> However, a quick guess would be the delay caused by atmospheric effects (I > don't think thermal noise would play a big role since the antenna is looking > straight up).
Seems to me that thermal noise depends only on the resistive impedance of the antenna and input circuit. See Johnson noise. Orientation of the antenna would affect reception of external noise radiation. Don't think cosmic background radiation is a problem for the usual GPS ground antenna. What causes the "atmospheric effects"? I'd expect radiation to slow down a bit as it passes through water. Are there heat effects as well? Does the density of the atmosphere change enough to make a 10E-10 second delay possible? If so, it seems there would be non-negligible changes due to turbulence over a kilometer or so. I have two each HP 58532A antenna, 58535A distribution amplifier, and Z3801A receiver connected to a laptop running a common (not HP) program that provides receiver status reports. The antennae are mounted 4 feet apart on a sturdy pole (6 inch plastic pipe). There are nearby trees above the pole. One has to live with one's mate when it comes to unnatural things that are visible from the street. I ran it for a while and got diverted to other matters, but I remember seeing relative variations in altitude and position. A Racal-Dana 1992 counter set for phase angle showed a constantly increasing phase difference between the receivers, with readings taken hours apart. I have not automated data collection yet. Is this setup able to quantify atmospheric effects or are there too many system errors? Regards, Bill Hawkins _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
