just use a bias tee to feed in the antenna volts :) -----Original Message----- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: 01 April 2018 23:29 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPS ANTENNA
An unusual attenuator with a DC pass. On Sun, Apr 1, 2018 at 10:21 PM, David C. Partridge <david.partri...@perdrix.co.uk> wrote: > Or use a choke ring survey antenna and an attenuator :) > > Dave > > -----Original Message----- > From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob > kb8tq > Sent: 01 April 2018 14:43 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] GPS ANTENNA > > Hi > > Indeed, it is *very* easy to put to much gain in front of a timing GNSS > receiver. These beasts are trying to dig out a signal that you can’t even see > with a spectrum analyzer. > It’s way to far below the noise floor to detect that way. They optimize > things pretty tightly to get that done (and to hit a price target ….). Put to > much gain in front of them and they get unhappy. > > Making this even more crazy, the survey industry standard antenna *does* have > a lot of gain. Survey receivers need way more gain in front of them than > timing receivers. Put a survey antenna directly on a timing device and > trouble will likely be the outcome. Equally, a survey instrument probably > will not be happy with a timing receiver. > > Why all this nonsense? As far as I can tell, it goes back to how the very > early L1 / L2 survey boxes were designed back in the 1980’s and early 1990’s. > They made a basic decision to put a lot of gain at the antenna. Motorola came > along with their GPS modules later on. They made a *very* different decision > about how to distribute the gain. There are very good arguments on both sides > for why they did it this way. > The bottom line is still - you need to match things up … > > Bob > >> On Apr 1, 2018, at 2:36 AM, cfo <xne...@luna.dyndns.dk> wrote: >> >> On Sat, 31 Mar 2018 10:58:19 -0500, >> donandarline-Re5JQEeQqe8AvxtiuMwx3w >> wrote: >> >>> I found a supplier for high quality GPS antennas at a very >>> reasonable price. PCTEL GPSL1-TMG-SPI-40NCB. >> >> *** SNIP *** >> >> I had one of those on 25m cable, and it worked fine on a Tbolt , >> until i got an active antenna splitter that also had some gain. >> Then i had to replace it w. a 26dB version of same type, else the >> "Jackson Lite" was loosing sync. >> >> What i mean here, is that you can get too much gain too. >> >> Btw: Good price. >> >> CFO >> Denmark >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
