Re: [time-nuts] Maxim DS1342
Le 12 nov. 2013 à 03:13, Chris Albertson a écrit : You want to drive the RTC with an external PPS to get time/date into an Arduino? Why not feed the PPS to the Arduino and have it compute date and time? It is really not that hard to count seconds. You don't really need an external chip to do that. Typically you need more fine time resolution them just a seconds counter. Especially if you are using an Arduino, you are maybe building a robot or real-time controller and want to measure something like Milliseconds per revolution so you need a faster running counter and then you want to calibrate that counter A typical method is to have the PPS trap the faster counter, than you can see how many periods per second your counter is moving. You can mount for a 1,000 seconds and get a pretty good idea. Then you use the fast counter, now that you know it's rate for you timing. So you don't need an external chip if you are willing to track the rate of the free running clock. True, if you don't need to know what your epoch is. Although the DS indicates GPS PPS is a choice for the reference, why bother as you get your date and time to a better resolution on first fix than any RTC is going to give you. The advantage of this chip I think, is that if you have a reference, you get to keep time with much better resolution than a normal RTC without GPS. If I am interpreting the DS correctly, the 1Hz out is held within 7,8ms of the reference, which is pretty good over very long Tau. Maybe the key is that one of the accepted references is 50/60Hz power line frequency. That nets billions of end users. -- Chris Albertson Redondo Beach, California ___ 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. ___ 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.
Re: [time-nuts] How hard is it to detect a GPS Jammer?
Le 8 oct. 2013 à 10:29, Chuck Forsberg WA7KGX a écrit : I for one would insist on complete situational awareness at all times. The alternative is being LOST. That can be bad for one's health. That is not the same as not wanting to be FOUND. ___ 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.
Re: [time-nuts] GPS to H-Maser comparison
Le 5 oct. 2013 à 18:15, Magnus Danielson a écrit : On 10/03/2013 01:33 PM, Jim Palfreyman wrote: Noticed an above average bump in our H-Maser vs GPS graphs - from sites all over Australia. Recent coronal mass ejection or US government shutdown not updating GPS? Considering that GPS Operational Advisery messages have been sent out as regular, and the critical level of the system, it's hardly likely. You will have to look elsewhere. Local issues are more likely. I doubt this as at least two of the sites showing the anomaly are around 3000km distant. I was wondering whether it might be due to grid issues, but the western australian grid has no connection to that covering the eastern states. I suppose it could be an admin foulup if the GPS receivers are all web administered. Cheers, Magnus ___ 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. ___ 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.
Re: [time-nuts] GPS to H-Maser comparison
Truly astonishing. I see nothing in my ntp gps data and unfortunately was not logging my thunderbolt. Le 4 oct. 2013 à 05:56, Jim Palfreyman a écrit : Hi all, If you go to this page: http://users.on.net/~cdadsl/ you will see some graphs (all in UT). Notice the larger than usual bump on Oct 02 around 0600 ish. The names are locations all over Australia. I never thought I'd have to do this. Yaragadee should have two r's Jim Palfreyman On Friday, 4 October 2013, Brian Inglis wrote: On 2013-10-03 05:33, Jim Palfreyman wrote: Noticed an above average bump in our H-Maser vs GPS graphs - from sites all over Australia. Recent coronal mass ejection or US government shutdown not updating GPS? Anyone else seen it? drop out gap between about 04.21-04.26 UTC? clockstats.20131003: 56568 15684.876 127.127.20.4 $GPRMC 042124 A ... 56568 16004.862 127.127.20.4 $GPRMC 042644 A ... peerstats.20131003: 56568 15684.876 127.127.20.4 961a -0.02270 ... 0.05344 56568 16004.862 127.127.20.4 961a -0.13150 ... 0.15721 loopstats.20131003: 56568 15684.876 -0.02270 0.899 0.07071 0.70 4 56568 16004.862 -0.13150 0.898 0.08830 0.000114 4 __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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. ___ 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.
