Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

Pat, I am not a ham, but would be interested in participating if there is someone in my neck of the woods that needs access to timing gear. I am in western norway, near stavanger. I have a hydrogen maser and many other precision oscillators. Ole > 17. nov. 2017 kl. 22:26 skrev Patrick

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

On 11/17/17 5:16 PM, Hal Murray wrote: kb...@n1k.org said: Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk� accuracy with a GPSDO. Much easier to obtain and set up in a school environment. The key will be orbit estimation for the +/- doppler part of it. Orbit

Re: [time-nuts] How good is your ADEV at 10E7 seconds? :)

Hi There are a number of papers on pulsars as time standards. The gotcha in the observed data (that has been measured over long time periods) has been random frequency jumps. Put another way, 10 million seconds and beyond *is* the problem. It’s going to take a *lot* of monitoring for a very

[time-nuts] How good is your ADEV at 10E7 seconds? :)

Context is the what-next portion of a recent LIGO talk. For those of you that missed it (or didn't pay enough attention), on Aug 17th, they got good data from a pair of neutron stars. 1.7 seconds later, the Fermi satellite got a gamma ray burst. Within a day, the optical guys had found a

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

Hi As you get into a bigger array, your antenna pointing / tracking requirements become more exotic. I doubt that your 8 X array antenna has to do much more than track the moon, I could be wrong …. Bob > On Nov 17, 2017, at 8:14 PM, Azelio Boriani wrote: > > With

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

kb...@n1k.org said: > Ok, 1 Hz at 437.5 MHZ is roughly 2 ppb. That is pretty much “slam dunk” > accuracy with a GPSDO. Much easier to obtain and set up in a school > environment. The key will be orbit estimation for the +/- doppler part of > it. Orbit estimation is not quite a slam dunk sort

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

With 197dB of path attenuation and, say, 1W or 2W of transmitter power, I think that a modest antenna is insufficient. The usual yagi array for this distance is made by 8 27-element antennas like this: On Sat, Nov 18, 2017 at 12:54 AM, Bob kb8tq

Re: [time-nuts] Time and frequency practical exercise 2018 late quarter; precision measure of 432mhz band Sat in Lunar Orbit

Hi > On Nov 17, 2017, at 4:26 PM, Patrick Barthelow wrote: > > From me, Pat a newbie, second post: > > A new project, STEM opportunity. A STEM/CitizenScience/Ham Space Science > project. Kids welcome. > In formative stages so this is for internal discussion, not for

Re: [time-nuts] Absolute phase

Hello Arthur, Might be interesting to try the same experiment both with the two receivers on the same antenna and on the two different antennas. In an ideal world I'd expect the time output(s) to track as well either way, but it would be interesting to know how well this works out in practice.

Re: [time-nuts] Absolute phase

When I first powered them on together, they seemed to drift all over the place with regards to relative phase. For the past hour now, they are keeping around 7 degrees and sometimes dropping to around 4. I think that is pretty amazing given all the stuff between the source and final display.

Re: [time-nuts] Absolute phase

Hi As the “filter” (or control loop) in some GPSDO’s scales, it impacts the degree of “agreement” between the GPSDO’s. Not all GPSDO’s scale filters so not all exhibit the behavior. The HP / Symmetricom Z38xx units are one family that do this kind of scaling. As the scale moves longer

[time-nuts] Absolute phase

I have 2 antennas mounted on opposite ends of a roof and both of them feed commercial GPS DA/splitters and I can have as many as 10 receivers running at one time for testing. I have also used one of the high frequency type F TV passive splitters with one D.C. feed through and added 200-300 ohm

[time-nuts] Programmed Test Sources PTS250

The PTS250 manual is available from mediafire as either a 55MB standard pdf file or a 41MB OCR pdf file. https://www.mediafire.com/file/v8vd4o33d7ta1rd/PTS250.pdf https://www.mediafire.com/file/5hp2hj1la7wws2s/PTS250%20OCR.pdf ___ time-nuts

Re: [time-nuts] Absolute phase

I don't know how power feed for active antenna is designed in your equipment. Sometimes equipment can be back-powered through its GPS antenna port. This might be benign or not. Get at least an RF DC block for one unit (fancy name for a cap stuck between two BNC ports.) Leo On 17 Nov 2017, at

Re: [time-nuts] Absolute phase

I agree. I disconnected it after wondering about the active antenna bias. > On Nov 17, 2017, at 12:35 PM, Magnus Danielson wrote: > > Can work, can go wrong. > > One should be careful and think it though. > > Cheers, > Magnus > > On 11/17/2017 09:25 PM, Jerry Hancock

Re: [time-nuts] Absolute phase

Can work, can go wrong. One should be careful and think it though. Cheers, Magnus On 11/17/2017 09:25 PM, Jerry Hancock wrote: I figured, what the heck, and just used a BNC T and it’s working. On Nov 17, 2017, at 12:20 PM, Magnus Danielson wrote: Hi, The reason I

Re: [time-nuts] Absolute phase

I figured, what the heck, and just used a BNC T and it’s working. > On Nov 17, 2017, at 12:20 PM, Magnus Danielson wrote: > > Hi, > > The reason I mention sharing antenna is that it takes out the difference that > is natural from having different antennas and the

Re: [time-nuts] Absolute phase

Hi, The reason I mention sharing antenna is that it takes out the difference that is natural from having different antennas and the difference in multipath. Sharing antenna has its own set of problems, so a suitable antenna splitter was assumed. Effectively you need to bypass DC to power

Re: [time-nuts] Absolute phase

Thanks, understand completely. You mention “sharing an antenna”. Is there a problem with connecting the same antenna to two units? I am referring to my REF0/REF1 pair. Thanks > On Nov 17, 2017, at 11:39 AM, Magnus Danielson > wrote: > > Hi, > > First of all,

Re: [time-nuts] Absolute phase

Hi, First of all, the receiver varies around some average phase. The average of two receivers may not be the same, even if sharing antenna. Their average can be offset from "absolute phase" because of offsets in the receiver, antenna cables and antenna. If you are not to careful, a GPSDO will

Re: [time-nuts] Absolute phase

Hi Most GPSDO’s use a divider to get straight from the 10 MHz to the PPS. There are some that derive both the PPS and the 10 MHz off a higher frequency, they are not common in the eBay world (yet). The divider is going to have a fixed delay based on it’s design. That might be 35 ns, it might

Re: [time-nuts] Absolute phase

On 11/17/17 11:05 AM, Jerry Hancock wrote: Granted I expect someone on this list to reply with something that makes me feel stupid, if you have two GPSDO units running side by side, should the phase delta on the 10Mhz output be zero (ideally)? Is there an absolute phase standard kept between

[time-nuts] Absolute phase

Granted I expect someone on this list to reply with something that makes me feel stupid, if you have two GPSDO units running side by side, should the phase delta on the 10Mhz output be zero (ideally)? Is there an absolute phase standard kept between GPSDO units as all it would take is one

Re: [time-nuts] HP5065A C-field mods and optical unit mods

Hi Corby, I would first like to thank you for sharing your precious studies with us. I love the HP5065A because it's an extremely interesting project and I'm convinced like you we have a lot of room for improving its performance. * In addition