Hi The “cheap” approach these days is to use a uBlox ZED-F9P
https://www.digikey.com/products/en/rf-if-and-rfid/rf-evaluation-and-development-kits-boards/859?k=F9P <https://www.digikey.com/products/en/rf-if-and-rfid/rf-evaluation-and-development-kits-boards/859?k=F9P> along with one (or more) the <$100 eBay antennas. You take 24 hour data runs and ship them off to any of several free analysis outfits. One is NRCan. There are a lot of others. They all do a fine job. Bob > On Nov 21, 2019, at 3:13 PM, Eric Scace <[email protected]> wrote: > > I need another project like a hole in the head — but curiosity continues to > nag me. > > I moved to Boulder CO a few months ago. The “curiosity” is to determine the > position of two antennas at either end of my house and monitor it over time, > with the idea that one could see plate movement in 3 dimensions plus rotation > around the axes. > > What hardware/software would be suitable for a TimeNuts (PositionNuts?) > project like this? > > — Eric K3NA > > >> On 11/21/19 8:00 AM, Bob kb8tq wrote: >> Hi >> >> Way back in time, the first gear out there to use what we now look at as >> “normal” antennas >> was survey gear. For various reasons they decided on a 12V power supply and >> 40 to 50 db >> of gain in the preamp mounted in the antenna. They also got into L1 / L2 >> pretty quickly. >> >> A bit later the cell phone (and later broadcast) guys got into this. In a >> location with a lot of >> RF (like a cell site) having a lot of gain at the antenna didn’t work all >> that well. IMD issues >> got into the act pretty quickly. In addition, front end filtering was >> required to reduce overload >> issues. The focus was on L1 only so filtering was relatively easy. >> >> There is a whole separate set of antennas that put a big chunk of the RF >> portion of the radio >> in the antenna. Those still survive here and there. I have one of them and >> probably a couple >> of dozen of the more “normal” antennas. >> >> As time marched on, supplying 12V to antennas became a bit less popular. >> Most of the cell >> guys went over to a 5V antenna supply. The net result was 12V 50 db survey >> antennas that did >> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas >> didn’t do L1/L2 so >> not going to work for survey. The survey antennas had way to much gain and >> no filtering so >> not going to work for a cell site. >> >> Indeed things did and do get crossed up in various pro and basement systems. >> With care and >> the right set of circumstances things may work. In other cases the result >> can be an ongoing set >> of systems issues over an entire network of stations. >> >> Prices for a good new survey antenna are up in the many thousands of dollars >> range. They have >> very stable phase centers and (usually) test results to allow correction of >> any residual phase >> issues. This is part of what lets you get into the “couple of mm” range on a >> survey. >> >> For timing, you have to dig a bit and answer a few questions. Is your >> concern how close you >> are to BIH? If so you will need to know all the delays in your system. This >> includes the delays >> in the antenna filters and the preamp. Is your concern (or measure) the ADEV >> at 1 second? >> If so the delays are not a concern. Your antenna choice may be a bit >> different depending on >> this focus. >> >> Bob > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