Re: [time-nuts] Pulsars make a GPS for the cosmos
Le 30 sept. 2013 à 09:19, Hal Murray a écrit : jim...@earthlink.net said: You also get direction, so for a navigation system, you can figure out where you are. I'm still missing the big picture. If I'm working off direction, why are pulsars interesting? Why radio vs optical? There are lots of bright stars out there. Why not use them for navigation? I think it is a question of improving accuracy. Comparing a group of pulsars tick arrival times being better than comparing apparent star positions, which depends on camera resolution ,and also , if position relative to earth is required, against a base catalog. Pulsars make that easier. -- These are my opinions. I hate spam. ___ 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. ___ 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.
Re: [time-nuts] Pulsars make a GPS for the cosmos
Le 28 sept. 2013 à 14:26, Magnus Danielson a écrit : On 09/28/2013 02:15 PM, Jim Lux wrote: Don't forget the Doppler and relativistic effects of the earth moving around the solar system barycenter. But that's not much different than you do for GPS (e.g. knowing satellite orbits, etc.) Naturally. You also needs to compensate for their decay-rate as you try to span longer periods. You can use them for navigation and time, just like GPS. Even seen a presentation on that. The big hiccup is that you need a fairly good sized antenna to detect the pulsars. They're bright in the sense of radio astronomy, but remember that those folks think in terms of 1000 ft apertures at Arecibo and huge arrays like the VLA or ATA. http://www.radio-astronomy.org/pdf/pulsars.pdf http://www.k5so.com/Radio_astronomy_pulsars.html - an 8.6 meter dish with a UHF feed. He's using a Rb, by the way http://www.moetronix.com/pulsar/index.htm They used a 26 meter antenna. Scrolling down, it looks like they're getting a whopping 0.5 dB SNR on the Crab Nebula pulsar. So, pulsar nav seems a bit impractical for present day space vehicles. NCC-1701 Enterprise might be big enough to carry a suitable phased array. I think the radio elescope(s) needed are much smaller. There are apparently 2 pulsar clocks installed here in europe, one in St Catherine's church Gdansk and the other in the European Parliament, Brussels. The Wiki article states The pulsar clock consists of a radiotelescope with 16 antennas, which receive signals from six designated pulsars. Digital processing of the pulsar signals is done by an FPGA device . I have tried to find more details without success, but the antennas must be reasonable sized to be installed in such places. I think the OP link indicates that X-ray wavelengths would be used which bring down the detector size. No use on earth though. On a space-craft it becomes easier to handle thermal noises thought. Cheers, Magnus ___ 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. ___ 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.
[time-nuts] CBT designation and usage?
Hi, Some Qs for someone with 5071A experience. I have picked up a cheapo second hand 5071A and would like to know what tube I have and what remaining life I might expect. It locked in about 10-15 mins after I applied power for the first time this morning. the box s/n is 3249A00498 and the tube s/n 3124A00248 has an (S) suffix . There is an opt 001 (high performance CBT) label on the box. *idn? returns HEWLETT-PACKARD,5071A,0,X.3249 The Symmetricom manual of 2006 give a SYMMETRICOM string returned. So it must be quite old I guess. X.3429 appears to correspond to the firmware version as seen on the LCD . Given that, does anyone know how to find out a) date of manufacture b) type of CBT I could not find any command sequence to indicate usage, so is there a way to find out c) The cumulated CBT power on time? d) If that is not available, is there anything in Status summary that could give a clue to aging? scpi syst:print? MJD56562 15:20:21 CBT ID: 3124A00248(S) Status summary: Operating normally Power source: AC Log status: 15 entries Freq Offset: 0e-15 Osc. control: -5.57 % RF amplitude 1:35.5 %RF amplitude 2:33.4 % Zeeman Freq: 39949 Hz C-field curr:12.157 mA E-multiplier: 1357 VSignal Gain: 14.4 % CBT Oven: 6.1 VCBT Oven Err: 0.02 C Osc. Oven: -9.0 VIon Pump: 0.2 uA HW Ionizer: 1.1 VMass spec: 11.0 V SAW Tuning: 1.9 VDRO Tuning: 5.7 V 87MHz PLL: 1.1 VuP Clock PLL: 2.7 V +12V supply: 12.4 V-12V supply: -12.3 V +5V supply:5.5 VThermometer: 42.3 C Regards, Mike ___ 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.
