What are you connecting it to? The computer hardware & OS are just as important. Will your antenna have an unobstructed view of the sky?
IMHO buying from major players like Garmin would be better. More compacted in size (can be attached to window easily) and does not need separate DC power line.
sure, the antenna would be on the roof, good to go… it would be connected to a reasonably powerful windows 10 system… I have used linux before, but I really dont want to screw around with that, everything I always wanted to do with linux proved to always be more difficult and provided a steeper learning curve.
This device is Cheap, so I was trying to take that into consideration too, but HOW will I interface it to an NTP time server is the biggest question, which is why I may simply go for this thing for $299 Instead:
Yes this is just a “kicking around” of ideas… obviously more expensive (although significantly cheaper than many other +$1000 solutions out there), but more likely to end in a successful project.
There are Windows builds of NTP out there, I think Meinberg is probably the most popular:
However, I have no idea how to setup a PPS input on Windows, or if the Meinberg distribution has the correct GPS refclocks compiled in. I’m sure some googling would yield some how-to guides.
For my GPS based NTP servers I prefer FreeBSD… But it can be done on Linux usually by using GPSD.
Funny, yes…thats exactly what I’m using and then through their program I poll a couple of strat 1 servers near me (relatively near) at Columbia U… I’m not sure if I "need " to use a meinberg GPS hardware product to be able to interface with this software or not, thats something I will need to ask them…also I see that going in through a serial port rs232/db9 is usually preferred over USB even when using a rs232 to USB converter due mainly to wildly unpredictable offsets in data transmission, so luckily there is a header for that on my motherboard to break out from and apparently unbeknownst to me a lot of boards have this!
I found out garmin makes 3 types of that model and the only one with PPS is this on 18xLVC
The TM1000A is only rated for 350 NTP requests per second. If you can afford a little bit more, the LeoNTP can do more than 100,000 in real world conditions.
+1 for the LeoNTP, we run one in a commercial datacentre for this reason: http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=272
Reading the description, the LEA-5T seems to be an accurate timing device, but the main problem is that you still have to find a way to feed the PPS signal to a computer running NTP software. I have been operating an NTP server based on the Garmin 18x LVC which W2AIQ mentioned above and it has the advantage over the LEA-5T that the power is 5 VDC which can be supplied by an attached computer through the USB port and the PPS signal can be connected to a serial port handshake input.
I have had this running since 2010 on a Xeon based server, and since a few months switched to a Raspberry PI 3B+ with the PPS signal connected through GPIO.
Looking at that past 8 years, my conclusion is that cost wise the hardware investment is not the biggest issue. In that time frame I spent significantly more money on electricity than on hardware. Due to its nature, a stratum 1 server will be running 24/7. So if you are searching for a cost effective solution do not only look at the initial hardware costs, but also at the total cost of ownership. A small complete system may in the end be cheaper than a cheap Chinese NTP clock from eBay connected to an power hungry computer.
I was thinking about a Rasberry Pi too… The 3 B+ is only $35, plus you would need a GPS module but those aren’t that much more. I think I read 4W power consumption? Quad-Core 1.4GHz w/ 1GB RAM… Seems more than powerful enough for a pool NTP server.
The Soekris Net4501 that I built several NTP servers from is only a 133MHz single-core 486-class CPU with 64MB of RAM and it does just fine.
Yes, I guess my Pi including the GPS is using around 5 Watt. If you go this route be sure to use the 3B+ because it has a much faster network controller than the older models. This Pi can easily saturate its 100Mbit up/down connection with the internet.
$35 is the board only price though. You need a power supply, housing and an SD card to let it function properly. I use a Swissbit 8GB micro SD card in it which costs about the same as the Pi itself, but provides industrial grade reliability and extended life. Most failing Pi deployments I have seen crash after some years due to SD card failures, not due to the failures in the computer board.