Re: [time-nuts] Loran-C Simulation

[Edesio Costa e Silva]

Hello!

I think you can get it from the Wayback Machine:
.
 This
is just one snapshot, there are other ones.

Edésio

On Tue, Sep 11, 2018 at 10:40:08PM +0200, Robert LaJeunesse wrote:
> FWIW there exists an online reference for SX BASIC at 
> http://www.piclist.com/techref/parallax/sxb/sxb/___index.html which may prove 
> helpful in understanding the SX-B code.
>
> Unfortunately I can not find the SX-B BASIC compiler online anymore. 
> http://www.parallax.com/sx/sxb.asp is 404.
>
> Bob L.
>
> > Sent: Tuesday, September 11, 2018 at 3:38 PM
> > From: "gandalfg8--- via time-nuts" 
> > To: time-nuts@lists.febo.com
> > Cc: gandal...@aol.com
> > Subject: [time-nuts] Loran-C Simulation
> >
> ...
> > Having said that, I did take a look at your Basic code and must admit is 
> > does look pretty straightforward, even to me,
> ...
> >
> > Nigel, GM8PZR
>
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Re: [time-nuts] Loran-C Simulation

[Robert LaJeunesse]

FWIW there exists an online reference for SX BASIC at 
http://www.piclist.com/techref/parallax/sxb/sxb/___index.html which may prove 
helpful in understanding the SX-B code.

Unfortunately I can not find the SX-B BASIC compiler online anymore. 
http://www.parallax.com/sx/sxb.asp is 404.

Bob L.

> Sent: Tuesday, September 11, 2018 at 3:38 PM
> From: "gandalfg8--- via time-nuts" 
> To: time-nuts@lists.febo.com
> Cc: gandal...@aol.com
> Subject: [time-nuts] Loran-C Simulation
>
...
> Having said that, I did take a look at your Basic code and must admit is does 
> look pretty straightforward, even to me,
...
> 
> Nigel, GM8PZR

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Re: [time-nuts] PLL/GPSDO/etc learning resources for mere mortals

[Lars Walenius]

Hello Nick (and all other)

>From the beginning I were not impressed at all of your design as you started 
>with a 100ns resolution TIC and a FLL. I compared it to the BG7TBL design. The 
>only benefit your design had was that it was open source. But your design has 
>got better and better and you took help from others.

I have no problem you have ”stolen” the phase detector design from me. I have 
no intention at all to make it commercial as you have done. Of course due 
credits to relevant persons are always good.

For the TIC I don’t believe in the JFET but the bipolar variant from JimH might 
work but of course you have to do the home work for variations and stability, 
also Jim indicates some other problems. As Bruce give hint of a simple RC 
design as my may be easier to linearize as I have done.  I will probably 
comment more on this.

For the DAC I think my PWM with 16 bits works fine for a DIY but for a 
commercial GPSDO I would go for something like the Stanford to get 20-22bits. 
But I have also long ago looked at the AD5680 that is reasonable cheap for a 
monotonic 18 bit DAC.

Lars








Från: time-nuts  för Nick Sayer via time-nuts 

Skickat: Friday, September 7, 2018 10:38:31 PM
Till: Discussion of precise time and frequency measurement
Kopia: Nick Sayer
Ämne: Re: [time-nuts] PLL/GPSDO/etc learning resources for mere mortals

I’d like to thank Jim and Lars both publicly for that design - I quite 
shamelessly stole the phase detector for my own GPSDO gizmos. Jim at one point 
suggested adding a JFET to make the pulse with to voltage curve more linear, 
but that probably doesn’t make all that much difference. On my 5660 controller, 
there is no DAC - you send digital commands to affect the EFC. For my OCXO I 
use an 18 bit DAC compressed somewhat into the most useful part of the XO’s EFC 
range. My project page on hackaday is at 
https://hackaday.io/project/6872-gps-disciplined-xcxo

> On Sep 7, 2018, at 12:25 PM, Lars Walenius  wrote:
>
> I heard Jim mentioned my GPSDO. I would not go to the time nuts archive as 
> that describes a far from ready software design. The hardware is almost 
> identical. Last year I published a new design on EEVBlog:
>
> https://www.eevblog.com/forum/projects/lars-diy-gpsdo-with-arduino-and-1ns-resolution-tic/?all
>
> This is a, as I think, a much more robust design and much more tested. By 
> just setting the”gain” it will make a stable 1Hz digital PLL. As the DAC can 
> be set and you have a counter with 1ns resolution you don’t need any extra 
> instruments to do this. The nice thing is that the controller is very 
> flexible and can handle all kinds of 10MHz oscillators as XO, TCXO, OXCO and 
> rubidium. The useful control range of the oscillators is 0.001-6ppm. As only 
> a 1PPS with 3.3-5V amplitude is needed a wide variation of GPS modules can be 
> used. The time constant can be set from 4 to 32000 seconds and stored in 
> EEPROM.
>
> In the 21 pages of instruction I describe the design and also give 
> performance data as both a GPSDO and a time interval counter. As Jim says my 
> GPSDO gives useful information how you can do your own GPSDO. On the first 
> pages I have some discussion of the GPS modules like NEO7M that can be used 
> and also about different oscillators. Note I think the oscillators are the 
> first you should think of as they set the most important specs for the GPSDO. 
> See also the user manual for Stanford FS740 that contains a lot of 
> information about a modern GPSDO. Here the link to Stanford FS740 seems to be 
> broken in my instruction. Today this worked: 
> https://www.thinksrs.com/downloads/pdfs/manuals/FS740m.pdf  See for example 
> pages 25-35 for a good description of the GPSDO part. In the end of the 
> manual you also find complete schematics!
>
> On pages 8-9 in my instruction you find a very short description of my 
> software and it is a standard PI-loop with a low pass filter before just as 
> in the FS740. Paul-Henning has a very simple introduction to the PI-loop that 
> I like http://phk.freebsd.dk/time/20141018.html  . I would also recommend 
> learning from the GPSDO simulator by Tom Van Baak 
> http://www.leapsecond.com/pages/gpsdo-sim/   it also uses a PI-loop + low 
> pass filter and his code tells you a lot.
>
> From Tom’s GPSDO simulator you can also learn how the time resolution and the 
> DAC resolution work with real time data. Magnus Danielsson in March 2014 
> published the result of some his simulations with different time and DAC 
> resolutions on time nuts. My takeaway was that a time resolution below 5-10ns 
> was ok and DAC resolutions in the ballpark of the oscillator ADEV was fine, 
> but have a look on his data.
>
> On page 15 in my instruction you find a list of basic links that I have found 
> useful. Some links seems broken so for example for Stanford’s you have to 
> find again on their homepage.
>
> On pages 16-17 you find help commands and description of