Re: [time-nuts] CBT designation and usage?
Le 27 sept. 2013 à 20:21, Tom Knox a écrit : With a cesium standards cheap is truly relative since the remaining of tube life will make of break just about any deal regardless of price. Which is why I am asking these Qs. Cheap is indeed relative, as is time itself. Where it is hard to pay to much for a 5071A with a fresh tube. But I am curious also what others would consider cheap. Thomas Knox Date: Fri, 27 Sep 2013 12:52:25 -0400 From: paulsw...@gmail.com To: time-nuts@febo.com Subject: Re: [time-nuts] CBT designation and usage? Cheap is relative. Curious what it means? Paul WB8TSL On Fri, Sep 27, 2013 at 12:20 PM, mc235960 mc235...@gmail.com wrote: Hi, Some Qs for someone with 5071A experience. I have picked up a cheapo second hand 5071A and would like to know what tube I have and what remaining life I might expect. It locked in about 10-15 mins after I applied power for the first time this morning. the box s/n is 3249A00498 and the tube s/n 3124A00248 has an (S) suffix . There is an opt 001 (high performance CBT) label on the box. *idn? returns HEWLETT-PACKARD,5071A,0,X.3249 The Symmetricom manual of 2006 give a SYMMETRICOM string returned. So it must be quite old I guess. X.3429 appears to correspond to the firmware version as seen on the LCD . Given that, does anyone know how to find out a) date of manufacture b) type of CBT I could not find any command sequence to indicate usage, so is there a way to find out c) The cumulated CBT power on time? d) If that is not available, is there anything in Status summary that could give a clue to aging? scpi syst:print? MJD56562 15:20:21 CBT ID: 3124A00248(S) Status summary: Operating normally Power source: AC Log status: 15 entries Freq Offset: 0e-15 Osc. control: -5.57 % RF amplitude 1:35.5 %RF amplitude 2:33.4 % Zeeman Freq: 39949 Hz C-field curr:12.157 mA E-multiplier: 1357 VSignal Gain: 14.4 % CBT Oven: 6.1 VCBT Oven Err: 0.02 C Osc. Oven: -9.0 VIon Pump: 0.2 uA HW Ionizer: 1.1 VMass spec: 11.0 V SAW Tuning: 1.9 VDRO Tuning: 5.7 V 87MHz PLL: 1.1 VuP Clock PLL: 2.7 V +12V supply: 12.4 V-12V supply: -12.3 V +5V supply:5.5 VThermometer: 42.3 C Regards, Mike ___ 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. ___ 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. ___ 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. ___ 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.
Re: [time-nuts] CBT designation and usage?
Le 27 sept. 2013 à 21:16, Tom Van Baak a écrit : Hi Mike, Cs tubes with S are standard-performance; tubes with H are high-performance. You can get that from the tube label, or from the front panel S/N. Don't trust the black dot on the rear of the instrument: frames change, tubes change, Sharpies add dots, acetone removes them. It depends on what you want the 5071A for. National labs keeping timescales prefer the H tubes since they are several times more stable than the S tubes. Casual labs prefer the S tube since they last much longer than H tubes. You have a standard tube. I thought so, but the figures looked ok so I went for it anyway. The good news is that it appears to work. Surplus, working, 5071A are not common. Your frame and tube S/N are quite low, meaning old. But I don't know of a way to tell if the instrument has been used a little or a lot during the last 20 years. There's no running hour meter in the tube itself, the hardware, or the software so AFAIK there's no way to tell how used it is. Shame, especially considering that it must have cost around 50k new. But do read: www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA484993 www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA508048 5071A_FAQs_Symm_Web.pdf www.ke5fx.com/cs_life.pdf Thanks for these links. Your syst:print? output looks ok to me. It would be interesting if you compared your 5071A 1PPS against a GPS timing receiver for a week or month. Then I could tell you better how well your 5071A is working. That looks like a good plan. I was going to just discipline the PPS against a timing receiver right off , but it would be interesting to see what its free running perf is like before I tweak that knob. /tvb ___ 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. ___ 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.
