http://blog.gmane.org/gmane.comp.time.nuts hourly 1 1901-01-01T00:00+00:00 http://gmane.org/img/gmane-25t.png http://gmane.org http://comments.gmane.org/gmane.comp.time.nuts/20768 <pre>What's the option on Lady Heather to do the GPS reception survey? I'm looking for the one that plots the signal strength vs azimuth and elevation to give a picture of satellite visibility over time. The only one I can seem to find is the one that tracks the current satellites over the horizon. Keith </pre> Keith E. Brandt, WD9GET 2012-05-26T14:50:29 http://comments.gmane.org/gmane.comp.time.nuts/20762 <pre> I got in a couple of Resolution-T receivers from fluke.l and have had a chance to compare them with the Resolution SMT: The -SMT receivers appear to be new. Mine were the TEP variant (Motorola compatible) that has to be reconfigured to be TSIP compatible. The -T receivers are used. Mine came with locations in rural China stored in their survey position. The -T serial port comes set for 9600,8,Odd,1 (Tbolts are 9600,8,N,1) The receivers are physically and electrically compatible. They are mostly software compatible. The -SMT only works at fixed locations. The -T can work in mobile applications or as a general purpose GPS receiver. The -T is a 12 channel receiver and the -SMT is 14 channel. The -SMT is 6-8 dB more sensitive. The -SMT tracks and reports info on all sats that it sees (even if below the elevation and signal level masks). The -T only tracks and reports info on the sats above the masks. The -T has a +/-20 ns PPS, the -SMT has a +/- 14 ns PPS. Both support external sawtooth cor</pre> Mark Sims 2012-05-25T21:02:18 http://comments.gmane.org/gmane.comp.time.nuts/20760 <pre> Hi; I have finally found a 70MHz IF GPS ant only to find the Austron 2201 is not Y2K complaint. Has anyone found a solution for this problem? I have looked at past threads and come up short, but thought I saw this problem addressed in the past. Thanks; Thomas Knox </pre> Tom Knox 2012-05-25T17:32:58 http://comments.gmane.org/gmane.comp.time.nuts/20759 <pre>---------------------------- Original Message ---------------------------- Subject: WWVB test notification From: "John Lowe" &lt;lowe-PlFwYbz7hoJHf7+it3YNdA&lt; at &gt;public.gmane.org&gt; Date: Thu, May 24, 2012 4:22 pm To: "Lowe, John P" &lt;john.lowe-R3+/ord2DXQ&lt; at &gt;public.gmane.org&gt; -------------------------------------------------------------------------- *Notice* NIST Radio Station WWVB will be conducting a test of a phase-modulated broadcast format beginning at 1800 UTC (12:00 noon MDT) Tuesday, May 29 to 1800 UTC on Wednesday, May 30 2012. The normal broadcast format will then be restored for a two-hour period. The test will then resume at 2000 UTC (2:00 PM MDT) and end at 1800 UTC, Thursday, May 31 2012. Radio-controlled clocks and watches will not be affected. Phase-locking 60 kHz timing and frequency standard receivers may lose lock during the test. For more information, call WWVB broadcast manager John Lowe at 303-497-5453, or email john.lowe-R3+/ord2DXQ&lt; at &gt;public.gmane.org &lt;mailto:john.lowe-R3+/ord2D</pre> J. Forster 2012-05-24T23:20:43 http://comments.gmane.org/gmane.comp.time.nuts/20747 <pre>Hi time-nuts! If I remember correctly here was a discussion about an older HP impedance measurement equipment. The one which is able to calculate a 6 ideal parts replacement circuit for the measured passive device. How does is it works? I would like to fit parts for simulation in SPICE. So I need something like a algorithm to fit for minimum error a input table with complex numbers (frequency-sweep) to this 6 part circuit. For example the universal capacitor component in LTspice is able to hold RLC and even XTAL data and more like residual current for electrolytics. Any ideas? Thanks - Henry </pre> ehydra 2012-05-23T18:12:41 http://comments.gmane.org/gmane.comp.time.nuts/20736 <pre>Hi guys, About 40 minutes in ESR talks about bufferbloat and NTP skew issues; https://plus.google.com/118131797905622113230/posts/FBTdvYhR8qS Anyone tinkered with measuring GPSd, NTPd and network delay tomography? regards, Kim </pre> Kim, VK5FJ 2012-05-23T03:37:41 http://comments.gmane.org/gmane.comp.time.nuts/20721 <pre>Serial Port Servers provide many advantages over serial port cards installed in a computer.  More than one computer on the network can access a serial port, though not simultaneously, and access can occur over a wireles network.  Two serial port servers I have and use are the Digi Portserver TS 16 and the Comtrol Devicemaster.  Each of these Serial Port Servers utilize an ethernet connection, are 1 rack unit (RU), appear as installed serial ports on each installed computer, have 16 serial ports, and require no installed operating system.  These can be obtained at reasonable prices on auction sites.  