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Re: [gpsd-dev] RFC 2783
From: |
Hal Murray |
Subject: |
Re: [gpsd-dev] RFC 2783 |
Date: |
Tue, 10 Mar 2015 14:17:00 -0700 |
address@hidden said:
> Is there always, and necessarily, only *one* pps device?
No.
If nothing else, I want to be able to connect two so I can compare them.
The kernel time stamping also counts events. That's a convenient hack for
measuring things. So gpsd and ntpd have to be sure not to gobble up a PPS
device that isn't theirs.
Here is a graph made by feeding the 60 Hz power line via a transformer into a
PPS input and counting cycles:
http://www.megapathdsl.net/~hmurray/time-nuts/line/Dec-2013.png
I think the Linux kernel supports PPS via the printer port. I haven't tried
it, but the printer port is an old standby for hardware hacking.
--
These are my opinions. I hate spam.
- Re: [gpsd-dev] RFC 2783, (continued)
- Re: [gpsd-dev] RFC 2783, Gary E. Miller, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Frank Nicholas, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Hal Murray, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Gary E. Miller, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Hal Murray, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Gary E. Miller, 2015/03/10
- Re: [gpsd-dev] RFC 2783, Gary E. Miller, 2015/03/10
Re: [gpsd-dev] RFC 2783, Hal Murray, 2015/03/10
Re: [gpsd-dev] RFC 2783, Eric S. Raymond, 2015/03/10
Re: [gpsd-dev] RFC 2783, Harlan Stenn, 2015/03/10
Re: [gpsd-dev] RFC 2783, Greg Troxel, 2015/03/11