No explanation for the house though; I see moderately slower TTFF times and sometimes poor C/no stats for certain parts of the sky, but otherwise things work just fine in my house. Is there a way to get a background noise level rating out of these receivers?
- cozzyd 6y ago
  First I heard of galmon... sounds cool! Yeah, probably my office building has some sort of shielding... I barely even get cell reception in my office, even sitting by the window. It worked better in my apartment, but I had to basically hang the antennas off my window. I have since moved from that apartment and have not tried in my new place, although I suspect it would be worse since there's another tall building across the street. I did (and still do) live very close to an elevated train line, which noticeably produces tons of noise (as in my TV antenna cuts out...) whenever a train goes by!

by cozzyd 6y ago

myself248 6y ago

Sadly the balloon never flew! Project disbanded for other reasons, after we got half the hardware built. Anyway! One of these days I'm gonna sit down with SatGen and figure out how to make a track that rises to high altitude, then simulate it with gps-sdr-sim and do some ITAR testing. I have a HackRF with a stable enough clock, and I have the shielded test enclosures, I just don't have a good way to generate a track that's not at sea level. As for your results... Those are some pretty fancy receivers, do I know you as a fellow Galmon contributor? There's an F9P on my windowsill as station #41, and I had an M8U on my desk last week. Each has gotten a fix just fine sitting on the desk, by the way. In your office I suspect the glass has a low-E coating which is metallic, and effectively forms a skin over the whole building. No explanation for the house though; I see moderately slower TTFF times and sometimes poor C/no stats for certain parts of the sky, but otherwise things work just fine in my house. Is there a way to get a background noise level rating out of these receivers?

cozzyd 6y ago
First I heard of galmon... sounds cool! Yeah, probably my office building has some sort of shielding... I barely even get cell reception in my office, even sitting by the window. It worked better in my apartment, but I had to basically hang the antennas off my window. I have since moved from that apartment and have not tried in my new place, although I suspect it would be worse since there's another tall building across the street. I did (and still do) live very close to an elevated train line, which noticeably produces tons of noise (as in my TV antenna cuts out...) whenever a train goes by!