[time-nuts] A tale of two NTP servers

[djl]

A while back, I decided to try putting together a small, gps local NTP 
server. I have several computers on a lan and wanted to serve them all 
with a locally controlled device.  A bit of research  (raspberry pi gps 
ntp server --in my searcher) came up with several instructive 
sites.Seemed easy.  Is there a kit? so my current theory of buy the 
biggest piece possible can be carried out?  Further consult of youtube 
came up with:

https://www.youtube.com/watch?v=VrDRAVy_bg4&ab_channel=JohnMiller

I saw something from John on the time-nuts forum in the past, so 
contacted him re the hat he had for sale. The youtube presentation was 
so clear and complete that I bought one of his hats with the 
accompanying sd card. So I bought in.  I put the hat on a PiB on hand, 
put the antenna outside my window, and inserted the sd card as 
instructed. Before the video was completely finished, the server was 
running and connected to a Linux machine I had tunning nearby. As 
advertised. In detail. No fuss, no muss, and it's still going strong 
after two months and two power outages. WELL DONE JOHN!!!

But what about a ready to run little server? well, there are several 
around. BUT, they're kinda expensive compared to the RPi setups in 
various forms.  I'm sort of a sucker for the cheap (er, inexpensive) 
Chinese modules for various uses available on ebay or alibaba or other 
sources. Apparently, a factory somewhere in Guangdong "designs" and 
makes a bunch of litte modules to do something like measure voltagews, 
generate frequencies, etc. These modules are then bought by the 
relatives of the maker and sold on the outlets for various prices. The 
problem with these modules is that there is NEVER any documentation. 
You're on your own to use all your wiles, including reverse engineering, 
perusal of ham radio sources, eval info from manufacturers of the ripped 
chip designs, etc.  Despite that, for me at least, the modules have been 
cost effective. Always buy at least two.
With that in mind, I hit ebay and came up with: 363361419214 as an 
example. Seemed a bit expensive, but supposed to be plug and play, wit 
antenna and power. So, I ordered one up and hit the documentation trail. 
Nothing!  So, contacted the seller via ebay, and, after a brief hiatus 
for Chinese new year, got what there is for documentaton. Mostly in 
Chinese. But, I was able to find the address of the device using ANGRY 
lan scanner (you do use that, no? a great piece of software!)  
(192.168.0.100 btw).  And that worked too. It's still working. Removing 
it's pants revealed a UBLOX and a 32 bit processor, with some glue 
chips. real simple.

One further note, I'm using one antenna for the two devices, courtesy of 
SV1AFN (https://www.sv1afn.com/en/gnss-gps/-7.html) who makes a bunch of 
good stuff.

So, it can be done. As for me, I would get the PI hat and go that way, 
simply because it is not a black box, and other things are possible 
using that setup. On the other hand, for less cost, the ebay module was, 
once te secrets have been pried out, is totally simple to implement.

I have not tried to compare these units in any way, as there are those 
of you who are far more experienced than I am. All I know is, these 
approaches worked.

As usual, YMMV
73, Don

-- 
------------
The whole world is a straight man.:
----------------------
Dr. Don Latham  AJ7LL
PO Box 404, Frenchtown, MT, 59834
VOX: 406-626-4304