Necessity of Building Kernel of Rpi while using gps-pps for achieving high accuracy

While making my own NTP server using GPS and Rpi, I found some instructional websites. One of them is

My System Details:
1. RPi V-3
2. Ublox NEO 6T Receiver, where PPS output is attached with GPIO 18 (pin no 12) using the jumper wire.
3. Raspbian Jessie Kernel 4.4

However, in some blog it has been saying about the building of Kernel for Rpi to enable PPS and to achieve high timing accuracy!
So, my question is,
1. to get higher accuracy do I really need to build the Kernel with the latest Rpi OS (Jessie kernel 4.4)
2. What does exactly mean by the Kernel Build? Whether the Rpi OS don't have kernel?

I am newbie both in RPi and also Linux. And having trouble with developing NTP server using Rpi. All I understand from the different blogs that the kernel is an issue for that.

This is another helping blog post where Greg says:

ntp -crl’ eg:
associd=0 status=041d leap_none, sync_uhf_radio, 1 event, kern,
version=”ntpd 4.2.8p7@1.3265 Fri Apr 29 10:05:19 UTC 2016 (1)”,
If kern isn’t there then it is running in user mode

Means, this need to be shifted from user to kernel mode. But what exactly have done kernel here in GPS-PPS support?

Any explanation and suggestion are much appreciated. :smile:



  • Hi, interesting question. Later during the day I go through the link which you shared. It is quite interesting and since it is huge page it may quite take time to get some overall picture.

    But BTW, like they showed in the link, I can see a GPS module in a post posted by my student:

    The board is different in his case. It is not a RPi, but instead it is LinkIt ONE. May be I can request him to probably answer your question. Since he really used the GPS module
    and did indeed read its raw data and plotted against a reference map, entered in a remote DB (cloud) etc. FYI, I never so far personally worked myself on any GPS module.

    So may be he will be able to give some valuable inputs :)

    cheers, Kiran
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