From: "Gary E. Miller" <gem@rellim.com>
To: Rodolfo Giometti <giometti@enneenne.com>
Cc: Paul Chavent <Paul.Chavent@onera.fr>,
linux-usb@vger.kernel.org, gregkh@linuxfoundation.org,
jhovold@gmail.com, fschaefer.oss@googlemail.com, jslaby@suse.cz,
max@suse.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/5] Enable PPS reporting for USB serial devices
Date: Tue, 10 Sep 2013 13:02:34 -0700 [thread overview]
Message-ID: <20130910130234.5106a5bc.gem@rellim.com> (raw)
In-Reply-To: <20130910073105.GB5030@enneenne.com>
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Yo Rodolfo!
On Tue, 10 Sep 2013 09:31:05 +0200
Rodolfo Giometti <giometti@enneenne.com> wrote:
> I have nothing against with this solution but consider that reporting
> a PPS signal through USB bus may add unknown delays that may vanish
> clock stability... as far as I know you should not use USB serial port
> with PPS. Have you some statistics about clock stability in a real
> implementation?
gpsd project has been using PPS over USB 1.1 for over a year. Typical
accuracy and repeatability in the range of +/- 1 milliSec. This is much
better than you can get using simple ntp over gigabit ethernet to an
adjacent stratum 1 server.
Sure PPS over a local UART is 10 to 100 times better, but often PPS
over USB is your best second choice. As serial ports become extinct
it may become your best choice.
RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97701
gem@rellim.com Tel:+1(541)382-8588
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next prev parent reply other threads:[~2013-09-10 20:14 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-09 16:01 [PATCH 0/5] Enable PPS reporting for USB serial devices Paul Chavent
2013-09-09 16:01 ` [PATCH 1/5] USB : serial : remove tty arg of handle_dcd_change Paul Chavent
2013-09-09 17:45 ` Johan Hovold
2013-09-09 17:48 ` Johan Hovold
2013-09-10 8:09 ` Paul Chavent
2013-09-09 16:01 ` [PATCH 2/5] USB : serial : get protected tty in handle_dcd_change Paul Chavent
2013-09-09 18:03 ` Sergei Shtylyov
2013-09-09 16:01 ` [PATCH 3/5] USB : serial : call handle_dcd_change in ftdi driver Paul Chavent
2013-09-09 16:01 ` [PATCH 4/5] USB : serial : invoke dcd_change ldisc's handler Paul Chavent
2013-09-09 16:36 ` Greg KH
2013-09-09 16:01 ` [PATCH 5/5] USB : serial : pl2303 wake up after dcd status check Paul Chavent
2013-09-10 7:31 ` [PATCH 0/5] Enable PPS reporting for USB serial devices Rodolfo Giometti
2013-09-10 8:00 ` Paul Chavent
2013-09-10 20:02 ` Gary E. Miller [this message]
2013-09-12 7:53 ` Rodolfo Giometti
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