Re: [time-nuts] New NTBW50AA
I am tempted to use the monty python exhortation Start again If I am reading your screen shots correctly the 01:51:57 UTC shot is before the antenna move and the 14:02:03 one after the move. HOWEVER, both shots show the same saved position. That is certainly not going to be optimal. You should let it survey again. Mike Le 11 sept. 2013 à 16:17, quartz55 a écrit : Thanks Charles, I'm not certain myself it it's the temp chip or the way LH handles the information. It doesn't matter like you say, there's no use doing any measurements with the unit unlocked. Otherwise here is a trace while I moved the antenna. Any comments on how it reacted in holdover? http://i251.photobucket.com/albums/gg287/DogTi/time/holdover_zps35d7e81b.jpg And here is where the antenna is now, this is looking straight north, so the sky behind me is nearly clear to the horizon and straight up isn't bad either. http://i251.photobucket.com/albums/gg287/DogTi/time/gpsant_zps2963365a.jpg Dave N3DT ___ 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. ___ 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.
Re: [time-nuts] NTP/1-PPS/RS232 question
Le 8 sept. 2013 à 17:08, Chris Albertson a écrit : You only need ONE inverter gate. true The purpose is the flip the pulse. The MAX 232 chip flips the logic once which works fine for the data but you need to flip the control lines (maybe if the GPS reciever did not already do this for you.) Flipping the PPS has the effect of moving the pulse by the length of the pulse so one gate in this case will move the pulse by 100MS. Not true. The pulse is not moved, just inverted. You just need to have the driver looking for it configured to detect the correct edge polarity. +ve or -ve. That's what the flag is for. If you have a piece of kit that outputs PPS, the chances are that it is TTL +ve. Here is how I see it:- IF we put an inverter between the GPS(other it) and the rs232 chip) 1 +ve TTL pulse on the line to the inverter 2 -ve TTL pulse to the max232 transmitter , inversion 3 mark (+ve) pulse from transmitter out on the line to DB9 pin1 (DCD) 4 same over cable to pin 1 of DB9 on a PC 5 same into the max232 receiver in , another inversion 6 -ve TTL from max232 receiver out to the cd_n pin on the UART (ex 16550A) The cd_n line is active LOW 7 uart MSR register bit 7 set to compliment of cd_n uart MSR bit 3 set to one as cd_n input level has changed. uart generates an interrupt 8 interrupt wakes up driver etc etc So the ATOM driver will get a tick on the +ve outgoing edge of the PPS kit ( plus sone nanoseconds delay in the inverters/uart chain) if there is an inverter between the kit and the max232. Conversely it will get the tick on the -ve outgoing edge if no intervening inverter is used. This means that the tick will be LATE by the length of the pulse. For example , with a UT+, it will be around 200ms late and you can see this in the ntpq offset. On Sat, Sep 7, 2013 at 9:22 PM, Bob Bownes bow...@gmail.com wrote: 100ms is an awful lot of 'inverter gates'! On Sep 7, 2013, at 23:15, Chris Albertson albertson.ch...@gmail.com wrote: With RS232 the data uses negative logic (low is 1) and the control lines use positive logic (high is 1.) That is, a control line is asserted when it is at logic 0, a positive voltage. Some one at one time must have thought this made sense. The good news is that a mistake is easy to detect and fix. If the pulse is 100MS long and you have it inverted then your time will be off by 100MS. When you are designing the board put in some extra inverter gates On Sat, Sep 7, 2013 at 7:15 PM, Mark Sims hol...@hotmail.com wrote: I got in those Adafruit GPS boards. They are a very nice little GPS. VERY sensitive. I could get good lock indoors on my (windowless) kitchen floor. The house is 2 story, stucco with wire mesh in the stucco. I could also get lock in a restaurant that had a tin roof. We were far from any windows. The 1PPS signal is normally low and pulses high for 100 milliseconds. The RS-232 adapter board that I built feeds this into an RS-232 transmitter chip (MAX3232), so on the interface connector CD will be at +V and pulse down to -V. Is this what stock NTP likes? Also, I laid out the adapter board so it an accommodate a Trimble Resolution T or a Crius CN06 receiver. The Crius receiver uses a U-Blox NEO-6M receiver. They can be had for around $22 at HobbyKing. They seem to perform even better than the AdaFruit module. It looks like you will need to bodge a wire onto the TIMEPULSE pin to use it for 1PPS. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. ___ 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. -- Chris Albertson Redondo Beach, California ___ 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. ___ 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.
