Re: [time-nuts] Building a mains frequency monitor

> record the duration of each cycle directly > 5) Double wide cycles are detectable but missed cycles are not. What do you mean by a double wide cycle? What do you mean by a missed cycle? They seem like the same thing - if you miss one, the next one will be twice as wide. > Here are the

Re: [time-nuts] Building a mains frequency monitor

> On Apr 11, 2016, at 2:31 PM, Tom Van Baak wrote: > > > 6) picPET output is directly readable by TimeLab via serial/USB. This one line item twigged my interest. Dedicating my 53220A to certain long running tasks that don’t require its full capabilities irks me a

Re: [time-nuts] Building a mains frequency monitor

Hi If you *do* want to go with the fancy ADC approach, there are MCU’s that are built specifically for power meter applications. They have cool stuff like 24 bit ADC’s and DSP capability. Since the target it high volume, the cost is sub $10 … That’s still an IF by the way. It’s still not at

Re: [time-nuts] Building a mains frequency monitor

Hi Jay, > Q1: Assuming the schmitt trigger in the picPET triggers at a consistent > point in the waveform, the frequency at any given cycle is easy to > calculate: 1.0 / (timestamp2 - timestamp1)...but, is there a better > way? That method just feels... naive, for some reason. Ah! if it

[time-nuts] Cheap LEA-6T [was: Re: Precise Time transfer and relative position over ashort baseline]

At 11:46 AM 4/11/2016, Tom Van Baak wrote: Another way might be to use single-channel common view GPS. I've not checked recently to see if 100 ps is possible over a 1 km baseline. If so that would be a less expensive solution. Someone should dig into the RINEX mode of the ublox 6T. It's on my

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Its an intensity interferometer, there are no fringes. The SNR is such thatseveral hours of integration are required. If this method is at all feasible each telescope would likely need a hydrogen maser or equivalent for such a technique to be useful. More frequent phase comparisons allow

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

I have not followed this closely. Why not use the data itself? The theoretical pattern for the telescope pair can be calculated. Even though the signals are not i.i.d, from phototubes, the data can be slid along and the delay pattern established and compared to the theoretical pattern? Timing

Re: [time-nuts] Precise Time transfer and relative position over ashort baseline

On Mon, 11 Apr 2016 19:58:33 +0200 Attila Kinali wrote: > The baseline is not the problem in this case, but the delay within > the GPS receivers and the cables. To keep their variation below 1ns > is already quite a challenge. The usual method for this is to have > the whole

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

If using this system can the relative positions of the telescopes be calculated also? You said the delay corresponding with 1mm is about 1ps, so during processing we'd calculate the relative positions also using delays between the various stations, if using common-view pulses at a different

Re: [time-nuts] Building a mains frequency monitor

>> A more modern name for a synchronous motor is a permanent magnet stepper >> motor. Any PM stepper, and a couple of microfarad capacitor becomes a >> synchronous motor when connected to the power line. I've seen a data sheet for a motor that's actually spec'd for both uses. I don't know how

[time-nuts] Suggestions for a Grandmaster source

Good afternoon I own a RTOS ( OS-9) and I have recently had some inquires about support for 1588. Does anyone have a suggestion for a grandmaster 1588 source ? In my office I do not have a requirement for precise time at this time, but i do have a couple of servers andserve3ral systems

Re: [time-nuts] Precise Time transfer and relative position over ashort baseline

On Mon, 11 Apr 2016 09:46:17 -0700 "Tom Van Baak" wrote: > Another way might be to use single-channel common view GPS. I've not > checked recently to see if 100 ps is possible over a 1 km baseline. If so > that would be a less expensive solution. Someone should dig into the

Re: [time-nuts] Precise Time transfer and relative position over ashort baseline

Bruce, So the time tag information will be processed off-line. In that case there's no requirement for real-time clock synchronization, is there? Why not let each station's clock free-run and provide periodic external pings amongst the stations as a way to continuously calibrate all the

Re: [time-nuts] Building a mains frequency monitor

IMHO the transients and harmonic content, are more interesting than the 60Hz frequency! But if the 60Hz frequency with superb rejection of transients is the only goal: The 60Hz line clock chips of the 1970's used the LV transformer secondary, a single pole of RC low-pass filtering to get rid of

Re: [time-nuts] Building a mains frequency monitor

On Wed, 6 Apr 2016 18:21:43 -0700, you wrote: >... > >Q1: Assuming the schmitt trigger in the picPET triggers at a consistent >point in the waveform, the frequency at any given cycle is easy to >calculate: 1.0 / (timestamp2 - timestamp1)...but, is there a better >way? That method just

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

If all independent clocks is stable enough, then correlation between of them could be re-considered after the data will be collected, I think. On 2016-04-11 01:00, Bruce Griffiths wrote: There is a proposal to use multiple light bucket style optical telescopes to do Intensity stellar

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

On 4/11/16 1:40 AM, Björn wrote: Hi Bruce, For such short baselines single frequency GNSS should be able to keep fixed integer solutions. Not sure how much money thas is going to save, since you might need timing specific geodetic receivers to get external 10MHz input. Did you consider

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Hi Is there a “common view” to a TV station or an FM radio station or a cell tower or …. Carrier phase works on terrestrial signals. If you have one with a stable enough career and a complex enough modulation to work out which cycle is which, it might be a cheaper approach. Bob > On Apr

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Hi Bruce, For such short baselines single frequency GNSS should be able to keep fixed integer solutions. Not sure how much money thas is going to save, since you might need timing specific geodetic receivers to get external 10MHz input. Did you consider implementing time transfer using time

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

bruce.griffi...@xtra.co.nz said: > There is a proposal to use multiple light bucket style optical telescopes to > do Intensity stellar Interferometry over short baselines (up to perhaps 1km  > or so) by using independent clocks to time tag photon  arrivals. > The relative positions of the

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Dear Bruce Posted too hastily ... Since you don't care about absolute time, maybe using identical receivers you might be able to get a few hundred ps synchronization using a PPP solution, for example. Attached is 6 months of data for two Javad receivers, with daily PPP solutions. The antennas

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

As alternative to independent clocks and single photon tagging, we considered to use TDCs: a possible solution would be radio cross links between the telescopes that drive the start/stop signals of the TDCs, then we'd tag only the lapses between photon detection from each telescope. In this way a

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Dear Bruce I think it will be very difficult to achieve synchronization at the level you want using GNSS signals. The BIPM would only claim 2 ns accuracy for calibration of the delays in a GNSS receiver plus antenna. When you process carrier phase data, you typically see jumps at the day boundary

Re: [time-nuts] Precise Time transfer and relative position over a short baseline

Hi, I would look at White Rabbit and fibre. Now, you say you can't use fibre. If you have line of sight you may use microwave (but not WLAN) or laser for a medium. I would *really* consider pulling fiber after all. After that it is relatively cheap to achieve the rest. Cheers, Magnus On

[time-nuts] Precise Time transfer and relative position over a short baseline

There is a proposal to use multiple light bucket style optical telescopes to do Intensity stellar Interferometry over short baselines (up to perhaps 1km  or so) by using independent clocks to time tag photon  arrivals. store the time tags and process the data off line. Depending on the time tag