Re: [time-nuts] PPS phase between two GPS units.

Seems to me you could adjust the feed line length value in one of the receivers to zero out the difference as it appears that the path length is slightly different. >From Tom Holmes, N8ZM > On Dec 23, 2015, at 11:11 AM, Dan Kemppainen wrote: > > Hi all, > > Thanks for all the responses. > >

Re: [time-nuts] PPS phase between two GPS units.

Dan Great and at least for me it makes sense from the active splitters I have seen that use diodes to allow one receiver to power the pre-amp. In my 8 way you have the diodes and L+Cs. The powered path is essentially the diode turned on. The non powered is a reverse biased diode and the C around th

Re: [time-nuts] PPS phase between two GPS units.

Hi all, Thanks for all the responses. The GPS units were swapped on the splitter ports, and the phase difference did in fact change. It changed from 21nS to around 5nS. Not exactly what was expected, although it would tend to indicate the RF path is not the same through the splitter. Last n

Re: [time-nuts] PPS phase between two GPS units.

Are they running off the same power supply? If so, I would run them from different power supplies as an experiment. --- Graham == On Tue, Dec 22, 2015 at 6:19 AM, Attila Kinali wrote: > On Tue, 22 Dec 2015 11:57:55 +0100 > Mike Cook wrote: > > > > A sampling difference of 1 cycle with 48Mhz cl

Re: [time-nuts] PPS phase between two GPS units.

On Tue, 22 Dec 2015 11:57:55 +0100 Mike Cook wrote: > > A sampling difference of 1 cycle with 48Mhz clocks would give you ~21ns > offset if not using sawtooth correction. Can you do the sawtooth correction > and see if the offset is reduced? This is the most likely explanation. The LEA-6 modules

Re: [time-nuts] PPS phase between two GPS units.

> Le 22 déc. 2015 à 06:16, Brian Inglis a > écrit : > > On 2015-12-21 18:24, d...@irtelemetrics.com wrote: >> So I've been playing with some timing hardware here, and have noticed >> something rather curious. I have two otherwise identical Lea-6T GPS modules, >> configured exactly the same. T

Re: [time-nuts] PPS phase between two GPS units.

paulsw...@gmail.com said: > I think you are doing the right test to see if the splitter delay is the > issue 21 ns is mighty small and a real possibility. 21 ns is huge. That's 10 inches of PCB trace. 74AC00 at 5V is 6.6 ns, so that's 3 gates. But in any case, it would be obvious after the O

Re: [time-nuts] PPS phase between two GPS units.

On Mon, Dec 21, 2015 at 08:24:37PM -0500, d...@irtelemetrics.com wrote: > difference of about 21nS between the PPS outputs. This is also evident in > the GPSDO output, as the phase of the 10Mhz is also skewed by 21nS or so.  21nS are about 1/48MHz, if internally LEA-6T has this clock and the PPS

Re: [time-nuts] PPS phase between two GPS units.

On 2015-12-21 18:24, d...@irtelemetrics.com wrote: So I've been playing with some timing hardware here, and have noticed something rather curious. I have two otherwise identical Lea-6T GPS modules, configured exactly the same. These units are tied to the same antenna, with a splitter with the

Re: [time-nuts] PPS phase between two GPS units.

To verify if the where the delay is generated, antenna and splitter or GPS, simply invert the antenna cable on the GPSs antenna connector and verify if the delay change as sign. Luciano On Tue 22/12/15 02:24 , d...@irtelemetrics.com wrote: > Hi All, >   > So I've been playing with some tim

Re: [time-nuts] PPS phase between two GPS units.

swap the two receivers and see which one is leading, if leading is changing the delay difference is with the antenna signal distribution 73 KJ6UHN Alex On 12/21/2015 8:03 PM, paul swed wrote: I think you are doing the right test to see if the splitter delay is the issue 21 ns is mighty small a

Re: [time-nuts] PPS phase between two GPS units.

I think you are doing the right test to see if the splitter delay is the issue 21 ns is mighty small and a real possibility. Regards Paul WB8TSL On Mon, Dec 21, 2015 at 8:24 PM, wrote: > Hi All, > > So I've been playing with some timing hardware here, and have noticed > something rather curious.

[time-nuts] PPS phase between two GPS units.

Hi All,   So I've been playing with some timing hardware here, and have noticed something rather curious. I have two otherwise identical Lea-6T GPS modules, configured exactly the same. These units are tied to the same antenna, with a splitter with the same length cables running to each unit.