[time-nuts] Brooks Shera GPSDO

Larry, Take a look at Brooks Shera's article in QST. you might know of it. In my opinion, this has been the 'best ever' description of rolling your own. The July, 1998 issueBrooks Shera, W5OJM, titled, "A GPS-Based Frequency Standard. "

[time-nuts] Re: Current-day GPS timing receivers

HI Here’s the basic problem: If you don’t already know that everything you are doing is perfect, you need something better than what you GPSDO does to compare to. If you are happy with the performance of an Rb then … why not just use the Rb? The grubby issues are all out past a number of hours

[time-nuts] Re: Current-day GPS timing receivers

On Fri, 18 Feb 2022 19:48:21 -0500 Bob kb8tq wrote: I would not be so negative about doing your own GPSDO. While it is not something the unintiated can just simply conjure out of thin air, it isn't difficult either... > By far, the most likely thing to buy as part of your GPSDO design project

[time-nuts] Re: Current-day GPS timing receivers

You might consider the design by Lars Walenius posted and discussed at length here https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/ I have built several GPSDOs based on this design, most recently incorporating a TDC7200 TDC chip for the time to digital

[time-nuts] Re: Current-day GPS timing receivers

Hi > On Feb 19, 2022, at 6:59 PM, Larry Gadallah wrote: > > After poring over the several valuable references people have posted > here, it seems that even the common commercial GPSDOs have > implementation problems, so it seems like there's no (financially > viable) off the shelf solution.

[time-nuts] Re: Types of noise (was: Phase Station 53100A Questions)

Hi, On 2022-02-20 00:08, Joseph Gwinn wrote: Message: 14 Date: Sat, 19 Feb 2022 01:12:05 +0100 From: Magnus Danielson Subject: [time-nuts] Re: Types of noise (was: Phase Station 53100A Questions) To: time-nuts@lists.febo.com Message-ID: Content-Type: text/plain; charset=UTF-8;

[time-nuts] Re: Current-day GPS timing receivers

After poring over the several valuable references people have posted here, it seems that even the common commercial GPSDOs have implementation problems, so it seems like there's no (financially viable) off the shelf solution. It would indeed be convenient to have a kit option, but I'd image the

[time-nuts] Re: Types of noise (was: Phase Station 53100A Questions)

time-nuts Digest, Vol 214, Issue 20 > > Message: 11 > Date: Fri, 18 Feb 2022 22:42:22 +0100 > From: Attila Kinali > Subject: [time-nuts] Re: Types of noise (was: Phase Station 53100A > Questions) > To: Discussion of precise time and frequency measurement > > Message-ID:

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

At that time the synth was set to one frequency and the code went into sleep , so any buffering resistors etc would have served no purpose. The TCXO really was hopping over four frequencies in a PN way at intervals of a little under one second per hop. Andy www.g4jnt.com On Sat, 19 Feb 2022 at

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, solved

Erik, What you describe is a classic problem. Especially oven controlled oscillators will have GND and VCC issues. I recommend you to look att both frequency and phase deviation plots. Systematics like these is mangled up in a ADEV plot. Regardless of what isuse you really had, I hope you

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

Andy, do you have the PIC and the synthesiser chip data control lines well buffered/isolated (nice big resistors etc on the data lines ?) Any sort of current you inject into the synth chip will find its way onto the output On 19/02/2022 7:55 pm, Andy Talbot wrote: A while back I

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, solved

Magnus, others My previous mail was not very clear but the jumping problem was solved. It was not caused by the TCXO but by small current fluctuations in the TCXO causing small VCC fluctuations causing feedback into he Vtune input because the Vtune was derived from the VCC. I just did not realize

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, cause identified

Erik, So, your pick of VC-TCXO is one that obviously seems to use the fractional synthesis to both set the output frequency as well as compensate for temperature. The modulations you have will be intrinsic to the pick. As you lock your VC-TCXO to a GPS, the average frequency will be locked

[time-nuts] Réf. : Trimble Thunderbolt- Frequency lock indicator

have a look here http://www.ko4bb.com/getsimple/index.php?id=the-new-thunderbolt-monitor-kit good luck ---Message original--- De : Wojciech Tomczyk via time-nuts Date : 19/02/2022 16:12:56 A : time-nuts@lists.febo.com Cc : Wojciech Tomczyk Sujet : [time-nuts] Trimble

[time-nuts] Re: Trimble Thunderbolt- Frequency lock indicator

Probably more than you want but ... < http://www.ko4bb.com/getsimple/index.php?id=the-new-thunderbolt-monitor-kit> -Original Message- From: Wojciech Tomczyk via time-nuts Sent: 19 February 2022 12:07 To: time-nuts@lists.febo.com Cc: Wojciech Tomczyk Subject: [time-nuts] Trimble

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, cause identified

Hi Sounds like you might want to try a different TCXO. Or even try an OCXO. Even with a good TCXO, 1x10^-9 accuracy is a stretch. I’m assuming we’re talking frequency accuracy so the usual “one sigma” time accuracy not the overriding number. GPS module “output jitter” forces you to a fairly

[time-nuts] Re: Current-day GPS timing receivers

Hi Building a kit is very different than a from scratch design. A Heathkit (to extend the years ago ham radio analogy) radio was an option when you shopped for your Drake. Building it would give you some experience. The Heathkit *design* was done for you and all the complicated higher level

[time-nuts] Trimble Thunderbolt- Frequency lock indicator

I use an early Thunderbolt as a 10 MHz external frequency standard for my Elecraft K3 transceiver.I would like do add to it a simple indicator which is activated when Thunderbolt's output frequency is locked.I someone aware of a circut diagram of a such indicator? Any other options to indicated

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down

A while back I purchased a low cost TCXO which I then used as the reference for a synthesizer generating 10GHz. Listening to the output on an SSB radio, the tone was hopping in a random fashion over four frequencies, spaced a few tens of Hz apart. This was surreal! I had, at that time, been

[time-nuts] Re: 10 MHz TCXO periodically jumping 20 mHz up and down, cause identified

Thanks for all the excellent info The TCXO is actually a VC-TCXO at 10MHz intended for use in a cheap GPSDO where the ambition is to have 1e-9 frequency accuracy so the 2e-9 jump was just too high. The VC-TCXO had its own low noise voltage regulator but the Vtune was connected to a variable

[time-nuts] Re: Current-day GPS timing receivers

But there is a magazine article By Brooks Shera, W5OJM. QST July, 1998. Following this article I built my unit in 1998 using his PCB and a Motorola UT+. It has been running almost continuously since then - almost 25 years. It has been thru