Re: [time-nuts] WWVB SDR discussion

No more so than for a GPSDO using a microcontroller.  In this case, the MCU would steer an external oscillator using an appropriately long time constant, based on a phase tracking loop.  In my tentative block diagram, the oscillator is a cheap 26 MHz OCXO which supplies the MCU clock and (as a bypr

Re: [time-nuts] WWVB SDR discussion

Hi As long as you sample “fast enough”, you can recover phase. Indeed, even if you sub-sample (sample to slow), you can still get phase back with a few relatively minor constraints. Since one of those is “don’t sub sample at exactly a fraction of the carrier”, a sub-sample “locked” receiver would

Re: [time-nuts] WWVB SDR discussion

On 8/10/20 11:45 AM, paul swed wrote: Hello to the group. Have been looking forward to seeing how the STM32 SDR project might be going. SDR is a weak spot for me. So been reading. And believe the answer is that a SDR solution may work for AM code and even BPSK code to an extent. But doesn't the s

[time-nuts] WWVB SDR discussion

Hello to the group. Have been looking forward to seeing how the STM32 SDR project might be going. SDR is a weak spot for me. So been reading. And believe the answer is that a SDR solution may work for AM code and even BPSK code to an extent. But doesn't the sampling destroy the quality of the incom

Re: [time-nuts] Satelles PNT from Iridium satellites

Allow me to clarify my GPS involvement. In 1973 TI moved me from Houston to Dallas to be part of the start up of calculators. This was followed by Marine projects since our chairman was an avid sailor. While working on Loran C my boss walked in one day and told me that at a staff meeting he had

Re: [time-nuts] Symmetricom X72

The lamp oscillator should not have an affect. It just excites the lamp. I did see in you picture some very complicated FPGA class chips. I would expect the photocell/diode to hit an opamp. Though maybe thats in the FPGA. On the face of the lamp when off and shining a light do you see a black film?

Re: [time-nuts] Satelles PNT from Iridium satellites

Hi Oddly enough, the two share a direct connection: "Report on NBS Dual Mixeer Time Difference System (DMTD) Built for Time-Domain Measurements Associated with Phase 1 of GPS" https://tf.nist.gov/general/pdf/84.pdf Came out in Jan 1976 Starting in 1980,

Re: [time-nuts] Satelles PNT from Iridium satellites

I did attend those conferences, it was my first ex poser to Dual Mixer, NIST presented it for high precision frequency measurements. Still have copies of the proceedings.Time is and was key but I do not recall any papers addressing using GPS for time distribution as we know it today, and that is

Re: [time-nuts] Symmetricom X72

Hi Paul, First of all, thank you for your advice. I did try with the cover on, and also with the magnetic shield on (which consists of about three sheets of mu metal wrapped around the resonator cavity over and below the board (you can see the slits on the bigger board, on the pictures). I'

Re: [time-nuts] Satelles PNT from Iridium satellites

Hi Kamiya san, I know there is only one company in Japan that uses STL service from Iridium (via Spectracom as Vendor). However I cant disclose the information more detail. Best Regards, Dikshie On Mon, Aug 10, 2020 at 12:23 PM Taka Kamiya via time-nuts wrote: > > I've done some quick research

Re: [time-nuts] Satelles PNT from Iridium satellites

Hi From what I saw as the system was developed, the people doing it realized that timing was at the core of the design. If there was a timing problem, nothing was going to work. There were GPS (and before that other sat-nav) presentations at the Frequency Control Symposium for many years. The “

Re: [time-nuts] Symmetricom X72

German have you tried with the cover back on? The external light in your picture could be affecting the system. The color of the RB lamp looks about right and its nice and bright. Also most Rbs I have worked on tend to insulate the various ovens and such. Temperature matters. Regards Paul On Mon,

[time-nuts] Symmetricom X72

Hi everyone This is my first post on the list, tought I've been subscribed for some time. I'm in the process of troubleshooting an X72 which recently started to be unable to acquire lock. I've searched online for pics of this standard and wasn't unable to find anything, so i took some nice pi

Re: [time-nuts] Satelles PNT from Iridium satellites

On 08/09/2020 09:33:07 PM, Taka Kamiya via time-nuts wrote: [snip] > On more broader sense, was GPS originally designed to provide timing > service?  Or is it a byproduct of needing to measure location and > speed, thus it needed a constant signal, and that using it to sync > reference signal is ju