Re: [time-nuts] WWV/H Doppler Shift
Tom: Thanks! Rob: your toolchain (to borrow a phrase) produces great results. If I read the graphics right, you might be able to obtain some outstanding results from the HAARP Research Campaign 29 Nov - 03 Dec 2018. U of Alaska Fairbanks Geophysical research Institute. A thought from another QS1R user. (btw, I'm told the QS1R is at the heart of the Icom IC-7300 SDR transceiver.) Good stuff Don On 2018-11-27 20:39, Tom Van Baak wrote: FYI: The wonderful plots that Rob included in his posting an hour ago did not make it to the list. This is because they were inline or embedded within html rather than plain file attachments. Anyway, I recovered his images and they are attached to this posting: plot_5.0_dBm_2018-11-25.jpg plot_5.0_Hz_2018-11-25.jpg /tvb Moderator, www.leapsecond.com/time-nuts.htm ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. -- Dr. Don Latham AJ7LL PO Box 404, Frenchtown, MT, 59834 VOX: 406-626-4304 ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] WWV/H Doppler Shift
I’ve been monitoring the Doppler shift of WWV/H and CHU for a while now from my location 100 km / 60 mi NW of Seattle. The receiver is a QS1R, using an LTC2208 16 bit ADC, and the 125 MHz clock is provided by a Bodnar GPSDO. A Wellbrook ALA1530S+ loop antenna provides good coverage for the entire range. I use a Python script to tune the QS1R to each frequency for 11 seconds while in CW mode. The 800 Hz beat frequency is measured using the open source program Fldigi. Fldigi is mainly intended for HF digital modes like RTTY and PSK31, but the “Frequency Analysis” function is effectively an audio frequency counter with .001 Hz resolution, updated every 1.024 seconds. The first 5 or 6 samples are discarded after a frequency change. The signal must be within about ± 5 Hz. During many minutes, WWV transmits a 500 Hz tone, and WWVH a 600 Hz tone (or the reverse). By treating these as separate carriers (e.g. tuning to 5.0006 MHz) I'm able to separate the Doppler shift and signal strength of the two stations. It's remarkable that Fldigi is able to make an accurate measurement of the 500/600 Hz "carriers", since there is a 40 ms gap surrounding the tick sound each second. I've just recently got enough of a handle on Python, Matplotlib, Pandas, JupyterLab, and other excellent tools to even begin to analyze and display the data. From my location: WWV: Ft Collins, CO1,675 km, 1,040 mi, 113° WWVH: Kauai, HI4,335 km, 2,694 mi, 241° Each datapoint for the 500/600 Hz signal is plotted, to give a sense of the signal variation. Only the smoothed carrier signal is plotted, because otherwise it made the graph "too" busy (ha). The 500/600 Hz plots are moved up by 15 dB to correspond with the carrier level. But this means their displayed noise floor is raised as well. For instance, the WWVH signal from 18:00 until past 00:00 is mostly in the noise. Each observation is for 5 or 6 seconds, and taken a few minutes apart. If the standard deviation of the observation exceeds 0.150 Hz it is rejected. The reject is plotted in light gray, but otherwise ignored. That's the only filter being applied to the data. WWV is usually stronger at my location, and the carrier data correlates with it pretty closely. Based on looking at a few days data, usually WWV gives a more accurate and higher confidence reading than the carrier alone, and considerably better than WWVH. Last week the largest daily 5 MHz WWV median was .010 Hz (2.0e-09); one other day was .003, but most were .001 (2.0e-10). I'm just now getting presentable results, and expect to find errors: cosmetic, conceptual, and fundamental. Currently the Python script is as shaky as my understanding of basic statistics. Oh well, back to the data Rob ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Symmetricom TS2100 Faults and Forgetfulness
Chris - Did you update this TS-2100 with HEOL Design’s replacement GPS receiver? Several time-nuts participants (and some scientific organizations) performed this update/upgrade (including me), replacing the obsolete TrimbleACE III GPS receiver. http://www.heoldesign.com/N024-GPS-receiver-board-for-Tymserve-2100 — On January 2015, TymServe 2100 servers started failing in the time displayed, and there was 1 second offset. On May 3, 2015, the TS2100 showed another bug, by displaying an incorrect date : September 17, 1995 (1024 weeks earlier, GPS Week Number Roll-over). Symmetricom (Microsemi) published a note about this WNRO bug, explaining that no fix was available (from Microsemi). HEOL Design (France) developed a solution for these TS2100 issues. http://www.heoldesign.com/IMG/pdf/heol-tech_note_119_en_r02.pdf HEOL DESIGN Pôle Phoenix Route du radome 22560 PLEUMEUR BODOU France T: (+33)296 48 46 05 M:(+33)603 55 19 45 E: cont...@heoldesign.com — greg, w9gb Subject: Symmetricom TS2100 Faults and Forgetfulness Date: Mon, 26 Nov 2018 18:31:30 + From: Chris Quayle To: time-nuts-requ...@lists.febo.com Hi, Question for the group. I have a Symmetricon TS2100 which has faults. It's been some time since it was last used, but powered it up recently to find that it had lost it's setup data, display showed rubbish and the year is stuck at 1997, though the time of day is accurate once it has achieved 1pps lock. Apart from that, everything else looks ok. The display can be reset with the "root util display 0x97900" command and the firmware was upgraded about a year ago to the latest revision from the symmetricom site. Just wondering if it could be a faulty eeprom, but not managed to find a schematic or service data for it, so difficult to debug at a hardware level. Any suggestions would be welcome... Chris Sent from iPad Air ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] RF isolation requirements for multiple GPS receivers