Re: [time-nuts] de Witte's Experiment
Le 28 août 2013 à 12:23, Poul-Henning Kamp a écrit : In message 1629133352.2066701377684015960.JavaMail.defaultUser@defaultHost, iov...@inwind.it writes: I would add that one could run the experiment over a full year. Please consider: 1. Nailing relativity is the biggest scalp you can aim for in physics. 2. NIST and timing.com showed sub-picosecond time-transfer over a 200km fiber in AZ: http://tf.boulder.nist.gov/general/pdf/1807.pdf Wouldn't you expect them to have noticed if a Nobel-prize were in reach ? I think if they were looking they would not have designed the experiment as a loop. Phoenix-Randolph is only 80 odd kms. I am not a physicist but I expect a loop would cause effects to cancel. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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. ___ 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.
Re: [time-nuts] de Witte's Experiment
Le 27 août 2013 à 20:27, Poul-Henning Kamp a écrit : In message CANX10hDW7BGH27=N0N8ZSMfUk+a2gT5ir_hv7h=e5kqewtj...@mail.gmail.com, Dr. David Kirkby writes: Maybe if the cables were burried sufficiently deep, there would be no short term changes of temperature, since the temperature underground is more contant than on the surface of the earth. If there is such an effect, why wouldn't it be trivial to measure on a transatlantic fiber ? maybe the numbers of repeaters involved make the measurements difficult. There is very little temperature variation at the bottom of the atlantic... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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. ___ 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.
Re: [time-nuts] RFTGm-II-Rb - can you gps discipline it without the XO module?
It can't be a coincidence that it is exactly 7*rollover. Le 23 août 2013 à 17:57, Alan Kamrowski II a écrit : Hi Guido, Do you have any idea why the unit interprets the date 7168 (0x1c00) days into the future? If I send it today's date in the correct Motorola format, this is how many days it adds to it. If I change the date to try another, it does the same thing. Any idea why? I can correct for it by subtracting 0x1c00 days before sending it, this just seems very odd. Thanks, Alan ___ 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. ___ 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.
Re: [time-nuts] Warped back to 1993
Le 14 août 2013 à 09:44, David Malone a écrit : On Sun, Aug 11, 2013 at 03:12:00PM +0200, Magnus Danielson wrote: I'm sure that the NTP drivers can be hacked to make necessary adjustments without too much code. I seem to have been caught by the same time warp (or a similar one) on a GPS unit that I've been using with our NTP server since 1999. I doubt I will be able to update the firmware, so I've made the change shown below to the NTP NMEA refclock. It assumes that your GPS unit might be slow by a multiple of 1024 weeks, and trys to get the timestamp within 512 weeks of the current system time before feeding it to NTP. Considering the small number of time nuts this issue is taking on leap second dimensions. I wonder how many commercial systems have had down time due to this? I'll have to dig out and test all my sleeping receivers to see which have turned into boat anchors. ___ 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.
