[time-nuts] Lowest Power NTP Server

[jimlux]

On 12/1/19 7:47 AM, Bob kb8tq wrote:
> Hi
> 
> If you are going to run the beast on batteries, and talk to it via WiFi, what’s the lowest power
> NTP server you can build? Timing source to keep it under a few ms would have to be included.
> GPS seems to be a reasonable choice.

Have you looked at Arduino? THere might be a NTP server implementation 
for Arduino, and in general, Arduinos are lower power. A lot would be 
determined by which WiFi interface you use.

Another possibility is the Beaglebone Green Wireless - it has WiFi on 
board, ARM processor, etc. and runs Linux. I've run ntpd with a uBlox-7 
(I think) GPS receiver on these. Since it doesn't have the HDMI video 
interface that the Beagle does, it might be lower power.

I might have some measurements of the green wireless.


> 
> So far this seems to be the leading contender:
> 
> https://www.researchgate.net/publication/332543537_BUILDING_A_RASPBERRY_PI_ZERO-W_GPS_NETWORK_TIME_SERVER_FOR_UNDER_50 <https://www.researchgate.net/publication/332543537_BUILDING_A_RASPBERRY_PI_ZERO-W_GPS_NETWORK_TIME_SERVER_FOR_UNDER_50>
> 
> Same paper at a different URL (thanks to TVB):
> 
> https://www.satsignal.eu/raspberry-pi/Schmidt-RPZ-NTP-2016.pdf <https://www.satsignal.eu/raspberry-pi/Schmidt-RPZ-NTP-2016.pdf>
> 
> Best guess is that it comes in around 0.5W. That is just a guess based on:
> 
> https://raspberry-projects.com/pi/pi-hardware/raspberry-pi-zero/raspberry-pi-zero-hardware-general-specifications <https://raspberry-projects.com/pi/pi-hardware/raspberry-pi-zero/raspberry-pi-zero-hardware-general-specifications>
> 
> and not (yet) a measured number.
> 
> Application is for off grid / remote / out of cell coverage timing of various “stuff”. Power is from
> a battery so fractions of a watt do count.  More or less, 0.5W on a 5AH 12V battery runs for
> 120 hours. Something at 5W only runs for 12 hours …..
> 
> Bob
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