Dana, As described in the following HP GPS splitter the isolation is > 40dB. https://www.febo.com/time-freq/gps/hp58516a/HP_58516A.pdf I use one of these 8-channel splitters. I had a bad experience using a passive splitter of the minicircuits in the 10MHz distribution in my lab. An instrument that accidentally generated instead of receiving the reference disturbed all other related instruments. In this case, an isolation of 25-30dB proved to be insufficient. Therefore, I recommend using a GPS splitter with active components such as the classic HP models and other brands. Luciano www.timeok.it Da "time-nuts" time-nuts-boun...@lists.febo.com A "Discussion of precise time and frequency measurement" time-nuts@lists.febo.com Cc Data Tue, 27 Nov 2018 07:44:23 -0600 Oggetto [time-nuts] RF isolation requirements for multiple GPS receivers I want to run about 4 separate GPS units of disparate manufacture from a single antenna. My plan is to provide power for the antenna via a bias tee (power inserter) at the bottom end of the antenna's cable, then use an isolating splitter on the receiver side of the bias tee to split to the various receivers. My question is: how much isolation between receivers is likely to be necessary? Real life splitters are only so-so in isolation performance (15-25 dB), and may e significantly worse if the antenna's LNA's output is a poor match. So I'm wondering if I'm going to need more amplifiers in the splitter's outputs just for the sake of adequate isolation between the GPS receivers. Thanks, Dana K8YUM ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] RF isolation requirements for multiple GPS receivers
Hi, I am using Mini-Circuits ZN4PD1-50+. They are about 30dB in the GPS frequency band. I hang 4 receivers each off three of these mixing Motorola, Ublox, Trimble and Navspark and never had an issue. Mike > Le 27 nov. 2018 à 14:44, Dana Whitlow a écrit : > > I want to run about 4 separate GPS units of disparate > manufacture from a single antenna. My plan is to > provide power for the antenna via a bias tee (power > inserter) at the bottom end of the antenna's cable, then > use an isolating splitter on the receiver side of the bias > tee to split to the various receivers. > > My question is: how much isolation between receivers > is likely to be necessary? Real life splitters are only > so-so in isolation performance (15-25 dB), and may > e significantly worse if the antenna's LNA's output is > a poor match. So I'm wondering if I'm going to need > more amplifiers in the splitter's outputs just for the sake > of adequate isolation between the GPS receivers. > > Thanks, > > DanaK8YUM > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. I am not a a vegetarian because I love animals. I’m a vegetarian because I hate plants. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] SRS FS 740
Has any one bought the SRS FS740 Bert Kehren In a message dated 11/21/2018 11:11:18 AM Eastern Standard Time, thol...@woh.rr.com writes: Thanks Steve and Tom for helping me sort that out. Much appreciated. Tom Holmes, N8ZM -Original Message- From: time-nuts On Behalf Of Tom Van Baak Sent: Wednesday, November 21, 2018 10:49 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] WWV Doppler Shift Tom Holmes, N8ZM wrote: > So if the SI second is specified at sea level, and we know from Einstein and > TVB's > work that going up a mountain changes a clock's period, how would the second > be > affected at the center of the Earth ( ignore thermal problems, this is a > conceptual > discussion) where the net gravity vector might conceivably zero? Or for that > matter, > at a Lagrange point in space? We do have some data from those locations I > would think. By convention, the SI second is defined at sea level. A clock at infinity runs about 6.95e-10 faster. A clock at the center runs about 3.48e-10 faster. There's a useful diagram in [1]. Image attached. Just follow the green "gravity speedup" line. If by "gravity vector" you mean the acceleration of gravity (as in "g") then yes, that's 0 at the center, also 0 at infinity and roughly 9.8 m/s^2 at the surface. If the Earth were homogeneous then g would drop by 1/r^2 outside and 1/r inside the surface. In reality the earth is far more interesting and complex. For a good time see [2] and also google: earth PREM > A second question (no pun intended) is that given the Earth's elliptical > orbit around the > Sun, has there been observed an effect of the change in its gravity on atomic > clocks? Right, an elliptical orbit means both velocity and distance will vary from a mean, so, yes, relativistic effects will also vary from their mean. For GPS the eccentricity is a mere 0.02 so the peak effect is only about 45 ns (this correction is done in GPS receiver software). For a wild satellite orbit like Molniya with eccentricity 0.7, the peak effect is 1.6 us. This data from the "Table 1" in [3]; a very useful paper. But you asked about earth/sun not gps/earth. I'll hunt or calculate those numbers. /tvb [1] https://en.wikipedia.org/wiki/Gravitational_time_dilation [2] https://en.wikipedia.org/wiki/Preliminary_reference_Earth_model [3] "Relativistic Time Transfer in the Solar System", Robert A. Nelson https://ieeexplore.ieee.org/document/4319282 https://www.ietf.org/mail-archive/web/dtn-interest/current/pdfnEfIcI08jz.pdf ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] RF isolation requirements for multiple GPS receivers
I want to run about 4 separate GPS units of disparate manufacture from a single antenna. My plan is to provide power for the antenna via a bias tee (power inserter) at the bottom end of the antenna's cable, then use an isolating splitter on the receiver side of the bias tee to split to the various receivers. My question is: how much isolation between receivers is likely to be necessary? Real life splitters are only so-so in isolation performance (15-25 dB), and may e significantly worse if the antenna's LNA's output is a poor match. So I'm wondering if I'm going to need more amplifiers in the splitter's outputs just for the sake of adequate isolation between the GPS receivers. Thanks, DanaK8YUM ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
