[time-nuts] RPi NTP was Net4501's cheap...

lists at lazygranch.com lists at lazygranch.com
Sat May 25 13:06:57 EDT 2013

Flightradar24 is using beagle bones in their ADS-B/mode-s system and will be incorporating MLAT soon. I suspect they work well in timing applications.

That said, the Allwinner they sell on Sparkfun will probably be my next SBC. Though not listed on the wiki, they have opensuse running on it. 

BTW, on some linux dists, there is a way to get around the clock speed stepping. It may not be universal, but selecting "performance" works on opensuse for Arm.

-----Original Message-----
From: Paul <tic-toc at bodosom.net>
Sender: time-nuts-bounces at febo.com
Date: Sat, 25 May 2013 12:47:38 
To: <time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: [time-nuts] RPi NTP was Net4501's cheap...

On Sat, May 25, 2013 at 2:43 AM, David J Taylor wrote:

>  Paul,
> Just what devices were you hot-plugging to produce this problem?  One with
> an initial current surge outside the USB spec I could understand.

I was plugging in a USB to RS232 adapter.  If you read the various bits
you'll find about the USB on Rev.B boards you'll see all the work-arounds
suggested here as well as an implication that Raspberry intends to fix the
problem in a later release.

> NTP performance on the three Raspberry Pi cards here can be of the same
> order as FreeBSD running on an Intel Atom PC:

Yes, I've looked at your stats.  As I said earlier you put me onto the Pi
and the Sure boards.  The offsets on the Pi are fine. I just don't like the
"weak" network  performance which you can see in the ntpq output for the
Pi.  Since I'm still testing bits all four of my clocks are on the same
gigabit switch so I don't expect to see simultaneous negative and positive
offsets.  The Laureline is jittery too but at least it always presents the
same offset "polarity".  I'll see how the Beaglebones do, check out the
next rev. of the Laureline and then dither some more.
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