I would not recommend building up a computer with numerous serial cards, as this solution is not as flexible. </pre> BD Systems Inc. 2012-05-22T16:25:15 http://comments.gmane.org/gmane.comp.time.nuts/20720 <pre>Hi, I have just acquired a Datum ExacTime 6000 GPS Time Code And Frequency Generator. So far, I am impressed how fast this unit has stabilized into the low 10e-11 accuracy range... I verify this against the CHU station carrier (located 15 Km away) . The version of ExacTime 6000 I have is equipped with an OCXO mounted on the motherboard. The former owner told me that the unit had been upgraded to fix an IRIG B format issue. I cannot find the info on that upgrade. So I have the following questions: - What is the general impression on the performance of this ExacTime 6000 box? - The SELECT MODE menu shows possible selections as AUTO, 1SV4, 2SV4, 3SV4, FW or something close to that (I go by memory)... but the manual provided by Symmetricom suggests selections as Auto, STATIONARY, DYNAMIC, FW... I would like to set it to stationary. What selection should I make? - The latest manual provided by Symmetricom is version 8500-0105. Is there a newer manual available? - I saw a claim that there is a Windows softwa</pre> Bert, VE2ZAZ 2012-05-22T16:15:45 http://comments.gmane.org/gmane.comp.time.nuts/20704 <pre>Like many time-nuts I have quite a few devices that communicate to the outside world with a serial port. And like many I have more then one. In a past life I use to have to connect to sometimes a 100 RS232 in one location. A popular device is called a terminal server or concentrator. They would take from 1 to 48 RS232 ports on one side and let you talk to them via an Ethernet interface. I so far have twelve RS232 ports in use. Now that the need for such devices has diminished, these terminal servers are showing up, sometimes for pennies. One brand and model Digi's TS family of models I and have verified they work with Lady Heather and Trimble Studio on a Windows XP PC. Digi offers for free a program that makes each RS232 Port look like a COM port, and after configuring the terminal server, and this driver, you just just fire up Lady Heather pointing to the correct "COM Port". Other RS232 ports on the terminal server can either be COM ports, or one can be connected to via Telnet of for security SSH. For e</pre> Pete Lancashire 2012-05-22T02:55:10 http://comments.gmane.org/gmane.comp.time.nuts/20703 <pre> Attached is a plot from when I first started running it. The oscillator was still settling in after a long, long, nap and a trip or two around the world. Still, the drift rate was 1.5e-10 parts per day. After another week, the DAC line slope went positive for a couple of days and then went horizontal (like low E-12 range). Ignore the tempco number, it's bogus since it depends upon the active temperature control for accurate numbers. But note that none of those temp cycles show up in the other plots. The PPS and OSC plots are well over an order of magnitude better than what an un-temperature-compensated tbolt would show. I'd say the receiver is a couple of dB better than a tbolt. My tbolts show some sats with dBc numbers in the 48-49 range on that antenna ------------------------ Do you have data/plots on this and your previous NTGS50AA? </pre> Mark Sims 2012-05-21T18:05:25 http://comments.gmane.org/gmane.comp.time.nuts/20702 <pre> An interesting test would be to test a Nortel unit and a Tbolt with the same oscillator and see if the basic hardware had any difference in performance (I bet they would be very close). One issue is the Tbolt can swing the DAC -5V .. +5V, the Nortel from 0V .. +10V (with a default of 0V .. 6V). The standard Tbolt osc EFC has a -3.5V/Hz gain. The Nortel has a +1.5V/Hz gain. The Tbolt can easily be driven with high quality/low noise linear supplies. The Nortel limits you to the onboard DC-DC power supply (unless you want to do some hacking). </pre> Mark Sims 2012-05-21T02:56:40 http://comments.gmane.org/gmane.comp.time.nuts/20701 <pre> Much of the improvement seems to be in the better oscillator temperature compensation... no telling how the phase noise is, but the Nortel osc has a VERY flat aging curve and no detectable DAC changes with temp. I have several tbolts and they all have a very temperature dependent DAC curve. The Tbolt DAC curve seems to follow the temp curve very closely. It does seem to be tracking the osc and not the temp sensor... I tried freezing the tbolt osc can with cold spray and the DAC showed changes the temp sensor did not. It is obviously compensating for temp changes in the oscillator. The Tbolt and the Nortel look like they use the same DS1620 temp sensor, but the Nortel firmware does not show the temperature sensor glitch. Once the oscillator settled in, I was seeing rms errors in the OSC plot in the sub 10 ppt range and the PPS plot in the 2 nsec range. Even a temperature stabilized tbolt was several times this. I have not run it a lot in holdover mode (except when I had the antenna disconnecte</pre> Mark Sims 2012-05-21T02:41:52 http://comments.gmane.org/gmane.comp.time.nuts/20691 <pre>Mine came from near Esquipulas Palo Gordo 2,593 meters up on a hilltop. It works well with Tboltmon but I cannot get LH 3.0 to talk to it. There must be some trick that I am ignorant of... Dan </pre> Dan Rae 2012-05-20T23:27:34 http://comments.gmane.org/gmane.comp.time.nuts/20683 <pre> Yes. I once read that the 37265 was a double oven unit, but it appears to be a single oven... and not particularly good oven. The 32765 oscillator's main claim to fame is its wonderful phase noise performance. ------------------ Which version of