On 18 Feb 2015 04:20, "Tom McDermott" <tom.n...@gmail.com> wrote: > > Hi Dave - agree that VNA is one good way to measure the delay. If required > accuracy is less than about > 0.5 nsec, then Tx antenna to Rx antenna mutual impedance starts to become > an issue.
I don't see why. The two antennas can (and should) be a reasonable distance apart. There will be no significant interaction between them. The biggest problem might be reflections from the ground. > Above about > 1 nsec error probably most of these can be ignored. No access to a vector > VNA that works at 1.5 GHz. > unfortunately. If it was a 10-15 minute job I would not mind doing it for you as I have several VNAs that cover 1.5 GHz. But it would take quite a bit of time to build the appropriate antenna then mount the two in such a way that reflections were not an issue. It means errecting two masts on non conductive poles. It is basically a days work. If you have a spectrum analyzer, you could probably see the bandwidth of the filters from looking at the noise spectrum. From what someone wrote earlier, with typical delays vs bandwidth, you could perhaps get a rough estimate of the delay. I just wonder if there's some other way, especially if one has multiple GPS receivers, a fast scope.... but I can't think of anything. A VNA is the obvious tool to me, but I would not be surprised if there was some trick that could be used without a VNA. > Thanks for the pointer to the Keysight VNA discussion list. No problem. For answers to VNA related questions, the Keysight forums are the place to go. Neither Anrisu or R&S have anything like this. > -- Tom, N5EG Dave. _______________________________________________ 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.