Re: [time-nuts] Rb video
Sells to France if asked. I mentioned there might be interest from the US. Mike Le 8 août 2013 à 11:19, Mark C. Stephens a écrit : Yup, Seller just emailed me. Something about antipodeans and convicts ;) -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Brooke Clarke Sent: Thursday, 8 August 2013 1:10 PM To: time-nuts@febo.com Subject: Re: [time-nuts] Rb video Hi Mark: These only ship to the UK. Does not ship to the US Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html Mark C. Stephens wrote: Seems they are rated to 5MHz according to the manufacturer.. They ebay item number is 161081736069. --marki -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Eric Garner Sent: Thursday, 8 August 2013 5:57 AM To: Steve G8EBM; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Rb video what's the performance of the distribution amplifier like? On Wed, Aug 7, 2013 at 9:12 AM, Steve G8EBM st...@g8ebm.com wrote: Great video. The distribution units are still available on eBay. I bought two today. Regards Steve G8EBM -Original Message- From: David J Taylor Sent: Tuesday, August 06, 2013 11:30 AM To: Time Nuts Subject: Re: [time-nuts] Rb video Found this on Hack-a-day http://www.youtube.com/watch?**v=chrzrod3tQYhttp://www.youtube.com/w a tch?v=chrzrod3tQY Cheers Raj, VU2ZAP Bangalore, India. ==**= Thanks for the pointer - I enjoyed that, particularly the PIC programming! 73, David GM8ARV -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listi n fo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listi n fo/time-nuts and follow the instructions there. -- --Eric _ Eric Garner ___ 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. ___ 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. ___ 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. ___ 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. ___ 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.
Re: [time-nuts] Rb video
None left from that batch. Hope you got yours. Points taken, but cheap enough to experiment with. Le 8 août 2013 à 13:08, Dr. David Kirkby a écrit : On 6 August 2013 09:37, Raj vu2...@gmail.com wrote: Found this on Hack-a-day http://www.youtube.com/watch?v=chrzrod3tQY Cheers -- Raj, VU2ZAP Interesting video. I decided to but one of the distribution amps. I already have the rubidium. There were a few things that struck me in the video. 1) Having a PIC to control an LED seems a bit OTT. Personally I'd just stick a second LED - one as a power indicator, the other as a lock indicator, rather than make it flash when warming up, and solid when locked. 2) If one does have a flashing LED, it would be better if it is slower, in case there are any epilepitcs about. As someone who suffers from photosensitive epilepsy, I would not want it flashing any faster than 1 Hz. He should just about be ok, but I'd feel a bit happier if it was slower. 3) I'm not really convinced there is a need to change the output impedance from 75 to 50 Ohms. The impedance mis-match is pretty small. 4) More concerning to me would be the fact the output connectors are 75 Ohm, and so would be damaged with the larger male pin of a 50 Ohm connector. I guess one might get away with it given one is not going to be disconnecting this a lot, but I think I'd buy 75 Ohm BNC plugs to put on one end of the cable, and 50 Ohm BNC plugs on the other end, sticking a bit of heatshrink on the 75 Ohm end of the cable so I know they are not standard BNC cables. 5) I wondered if there is enough cooling air there? What size heatsink would be optimal? I think unlike most electronics, one does not want to cool the rubidiums too much, so bigger is better might not apply here. 6) Is the use of a SMPS a good idea? I thought the Rb oscillators should be powered from a linear supply. I don;t suppose it is possible to get a linear power supply in there. 7) He scrapped the BNCs configured as digital lines. I would have thought it worthwhile bringing out a 1 pps output, which I think those Rb oscillators have. 8) I wonder if one could fit a GPS locking module in that box and antenna connector on the box. 9) It will look very odd to have the heatsink as the front panel !! But I guess that is a small price to pay for getting a reasonably sized box and 10) I suspect the box will be hard to keep in place, since with a dozen or so BNCs on the rear, that is going to go where the cables tell it to go, rather than the other way around. Perhaps a heavy heatsink will mittigate that. 11) If I recall correctly, there is a way of adjusting the freqency of those rubidiums, though I guess for the intended application, a Rb is plenty good enough. I know it is for me, but perhaps not for a dedicated time-nut. Dave, G8WRB ___ 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. ___ 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.