the TBolt? The one with the 37265 OCXO ? </pre> Mark Sims 2012-05-20T19:35:35 http://comments.gmane.org/gmane.comp.time.nuts/20681 <pre> It appears to be the same as the other one (which has an unreadable label). This one is marked Trimble 0001-262T 34310-T2. So far it appears to be oblivious to external temperature changes. I don't know about its phase noise. The other unit had been running 24/7 for several weeks. It settled in to a VERY flat line aging curve... like pretty much zero aging and zero temp coefficient. The Trimble oscillator in a Tbolt has a horrendous temperature coefficient (DAC voltage tracks the temp sensor reading very closely) and a rather pronounced aging curve (DAC voltage plot is sloped... very constant slope when active temperature control is used) --------------------- Which OCXO did you get in this one? </pre> Mark Sims 2012-05-20T19:24:55 http://comments.gmane.org/gmane.comp.time.nuts/20679 <pre> My second NTGS50AA came in from Old Cathay. Seems to be working OK. A couple weeks of oscillator aging will tell more. This one originated from Guatemala City, Guatemala (the other one also came from Guatemala) The seller on Ebay has scaled back his dirty capitalist pig escalation in price down to $100... shipping still at the 100% markup of $60 (unit was was $69/$30 before the excitement). Note that these units do have the pads for SMA connectors if you want to replace the oscillator. </pre> Mark Sims 2012-05-20T17:41:34 http://comments.gmane.org/gmane.comp.time.nuts/20672 <pre>It wasn't hard to find the right people at the Open House. GPS is interesting for big quakes. Most seismometers measure acceleration. It's a double integration to get displacement which is what they are used to working with. Big quakes last longer which leads normal seismometers to get into troubles with drift. GPS doesn't have any drift problems. The cross over is somewhere in the mag 7-8 range. Japan has a large earthquake warning system. On the big tsunami of last year, they weren't looking for long enough. They estimated 7.9. In hindsight, they probably could have gotten better data sooner by using GPS. This news story says that they can see the disturbance in the ionosphere. http://www.cbc.ca/news/technology/story/2012/04/23/f-tsunami-research.html </pre> Hal Murray 2012-05-20T01:09:20 http://comments.gmane.org/gmane.comp.time.nuts/20671 <pre> I just picked up an Austron 10 MHz LO 75.42MHz IF Dome Antenna Model 2029 12812282-1. I believe this is the GPS antenna with the IF down converter for the majority of the Austron GPS receivers. One of the reasons I purchased it is that I get the impression many in the group also have Austron GPS receivers lacking down converters since I have read many threads discussing down converters solutions. Before I put this Ant to use I would like to offer it to the most qualified person interested in reverse engineering it. It seems to me most Austron GPS units long ago lost their down converters. I would not mind if someone approached this commercially as long as the price was kept as low as possible to fellow Time Nuts. I would approach this myself but have so many unfinished project I fear this well end up on the shelf. Members are welcome to contact directly or through the Time-Nut which ever is considered appropriate. Thomas Knox actast-PkbjNfxxIARBDgjK7y7TUQ&lt; at &gt;public.gmane.org 1-303-554-0307 </pre> Tom Knox 2012-05-19T16:10:04 http://comments.gmane.org/gmane.comp.time.nuts/20667 <pre> No, actually it is for my alarm clock. Ignore the sawtooth? Poppycock! What self-respecting time nut could possibly tolerate being woken up with a +/- 15 ns uncertainty... ----------------------- If this is for a computer and NTP then you may ignore the sawtooth. GPS receiver sawtooth corrections are for people working at the nanosecond level; important when you're working with disciplining quartz or rubidium oscillators with stability at the 1e-12 level. Computer timekeeping and NTP is a million times worse than this. </pre> Mark Sims 2012-05-19T01:31:23 http://comments.gmane.org/gmane.comp.time.nuts/20657 <pre> Hi, Time-Nuts guys anyone know where I can get software for a Navman jupiter T Tu60 GPS Kit 1pps 10khz GPS Module. Thankyou Ken Kubick </pre> Ken Kubick 2012-05-18T18:14:57 http://comments.gmane.org/gmane.comp.time.nuts/20655 <pre> While you're at it, add an ATMEGA328 processor and a 250 ps res/256 step delay line. The processor reads the timing message, picks off the sawtooth correction factor, converts it to an 8-bit value that it output on a port to the delay line. The 1PPS signal clocks the port into the delay line for sawtooth correction. (This all assumes that the correction factor applies to the NEXT 1PPS that is output (the PPS correction is not documented... the time field in the message applies to the previous 1PPS pulse). Another useful feature might be a fan driver FET controlled by the computer RTS and DTR lines. That way Lady Heather can do the temperature control thing... RTS is enable, DTR is heat/cool. Since a fan only cools, you could skip using the RTS signal. </pre> Mark Sims 2012-05-18T17:33:39 Search the mailing list at Gmane query http://search.gmane.org/?group=$group=gmane.comp.time.nuts